case study of marine pollution

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Four IUCN economic case studies show the impacts of plastic pollution in the marine environment on biodiversity, livelihoods, and more in Africa and Asia

Research into the economic aspects of the Marine Plastics and Coastal Communities project, to contain and reduce plastic pollution in the ocean, delivers insight into the true costs of plastic pollution on communities, livelihoods, coasts, and the global ocean.

Photo: Adobe Stock Image

The objective

The Marine Plastics and Coastal Communities (MARPLASTICCs) project goal was to assist governments and regional bodies in Eastern and Southern Africa and Asia to promote, enact, and enforce legislation and other effective measures to contain and reduce plastic pollution in the ocean. Part of the research completed included defining an economic assessment approach and producing economics case studies that reflected the impacts of plastic pollution on the marine environment, on coastal livelihoods, and more.

National case studies

Four national level economic case studies are available: for Mozambique, South Africa, Thailand, and Viet Nam. The important economic sectors of fisheries and tourism were studied, using different lenses to examine how plastic pollution causes detrimental economic impacts at national and local levels. Each assessment differs and explores wide-ranging economic dimensions that should be considered when creating a national plan of action to mitigate marine litter and plastic pollution in the environment. From impacts upon export revenue, employment and food security, to the economic efficiency of beach cleaning in conjunction with deposit refund schemes, and the impact of ghost gear on fisheries, these four case studies take a reader into the true costs of plastic pollution on our global ocean and coastal communities.

Mozambique Economic Report

What is the impact of plastic pollution on fisheries – including the broader economic dimension relating to export revenue, employment, food security, and marine ecosystems, and biodiversity? This economic policy brief explains these impacts within the Republic of Mozambique.

South Africa: Efficiency of beach clean-ups and deposit refund schemes (DRS) to avoid damages from plastic pollution on the tourism sector in Cape Town, South Africa (2021)

What are the impacts of plastic pollution on tourism revenue and tourism employment? What is the efficiency of beach cleaning with the implementation of a DRS? What is the impact on employment after DRS implementation? This economic policy brief explains these impacts within the context of the city of Cape Town, South Africa.

Case study on net fisheries in the Gulf of Thailand

This issues brief presents the results of a study that estimated the impact of marine macroplastic on Thai net fisheries operating in the Gulf of Thailand. The study has estimated the reduction in the net fisheries’ revenue due to the plastic stock and annual flow into the fishing zone/Thai Exclusive Economic Zone (EEZ) (Gulf of Thailand).

The economic impact of marine plastics, including ghost fishing, on fishing boats in Phước Tinh and Loc An, Ba Ria Vung Tau Province, Viet Nam (2022)

What are the impacts of plastic pollution caused by abandoned, lost or otherwise discarded fishing gear (ALDFG), also known as ‘ghost gear’? What are the costs to biodiversity of ghost gear? This economic policy brief explains the impacts on fishing boats in Phước Tinh and Loc An, Ba Ria Vung Tau Province, Viet Nam.

On-the-ground work

The work IUCN is doing on the impacts of plastic pollution, especially on tourism, fisheries, and waste management aims to identify the plastic applications and polymers and the waste management gaps that are contributing to the global problem.

IUCN works on-the-ground with partners from NGOs, the private sector, and national governments, in order to determine the priority problems and the most effective interventions, to advise countries how to stop the problem within their specific national context. IUCN bring science and knowledge together with policy, for action, in this case economic policies can be examined for their role in dealing with plastic pollution.

As the world is now focused on the establishment of a global plastic pollution treaty , understanding the scope of the impacts and prioritising interventions – including economic interventions – will be needed.

Acknowledgments and Support

The Marine Plastics and Coastal Communities project (MARPLASTICCs), generously supported by the Swedish International Development Cooperation Agency (Sida), provided  support for the research and production of these Economic Case Studies.

For further information

• [email protected]

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December 3, 2020

Paper finds ocean pollution is a complex mix of chemicals and materials, primarily land-based in origin, with far-reaching consequences for environmental and human health, but there are options available for world leaders

For centuries, the ocean has been viewed as an inexhaustible receptacle for the byproducts of human activity. Today, marine pollution is widespread and getting worse and, in most countries, poorly controlled with the vast majority of contaminants coming from land-based sources. That’s the conclusion of a new study by an international coalition of scientists taking a hard look at the sources, spread, and impacts of ocean pollution worldwide.

The study is the first comprehensive examination of the impacts of ocean pollution on human health. It was published December 3 in the online edition of the Annals of Global Health and released the same day at the Monaco International Symposium on Human Health & the Ocean in a Changing World, convened in Monaco and online by the Prince Albert II de Monaco Foundation, the Centre Scientifique de Monaco and Boston College.

“This paper is part of a global effort to address questions related to oceans and human health,” said Woods Hole Oceanographic Institution (WHOI) toxicologist and senior scientist John Stegeman who is second author on the paper. “Concern is beginning to bubble up in a way that resembles a pot on the stove. It’s reaching the boiling point where action will follow where it’s so clearly needed.”

Despite the ocean’s size—more than two-thirds of the planet is covered by water—and fundamental importance supporting life on Earth, it is under threat, primarily and paradoxically from human activity. The paper, which draws on 584 peer-reviewed scientific studies and independent reports, examines six major contaminants: plastic waste, oil spills, mercury, manufactured chemicals, pesticides, and nutrients, as well as biological threats including harmful algal blooms and human pathogens.

It finds that ocean chemical pollution is a complex mix of substances, more than 80% of which arises from land-based sources. These contaminants reach the oceans through rivers, surface runoff, atmospheric deposition, and direct discharges and are often heaviest near the coasts and most highly concentrated along the coasts of low- and middle-income countries. Waters most seriously impacted by ocean pollution include the Mediterranean Sea, the Baltic Sea, and Asian rivers. For the many ocean-based ecosystems on which humans rely, these impacts are exacerbated by global climate change. According to the researchers, all of this has led to a worldwide human health impacts that fall disproportionately on vulnerable populations in the Global South, making it a planetary environmental justice problem, as well.

In addition to Stegeman, who is also director of the NSF- and NIH-funded Woods Hole Center for Oceans and Human Health , WHOIbiologists Donald Anderson and Mark Hahn , and chemist Chris Reddy also contributed to the report. Stegeman and the rest of the WHOI team worked on the analysis with researchers from Boston College’s Global Observatory on Pollution and Health, directed by the study’s lead author and Professor of Biology Philip J. Landrigan, MD. Anderson led the report’s section on harmful algal blooms, Hahn contributed to a section on persistent organic pollutants (POPs) with Stegeman, and Reddy led the section on oil spills. The Observatory, which tracks efforts to control pollution and prevent pollution-related diseases that account for 9 million deaths worldwide each year, is a program of the new Schiller Institute for Integrated Science and Society, part of a $300-million investment in the sciences at BC. Altogether, over 40 researchers from institutions across the United States, Europe and Africa were involved in the report.

In an introduction printed in Annals of Global Health , Prince Albert of Monaco points out that their analysis, in addition to providing a global wake-up, serves as a call to mobilize global resolve to curb ocean pollution and to mount even greater scientific efforts to better understand its causes, impacts, and cures.

“The link between ocean pollution and human health has, for a long time, given rise to very few studies,” he says. “Taking into account the effects of ocean pollution—due to plastic, water and industrial waste, chemicals, hydrocarbons, to name a few—on human health should mean that this threat must be permanently included in the international scientific activity.”

The report concludes with a series of urgent recommendations. It calls for eliminating coal combustion, banning all uses of mercury, banning single-use plastics, controlling coastal discharges, and reducing applications of chemical pesticides and fertilizers. It argues that national, regional and international marine pollution control programs must extend to all countries and where necessary supported by the international community. It calls for robust monitoring of all forms of ocean pollution, including satellite monitoring and autonomous drones. It also appeals for the formation of large, new marine protected areas that safeguard critical ecosystems, protect vulnerable fish stocks, and ultimately enhance human health and well-being.

Most urgently, the report calls upon world leaders to recognize the near-existential threats posed by ocean pollution, acknowledge its growing dangers to human and planetary health, and take bold, evidence-based action to stop ocean pollution at its source.

“The key thing to realize about ocean pollution is that, like all forms of pollution, it can be prevented using laws, policies, technology, and enforcement actions that target the most important pollution sources,” said Professor Philip Landrigan, MD, lead author and Director of the Global Observatory on Pollution on Health and of the Global Public Health and the Common Good Program at Boston College. “Many countries have used these tools and have successfully cleaned fouled harbors, rejuvenated estuaries, and restored coral reefs. The results have been increased tourism, restored fisheries, improved human health, and economic growth. These benefits will last for centuries.”

The report is being released in tandem with the Declaration of Monaco: Advancing Human Health & Well-Being by Preventing Ocean Pollution, which was read at the symposium’s closing session. Endorsed by the scientists, physicians and global stakeholders who participated in the symposium in-person and virtually, the declaration summarizes the key findings and conclusions of the Monaco Commission on Human Health and Ocean Pollution. Based on the recognition that all life on Earth depends on the health of the seas, the authors call on leaders and citizens of all nations to “safeguard human health and preserve our Common Home by acting now to end pollution of the ocean.”

“This paper is a clarion call for all of us to pay renewed attention to the ocean that supports life on Earth and to follow the directions laid out by strong science and a committed group of scientists,” said Rick Murray, WHOI Deputy Director and Vice President for research and a member of the conference steering committee. “The ocean has sustained humanity throughout the course of our evolution—it’s time to return the favor and do what is necessary to prevent further, needless damage to our life planetary support system.”

Funding for this work was provided in part by the U.S. Oceans and Human Health Program (NIH grant P01ES028938 and National Science Foundation grant OCE-1840381), the Centre Scientifique de Monaco, the Prince Albert II of Monaco Foundation, the Government of the Principality of Monaco, and Boston College.

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation, and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit www.whoi.edu

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Original research article, microplastics in florida, united states: a case study of quantification and characterization with intertidal snails.

• Department of Biology, University of West Florida, Pensacola, FL, United States

Concentrations of microplastics are increasing within the oceans, including waters surrounding Florida, United States. Miles of sandy beaches make the sunshine state a prime tourist destination leading to an increased amount of pollution along Florida coasts. Microplastics can cause damage to intertidal organisms, as well as causing issues up the food chain with biomagnification and seafood consumers, such as humans. Florida is also subject to hurricanes which often distribute sediments, filling the water column with previously settled microplastics. These factors make Florida a special case to review considering the state is affected heavily by hurricanes and tourism, which can contribute to microplastic concentrations in the Gulf of Mexico. The focus of this study was to quantify, characterize, and compare microplastics contamination in two predatory marine snail species from intertidal habitats in Florida, United States Ingestion results were also compared to microplastics contamination of water samples collected from the same locations. Red-mouth rock shell ( Stramonita haemastoma , n = 30) and Crown conch ( Melongena corona , n = 30) snails were collected from intertidal habitats in Florida and digested for microplastics quantification. Water samples were filtered and microplastics were quantified. 256 microplastics, of which 93% were microfibers and 7% were microfragments were isolated from snails ( n = 60). Additionally, 67 microplastics were isolated from 8 L of seawater (8.375 microplastics/L), of which 97% were microfibers and 3% were microfragments. This is the first known study to demonstrate microplastics contamination of tissues in predatory marine intertidal snails. Marine intertidal snails may be good organisms for biomonitoring of microplastics in intertidal sandy habitats.

Introduction

Marine pollution, in particular plastic pollution, is widely recognized as a global issue ( Shim and Thomposon, 2015 ). Plastic pollution is ubiquitous in the ocean and accounts for upwards of 60–80% of marine debris ( Derraik, 2002 ). As a result of great durability, plastic persists in marine ecosystems from hundreds to thousands of years ( Barnes et al., 2009 ). Of particular focus for this study, microplastics are defined as small pieces of plastic debris that measure 5 mm or less in size ( Von Moos et al., 2012 ). Microplastics originate from direct manufacturing of small plastics for beauty products or other manufactured goods such as (primary microplastics), or from the degradation and breakdown of larger plastic debris (secondary microplastics) ( Hale et al., 2020 ). Globally, estimates of total microplastics in the ocean range from 5.25 to 125 trillion pieces ( Cozar et al., 2014 ; Lindeque et al., 2020 ).

Though microplastics are found in water bodies all over the world ( Rezania et al., 2018 ), microplastic debris is most prevalent within the ocean ( Ivar do Sul et al., 2013 ). Microplastics in aquatic ecosystems originate from both land-based and sea-based sources and can make their way to marine ecosystems through runoff, industrial activity, human activities such as tourism and textile industries, and from sewage treatment plants ( Rezania et al., 2018 ). Primary microplastics originate from spillage during the production or recycling or as micro-cleansing beads in personal care products such as facial scrubs and toothpastes are washed into aquatic ecosystems ( Anderson et al., 2017 ). Secondary microplastics most commonly originate from marine litter, laundry discharge, discharge from landfills, and industrial or agricultural sources ( Rezania et al., 2018 ; Hale et al., 2020 ).

Microplastics in aquatic environments are considered to be a serious issue and threat to aquatic ecosystems and the organisms that inhabit these ecosystems. Many studies have been conducted in the marine environment, from tropical to polar ecosystems, to characterize and quantify microplastics contamination in marine systems ( Barnes et al., 2009 ; Wessel et al., 2016 ; Waller et al., 2017 ). Further, due to their small size, microplastics are bioavailable to many organisms across trophic levels. Microplastics have been documented negatively affecting the fecundity, growth, and feeding rates of zooplankton. Though the documented effects on zooplankton are categorized as sublethal, the microplastics can prompt transgenerational mortality effects ( Yu et al., 2020 ; Yu and Chan, 2020 ). Several studies have demonstrated contamination of microplastics in marine organisms with various feeding strategies such as marine invertebrates, fishes, mammals, and birds ( Brillant and MacDonald, 2000 ; Besseling et al., 2012 , 2015 ; Browne et al., 2013 ; Cole et al., 2013 ; Romeo et al., 2015 ; Carlin et al., 2020 ). Although it is not clear yet how microplastics might affect human health, evidence from aquatic organisms shows that microplastics cause negative effects on organism growth, metabolism, reproduction, and lead to weakened immune systems ( Wright et al., 2013 ; Costa et al., 2015 ; Lu et al., 2016 ; Sussarellu et al., 2016 ). Humans rely heavily on aquatic biodiversity and ecosystems, both of which are greatly impacted by microplastics.

Microplastics in Florida

Peninsular Florida (United States), is surrounded by the Gulf of Mexico on the west side and the Atlantic Ocean on the east side. Waters surrounding Florida are polluted with a variety of debris, including microplastics, resulting from anthropogenic activity. Specifically, several studies have quantified microplastics from both seawater and sediment samples from Florida. For example, McEachern et al. (2019) quantified microplastic contamination from surface seawater and sediment samples from Tampa Bay, Florida, with seawater samples ranging from 0.25 to 7.0 particles/L and sediment samples ranging from 30 to 790 particles/kg. In a study by Yu et al. (2018) , occurrence and distribution of microplastics was determined from sand samples in Florida from Dry Tortugas National Park, Everglades National Park, Biscayne National Park, Canaveral National Seashore, Fort Matanzas National Monument, and Timucuan Ecological and Historical Reserve. Counts of microplastics from these locations ranged from 43 to 253 pieces/kg of sand ( Yu et al., 2018 ). Further, citizen scientists have been employed throughout the Gulf Coast of the United States to quantify nurdles, or plastic pellets that are manufactured to melt down to make plastic products, along shorelines. Approximately 12% of the sampling sites of this citizen science project were along the Gulf Coast of Florida. Interestingly, very few nurdles were collected along the coast of Florida, while 20 of the highest standardized counts were collected in Texas, close to the location where the majority of nurdles are manufactured in the United States ( Tunnell et al., 2020 ).

Microplastics have also been documented in a variety of organisms that live in or associated with waters surrounding Florida, such as osprey, fishes, jellyfish, oysters, mud crabs, sand dollars, and sea cucumbers ( Phillips and Bonner, 2015 ; Waite et al., 2018 ; Carlin et al., 2020 ; Iliff et al., 2020 ; Plee and Pomory, 2020 ). For example, Carlin et al. (2020) quantified the abundance of microplastic accumulation in gastrointestinal tracts of birds of prey in central Florida and found that all birds examined contained microplastics. Further, Waite et al. (2018) digested oysters ( Crassostrea virginica ) and mud crabs ( Panopeus herbstii ) from an estuary along the east coast of central Florida and discovered 1,482 microplastics from 90 oysters and 1,979 microplastics from mud crabs, with microfibers being the most common type of microplastics. Microplastic contamination can have negative impacts, such as false satiation, reproductive complications ( Auta et al., 2017 ), and toxicological impacts ( Ogunola et al., 2018 ) on marine organisms.

Subject to tourism and hurricanes, the state of Florida, may also be particularly vulnerable to marine pollution. Both tourism and storms can increase microplastic pollution in marine ecosystems. Florida has been subject to some of the most catastrophic storms and hurricanes that have been recorded in the United States ( Malmstadt et al., 2009 ). Hurricanes can increase the amount of microplastics transferred from land to water, thus expediting the process of the pollutants entering the ocean ( Barnes et al., 2009 ). Further, storms that disturb sediments can also move and resuspend once settled microplastics throughout the water column ( Von Moos et al., 2012 ). Hurricanes and other natural phenomena can also transfer more personal products, and potentially microplastics into the ocean ( Duis and Coors, 2016 ). Florida has been named the “tourism capital of the world” in reference to the vast number of theme parks and tourist destinations ( Carlin et al., 2020 ). In South Florida during the winter months, Wightman (2020) observed an increase of microplastics in the water column. This observation correlated with the increased tourism during the wintertime which left a higher amount of litter on the beaches, and a higher amount of microplastics being washed down drains ( Wightman, 2020 ). With increased tourism and the frequent occurrence of hurricanes, the waters surrounding Florida and the organisms that inhabit these waters become a special case to study microplastics.

Case Study With Snails in Florida

The species Stramonita haemastoma (Red-mouth rock shell) and Melongena corona (Crown conch) are both predatory gastropod molluscs that can be found in coastal intertidal areas and are the focus of species of this case study in microplastics contamination. Both species of snails are commonly seen clinging to rocks and marine vegetation, as well as on other organisms such as crustaceans. Red-mouth rock shells feed primarily on filter feeding organisms such as bivalves, gastropods and barnacles ( Watanabe and Young, 2005 ). Crown conchs prey upon bivalves and gastropods, including the Marsh periwinkle ( Littorina irrotata ) ( Randall, 2013 ). Crown conchs are also known to be opportunistic scavengers preying upon horseshoe crabs and other dead organisms ( Hayes, 2003 ). In general, marine snails serve as a food source for other organisms in the ecosystem, such as whelks, murex ( O’Connor, 2018 ) and stone crabs ( Richardson and Brown, 1992 ; Whitenack and Herbert, 2015 ), which creates the potential for transfer of microplastics to other organisms, as well as impacts on overall ecosystem health ( Walkinshaw et al., 2020 ). Additionally, neither species of snail migrates great distances, thus any microplastic contamination should be from the localized areas of collection.

The objective of this study was to quantify and compare the amount and type of microplastics present in two predatory species of snails collected from Florida, United States. Ingestion results were also compared to microplastics contamination of water samples collected from the same locations. Red-mouth rock shells from the panhandle of Florida and Crown conchs from Central Florida were examined for microplastics to determine the abundance, type, and size ranges of microplastics ingested by each species. Though Red-mouth rock shells and Crown conchs are both predatory snails and have similar prey items, they are different in size, thus microplastic contamination will be compared between the two.

Materials and Methods

Seawater and snail collection.

Both seawater and snails were collected from intertidal beach habitats in Florida, United States. Two major locations of Northwest Panhandle Florida and Central Florida were selected for this study. At each of the two major locations, two sampling sites were selected for seawater and snail collection. Prior to snail collection, at each site, two replicates of 1 L of seawater were collected in sterile and rinsed 1 L Nalgene bottles. Immediately before collection of seawater samples, Nalgene bottles were dipped in the seawater and rinsed three times before a final dip for collection. Nalgene bottles were immediately sealed in order to prevent contamination. Stramonita haemastoma samples ( n = 30) were collected haphazardly by hand from Shoreline Park (30.3540883 N, 87.1752466 W), 3- Mile Bridge (30.3741196 N, 87.1795937 W), in Pensacola Florida (Northwest Panhandle Florida). Additionally, Melongena corona samples ( n = 30) were collected haphazardly by hand from Sand Key Park (27.960541 N, 82.824362 W), and Shell Point Park (27.916478 N, −82.840774 W), in Clearwater Florida (Central Florida) ( Figure 1 ). Snails were placed into sealable plastic bags, and then placed into the cooler with ice. Upon returning from the field, snails were immediately placed in the freezer still contained in their plastic bags until tissue digestion.

Figure 1. Map showing collection sites and major location of seawater samples and snail tissues as well as the quantity of microplastics from both seawater samples and snail tissue samples. Collection sites Shoreline Park and 3-Mile Bridge are at the major location Northwest Panhandle Florida and collection sites Shell Point Park and Sand Key Park are at the major location Central Florida. Size of each pie graph is correlated to the number of microplastics counted. Both seawater and snail microplastic counts for both microfibers and microfragments and are indicated by colors labeled in the key (RS, Stramonita haemastoma ; CC, Melongena corona ).

Each of the sites in this study have varying levels of anthropogenic impacts, though not explicitly measured. For instance, Shoreline Park has many daily visitors that use the location for recreational activities such as boating, fishing, and swimming ( Shoreline Park South, 2020 ). The 3-Mile Bridge site has been subject to ongoing construction and many people fish within the area for tourism and fishing. Both Sand Key Park and Shell Point Park are impacted by beach development along with recreational activities (boating, fishing, and swimming). Additionally, the Gulf of Mexico is subject to a long history of tropical storms and hurricanes dating back to the Holocene period ( Conner et al., 1989 ). Over the last 30 years, the Atlantic Ocean averages 14 named storms, of which seven become hurricanes ( NOAA, 2021 ).

Tissue Digestion and Sample Filtration

Before tissue digestion, individual snails were measured using Neiko 12” calipers to gather measurements on individual shell height, width, thickness, lip height, and lip width. Following shell measurements, soft tissue was removed from the shell using sterile and rinsed forceps. Snails were prepared for tissue digestion according to Claessens et al. (2013) . All glassware was thoroughly rinsed with milliQ water prior to digestion to help eliminate microplastics contamination. Frozen individual snails were then transferred to a sterile separate 250 mL Erlenmeyer flask and 20 mL of nitric acid was added. Flasks containing individual snails were left overnight at room temperature in a semi-enclosed chemical hood. The nitric acid and snail tissue mixture was then diluted with 200 ml of warm (∼80°C) filtered deionized water. After the addition of warm milliQ water, flasks containing Stramonita haemastoma were completely digested, while flasks containing Melongena corona were boiled for 5 min for complete tissue digestion. Following tissue digestion, the remaining liquid was filtered using a vacuum hand pump through a 0.45 μ gridded cellulose filter (Whatman). To avoid contamination the filtering apparatus, a magnetic 500 mL filter cup and magnetic filter base were flushed using milliQ water in between each sample and were covered during filtration to help prevent contamination. Each filter was then stored in a sterile Petrislide TM (MilleporeSigma TM ) for drying and quantification. To control for microplastics contamination from the air during digestion, a control flask only containing nitric acid (no tissue) was placed alongside flasks during tissue digestion. After digestion, the control flask was also diluted with milliQ water and filtered in the same way. Seawater samples were filtered following the same protocol as the tissue samples. A 1-L sample of milliQ water was also filtered to be used as a control for microplastics contamination during the seawater filtration process.

Quantification of Microplastics

Using a compound microscope (4X and 10X), microplastics on filters from tissue and seawater samples were directly quantified and characterized according to abundance and diversity. Visual identification was employed to differentiate plastics from other natural organic debris (algae, sediment, invertebrates, and plant material). To help ensure proper identification, each suspected microplastic was examined following methods of Whitaker et al. (2019) . Specifically, suspected microplastics were examined for cellular and organic structures, for even thickness of fibers, and homogenous color, according to Hidalgo-Ruz et al. (2012) . To further distinguish between organic and plastic material, a metal probe was heated and placed next to the putative plastic. According to Hendrickson et al. (2018) , employing a “melt test” will cause plastic fibers to melt, while cotton and wool fibers will burn. Thus, in this study, if an item melted, it was classified as microplastic. Microplastics were categorized by type (microbeads, microfragments, and microfibers), size, and color. Measurements of microplastics were made using ImageJ 1 v 1.52a bundled with Java 1.8.0_172 for Windows. Photographs of each filter were taken prior to the “melt test” with a Nikon DS-Fi2 microscope and the corresponding soft-ware, NIS-Elements, was used to burn the set scale of 100 μm for every photograph. Measuring required the scale to be set on each individual photo, as each filter had multiple photos to capture all plastic debris. Using the straight-line tool in ImageJ, the scale line was traced and set before beginning measurements. All fibers and fragments were traced using the freehand tool to accommodate twisting and bending of fibers and irregular edges of fragments. Thus, length of fibers and surface area of microfragments were estimated.

Statistical analyses were conducted in R ( R Core Team, 2014 ) and boxplots were produced using the package ggplot2 ( Wickham, 2009 ). A Welch two sample t -test was also used to determine if there was a significant difference in shell height between the species of snails ( Stramonita haemastoma and Melongena corona ) to demonstrate if size differences were apparent of collected specimens between species. To determine if there was a difference in the number of microplastics from filtered seawater samples from the two major locations of this study (Northwest Panhandle Florida and Central Florida) a Wilcoxon rank-sum test with continuity correction was employed ( Wilcoxon, 1945 ). Further, to determine if there was a difference in the number of microplastics from digested tissues between species of snails ( Stramonita haemastoma and Melongena corona ) a Wilcoxon rank-sum test with continuity correction was also used.

One-way Analysis of Variance (ANOVA) with Tukey’s multiple comparison adjustment was employed to determine if there was a significant difference in size and color of microfibers between seawater samples collected from two major locations in this study (Northwest Panhandle Florida and Central Florida). Additionally, an ANOVA with Tukey’s multiple comparison adjustment was also employed to determine if there was a significant difference between species ( Stramonita haemastoma and Melongena corona ) by size and color of microfibers contamination in terms of fiber length. Microfragment sizes and colors were not compared between species due to low sample size of recovered microfragments.

To validate that seawater samples were statistically different from filtration milliQ water blanks (control), a Welch two sample t -test was employed. Further to validate that snail tissue samples were statistically different from digestion blanks (control), a Welch two sample t -test was used.

In total 8 L of seawater were collected. Specifically, 2 L of seawater were collected at each of the following sites: Northwest Florida: Shoreline Park, 3-Mile Bridge; Central Florida: Shell Point Park, and Sand Key Park. Seawater filtration for microplastics revealed a total of 67 microplastics from 8 L of seawater (8.375 microplastics/L), of which 97% were microfibers and 3% were microfragments. Specifically, seawater filtration of Northwest Panhandle Florida samples revealed 24 microplastics from 4 L of seawater (6 microplastics/L), of which 95% were microfibers and 5% were microfragments ( Table 1 and Figure 1 ). Seawater filtration of Central Florida samples revealed 43 microplastics from 4 L of seawater (10.75 microplastics/L), of which 98% were microfibers and 2% were microfragments ( Table 1 and Figure 1 ). No microbeads were identified from seawater samples. Microfibers from seawater samples were primarily red, black, translucent, and blue, varying in length ranging from 14 to 886 μm. The majority of microfragments from seawater samples were black with one clear fragment and varied in surface area from 169 to 275 μm. Color distribution of both microfibers and microfragments from seawater samples can be seen in Figure 2 .

Table 1. Microplastics identified for seawater samples for 2 L of water.

Figure 2. Graph of color distribution of microplastics from seawater samples and snail tissue samples. (A) Shows the percent of each color of microplastics from seawater samples. Dark gray bars correspond to seawater microplastics from Northwest Panhandle Florida and light gray bars correspond to seawater microplastics from Central Florida. (B) Shows the percent of each color of microplastics from snail tissue samples. Dark gray bars correspond to snail tissue microplastics from Northwest Panhandle Florida and light gray bars correspond to snail tissue microplastics from Central Florida.

Tissue digestion for microplastics of 60 snails (Northwest Florida Panhandle: Stramonita haemastoma , n = 30; Central Florida: Melongena corona, n = 30) showed a total of 256 microplastics, of which 93% were microfibers and 7% were microfragments. Specifically, tissue digestion of Stramonita haemastoma ( n = 30) from Northwest Panhandle Florida revealed 182 microplastics, of which 96% were microfibers and 4% were microfragments (3-mile Bridge mean 6.86 (± 3.41), Shoreline Park mean 5.26 (± 4.44); Table 2 and Figure 1 ). Tissue digestion of Melongena corona ( n = 30) from Central Florida showed 74 microplastics, of which 85% were microfibers and 15% were microfragments (Sand Key Park mean 2.13 (± 1.82), Shell Point Park mean 2.8 (± 3.41.79); Table 2 and Figure 1 ). The majority of microfibers from snail tissue samples were clear, while others were blue, green, black, red, and pink, with length ranging from 21 to 1492 μm. Microfragments from snail tissue samples were mostly commonly clear, while others were black, red, and blue and varied in surface area from 48 to 220 μm. A graph of color distribution of both microfibers and microfragments from snail tissue samples can be seen in Figure 2 . A composition of representative microfibers and microfragments for both seawater and snail tissue samples can be seen in Figure 3 .

Table 2. Microplastics identified for snail tissue samples.

Figure 3. Examples of microplastics from seawater samples and snail tissues. (a) Clear microfragment from Shell Point Park seawater sample; (b) red microfiber from Sand Key Park seawater sample; (c) blue and clear microfiber from Shell Point Park seawater sample; (d) blue microfragment from Crown conch snail tissue from Sand Key Park; (e) red microfragment from Crown conch snail tissue from Shell Point Park; (f) blue microfiber from Red-mouth rock shell tissue from 3-Mile Bridge.

There was no significant difference in the number of microplastics from seawater samples collected from Northwest Panhandle Florida and Central Florida (Wilcoxon rank-sum test: p = 0.3719). There was, however, a statistical difference in the number of microplastics from digested tissues between species Stramonita haemastoma (Northwest Panhandle Florida) and Melongena corona (Central Florida) as seen in Figure 4 (Wilcoxon rank-sum test: p = 1.927e-05).

Figure 4. Box plots of microplastics in seawater and snail tissue samples. (A) Microplastics from seawater samples per 4 L collected from two major locations (Northwest Panhandle Florida and Central Florida) are not significantly different. (B) Microplastics from snail tissue samples between the two species of snails (RS, Stramonita haemastoma ; CC, Melongena corona ) are significantly different.

Further, there was a significant difference in the size of microplastic fibers comparing the two major locations, Northwest Panhandle Florida and Central Florida seawater samples (ANOVA: p = 0.039; F = 4.706; df = 1). There was also no significant difference between the size of microplastic fibers between the two snail species tissue samples, Stramonita haemastoma (Northwest Panhandle Florida) and Melongena corona (Central Florida) (ANOVA: p = 0.53; F = 0.396; df = 1). There was a significant difference in the color of microplastics in seawater samples from the two major sampling locations, Northwest Panhandle Florida and Central Florida (ANOVA: p = 4.17e–4; F = 13.92; df = 1). Black microfibers dominated the seawater from Northwest Panhandle Florida (52%) and Central Florida (51%), however, Northwest Florida had a greater number of clear microfibers, while Central Florida had a greater number of red and blue microfibers. There was also a significant difference in the color of microplastics from digested tissues between Stramonita haemastoma (Northwest Panhandle Florida) and to Melongena corona (Central Florida) (ANOVA: p = 7.09e–6; F = 21.05; df = 1). Clear microfibers dominated the tissues of Stramonita haemastoma (Northwest Panhandle Florida), while black microfibers dominated the tissues of Melongena corona (Central Florida) ( Figure 2 ). Given that there were so few microfragments from both seawater and tissue samples ( Table 3 ), they were not included in statistical analyses.

Table 3. Body measurements of Stramonita haemastoma from Northwest Panhandle Florida sites (Shoreline Park, 3-Mile Bridge) and Melongena corona from Central Florida sites (Sand Key Park and Shell Point Park).

Water filtration blanks had significantly fewer microplastics than seawater samples (Welch two sample t -test: p = 2.238e–12). Digestion blanks had significantly fewer microplastics than tissue samples (Welch two sample t -test: p = 3.502e–09).

The results from this study indicate that both seawater and snail tissue samples from Northwest Panhandle Florida and Central Florida were contaminated with microplastics. The number of microplastics in seawater samples from Northwest Panhandle Florida and Central Florida was not significantly different, though in general there were more microplastics in the seawater samples from Central Florida. There were, however, significantly more microplastics in Red-mouth rock shells ( Stramonita haemastoma ) that were collected from Northwest Panhandle Florida, when compared to Crown conchs ( Melongena corona ) that were collected from Central Florida. Possible reasons for this difference in microplastics quantity will be discussed below.

Microfibers were the dominant type of microplastic from both seawater samples (97% microfibers) and snail tissue samples (93% microfibers) from Northwest Panhandle Florida and Central Florida, respectively. These results are similar to findings in several other studies both in waters surrounding Florida and other locations around the globe (e.g., Waite et al., 2018 ; Akindele et al., 2019 ; Whitaker et al., 2019 ). Sizes of microfibers from both seawater and snail tissue samples were similar, indicating that fibers are likely being consumed from the environment, transferred indirectly through trophic transfer from prey items of both Red-mouth rock shells and Crown conchs. Microfibers in marine samples originate from a variety of sources including wastewater, clothing, ropes and nets, cigarettes, and fishing activity ( Wright et al., 2013 ; Wang et al., 2018 ; Hale et al., 2020 ). Microfragments in marine samples originate from the breakdown of larger pieces of plastic debris. Only a few microfragments (<3%) were isolated from snail and water samples, which is similar to findings of other studies (e.g., Waite et al., 2018 ; Akindele et al., 2019 ; Whitaker et al., 2019 ). Though it is not known how microplastics impact Red-mouth rock shells or Crown conchs, microplastic impacts have been demonstrated in several other organisms. For example, microplastic ingestion has been shown to clog and block feeding structures and the digestive tract, thus limiting food intake ( Cole et al., 2013 ). Further, microplastics have been shown to cause a change in behavioral vigilance and predator avoidance in the Common periwinkle ( Seuront, 2018 ). Ingested microplastics may also be transferred to the circulatory system ( Browne et al., 2008 ), causing a reduction of feeding activity ( Besseling et al., 2012 ), and an increased immune response ( Avio et al., 2015 ). Ultimately, microplastics may act as vectors for transferring novel bacterial assemblages ( Barnes, 2002 ; Gregory, 2009 ) and may contain adsorbed chemical pollutants ( Carpenter and Smith, 1972 ; Hale et al., 2020 ).

In general, feeding strategy and environmental prevalence have been shown to be the main drivers of microplastic consumption ( Walkinshaw et al., 2020 ). As predatory snails, Red-mouth rock shells and Crown conchs are both likely consuming microplastics indirectly through trophic transfer from prey items from their marine environment, though unlikely, microplastic consumption may be occurring directly from the environment. Red-mouth rock shells are smaller bodied compared to Crown conchs. Specifically, Red-mouth rock shells typically reach 40 mm in length, while Crown conchs reach approximately 120 mm in length ( Limaverde et al., 2007 ; Masterson, 2008 ). The snails used in this study are not full length, however, they were significantly different in shell length, with Crown conchs being the larger of the two species. Despite the overall size difference between snail species, the generally smaller bodied Red-mouth rock shells contained significantly more microplastics compared to the generally larger bodied Crown conchs. This difference in microplastic contamination could result from one or more of the following reasons.

Differences in contamination could result from differences in prey items and subsequent microplastic contamination of prey items of each snail. As such, Red-mouth rock shells and Crown conchs, have similar ecological roles, and feed mostly on bivalves, gastropods, and barnacles that are likely directly filtering/consuming microplastics as they feed in the benthos ( Bowling, 1994 ; Watanabe and Young, 2005 ). In fact, filter feeders have been shown to more effectively consume microplastics from surrounding waters than non-filter feeding organisms ( Van Cauwenberghe and Janssen, 2014 ; Setälä et al., 2016 ; Gonçalves et al., 2019 ). Thus, perhaps a difference in microplastic contamination of snails resulted from a difference in contamination of prey items. Further, trophic transfer from snails to other predators could potentially be occurring as the Red-mouth rock shells and Crown conchs consume contaminated prey items, and then are consumed by other predators such as crabs ( Brown, 1997 ) and birds ( Krueger, 2021 ). There is also some evidence to suggest that microplastic contamination of body tissues could also arise from filtration of water through the gills ( Watts et al., 2014 ). Further, there is evidence to demonstrate that filter feeding bivalves such as Crassostrea virginica and Mytilus edulis selectively ingested microplastics preferentially, based on the physical characteristics of the plastic ( Ward et al., 2019 ). A key factor in bioavailability of microplastics is their small size, making them more likely to be available to lower trophic levels ( Wright et al., 2013 ). Thus, it is possible that the Red-mouth rock shells examined in this study consumed prey items that were more contaminated with microplastics, due to preferential selection or retention of microplastics, compared to the prey items of the Crown conchs. Another possible reason that Red-mouth rock shells contained more microplastic contamination is that the snails themselves had microplastic retention or transfer of microplastics into tissues other than the digestive system ( Walkinshaw et al., 2020 ).

Further, a lower concentration of microplastics in the Crown conchs may indicate that microplastics could be egested through the digestive system, instead of being retained or translocated to tissues. Fewer microplastics in predatory Crown conchs could also indicate that microplastics are commonly passed through the guts and released in the feces of prey items, rather than building up in the consumed organisms as was also seen in Littorina littorea ( Gutow et al., 2016 ). Consequently, microplastic contamination likely poses a greater threat to certain species depending upon prey items consumed, retention or lack thereof of microplastics, and place in the food chain ( Walkinshaw et al., 2020 ).

Although there was no significant difference in the number of microplastics in the seawater samples from the two major locations sampled in this study, there was a significant difference in terms of size of microplastics from the two major locations. As such, Northwest Florida Panhandle water samples showed significantly larger microplastics, though snail samples did not show a significant difference in size of microplastics consumed. This may indicate that prey items of both species of predatory snails are possibly selecting and consuming similar sizes of microplastics from the environment. Filter feeding organisms have been shown to show selection based on physical characteristics of microplastics ( Ward et al., 2019 ). It is important to mention that microplastic contamination of seawater can fluctuate with storms and effluence and was only sampled at one place and time in this study. Fluctuations of microplastics in the water could also potentially account for the difference in contamination of snail tissues seen in this study.

There was a significant difference in terms of color of ingested microplastics between the two major locations of this study. Both Northwest Panhandle Florida and Central Florida seawater samples had similar numbers of black microfibers, however, Central Florida seawater samples had a greater number of red and blue microfibers, while Northwest Panhandle Florida had a greater number of clear microfibers. Interestingly, in the snail tissue samples, Red-mouth rock shells from Northwest Panhandle Florida, were contaminated with a greater number of clear microfibers (77%), while Crown conchs from Central Florida, were contaminated mostly with black microfibers (54%). Clear microfibers are commonly recovered as the dominant color of microplastics from tissues of organisms such as birds ( Zhu et al., 2019 ; Carlin et al., 2020 ), fishes ( Romeo et al., 2015 ; Peters et al., 2017 ) and invertebrates ( Waite et al., 2018 ).

Microplastics have been documented to cause many deleterious effects in a variety of different organisms (see citations above). If microplastics cause deleterious effects (e.g., reduced feeding and reproduction) to the intertidal snails of this study, snail populations could decline. Likewise, a decline in snail populations could cause a trophic cascade impacting food availability for other species and ecosystem health ( Walkinshaw et al., 2020 ). In this study, both Red-mouth rock shells and Crown conchs were contaminated with microplastics, which is likely originating from indirect trophic transfer from prey items. It is still questionable if microplastics can be transferred to even higher trophic levels following predation. However, Red-mouth rock shells and Crown conch are commonly found in intertidal habitats and serve as prey items for several other organisms in these ecosystems, creating the potential for the trophic transfer of microplastics potentially having an effect on both ecosystem and human health ( Carbery et al., 2018 ; Walkinshaw et al., 2020 ).

Overall, this is the first study on predatory marine intertidal snails to demonstrate microplastics contamination, indicating these snail species are likely consuming microplastics indirectly through trophic transfer from prey items from their environment. As such, Red-mouth rock shells may have greater contamination of microplastics as a result of increased microplastic contamination of prey items or from retention of microplastics. The results from this study raise substantial ecotoxicological concern for small invertebrate species which are often not the focus of ecological or conservation studies. Understanding the types and abundance of microplastics is necessary for future studies to understand how microplastics move through the food web and how microplastics directly and indirectly impact organisms. Further work is needed to determine the impacts of microplastics on these two benthic species and the overall impact on ecosystem health, particularly for Florida ecosystems.

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Author Contributions

JK and AJ identified the research question and study approach, carried out specimen collection, designed laboratory methods, and were responsible for manuscript data and writing. JK performed the laboratory methods and data analysis. AJ oversaw data analysis and interpretation. Both authors contributed to the article and approved the submitted version.

Funding was provided for this study from the Office of Undergraduate Research at the University of West Florida.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Acknowledgments

We thank the Office of Undergraduate Research at the University of Florida for funding support and undergraduate research support. We also thank Tristyn Garza for assistance with microplastic identification and measuring and Victoria Bogantes Aguilar for assistance with the map.

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Keywords : marine pollution, Stramonita haemastoma , Melongena corona , Gulf of Mexico, microfibers, microfragments

Citation: Kleinschmidt JM and Janosik AM (2021) Microplastics in Florida, United States: A Case Study of Quantification and Characterization With Intertidal Snails. Front. Ecol. Evol. 9:645727. doi: 10.3389/fevo.2021.645727

Received: 23 December 2020; Accepted: 02 September 2021; Published: 22 September 2021.

Reviewed by:

Copyright © 2021 Kleinschmidt and Janosik. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Alexis M. Janosik, [email protected]

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• Published: 07 July 2022

A global horizon scan of issues impacting marine and coastal biodiversity conservation

• James E. Herbert-Read   ORCID: orcid.org/0000-0003-0243-4518 1   na1 ,
• Ann Thornton   ORCID: orcid.org/0000-0002-7448-8497 2   na1 ,
• Diva J. Amon   ORCID: orcid.org/0000-0003-3044-107X 3 , 4 ,
• Silvana N. R. Birchenough   ORCID: orcid.org/0000-0001-5321-8108 5 ,
• Isabelle M. Côté   ORCID: orcid.org/0000-0001-5368-4061 6 ,
• Maria P. Dias   ORCID: orcid.org/0000-0002-7281-4391 7 , 8 ,
• Brendan J. Godley 9 ,
• Sally A. Keith   ORCID: orcid.org/0000-0002-9634-2763 10 ,
• Emma McKinley   ORCID: orcid.org/0000-0002-8250-2842 11 ,
• Lloyd S. Peck   ORCID: orcid.org/0000-0003-3479-6791 12 ,
• Ricardo Calado 13 ,
• Omar Defeo   ORCID: orcid.org/0000-0001-8318-528X 14 ,
• Steven Degraer   ORCID: orcid.org/0000-0002-3159-5751 15 ,
• Emma L. Johnston   ORCID: orcid.org/0000-0002-2117-366X 16 ,
• Hermanni Kaartokallio 17 ,
• Peter I. Macreadie   ORCID: orcid.org/0000-0001-7362-0882 18 ,
• Anna Metaxas   ORCID: orcid.org/0000-0002-1935-6213 19 ,
• Agnes W. N. Muthumbi 20 ,
• David O. Obura   ORCID: orcid.org/0000-0003-2256-6649 21 , 22 ,
• David M. Paterson 23 ,
• Alberto R. Piola   ORCID: orcid.org/0000-0002-5003-8926 24 , 25 ,
• Anthony J. Richardson   ORCID: orcid.org/0000-0002-9289-7366 26 , 27 ,
• Irene R. Schloss   ORCID: orcid.org/0000-0002-5917-8925 28 , 29 , 30 ,
• Paul V. R. Snelgrove   ORCID: orcid.org/0000-0002-6725-0472 31 ,
• Bryce D. Stewart 32 ,
• Paul M. Thompson   ORCID: orcid.org/0000-0001-6195-3284 33 ,
• Gordon J. Watson   ORCID: orcid.org/0000-0001-8274-7658 34 ,
• Thomas A. Worthington   ORCID: orcid.org/0000-0002-8138-9075 2 ,
• Moriaki Yasuhara   ORCID: orcid.org/0000-0003-0990-1764 35 &
• William J. Sutherland 2 , 36  

Nature Ecology & Evolution volume  6 ,  pages 1262–1270 ( 2022 ) Cite this article

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The biodiversity of marine and coastal habitats is experiencing unprecedented change. While there are well-known drivers of these changes, such as overexploitation, climate change and pollution, there are also relatively unknown emerging issues that are poorly understood or recognized that have potentially positive or negative impacts on marine and coastal ecosystems. In this inaugural Marine and Coastal Horizon Scan, we brought together 30 scientists, policymakers and practitioners with transdisciplinary expertise in marine and coastal systems to identify new issues that are likely to have a significant impact on the functioning and conservation of marine and coastal biodiversity over the next 5–10 years. Based on a modified Delphi voting process, the final 15 issues presented were distilled from a list of 75 submitted by participants at the start of the process. These issues are grouped into three categories: ecosystem impacts, for example the impact of wildfires and the effect of poleward migration on equatorial biodiversity; resource exploitation, including an increase in the trade of fish swim bladders and increased exploitation of marine collagens; and new technologies, such as soft robotics and new biodegradable products. Our early identification of these issues and their potential impacts on marine and coastal biodiversity will support scientists, conservationists, resource managers and policymakers to address the challenges facing marine ecosystems.

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The fifteenth Conference of the Parties (COP) to the United Nations Convention on Biological Diversity will conclude negotiations on a global biodiversity framework in late-2022 that will aim to slow and reverse the loss of biodiversity and establish goals for positive outcomes by 2050 1 . Currently recognized drivers of declines in marine and coastal ecosystems include overexploitation of resources (for example, fishes, oil and gas), expansion of anthropogenic activities leading to cumulative impacts on the marine and coastal environment (for example, habitat loss, introduction of contaminants and pollution) and effects of climate change (for example, ocean warming, freshening and acidification). Within these broad categories, marine and coastal ecosystems face a wide range of emerging issues that are poorly recognized or understood, each having the potential to impact biodiversity. Researchers, conservation practitioners and marine resource managers must identify, understand and raise awareness of these relatively ‘unknown’ issues to catalyse further research into their underlying processes and impacts. Moreover, informing the public and policymakers of these issues can mitigate potentially negative impacts through precautionary principles before those effects become realized: horizon scans provide a platform to do this.

Horizon scans bring together experts from diverse disciplines to discuss issues that are (1) likely to have a positive or negative impact on biodiversity and conservation within the coming years and (2) not well known to the public or wider scientific community or face a substantial ‘step-change’ in their importance or application 2 . Horizon scans are an effective approach for pre-emptively identifying issues facing global conservation 3 . Indeed, marine issues previously identified through this approach include microplastics 4 , invasive lionfish 4 and electric pulse trawling 5 . To date, however, no horizon scan of this type has focused solely on issues related to marine and coastal biodiversity, although a scan on coastal shorebirds in 2012 identified potential threats to coastal ecosystems 6 . This horizon scan aims to benefit our ocean and human society by stimulating research and policy development that will underpin appropriate scientific advice on prevention, mitigation, management and conservation approaches in marine and coastal ecosystems.

We present the final 15 issues below in thematic groups identified post-scoring, rather than rank order (Fig. 1 ).

Numbers refer to the order presented in this article, rather than final ranking. Image of brine pool courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2014. Image of biodegradable bag courtesy of Katie Dunkley.

Ecosystem impacts

Wildfire impacts on coastal and marine ecosystems.

The frequency and severity of wildfires are increasing with climate change 7 . Since 2017, there have been fires of unprecedented scale and duration in Australia, Brazil, Portugal, Russia and along the Pacific coast of North America. In addition to threatening human life and releasing stored carbon, wildfires release aerosols, particles and large volumes of materials containing soluble forms of nutrients including nitrogen, phosphorus and trace metals such as copper, lead and iron. Winds and rains can transport these materials over long distances to reach coastal and marine ecosystems. Australian wildfires, for example, triggered widespread phytoplankton blooms in the Southern Ocean 8 along with fish and invertebrate kills in estuaries 9 . Predicting the magnitude and effects of these acute inputs is difficult because they vary with the size and duration of wildfires, the burning vegetation type, rainfall patterns, riparian vegetation buffers, dispersal by aerosols and currents, seasonal timing and nutrient limitation in the recipient ecosystem. Wildfires might therefore lead to beneficial, albeit temporary, increases in primary productivity, produce no effect or have deleterious consequences, such as the mortality of benthic invertebrates, including corals, from sedimentation, coastal darkening (see below), eutrophication or algal blooms 10 .

Coastal darkening

Coastal ecosystems depend on the penetration of light for primary production by planktonic and attached algae and seagrass. However, climate change and human activities increase light attenuation through changes in dissolved materials modifying water colour and suspended particles. Increased precipitation, storms, permafrost thawing and coastal erosion have led to the ‘browning’ of freshwater ecosystems by elevated organic carbon, iron and particles, all of which are eventually discharged into the ocean 11 . Coastal eutrophication leading to algal blooms compounds this darkening by further blocking light penetration. Additionally, land-use change, dredging and bottom fishing can increase seafloor disturbance, resuspending sediments and increasing turbidity. Such changes could affect ocean chemistry, including photochemical degradation of dissolved organic carbon and generation of toxic chemicals. At moderate intensities, limited spatial scales and during heatwaves, coastal darkening may have some positive impacts such as limiting coral bleaching on shallow reefs 12 but, at high intensities and prolonged spatial and temporal extents, lower light-regimes can contribute to cumulative stressor effects thereby profoundly altering ecosystems. This darkening may result in shifts in species composition, distribution, behaviour and phenology, as well as declines in coastal habitats and their functions (for example, carbon sequestration) 13 .

Increased toxicity of metal pollution due to ocean acidification

Concerns about metal toxicity in the marine environment are increasing as we learn more about the complex interactions between metals and global climate change 14 . Despite tight regulation of polluters and remediation efforts in some countries, the high persistence of metals in contaminated sediments results in the ongoing remobilization of existing metal pollutants by storms, trawling and coastal development, augmented by continuing release of additional contaminants into coastal waters, particularly in urban and industrial areas across the globe 14 . Ocean acidification increases the bioavailability, uptake and toxicity of metals in seawater and sediments, with direct toxicity effects on some marine organisms 15 . Not all biogeochemical changes will result in increased toxicity; in pelagic and deep-sea ecosystems, where trace metals are often deficient, increasing acidity may increase bioavailability and, in shallow waters, stimulate productivity for non-calcifying phytoplankton 16 . However, increased uptake of metals in wild-caught and farmed bivalves linked to ocean acidification could also affect human health, especially given that these species provide 25% of the world’s seafood. The combined effects of ocean acidification and metals could not only increase the levels of contamination in these organisms but could also impact their populations in the future 14 .

Equatorial marine communities are becoming depauperate due to climate migration

Climate change is causing ocean warming, resulting in a poleward shift of existing thermal zones. In response, species are tracking the changing ocean environmental conditions globally, with range shifts moving five times faster than on land 17 . In mid-latitudes and higher latitudes, as some species move away from current distribution ranges, other species from warmer regions can replace them 18 . However, the hottest climatic zones already host the most thermally tolerant species, which cannot be replaced due to their geographical position. Thus, climate change reduces equatorial species richness and has caused the formerly unimodal latitudinal diversity gradient in many communities to now become bimodal. This bimodality (dip in equatorial diversity) is projected to increase within the next 100 years if carbon dioxide emissions are not reduced 19 . The ecological consequences of this decline in equatorial zones are unclear, especially when combined with impacts of increasing human extraction and pollution 20 . Nevertheless, emerging ecological communities in equatorial systems are likely to have reduced resilience and capacity to support ecosystem services and human livelihoods.

Effects of altered nutritional content of fish due to climate change

Essential fatty acids (EFAs) are critical to maintaining human and animal health and fish consumption provides the primary source of EFAs for billions of people. In aquatic ecosystems, phytoplankton synthesize EFAs, such as docosahexaenoic acid (DHA) 21 , with pelagic fishes then consuming phytoplankton. However, concentrations of EFAs in fishes vary, with generally higher concentrations of omega-3 fatty acids in slower-growing species from colder waters 22 . Ongoing effects of climate change are impacting the production of EFAs by phytoplankton, with warming waters predicted to reduce the availability of DHA by about 10–58% by 2100 23 ; a 27.8% reduction in available DHA is associated with a 2.5 °C rise in water temperature 21 . Combined with geographical range shifts in response to environmental change affecting the abundance and distribution of fishes, this could lead to a reduction in sufficient quantities of EFAs for fishes, particularly in the tropics 24 . Changes to EFA production by phytoplankton in response to climate change, as shown for Antarctic waters 25 , could have cascading effects on the nutrient content of species further up the food web, with consequences for marine predators and human health 26 .

Resource exploitation

The untapped potential of marine collagens and their impacts on marine ecosystems.

Collagens are structural proteins increasingly used in cosmetics, pharmaceuticals, nutraceuticals and biomedical applications. Growing demand for collagen has fuelled recent efforts to find new sources that avoid religious constraints and alleviate risks associated with disease transmission from conventional bovine and porcine sources 27 . The search for alternative sources has revealed an untapped opportunity in marine organisms, such as from fisheries bycatch 28 . However, this new source may discourage efforts to reduce the capture of non-target species. Sponges and jellyfish offer a premium source of marine collagens. While the commercial-scale harvesting of sponges is unlikely to be widely sustainable, there may be some opportunity in sponge aquaculture and jellyfish harvesting, especially in areas where nuisance jellyfish species bloom regularly (for example, Mediterranean and Japan Seas). The use of sharks and other cartilaginous fish to supply marine collagens is of concern given the unprecedented pressure on these species. However, the use of coproducts derived from the fish-processing industry (for example, skin, bones and trims) offers a more sustainable approach to marine collagen production and could actively contribute to the blue bio-economy agenda and foster circularity 29 .

Impacts of expanding trade for fish swim bladders on target and non-target species

In addition to better-known luxury dried seafoods, such as shark fins, abalone and sea cucumbers, there is an increasing demand for fish swim bladders, also known as fish maw 30 . This demand may trigger an expansion of unsustainable harvests of target fish populations, with additional impacts on marine biodiversity through bycatch 30 , 31 . The fish swim-bladder trade has gained a high profile because the overexploitation of totoaba ( Totoaba macdonaldi) has driven both the target population and the vaquita ( Phocoena sinus) (which is bycaught in the Gulf of Mexico fishery) to near extinction 32 . By 2018, totoaba swim bladders were being sold for US$46,000 kg −1 . This extremely lucrative trade disrupts efforts to encourage sustainable fisheries. However, increased demand on the totoaba was itself caused by overexploitation over the last century of the closely related traditional species of choice, the Chinese bahaba ( Bahaba taipingensis) . We now risk both repeating this pattern and increasing its scale of impact, where depletion of a target species causes markets to switch to species across broader taxonomic and biogeographical ranges 31 . Not only does this cascading effect threaten other croakers and target species, such as catfish and pufferfish but maw nets set in more diverse marine habitats are likely to create bycatch of sharks, rays, turtles and other species of conservation concern.

Impacts of fishing for mesopelagic species on the biological ocean carbon pump

Growing concerns about food security have generated interest in harvesting largely unexploited mesopelagic fishes that live at depths of 200–1,000 m (ref. 33 ). Small lanternfishes (Myctophidae) dominate this potentially 10 billion ton community, exceeding the mass of all other marine fishes combined 34 and spanning millions of square kilometres of the open ocean. Mesopelagic fish are generally unsuitable for human consumption but could potentially provide fishmeal for aquaculture 34 or be used for fertilizers. Although we know little of their biology, their diel vertical migration transfers carbon, obtained by feeding in surface waters at night, to deeper waters during the day across many hundreds and even thousands of metres depth where it is released by excretion, egestion and death. This globally important carbon transport pathway contributes to the biological pump 35 and sequesters carbon to the deep sea 36 . Recent estimates put the contribution of all fishes to the biological ocean pump at 16.1% (± s.d. 13%) (ref. 37 ). The potential large-scale removal of mesopelagic fishes could disrupt a major pathway of carbon transport into the ocean depths.

Extraction of lithium from deep-sea brine pools

Global groups, such as the Deep-Ocean Stewardship Initiative, emphasize increasing concern about the ecosystem impacts from deep-sea resource extraction 38 . The demand for batteries, including for electric vehicles, will probably lead to a demand for lithium that is more than five times its current level by 2030 39 . While concentrations are relatively low in seawater, some deep-sea brines and cold seeps offer higher concentrations of lithium. Furthermore, new technologies, such as solid-state electrolyte membranes, can enrich the concentration of lithium from seawater sources by 43,000 times, increasing the energy efficiency and profitability of lithium extraction from the sea 39 . These factors could divert extraction of lithium resources away from terrestrial to marine mining, with the potential for significant impacts to localized deep-sea brine ecosystems. These brine pools probably host many endemic and genetically distinct species that are largely undiscovered or awaiting formal description. Moreover, the extremophilic species in these environments offer potential sources of marine genetic resources that could be used in new biomedical applications including pharmaceuticals, industrial agents and biomaterials 40 . These concerns point to the need to better quantify and monitor biodiversity in these extreme environments to establish baselines and aid management.

New technologies

Colocation of marine activities.

Climate change, energy needs and food security have moved to the top of global policy agendas 41 . Increasing energy needs, alongside the demands of fisheries and transport infrastructure, have led to the proposal of colocated and multifunctional structures to deliver economic benefits, optimize spatial planning and minimize the environmental impacts of marine activities 42 . These designs often bring technical, social, economic and environmental challenges. Some studies have begun to explore these multipurpose projects (for example, offshore windfarms colocated with aquaculture developments and/or Marine Protected Areas) and how to adapt these concepts to ensure they are ‘fit for purpose’, economically viable and reliable. However, environmental and ecosystem assessment, management and regulatory frameworks for colocated and multi-use structures need to be established to prevent these activities from compounding rather than mitigating the environmental impacts from climate change 43 .

Floating marine cities

In April 2019, the UN-HABITAT programme convened a meeting of scientists, architects, designers and entrepreneurs to discuss how floating cities might be a solution to urban challenges such as climate change and lack of housing associated with a rising human population ( https://unhabitat.org/roundtable-on-floating-cities-at-unhq-calls-for-innovation-to-benefit-all ). The concept of floating marine cities—hubs of floating structures placed at sea—was born in the middle of the twentieth century and updated designs now aim to translate this vision into reality 44 . Oceanic locations provide benefits from wave and tidal renewable energy and food production supported by hydroponic agriculture 45 . Modular designs also offer greater flexibility than traditional static terrestrial cities, whereby accommodation and facilities could be incorporated or removed in response to changes in population or specific events. The cost of construction in harsh offshore environments, rather than technology, currently limits the development of marine cities and potential designs will need to consider the consequences of more frequent and extreme climate events. Although the artificial hard substrates created for these floating cities could act as stepping stones, facilitating species movement in response to climate change 46 , this could also increase the spread of invasive species. Finally, the development of offshore living will raise issues in relation to governance and land ownership that must be addressed for marine cities to be viable 47 .

Trace-element contamination compounded by the global transition to green technologies

The persistent environmental impacts of metal and metalloid trace-element contamination in coastal sediments are now increasing after a long decline 48 . However, the complex sources of contamination challenge their management. The acceleration of the global transition to green technologies, including electric vehicles, will increase demand for batteries by over 10% annually in the coming years 49 . Electric vehicle batteries currently depend almost exclusively on lithium-ion chemistries, with potential trace-element emissions across their life cycle from raw material extraction to recycling or end-of-life disposal. Few jurisdictions treat lithium-ion batteries as harmful waste, enabling landfill disposal with minimal recycling 49 . Cobalt and nickel are the primary ecotoxic elements in next-generation lithium-ion batteries 50 , although there is a drive to develop a cobalt-free alternative likely to contain higher nickel content 50 . Some battery binder and electrolyte chemicals are toxic to aquatic life or form persistent organic pollutants during incomplete burning. Increasing pollution from battery production, recycling and disposal in the next decade could substantially increase the potentially toxic trace-element contamination in marine and coastal systems worldwide.

New underwater tracking systems to study non-surfacing marine animals

The use of tracking data in science and conservation has grown exponentially in recent decades. Most trajectory data collected on marine species to date, however, has been restricted to large and near-surface species, limited by the size of the devices and reliance on radio signals that do not propagate well underwater. New battery-free technology based on acoustic telemetry, named ‘underwater backscatter localization’ (UBL), may allow high-accuracy (<1 m) tracking of animals travelling at any depth and over large distances 51 . Still in the early stages of development, UBL technology has significant potential to help fill knowledge gaps in the distribution and spatial ecology of small, non-surfacing marine species, as well as the early life-history stages of many species 52 , over the next decades. However, the potential negative impacts of this methodology on the behaviour of animals are still to be determined. Ultimately, UBL may inform spatial management both in coastal and offshore regions, as well as in the high seas and address a currently biased perspective of how marine animals use ocean space, which is largely based on near-surface or aerial marine megafauna (for example, ref. 53 ).

Soft robotics for marine research

The application and utility of soft robotics in marine environments is expected to accelerate in the next decade. Soft robotics, using compliant materials inspired by living organisms, could eventually offer increased flexibility at depth because they do not face the same constraints as rigid robots that need pressurized systems to function 54 . This technology could increase our ability to monitor and map the deep sea, with both positive and negative consequences for deep-sea fauna. Soft-grab robots could facilitate collection of delicate samples for biodiversity monitoring but, without careful management, could also add pollutants and waste to these previously unexplored and poorly understood environments 55 . With advancing technology, potential deployment of swarms of small robots could collect basic environmental data to facilitate mapping of the seabed. Currently limited by power supply, energy-harvesting modules are in development that enable soft robots to ‘swallow’ organic material and convert it into power 56 , although this could result in inadvertently harvesting rare deep-sea organisms. Soft robots themselves may also be ingested by predatory species mistaking them for prey. Deployment of soft robotics will require careful monitoring of both its benefits and risks to marine biodiversity.

The effects of new biodegradable materials in the marine environment

Mounting public pressure to address marine plastic pollution has prompted the replacement of some fossil fuel-based plastics with bio-based biodegradable polymers. This consumer pressure is creating an economic incentive to adopt such products rapidly and some companies are promoting their environmental benefits without rigorous toxicity testing and/or life-cycle assessments. Materials such as polybutylene succinate (PBS), polylactic acid (PLA) or cellulose and starch-based materials may become marine litter and cause harmful effects akin to conventional plastics 57 . The long-term and large-scale effect of the use of biodegradable polymers in products (for example, clothing) and the unintended release of byproducts, such as microfibres, into the environment remain unknown. However, some natural microfibres have greater toxicity than plastic microfibres when consumed by aquatic invertebrates 58 . Jurisdictions should enact and enforce suitable regulations to require the individual assessment of all new materials intended to biodegrade in a full range of marine environmental conditions. In addition, testing should include studies on the toxicity of major transition chemicals created during the breakdown process 59 , ideally considering the different trophic levels of marine food webs.

This scan identified three categories of horizon issues: impacts on, and alterations to, ecosystems; changes to resource use and extraction; and the emergence of technologies. While some of the issues discussed, such as improved monitoring of species (underwater tracking and soft robotics) and more sustainable resource use (marine collagens), may have some positive outcomes for marine and coastal biodiversity, most identified issues are expected to have substantial negative impacts if not managed or mitigated appropriately. This imbalance highlights the considerable emerging pressures facing marine ecosystems that are often a byproduct of human activities.

Four issues identified in this scan related to ongoing large-scale (hundreds to many thousands of square kilometres) alterations to marine ecosystems (wildfires, coastal darkening, depauperate equatorial communities and altered nutritional fish content), either through the impacts of global climate change or other human activities. There are already clear impacts of climate change, for example, on stores of blue carbon (for example, ref. 60 ) and small-scale fisheries (for example, ref. 61 ) but the identification of these issues highlights the need for global action that reverses such trends. The United Nations Decade of Ocean Science for Sustainable Development (2021–2030) is now underway, aligning with other decadal policy priorities, including the Sustainable Development Goals ( https://sdgs.un.org/ ), the 2030 targets for biodiversity to be agreed in 2022, the conclusion of the ongoing negotiations on biodiversity beyond national jurisdictions (BBNJ) ( https://www.un.org/bbnj/ ), the UN Conference on Biodiversity (COP15) ( https://www.unep.org/events/conference/un-biodiversity-conference-cop-15 ) and the UN Climate Change Conference 2021 (COP26) ( https://ukcop26.org/ ). While some campaigns to allocate 30% of the ocean to Marine Protected Areas by 2030 are prominently aired 62 , the unintended future consequences of such protection and how to monitor and manage these areas, remain unclear 63 , 64 , 65 .

Another set of issues related to anticipated increases in marine resource use and extraction (swim bladders, marine collagens, lithium extraction and mesopelagic fisheries). The complex issue of mitigating the impacts on marine conservation and biodiversity of exploiting and using newly discovered resources must consider public perceptions of the ocean 66 , 67 , market forces and the sustainable blue economy 68 , 69 .

The final set of issues related to new technological advancements, with many offering more sustainable opportunities, albeit some having potentially unintended negative consequences on marine and coastal biodiversity. For example, trace-element contamination from green technologies and harmful effects of biodegradable products highlights the need to assess the step-changes in impacts from their increased use and avoid the paradox of technologies designed to mitigate the damaging effects of climate change on biodiversity themselves damaging biodiversity. Indeed, the impacts on marine and coastal biodiversity from emerging technologies currently in development (such as underwater tracking or soft robotics) need to be assessed before deployment at scale.

There are limitations to any horizon scanning process that aims to identify global issues and a different group of experts may have identified a different set of issues. By inviting participants from a range of subject backgrounds and global regions and asking them to canvass their network of colleagues and collaborators, we aimed to identify as broad a set of issues as possible. We acknowledge, however, that only about one-quarter of the participants were from non-academic organizations, which may have skewed the submitted issues and how they were voted on. However, others 3 reported no significant correlation between participants’ areas of research expertise and the top issues selected in the horizon scan conducted in 2009. Therefore, horizon scans do not necessarily simply represent issues that reflect the expertise of participants. We also sought to achieve diversity by inviting participants from 22 countries and actively seeking representatives from the global south. However, the final panel of 30 participants spanned only 11 countries, most in the global north. We were forced by the COVID-19 pandemic to hold the scan online and while we hoped that this would enable participants to engage from around the world alleviating broader global inequalities in science 63 , digital inequality was in fact enhanced during the pandemic 70 . Our experience highlights the need for other mechanisms that can promote global representation in these scans.

This Marine and Coastal Horizon Scan seeks to raise awareness of issues that may impact marine and coastal biodiversity conservation in the next 5–10 years. Our aim is to bring these issues to the attention of scientists, policymakers, practitioners and the wider community, either directly, through social networks or the mainstream media. Whilst it is almost impossible to determine whether issues gained prominence as a direct result of a horizon scan, some issues featured in previous scans have seen growth in reporting and awareness. Others 3 found that 71% of topics identified in the Horizon Scan in 2009 had seen an increase in their importance over the next 10 years. Issues such as microplastics and invasive lionfish had received increased research and investment from scientists, funders, managers and policymakers to understand their impacts and the horizon scans may have helped motivate this increase. Horizon scans, therefore, should primarily act as signposts, putting focus onto particular issues and providing support for researchers and practitioners to seek investment in these areas.

Whilst recognizing that marine and coastal environments are complex social-ecological systems, the role of governance, policy and litigation on all areas of marine science needs to be developed, as it is yet to be established to the same extent as in terrestrial ecosystems 71 . Indeed, tackling many of the issues presented in this scan will require an understanding of the human dimensions relating to these issues, through fields of research including but not limited to ocean literacy 72 , 73 , social justice, equity 74 and human health 75 . Importantly, however, horizon scanning has proved an efficient tool in identifying issues that have subsequently come to the forefront of public knowledge and policy decisions, while also helping to focus future research. The scale of the issues facing marine and coastal areas emphasizes the need to identify and prioritize, at an early stage, those issues specifically facing marine ecosystems, especially within this UN Decade of Ocean Science for Sustainable Development.

Identification of issues

In March 2021, we brought together a core team of 11 participants from a broad range of marine and coastal disciplines. The core team suggested names of individuals outside their subject area who were also invited to participate in the horizon scan. To ensure we included as many different subject areas as possible within marine and coastal conservation, we selected one individual from each discipline. Our panel of experts comprised 30 (37% female) marine and coastal scientists, policymakers and practitioners (27% from non-academic institutions), with cross-disciplinary expertise in ecology (including tropical, temperate, polar and deep-sea ecosystems), palaeoecology, conservation, oceanography, climate change, ecotoxicology, technology, engineering and marine social sciences (including governance, blue economy and ocean literacy). Participants were invited from 22 countries across six continents, resulting in a final panel of 30 experts from 11 countries (Europe n  = 17 (including the three organizers); North America and Caribbean n  = 4; South America n  = 3; Australasia n  = 3; Asia n  = 1; Africa n  = 2). All experts co-authored this paper.

To reduce the potential for bias in the identification of suitable issues, each participant was invited to consult their own network and required to submit two to five issues that they considered new and likely to have a positive or negative impact on marine and coastal biodiversity conservation in the next 5–10 years ( Supplementary Information text describes instructions given to participants). Each issue was described in paragraphs of ~200 words (plus references). Due to the COVID-19 pandemic, participants relied mainly on virtual meetings and online communication using email, social-media platforms, online conferences and networking events. Through these channels ~680 people were canvassed by the participants, counting all direct in-person or online discussions as individual contacts but treating social-media posts or generic emails as a single contact. This process resulted in a long list of 75 issues that were considered in the first round of scoring (see Supplementary Table 1 for the full list of initially submitted issues).

Round 1 scoring

The initial list of proposed issues was then shortened through a scoring process. We used a modified Delphi-style 76 voting process, which has been consistently applied in horizon scans since 2009 (refs. 4 , 77 ) (see Fig. 2 for the stepwise process). This process ensured that consideration and selection of issues remained repeatable, transparent and inclusive. Panel members were asked to confidentially and independently score the long list of 75 issues from 1 (low) to 1,000 (high) on the basis of the following criteria:

Whether the issue is new (with ‘new’ issues scoring higher) or is a well-known issue likely to exhibit a significant step-change in impact

Whether the issue is likely to be important and impactful over the next 5–10 years

Whether the issue specifically impacts marine and coastal biodiversity

Left and right columns show the process for the first and second rounds of scoring, respectively.

Participants were also asked whether they had heard of the issue or not.

‘Voter fatigue’ can result in issues at the end of a lengthy list not receiving the same consideration as those at the beginning 76 . We counteracted this potential bias by randomly assigning participants to one of three differently ordered long-lists of issues. Participants’ scores were converted to ranks (1–75). We had aimed to retain the top 30 issues with the highest median ranks for the second round of assessment at the workshop but kept 31 issues because two issues achieved equal median ranks. In addition, we identified one issue that had been incorrectly grouped with three others and presented this as a separate issue. The subsequent online workshop to discuss this shortlist, therefore, considered the top-ranked 32 issues (Fig. 3a ) (see Supplementary Table 2 for the full list).

a , Round 1. Each point represents an individual issue. For all issue titles, see Supplementary Table 1 . Issues in dark blue were retained for the second round. Issues that were ranked higher were generally those that participants had not heard of (Spearman rank correlation = 0.38, P  < 0.001). b , Round 2. Scores as in round 1. For titles of the second round of 32 issues, see Supplementary Table 2 . The 15 final issues (marked in red) achieved the top ranks (horizontal dashed line) and had only been heard of by 50% of participants (vertical dashed line). Red circles, squares and triangles denote issues relating to ecosystem impacts, resource exploitation and new technologies, respectively. The two grey issues marked with crosses were discounted during final discussions because participants could not identify the horizon component of these issues.

Source data

Workshop and round 2 scoring.

Before the workshop, each participant was assigned up to four of the 32 issues to research in more detail and contribute further information to the discussion. We convened a one-day workshop online in September 2021. The geographic spread of participants meant that time zones spanned 17 h. Despite these constraints, discussions remained detailed, focused, varied and lively. In addition, participants made use of the chat function on the platform to add notes, links to articles and comments to the discussion. After discussing each issue, participants re-scored the topic (1–1,000, low to high) based on novelty and the issue’s importance for, and probable impact on, marine and coastal biodiversity (3 participants out of 30 did not score all issues and therefore their scores were discounted). At the end of the selection process, scores were again converted to ranks and collated. Highest-ranked issues were then discussed by correspondence focusing on the same three criteria as outlined above, after which the top 15 horizon issues were selected (Fig. 3b ).

Reporting summary

Further information on research design is available in the Nature Research Reporting Summary linked to this article.

Data availability

The datasets generated during and/or analysed during the current study are available from figshare https://doi.org/10.6084/m9.figshare.19703485.v1 . Source data are provided with this paper.

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Acknowledgements

This Marine and Coastal Horizon Scan was funded by Oceankind. S.N.R.B. is supported by EcoStar (DM048) and Cefas (My time). R.C. acknowledges FCT/MCTES for the financial support to CESAM (UIDP/50017/2020, UIDB/50017/2020, LA/P/0094/2020) through national funds. O.D. is supported by CSIC Uruguay and Inter-American Institute for Global Change Research. J.E.H.-R. is supported by the Whitten Lectureship in Marine Biology. S.A.K. is supported by a Natural Environment Research Council grant (NE/S00050X/1). P.I.M. is supported by an Australian Research Council Discovery Grant (DP200100575). D.M.P. is supported by the Marine Alliance for Science and Technology for Scotland (MASTS). A.R.P. is supported by the Inter-American Institute for Global Change Research. W.J.S. is funded by Arcadia. A.T. is supported by Oceankind. M.Y. is supported by the Deep Ocean Stewardship Initiative and bioDISCOVERY. We are grateful to everyone who submitted ideas to the exercise and the following who are not authors but who suggested a topic that made the final list: R. Brown (colocation of marine activities), N. Graham and C. Hicks (altered nutritional content of fish), A. Thornton (soft robotics), A. Vincent (fish swim bladders) and T. Webb (mesopelagic fisheries).

Author information

These authors contributed equally: James E. Herbert-Read, Ann Thornton.

Authors and Affiliations

Department of Zoology, University of Cambridge, Cambridge, UK

James E. Herbert-Read

Conservation Science Group, Department of Zoology, Cambridge University, Cambridge, UK

Ann Thornton, Thomas A. Worthington & William J. Sutherland

SpeSeas, D’Abadie, Trinidad and Tobago

Diva J. Amon

Marine Science Institute, University of California, Santa Barbara, CA, USA

The Centre for Environment, Fisheries and Aquaculture Science (Cefas), Lowestoft, UK

Silvana N. R. Birchenough

Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada

Isabelle M. Côté

Centre for Ecology, Evolution and Environmental Changes (cE3c), Department of Animal Biology, Faculdade de Ciências da Universidade de Lisboa, Lisbon, Portugal

Maria P. Dias

BirdLife International, The David Attenborough Building, Cambridge, UK

Centre for Ecology and Conservation, University of Exeter, Penryn, UK

Brendan J. Godley

Lancaster Environment Centre, Lancaster University, Lancaster, UK

Sally A. Keith

School of Earth and Environmental Sciences, Cardiff University, Cardiff, UK

Emma McKinley

British Antarctic Survey, Natural Environment Research Council, Cambridge, UK

Lloyd S. Peck

ECOMARE, CESAM—Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Santiago University Campus, Aveiro, Portugal

Ricardo Calado

Laboratory of Marine Sciences (UNDECIMAR), Faculty of Sciences, University of the Republic, Montevideo, Uruguay

Royal Belgian Institute of Natural Sciences, Operational Directorate Natural Environment, Marine Ecology and Management, Brussels, Belgium

Steven Degraer

School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia

Emma L. Johnston

Finnish Environment Institute, Helsinki, Finland

Hermanni Kaartokallio

Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood Campus, Burwood, Victoria, Australia

Peter I. Macreadie

Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada

Anna Metaxas

Department of Biology, University of Nairobi, Nairobi, Kenya

Agnes W. N. Muthumbi

Coastal Oceans Research and Development in the Indian Ocean, Mombasa, Kenya

David O. Obura

School of Biological Sciences, University of Queensland, St Lucia, Brisbane, Queensland, Australia

Scottish Oceans Institute, School of Biology, University of St Andrews, St Andrews, UK

David M. Paterson

Servício de Hidrografía Naval, Buenos Aires, Argentina

Alberto R. Piola

Instituto Franco-Argentino sobre Estudios de Clima y sus Impactos, CONICET/CNRS, Universidad de Buenos Aires, Buenos Aires, Argentina

School of Mathematics and Physics, The University of Queensland, St Lucia, Brisbane, Queensland, Australia

Anthony J. Richardson

Commonwealth Scientific and Industrial Research Organisation (CSIRO) Oceans and Atmosphere, Queensland Biosciences Precinct, St Lucia, Brisbane, Queensland, Australia

Instituto Antártico Argentino, Buenos Aires, Argentina

Irene R. Schloss

Centro Austral de Investigaciones Científicas (CADIC-CONICET), Ushuaia, Argentina

Universidad Nacional de Tierra del Fuego, Antártida e Islas del Atlántico Sur, Ushuaia, Argentina

Department of Ocean Sciences and Biology Department, Memorial University, St John’s, Newfoundland and Labrador, Canada

Paul V. R. Snelgrove

Department of Environment and Geography, University of York, York, UK

Bryce D. Stewart

Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, Cromarty, UK

Paul M. Thompson

Institute of Marine Sciences, School of Biological Sciences, University of Portsmouth, Portsmouth, UK

Gordon J. Watson

School of Biological Sciences, Area of Ecology and Biodiversity, Swire Institute of Marine Science, Institute for Climate and Carbon Neutrality, Musketeers Foundation Institute of Data Science, and State Key Laboratory of Marine Pollution, The University of Hong Kong, Kadoorie Biological Sciences Building, Hong Kong, China

Moriaki Yasuhara

Biosecurity Research Initiative at St Catharine’s (BioRISC), St Catharine’s College, University of Cambridge, Cambridge, UK

William J. Sutherland

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Contributions

J.E.H.-R. and A.T. contributed equally to the manuscript. J.E.H.-R., A.T. and W.J.S. devised, organized and led the Marine and Coastal Horizon Scan. D.J.A., S.N.R.B., I.M.C., M.P.D., B.J.G., S.A.K., E.M. and L.S.P. formed the core team and are listed alphabetically in the author list. All other authors, R.C., O.D., S.D., E.L.J., H.K., P.I.M., A.M., A.W.N.M., D.O.O., D.M.P., A.R.P., A.J.R., I.R.S., P.V.R.S., B.D.S., P.M.T., G.J.W., T.A.W. and M.Y. are listed alphabetically. All authors contributed to and participated in the process and all were involved in writing and editing the manuscript.

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Correspondence to James E. Herbert-Read or Ann Thornton .

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Issue number, final rank and proportion heard of for each issue in round 1 and round 2.

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Herbert-Read, J.E., Thornton, A., Amon, D.J. et al. A global horizon scan of issues impacting marine and coastal biodiversity conservation. Nat Ecol Evol 6 , 1262–1270 (2022). https://doi.org/10.1038/s41559-022-01812-0

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Issue Date : September 2022

DOI : https://doi.org/10.1038/s41559-022-01812-0

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Cleaning up plastic pollution in marine environ : a case study of Australian waters’

Plastic production, consumption, and subsequent management of plastic debris is one of the major environmental issues facing global society. Marine plastic pollution is extensively acknowledged as a severe anthropogenic threat to marine environments. Due to their low costs and great functional capabilities, plastics have become exceptionally essential in modern economies. For instance, the coronavirus disease (COVID-19) is a great illustration of the benefits and drawbacks of plastic use. Personal protective equipment such as face shields and medical equipment such as syringes are made of single-use plastics to help protect people worldwide, however, after their use, sustainable disposal and potential reuse is challenging. Research has documented their existence in oceans. Although plastic is consumed worldwide, the magnitude of waste mismanagement and pollution varies greatly across regions. Most of the global plastic debris is generated by high-income countries where per capita plastic consumption is particularly high. Over time, the control of the massive increase in plastic debris has proven challenging. Waste mismanagement has tremendously exacerbated the likelihood of plastic leakage, particularly into the oceans where options for removal are extremely limited. Globally, marine plastic debris is found across beaches, floating on the ocean surface and in the water column, on deep ocean floors, inside marine wildlife, and frozen within polar ice. The commonly documented impacts of marine plastic pollution are detrimental effects on human health, wildlife, marine ecosystems, ocean waters, maritime activities as well as coastal economies. In addition, plastics in marine environments degrade and progressively fragment into smaller particles, microplastics, which further exacerbate the adverse effects of marine plastic pollution. Given the growing awareness of marine plastic pollution, governments are investing more resources in the development and implementation of policies and strategies to effectively manage and minimise this pollution and its related effects. A shift from the traditional linear economy of ‘take-make-dispose’ to a circular economy of ‘efficient resource use through a closed-loop system’ which aims to reduce waste and keep resources in use infinitely to promote sustainable development has increasingly gained attention from scholars, practitioners and policy makers. In Australia, plastic pollution in the oceans is the most serious environmental threat to marine life after climate change. Australia’s marine environment is the world’s third largest marine jurisdiction which is home to a diverse array of marine species. Marine plastics are having an adverse impact on Australian marine waters with entanglement, ingestion, transportation of invasive species, seafood contamination, and reduced tourism revenue. To combat marine plastic pollution, Australia's Commonwealth government has developed a roadmap for transition from a linear economy to a circular economy for plastics at the national and state levels, to contribute to the Sustainable Development Goals (SDG) 14 and 12. However, the proposed or implemented policies, in Australia’s National Plastic Plan of 2021, aimed at promoting the transition from a linear to circular economy have been explored largely from a production or government policy perspective and less effort has focussed on the preferences of consumers and the wider society. A circular economy for plastics requires a participatory approach, and households are the largest source of municipal plastic debris in Australia, therefore, this information helps policymakers prioritise initiatives. The overall aim of the thesis is to provide meaningful insights into the management of marine plastic pollution especially preferences for addressing marine plastic pollution and contribute to creating a circular economy in plastics. This thesis employs a number of methods to add to the environmental economics literature on this topic. The thesis begins with a general introduction to contextualise the problem. To understand the abundance of marine plastic pollution in oceans, Chapter Two presents a global review of literature on the abundance and distribution of microplastics across surface waters of the five world’s oceans including the Pacific, Atlantic, Indian, Arctic and Southern (Antarctic) Oceans. Using a systematic review approach, this chapter reviews a global dataset derived from 45 primary studies undertaken since the year 2010 following the Oslo and Paris Conventions (OSPAR) guidelines, under the North-East Atlantic Marine Environment Strategy Convention, to monitor and harmonize data collection about marine debris. The results are heterogeneous in terms of the concentration and distribution of microplastics in surface waters in the oceans. Chapter Three presents a global overview with a meta-analysis of Willingness to Pay (WTP) to clean up coastal plastic debris. Over the years, researchers have estimated WTP for the reduction of beach debris using non-market valuation methods. This chapter utilises a worldwide dataset of 63 primary studies over 22 years to evaluate the overall effect size and assess the variability in the WTP estimates. The findings show that people are willing to pay $US0.71 per person per year for a one per cent reduction in beach debris. The observed heterogeneity in WTP estimates is associated with elicitation methods used, beach attributes, geographic locations, and per-capita income. To assess the public perceptions of the outlined circular economy policies in the reduction of marine plastic pollution in Australian marine waters, a multi-state Discrete Choice Experiment (DCE) survey was conducted across six states in Australia (n=1274) and the data was utilized for analysis in chapters four and five. Chapter four identifies policy strategies that align with the 4R framework (Reduce, Recycle or Reuse and Recover) of a circular economy for plastics and Australia’s National Plastic Plan of 2021 to estimate the WTP for the reduction of plastics in Australian marine waters using a full correlation Multinomial Logit model— estimated in WTP space. The results indicate a preference for Redesigning (Reduce) and Recovering approaches over Recycling or Reuse policies. Attitudes are thought to influence behavioural intentions and choices but there are limits to the number of attitudinal scales which could be used in a survey. A common media image associated with marine plastics involves entangled marine life or the impact of ingested plastic on marine life. In Chapter Four, the influence of attitudes towards animals on choices is explored through the Animal Attitude Scale (AAS), a 20-item scale on animal welfare. Chapter five utilises a Hybrid Choice Model (HCM) to estimate the influence of positive attitudes toward animal welfare on WTP to support circular economy policies. The findings indicate that a positive attitude towards animal welfare is associated with age, gender and membership in an environmental organisation, and influences respondents’ WTP for Ocean clean-ups initiatives aimed at reducing marine plastic pollution. Overall, this thesis highlights the importance of developing reliable and standardised methods to enable efficient data comparisons of marine debris information at global, regional and national scales for government agencies. For researchers, these definitions would facilitate data comparability and reproducibility through benefit transfers in meta-analysis. The findings from the estimated WTP for circular economy-based initiatives could assist policymakers in their assessment and decision-making processes as Australia transitions to a sustainable circular economy for plastics. In a broader context, these findings could inform future approaches for strengthening the efforts and resources invested in circular economy strategies for the management of marine plastic pollution.

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• About USAID’s Urban Work

Case Study: Marine Plastic Debris and Solid Waste Management in Peru

The negative impact of plastic debris on marine ecosystems and species is a global challenge. While the causes vary by region, most scientists agree that poor solid waste management is a leading factor.

Click here to open the Spanish version of the Case Study

 Introduction

The negative impact of plastic debris on marine ecosystems and species is a global challenge. While the causes vary by region, most scientists agree that poor solid waste management is a leading factor. This is particularly true in the developing world, where infrastructure has not kept pace with economic growth. For the past several years, a range of public and private sector partners in Peru have worked to improve solid waste management—for human well-being and to reduce threats to marine ecosystems. Their work offers insight into effective strategies while also illuminating gaps in key data on the impact of plastic pollution on marine biodiversity. This case study includes a look at the challenges facing Peru, the strategies undertaken to date, and the types of additional data and interventions required to address this global issue at the local and national level.

The Global Challenge

Plastic debris is a persistent and ubiquitous global issue threatening marine life throughout the world’s oceans (Thevenon, Carroll and Sousa 2014; Jambeck, et al. 2015; Boucher and Friot 2017; The CADMUS Group 2018). Global plastic production has increased significantly, with more than 300 million metric tons of plastics currently produced annually, compared to 1.5 million metric tons in 1950 (Boucher and Friot 2017). As plastic consumption increases, so does solid waste and, ultimately, marine debris. Currently, plastic debris can be found in a wide range of sizes: from nanoplastics and microplastics, such as the ones used in synthetic textiles and tires (Ibid), to macroplastics, such as plastic bags.

A significant portion of marine plastic pollution is generated inland and transported to the coastal areas through rivers (Lebreton et al. 2017) and runoff (Boucher and Friot 2017). Industrial fisheries also contribute to marine plastic debris (Luna-Jorquera et al. 2019). On a global scale, the most significant polluting rivers are located in Asia (Lebreton, et al. 2019). Rivers in South America account for an estimated 4.8 percent of the river mass plastic input to the oceans (Ibid).

Most plastic debris remains near coastal areas for years, degrading ecosystems key to economic and human health. Over time, debris can be degraded and transported by ocean currents to open waters and gyres, where particles accumulate and create “garbage patches” (Lebreton, Egger, and Slat 2019; Thiel, et al. 2018). Plastics in the South Pacific Subtropical Gyre (SPSG) largely originate from debris in the coastal waters of the Humboldt Current, spanning across the coast of Chile and Peru (Thiel, et al. 2018). Marine protected areas located near the five oceanic gyres and garbage accumulation points are at risk of receiving large amounts of marine plastic debris, undermining efforts to protect local wildlife (Luna-Jorquera, et al. 2019).

Plastic debris has negative effects on marine wildlife, including entanglement, ingestion, the transport of invasive species, and toxic pollutants (Thevenon, Carroll, and Sousa 2014). Microplastics have been reported in a wide range of marine taxa, including amphipods living in six of the deepest marine ecosystems on Earth (Thiel et al., 2018; Jamieson, et al. 2019), pointing at the ubiquitous distribution of these particles. However, a nuanced understanding of the impact of plastic on the biology of specific marine species is still poorly understood. The risk of exposure to plastics and microplastics depends on the distribution and abundance of the plastics and the biology of the species (Thiel et al. 2018).

Until scientists collect more data on the impact of marine debris on species and ecosystems, public and private sector institutions are focusing on better solid waste management upstream to reduce the flow of plastic pollution. Of the 6,300 million metric tons of plastic waste produced globally as of 2015, 9 percent has been recycled, 12 percent has been incinerated, and about 79 percent has accumulated in landfills or in the natural environment (Geyer et al. 2017). At the current trend, 12 billion tons of plastic waste will accumulate in landfills and the natural environment by 2050 (Idem).

In many developing countries, the consumption of disposable goods has increased at a higher rate than the development of proper waste management practices and infrastructure (Jambeck, et al. 2015). Developing sustainable waste management systems requires several key strategies, including strengthening the capacity of public waste management authorities; closing the infrastructure gap; partnering with and building the capacity of the private sector and civil society organizations; and implementing adequate laws, regulations, and standards (The Cadmus Group 2018). Countries, including Peru, are increasingly taking bold measures to tackle plastic pollution. With over 3,000 km of coastline and home to some of the most polluted beaches in Latin America, Peru provides a model to better understand the relationship between marine plastic debris and solid waste management, and the types of interventions having a positive impact.

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Plastic trash litters the waters of a fishing village in the Niger Delta of Nigeria. Plastic pollution is only one type of pollution that harms the marine environment.

Marine pollution, explained

A wide range of pollution—from plastic pollution to light pollution—affects marine ecosystems.

THE OCEANS ARE so vast and deep that until fairly recently, it was widely assumed that no matter how much trash and chemicals humans dumped into them, the effects would be negligible.

Today, we need look no further than the New Jersey-size dead zone that forms each summer in the Gulf of Mexico, or the thousand-mile-wide belt of plastic trash in the northern Pacific Ocean to see that this early “policy” placed a once flourishing ocean ecosystem on the brink of collapse.

Many “flavors” of marine pollution

Ocean water covers more than 70 percent of the Earth, and only in recent decades have we begun to understand how humans impact this watery habitat. Marine pollution, as distinct from overall water pollution , focuses on human-created products that enter the ocean.

Before 1972 , humans around the word spewed trash, sewage sludge, and chemical, industrial, and radioactive wastes into the ocean with impunity. Millions of tons of heavy metals and chemical contaminants, along with thousands of containers of radioactive waste, were purposely thrown into the ocean.

The London Convention , ratified in 1975 by the United States, was the first international agreement to spell out better protection for the marine environment. The agreement implemented regulatory programs and prohibited the disposal of hazardous materials at sea. An updated agreement, the London Protocol , went into effect in 2006, more specifically banning all wastes and materials except for a short list of items, like leftover materials from dredging.

Many of these pollutants sink to the ocean's depths or float far distances from their original source, where they are consumed by small marine organisms and introduced into the global food chain . Marine pollution encompasses many types of pollution that disrupt the marine ecosystem, including chemical, light, noise, and plastic pollution.

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Chemical pollution.

Chemical pollution is the introduction of harmful contaminants. Common man-made pollutants that reach the ocean include pesticides, herbicides, fertilizers, detergents, oil, industrial chemicals, and sewage.

Many ocean pollutants are released into the environment far upstream from coastlines. Nutrient-packed fertilizers applied to farmland, for example, often end up in local streams and are eventually deposited into estuaries and bays. These excess nutrients trigger massive blooms of algae that rob the water of oxygen, leaving dead zones where few marine organisms can live. Some chemical pollutants climb high into the food webs—like DDT, the insecticide that placed the bald eagle on the United States Fish and Wildlife’s endangered species list .

Scientists are starting to better understand how specific pollutants, leached into the ocean from other materials, affect marine wildlife. PFAS , a chemical incorporated into many household products, accumulates in human and marine mammal blood. Even pharmaceuticals ingested by humans, but not fully processed by our bodies, end up in aquatic food webs .

Light pollution

Since the invention of the lightbulb, light has spread across the globe , reaching almost every ecosystem. Often thought of as a terrestrial problem, scientists are starting to understand how artificial light at night affects many marine organisms.

Light pollution penetrates under the water, creating a vastly different world for fish living in shallow reefs near urban environments. Light disrupts the normal cues associated with circadian rhythms , to which species have evolved timing of migration, reproducing, and feeding. Artificial light at night can make it easier for predators to find smaller fish prey and can affect breeding in reef fish .

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Noise pollution.

Pollution is not always visible. In large bodies of water, sound waves can carry undiminished for miles. The increased presence of loud or persistent sounds from ships, sonar devices, and oil rigs disrupts natural noises in the marine environment.

For many marine mammals, like whales and dolphins, low visibility and large distances make non-visual underwater communication critical . Toothed whales use echolocation—emitting sounds that reflect off surfaces—to help them “see” in the ocean. Unnatural noises interrupt communication , disrupting migration, communication, hunting, and reproduction patterns for many marine animals.

Plastic pollution

Plastic pollution seeps into the ocean through run-off and even purposeful dumping. The amount of plastic in the Atlantic Ocean has tripled since the 1960s . The garbage patch floating in the Pacific Ocean , almost 620,000 square miles— twice the size of Texas —is a powerful image of our plastic problem.

A huge culprit is single-use plastics, used once before tossed into the trash or directly into the ocean. These single-use items are accidentally consumed by many marine mammals. Plastic bags resemble jellyfish , a common food for sea turtles, while some seabirds eat plastic because it releases a chemical that makes it smell like its natural food. Discarded fishing nets drift for years, ensnaring fish and mammals.

Bits of plastic swirl throughout the water column, even sinking to the deepest depths of the ocean . Scientists found plastic fibers in corals in the Atlantic Ocean—and more concerning, they found that the corals readily ate plastic over food . Dying marine mammals, washing up on shore, also contain plastic inside their stomachs .

Related: see photos from marine protected areas

Is there a “fix” to marine pollution?

Many national laws, as well as international agreements, now forbid dumping of harmful materials into the ocean, although enforcing these regulations remains a challenge.

Many pollutants still persist in the environment, difficult to fully remove. Chemical pollutants often cannot be broken down for long periods of time, or they increase in concentration as they move up the food web. Because plastic is thought to take hundreds of years to break down, it poses a threat to the marine environment for centuries .

Isolated efforts to restore estuaries and bays have met with some success , but pollution gets trapped in marine sediment and makes complete clean-ups nearly impossible.

Moving forward, encouraging recycling and reuse can minimize plastic pollution. Dampening unnecessary lights at night can limit light pollution. And encouraging responsible chemical-use through consumer and political actions can protect the environment for the future.

Related Topics

• WATER POLLUTION

Microplastics are in our bodies. How much do they harm us?

Can air pollution cause inflammation? Scientists are starting to unravel the connection.

How a dramatic win in plastic waste case may curb ocean pollution

California’s sweeping new plastics law could be a game changer

The world’s nations agree to fix the plastic waste crisis

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Plastic pollution on course to double by 2030 

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Plastic pollution in oceans and other bodies of water continues to grow sharply and could more than double by 2030, according to an  assessment  released on Thursday by the UN Environment Programme ( UNEP ). 

The report highlights dire consequences for health, the economy, biodiversity and the climate. It also says a drastic reduction in unnecessary, avoidable and problematic plastic, is crucial to addressing the global pollution crisis overall.  

To help reduce plastic waste at the needed scale, it proposes an accelerated transition from fossil fuels to renewable energies, the removal of subsidies and a shift towards more circular approaches towards reduction. 

Titled  From Pollution to Solution: a global assessment of marine litter and plastic pollution , the report shows that there is a growing threat, across all ecosystems, from source to sea. 

Solutions to hand 

Our oceans are full of plastic. A new @ UNEP assessment provides a strong scientific case for the urgency to act, and for collective action to protect and restore our oceans from source to sea. #CleanSeas https://t.co/97DMOZD3Ee pic.twitter.com/3xjthnsTh2 Inger Andersen andersen_inger

But it also shows that there is the know-how to reverse the mounting crisis, provided the political will is there, and urgent action is taken. 

The document is being released 10 days ahead of the start of the crucial UN Climate Conference,  COP26 , stressing that plastics are a climate problem as well.  

For example, in 2015, greenhouse gas emissions from plastics were 1.7 gigatonnes of CO2 equivalent; by 2050, they’re projected to increase to approximately 6.5 gigatonnes. That number represents 15 per cent of the whole global carbon budget - the​​ amount of greenhouse gas that can be emitted, while still keeping warming within the Paris Agreement goals. 

Recycling not enough 

Addressing solutions to the problem, the authors pour cold water on the chances of recycling our way out of the plastic pollution crisis. 

They also warn against damaging alternatives, such as bio-based or biodegradable plastics, which currently pose a threat similar to conventional plastics. 

The report looks at critical market failures, such as the low price of virgin fossil fuel feedstocks (any renewable biological material that can be used directly as a fuel) compared to recycled materials, disjointed efforts in informal and formal plastic waste management, and the lack of consensus on global solutions. 

Instead, the assessment calls for the immediate reduction in plastic production and consumption, and encourages a transformation across the whole value chain. 

It also asks for investments in far more robust and effective monitoring systems to identify the sources, scale and fate of plastic. Ultimately, a shift to circular approaches and more alternatives are necessary.  

Making the case for change 

For the Executive Director of UNEP, Inger Andersen, this assessment “provides the strongest scientific argument to date for the urgency to act, and for collective action to protect and restore our oceans, from source to sea.” 

She said that a major concern is what happens with breakdown products, such as microplastics and chemical additives, which are known to be toxic and hazardous to human and wildlife health and ecosystems. 

“The speed at which ocean plastic pollution is capturing public attention is encouraging. It is vital that we use this momentum to focus on the opportunities for a clean, healthy and resilient ocean”, Ms. Andersen argued.  

Growing problem 

Currently, plastic accounts for 85 per cent of all marine litter. 

By 2040, it will nearly triple, adding 23-37 million metric tons of waste into the ocean per year. This means about 50kg of plastic per meter of coastline. 

Because of this, all marine life, from plankton and shellfish; to birds, turtles and mammals; faces the grave risk of toxification, behavioral disorder, starvation and suffocation. 

The human body is similarly vulnerable. Plastics are ingested through seafood, drinks and even common salt. They also penetrate the skin and are inhaled when suspended in the air. 

In water sources, this type of pollution can cause hormonal changes, developmental disorders, reproductive abnormalities and even cancer. 

According to the report, there are also significant consequences for the global economy. 

Globally, when accounting for impacts on tourism, fisheries and aquaculture, together with the price of projects such as clean-ups, the costs were estimated to be six to 19 billion dollars per year, during 2018. 

By 2040, there could be a $100 billion annual financial risk for businesses if governments require them to cover waste management costs. It can also lead to a rise in illegal domestic and international waste disposal. 

The report will inform discussions at the  UN Environment Assembly  in 2022, where countries will come together to decide a way forward for more global cooperation. 

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• Science & Case Studies
• Where the Rubber Meets the Road: Opportunities to Address Tire Wear Particles in Waterways (2023)

Report on Priority Microplastics Research Needs: Update to the 2017 Microplastics Expert Workshop

• Microplastics Expert Workshop Report  (2017)

State of the Science White Paper: A Summary of the Effects of Plastics Pollution on Aquatic Life and Aquatic-Dependent Wildlife

• Summary of Expert Discussion Forum on Possible Human Health Risks from Microplastics in the Marine Environment

Tern Island Preliminary Assessment and Technical Support Document

EPA conducts analysis and research to address important issues related to the potential health, ecological, and socio-economic impacts of trash and debris in the aquatic environment.

Where the Rubber Meets the Road: Opportunities to Address Tire Wear Particles in Waterways 

EPA’s Trash Free Waters (TFW) program announces the publication of  “Where the Rubber Meets the Road: Opportunities to Address Tire Wear Particles in Waterways.”  Tire wear particles as a pollutant in waterways is a relatively new field of study without standardized terminology, assessment methodologies, or established solutions. The emergence of tire wear particles as a significant category of microplastics found in waterways prompted EPA to convene stakeholders in two roundtable discussions in Spring 2022 to facilitate shared learning about the challenges of addressing the problem of tire wear particle pollution. Stakeholders represented diverse perspectives on the nature of the problem and how to effectively address it. The roundtables provided a forum for discussion among participants without committing to a specific course of action. Participants discussed a set of questions aimed at understanding the barriers to and opportunities for managing tire wear particles in waterways. This brief report summarizes the roundtable discussions. In producing it, EPA seeks to share the challenges and potential solutions discussed during the roundtables, in order to inform the public and broaden the community engaged in addressing tire wear particle pollution.

• View the Report:  Where the Rubber Meets the Road (pdf) (835 KB, April 2023, EPA-830-S-23-001)

In June 2017, the U.S. Environmental Protection Agency (EPA) Trash Free Waters Program convened a workshop that brought together subject matter experts (SME) in the fields of environmental monitoring, waste management, toxicology, ecological assessments, and human health assessments to discuss and summarize the risks posed by microplastics to ecological and human health (See "Microplastics Expert Workshop Report" below). The resulting workshop report outlined priority scientific information needs within four broad categories of research: Field and analytical methods; sources, transport, and fate; ecological assessments; and human health assessments.

The EPA Trash Free Waters Program has updated the 2017 Microplastics Expert Workshop (MEW) report to assist the scientific research and funding communities in identifying information gaps and emerging areas of interest within microplastics research. This report  includes a status update on the state of the science for each of the four categories listed above, informed by conversations with SMEs and a targeted review of the peer-reviewed literature.

• View the Report: A Trash Free Waters Report on Priority Microplastics Research Needs: Update to the 2017 Microplastics Expert Workshop (pdf) (2.1 MB, December 2021, EPA-842-R-21-005)

Microplastics Expert Workshop Report

The EPA Trash Free Waters program convened a Microplastics Expert Workshop (MEW) on June 28-29, 2017 to identify and prioritize the scientific information needed to understand the risks posed by microplastics to human and ecological health. The workshop gave priority to gaining greater understanding of these risks, while recognizing that there are many research gaps needing to be addressed and scientific uncertainties existing around microplastics risk management.  The workshop participants adopted a risk assessment-based approach and addressed four major topics: 1) microplastics methods, including deficits and needs; 2) microplastics sources, transport and fate; and 3) the ecological and 4) human health risks of microplastics exposure.  Workshop participants recommended developed detailed conceptual models to illustrate the fate of microplastics from source to receptor and assess the ecological and human health risks of microplastics, the degree to which information is available for each, and the interconnections among these uncertainties.  The expert panelists did not provide recommendations for specific regulatory or non-regulatory actions to be taken. This document presents a summary of the expert panel discussion.

• View the Report

Plastics have become a pervasive problem in oceans, coasts, and inland watersheds. Recent estimates suggest that 4.8 to 12.7 million metric tons of plastic waste entered the global marine environment in 2010. Areas of accumulation of plastic debris include enclosed basins, ocean gyres, and bottom sediments. Plastics in the aquatic environment primarily originate from land-based sources such as littering and wind-blown debris, though plastic debris from fishing activities may be a key source in some areas. Plastic particles are generally the most abundant type of debris encountered in the marine environment, with estimates suggesting that 60% to 80% of marine debris is plastic, and more than 90% of all floating debris particles are plastic. This document is a state-of-the-science review – one that summarizes available scientific information on the effects of chemicals associated with plastic pollution and their potential impacts on aquatic life and aquatic-dependent wildlife.

Summary of Expert Discussion Forum on Possible Human Health Risks from Microplastics in the Marine Environment

The EPA Trash Free Waters program convened a panel of scientific experts on April 23, 2014. The purpose of the forum was to discuss available data and studies on the issue of possible human health risks from microplastics in the marine environment. The participating subject matter experts were asked to provide insights on the current scientific basis for determining human health risks, based on a review of scientific research done to date. The experts also were asked to identify data gaps and make suggestions for further study. The expert panelists did not provide recommendations for specific regulatory or non-regulatory actions to be taken. This document presents a summary of the expert panel discussion.

In September 2014, EPA and the U.S. Fish and Wildlife Service released an initial assessment of contamination at Tern Island, a remote island in the chain of Northwestern Hawaiian Islands (NWHI). The results show that there have been releases of hazardous substances such as polychlorinated biphenyls (PCBs) and lead from military wastes buried on the island between World War II and 1979, and further action is warranted.

• View the report
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  maritime law virtual database, marine environmental pollution.

Moses v MV Sea Chase [2001] FMSC 56; 10 FSM Intrm. 45 (Chk. 2001) (15 February 2001)

Marine Environmental Pollution- Only State allowed to collect under Environmental Protection Act- Vessel must be under court’s control in order to exercise in rem jurisdiction- Common law prohibits 3rd party action against insurer.

The defendant vessel ran aground on a reef. The reef was damaged and petroleum products spilled. The vessel was salvaged and was no longer on the reef. The plaintiffs including a person claiming ownership of the reef, and the municipal government claiming the reef as part of its municipality sought compensation for damage to the reef system as a result of negligent navigation. The plaintiffs included the vessel’s insurer as well as the vessel among the defendants. The defendants filed a number of motions to dismiss the action. DECISION: Action for $100,000 per day damages pursuant to Chuuk State Environmental Protection Act dismissed. In rem action against vessel dismissed. Claim against insurer dismissed. HELD: The plaintiffs relied on s.8(1) of the Chuuk State Environmental Protection Actin their claim for $100,000 per day for damage to the reef. The court stated that the penalty created under the Act may only be asserted and collected by the Chuuk Environmental Protection Agency. The claim against the vessel was dismissed because the vessel had not been seized by court process and was no longer in the jurisdiction. Thus the court could not exercise in rem jurisdiction over the vessel. The claim against the vessel’s insurer was dismissed. As a general rule common law prohibits actions by a 3rd party against an insurer absent some statute or contractual provision.

People of Rull ex rel Ruepong v MV Kyowa Violet [2006] FMSC 53; 14 FSM Intrm. 403 (Yap. 2006) (21 September 2006)

The defendant vessel struck a reef while navigating a channel into the lagoon. The reef was damaged, and fuel leaked from oil tanks into the lagoon. A cleanup effort was undertaken but all of the oil could not be removed, especially along the mangroves. There was a ban which lasted for 5 months on the use of the lagoon which affected swimming, fishing and shelling. A class action suit was brought by 3 traditional chiefs as representatives of the people of the coastal municipalities. The plaintiffs sought compensation for physical damage to the reef structure and resources asserting that the reef was subject to traditional ownership and use by the residents of the coastal municipalities; and compensation for the effects of the oil spill including the inability to use the resources of the inner lagoon as well as for injuries to the natural resources themselves. The action was brought in rem against the vessel and in personem against the vessel owner, the vessel’s charterer and the vessel’s owner. The claim was for compensation was based in negligence, and public and private nuisance. DECISION: Claims in negligence and nuisance allowed. Damages were awarded for damage to reef, mangroves and marine resources, and loss of use. Compensation was denied for mental anguish, and loss of swimming opportunity. HELD: A cause of action is available in maritime negligence for recovery of damages resulting from groundings and oil spills. Causation in maritime tort law is similar to the common law causation principle: “An injury is proximately caused by an act, or failure to act, whenever it appears from the evidence that the act or omission played a substantial part in bringing about or actually causing the injury or damage, and that the injury or damage was either a direct result or a reasonably probable consequence of the act or omission.” Fornier v. Petroleum Helicopters, Inc., 665 F. Supp. 483, 486 (E.D. La. 1987) (proximate cause standard generally applicable in maritime tort cases); see also Lebehn v. Mobil Oil Micronesia, Inc., 10 FSM Intrm. 348, 353 (Pon. 2001). The vessel breached its duty to safely navigate the channel and that caused the fuel oil spill which damaged the plaintiffs’ marine resources. Damages were also available in private nuisance because the plaintiffs suffered substantial interference with the use and enjoyment of their property as a result of the defendants’ improper navigation which could be characterized as negligent or reckless. The claim in public nuisance was also successful, the court finding that the plaintiffs suffered damages different in kind from that suffered by the public at large.3

People of Satawal ex rel Ramoloilug v Mina Maru No 3 [2001] FMSC 24; 10 FSM Intrm. 337 (Yap 2001) (20 July 2001)

Marine Environmental Pollution- Determination of quantum of damages awarded as a result of reef grounding.

The case arose out of a reef grounding. The plaintiffs sought compensation for damage to the nearby reef that was the source of the community’s fish supply. The productivity of the reef was diminished following the grounding. Additionally there were incidents of ciquatera poisoning from eating the fish and this may have been the result of the damage to the reef. The plaintiffs were granted summary judgement and there was a hearing to determine damages. The court considered various means of monetary valuation including commodity values, tourism value and replacement value. The court also considered the amount of compensation awarded in a previous grounding. Expert testimony was relied upon to determine damages. Cost of clean up was also awarded.

People of Welroy ex rel Pong v MV CEC Ace [2007] FMSC 28; 15 FSM Intrm. 151 (Yap. 2007) (29 June 2007)

Marine Environment Pollution- Class certification for class action- Reef grounding- Damage to traditional resources.

The defendant vessel grounded on the reef. The plaintiffs named 3 chiefs to maintain the action as a class action and alleged 6 causes action: maritime negligence, infliction of emotional distress, unseaworthiness of the vessel, trespass, nuisance (public and private) and punitive damages. There were 2 classes of plaintiffs- all residents of the affected community and those who owned the natural resources by tradition. The plaintiffs filed a motion for Class Certification. DECISION: Plaintiffs who owned the resources by tradition were granted conditional certification for all causes of action except for the infliction of emotional distress claims HELD: Only the class of plaintiffs who had traditional rights to the resources were considered for certification because they were the only class that was represented by a named plaintiff of that class. The court found the requisite commonality to the class where the common questions as to liability predominated over individual questions. The court did not include the emotional distress claim because the complaint did not allege that the class as a whole suffered a common physical injury. The certification was conditional upon the court receiving more information of the potential number of affected residents to confirm the numerosity requirement; and the court also required further evidence that the named plaintiffs were adequate class representatives especially in light of the fact that only one class of plaintiffs was considered for certification.

Pohnpei v KSVI No 3 [2001] FMSC 58; 10 FSM Intrm. 53 (Pon. 2001) (16 February 2001)

Marine Environmental Pollution- State is party to recover for losses suffered as a result of reef grounding.

A vessel grounded on the outside edge of the reef which surrounds Pohnpei. The state of Pohnpei and the municipality of Kitti filed separate complaints seeking compensation for damage to the reef, submerged lands and marine resources. The state filed a motion to dismiss the municipality’s complaint stating that the state was entitled to damages from the grounding because the state is the owner of the reef, submerged lands and affected marine resources. The parties requested that the court determine before trial the legal ownership of the submerged areas allegedly damaged by the grounding. DECISION: Pohnpei is the legal owner of the submerged lands and living resources and is the party entitled to recover for any injury to these resources. Motion to dismiss not granted because municipality may be able to recover other losses (such as damaged nets and traps). HELD: The court looked to the Constitution to decide that the state was the owner of the submerged reef and marine resources. However the Constitution also guaranteed traditional rights to fishing and to the use of the marine resources. As such, damages recovered by the state for injury to this property should be placed in a trust for the people and the funds are to be used to repair harm done to damaged areas. The municipality failed to define the specific group within a specific area that had suffered the loss as a result of the grounding. The municipality had no general right to recovery for damages to the reef whose ownership rested in the state.

Rabaul Shipping Ltd v Rupen, General Manager, National Maritime Safety Authority [2008] PGNC 162; N3513 (23 October 2008)

Marine Environmental Pollution- Protection of the Sea (Shipping Levy Act) No. 8 of 2003- Interpretation of “ship”

The plaintiff sought the court’s interpretation of the word “ship” as used in the Protection of the Sea (Shipping Levy Act) No. 8 of 2003. DECISION: The plaintiff’s vessel does not come within the meaning of the Act and does not attract levy. HELD: The vessel may carry oil for its use in the operation and running of the vessel. The plaintiff’s vessel does not actually carry oil in bulk as cargo and therefore does not come within the purview of the Act.

Tupa v Ravuso and Tupa v Taio Shipping Services Ltd [1997] CKHC 1; Cr 288.1997 and Cr 290.1997 (21 August 1997)

Marine Environmental Pollution- Quantum of fine for oil discharge in territorial waters- circumstances considered

The was an accidental discharge of diesel oil into the harbour. The court considered the amount of fine which should be levied under the legislation. The maximum fine was $200,000. DECISION: Fine of $1,000. HELD: The court treated the discharge seriously but there were a number of factors that kept the amount of the fine at the lower end. The oil discharged was diesel oil and not the more damaging heavy oil. There was no appearance of gross negligence. It was a new vessel and the discharge arose out of lack of knowledge of the vessel’s operation. There was no discernable damage caused as the oil drifted out to sea.

Wardens’ Court at Jaba River; ex parte Bougainville Copper Pty. Ltd., Regina v [1971] PGSC 48; [1971-72] PNGLR 11 (4 December 1970)

Marine Environmental Pollution- Lump sum payment appropriate for loss of fishing rights over long term mining contract

The Wardens’ Court had awarded periodic payments of 1500 pounds of fish per year for the duration of a 42 year mining lease to the clan whose fishing had been affected by the mining company’s operations. This was purportedly pursuant to the Mining (Bougainville Copper Agreement) Ordinance 1967. The mining company sought to have the order quashed. DECISION: Order quashed. HELD: It was not clear that the Wardens’ Court acted under the correct provision of the legislation. There was a failure to clearly identify and specify the persons on whose behalf the award for compensation was made. Compensation was not necessarily tied to the duration of the lease. The compensation was for the loss of a right and would be more properly paid in a lump sum.

Yap v MV Cecilia I [2005] FMSC 41; 13 FSM Intrm. 403 (Yap 2005) (19 September 2005)

Marine Environmental Pollution- Charterparties- Pollution offences alleged against charterer and owner of vessel- Court gains no personal jurisdiction over vessel owner on basis of bareboat charter

There were 5 causes of action all based on a central allegation that the vessel had on numerous occasions discharged petroleum based effluent. The vessel was under a bareboat charter between the defendant owner and the defendant charterer. The defendant owner served a motion to dismiss for lack of personal jurisdiction on the basis that he had no control over the vessel and he lacked the minimum contacts with the forum sufficient to subject to the court’s jurisdiction. DECISION: Motion granted HELD: Under a demise or bareboat charter the charterer takes complete control of the vessel, mans it with its own crew and is treated by law as its legal owner. The charterer is potentially liable for collision, personal injury to master, crew and third parties, pollution damages, and for the loss or damage to the chartered vessel. Vessel owners normally have no personal liability but the vessel may be liable in rem. As such, the existence of the bareboat charter did not bring the owner into the court’s jurisdiction either on the basis of ‘doing business’ provision of the long arm statute, or under the provision based on the operation of the vessel within territorial waters.

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Indian Journal of Science and Technology

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DOI : 10.17485/ijst/2011/v4i3.9

Year : 2011, Volume : 4, Issue : 3, Pages : 259-262

Original Article

Impact of pollution on marine environment -A case study of coastal Chennai

A. Duraisamy 1 and S. Latha 2*

1 Department of Economics, Madras Christian College, Chennai, India 2 Department of Economics, D.G. Vaishnav college, Chennai, India [email protected]

*Author for correspondence S. Latha Department of Economics, D.G. Vaishnav college, Chennai, India.   Email: [email protected]

This paper reports the impact of pollution on marine ecosystem; it analyses the factors responsible for degradation and suggests suitable corrective measures. Around the world, marine ecosystems are being threatened, degraded, damaged or destroyed by human activities, one of which is pollution The rapid population growth and enormous urban and coastal development in many of the world's coastal regions have caused considerable concern that anthropogenic pollution may reduce biodiversity and productivity of marine ecosystems, resulting in reduction and depletion of human marine food resources. In addition, pollution reduces the aesthetic value and also the intrinsic value of the marine environment, whether the pollution is visual (such as oil pollution and plastic debris) or invisible (such as chemical compounds). The recent pictures coming out of the oil spills off the Gulf of Mexico in the United States and also the container tanker collision off the Mumbai coast are vivid examples. Another main reason for concern about marine pollution is related to the direct effects of pollution on human health. Because many pollutants accumulate in marine organisms, humans are exposed to pollutants when they consume food from polluted areas. Marine pollution occurs when unsustainable elements gain entry to water masses, potentially causing spread of invasive organisms, diseases and can turn water quality potentially toxic. Most sources of marine pollution are land based, such as wind blown debris, industrial / domestic pollutants discharged and potential spillovers from freight/ bulk ocean carriers. When toxins are concentrated upward within the ocean food chain, many elements combine in a manner highly depletive of oxygen, causing estuaries to become anoxic. As these materials are incorporated into the marine eco system, they quickly become absorbed into marine food webs. Once in the food webs, these cause mutations, as well as diseases, this can be harmful to humans as well as the entire food web. Globalization has brought in its wake increased demand on scarce resources leading to rapid depletion of a wide range of non degradable products viz., metals, plastics, rubber products, which in turn generate huge amounts of solid wastes causing pollution at the entry of marine waters. Besides the coastal regions of India are characterized by slums, with poor sanitation facilities aggravating the problem. Suggestions are offered, both invasive and non invasive which can definitely reduce the burden placed on our valuable resources which may soon vanish unless the counter measures are implemented effectively. Keywords : Marine ecosystem, anthropogenic pollution, estuaries, poor sanitation.

03 April 2020

How to cite this paper

S. Latha, Impact of pollution on marine environment -A case study of coastal Chennai. Indian Journal of Science and Technology. 2011: 4(3).

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Impacts of noise pollution from high-speed rail and road on bird diversity: a case study in a protected area of Italy

• Research Article
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• Published: 20 April 2024

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• Ester Bergamini 1 , 2   na1 ,
• Sofia Prandelli   ORCID: orcid.org/0009-0007-0922-5790 2   na1 ,
• Fausto Minelli 3 &
• Roberto Cazzolla Gatti 2 , 4  

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The disturbance of infrastructures may affect biological communities that are exposed to them. This study assesses the impact of high-speed (highway and railway) infrastructures in a protected study site, the Natural Reserve Fontanili di Corte Valle Re (Emilia–Romagna, Italy). We compared bird diversity with sound intensity and frequency in three sampling areas, increasingly distant from the infrastructures at the border with the reserve, during the last 4 years (2019–2022), monitoring sedentary, nesting, and migratory bird species. We hypothesize a decreasing diversity closer to the source of disturbance, which is mostly attributable to noise pollution. Our findings confirmed this trend, and we show that, in particular, disturbance seems to influence species richness more than the total abundance of birds. We also discovered that highway disturbance was much higher than railway in terms of frequency and duration. In light of these results, we suggest that some species, which have a behavioral ecology strongly based on singing to communicate with each other for their reproductive and defensive strategies, may suffer more from constant acoustic disturbance. The installation of effective noise barriers to shield the sound produced by the highways should be considered a mandatory request not only in proximity to houses but also in the vicinity of protected areas.

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Introduction

Anthropogenic disturbance has been widely studied in ecology since its effects have consequences on communities and their composition (Ausprey et al. 2023 ). According to Pickett et al. ( 1989 ), disturbance can be defined as a change in the ecosystem caused by an external factor to the level of interest. Another well-accepted idea is that disturbance, as every process that causes loss of biomass in a community (Grime 1977 ), also has a negative impact on a community and its elements.

Previous studies showed that the proximity to disturbing infrastructures is one of the biggest causes of biodiversity loss (Van Der Zande et al. 1980 ). In particular, the number of negative effects of roads and railways is high when considering mortality due to vehicle collisions, particularly for reptiles, amphibians, and mammals. Although birds showed contrasting effects on infrastructure’s presence, the impact of the acoustic disturbance may be relevant for these taxa, even if poorly investigated. A recent study from Ausprey et al. shows how any kind of disturbance, in agricultural landscapes, leads to a decline in species and that sensitivities to anthropogenic disturbance are species-specific (Ausprey et al. 2023 ). The decrease in abundance and species diversity in birds is particularly documented at short distances, up to 1 km from the source of disturbance (Benítez-López et al. 2010 ). The disturbance from viable infrastructures is mostly acoustic and its consequences are proportional to the magnitude of the noise. There is preliminary evidence that birds are less affected by train passage, which is discontinuous than by the motor vehicles on the highways, which is quite constant (Wiącek et al. 2015 ). Species that possess communicative skills and base their reproductive behaviors mostly on vocalization are certainly the most affected (Lucas et al. 2017 ). A study conducted by Reijnen and Foppen ( 2006 ) showed that an important level of disturbance, such as big and busy roads, is the main cause of negative abundance trends of birds, compared to the presence of the infrastructure itself.

At the same time, there might be a positive effect that increases bird diversity due to the landscape’s heterogeneity created by roads and railways (Morelli et al. 2014 ; Kajazer-Bonk et al. 2019 ). Close to the infrastructure, woody habitats would be side by side with crops, leading to an increase in the amount of food availability. Moreover, the traffic could lead to a reduction in the number of predators, while artificial light would extend diurnal activities in winter. Having different habitats also means having more nesting sites and chances of hiding (Kajzer-Bonk et al. 2019 ).

This study aims to analyze the impact of acoustic disturbance produced by high-speed road and rail on bird diversity of migratory, nesting, and sedentary species of a protected area in northern Italy. We hypothesize that both species abundance and richness increase with incremental distance from the source of disturbance. On the other hand, we evaluated how the mid-domain effect could lead to a higher abundance and diversity in the core of the reserve and a decrease of them at the edge (Colwell and Lees 2000 ).

Materials and methods

The study was conducted in the bird-ringing site of Natural Reserve Fontanili di Corte Valle Re, in Italy. The site (coordinates 44.7672 N, 10.5328 E) has an area of 37 hectares and is located in the municipality of Campegine (Reggio Emilia). Data were collected at an increasing distance from two big infrastructures: the A1 highway and the high-speed railway Milano–Bologna, both adjacent to the protected area. The presence of specimens was studied for the reproductive and migratory seasons, from autumn 2019 to autumn 2022. The monitoring was done for the MonITRing Project of the National Centre of Ringing (CNI), of the Superior Institute for Environmental Protection and Research (ISPRA).

The protected area is one of the last flatland springs remaining in its natural state. Around the regional Reserve, water crosses cultivated fields and, near the springs, it leads to the growth of hydrophilic plants and reeds. The woods in which nets were located is mainly composed of black alder ( Alnus glutinosa ), grey sallow ( Salix cinerea ), alder buckthorn ( Rhamnus frangula ), black elderberry ( Sambucus nigra ), field elm ( Ulmus minor ), blackthorn ( Prunus spinosa ), English hawthorn ( Crataegus laevigata ), and dogwood ( Cornus sanguinea ). Different microhabitats allow the presence of a rich and varied fauna (Parchi Emilia Centrale 2022 ). The vulnerability of the Reserve, besides the rarity of its flatlands, is due to the closeness to the A1 highway, one of the busiest in Italy, and the adjacent high-speed railroad. The area is also part of the EU Natura 2000 network (Mézard et al., 2009 ) within the Area of ecological restoration Fontanili Media Pianura Reggiana and it is a Site of Community Importance (SCI), in which habitats are protected (Ambiente, Regione Emilia Romagna 2022 ).

Sampling methods and data analysis

The catch of the specimens took place using mist nets that have a mesh size of 16 mm, height of 2.5 m, and width of 12 m. Four of them were placed in three spots hereafter denominated Near, Intermediate, and Far, for a total net length of 48 m in each of them. The three transects were all placed perpendicular to the viable infrastructures and in areas where plant cover and composition are mostly the same.

Highways and railways can be considered the main sources of disturbance since the Reserve has few visitors per year and the trails are far from the nets. The seasonal presence of hunters in the surrounding areas may be considered an additional disturbance factor for the birds and may push them into the Reserve’s core. Distance from the Reserve and high-speed ways was 160 m from the nearest net (Near), 320 m from the intermediate one (Intermediate), and 425 m from the farthest one (Far) (Fig. 1 ). To ensure comparability, we checked that the three areas, although different in shape, have similar vegetation and are surrounded by the same type of agricultural field. One main difference among the three sampling sites is that the Near site is surrounded by a slightly higher forest cover, in an L shape, than the other two sites. We also confirmed that the three sampling points were located in areas with similar vegetation and environmental conditions.

Map of the study site, the regional Natural Reserve Fontanili di Corte Valle Re, with the indication of the three sampling points in which the mist nets were located and the high-speed ways

Acoustic disturbance has been measured in the center of three transects using professional digital phonometers with a range of measures from 30 to 130 dBA and a sensitivity of 0.1 dBA, during optimal weather conditions, without wind or adverse meteorological conditions. The phonometers were set in the center of the three transects, detecting values at the same time for periods of 30 min and three repetitions during the day. We measured the acoustic disturbance in randomly selected days to provide empirical evidence of the differential acoustic impacts in the three sampling areas. We assumed that the acoustic disturbance throughout the year is similar to the average noise detected during the randomly selected days of recordings. We have good reasons to believe that our assumption is correct because the only variable factor is the wind and it is quite unpredictable during the seasons, while the railway and highway traffic noise remains almost constant throughout the year. The measurements returned 3573 records — two measurements every second — for every point, for a total of 10,719. To separate noise pollution caused respectively by railway and highway infrastructure, data were separated by calculating, for each study point, the value corresponding to the 95th percentile, dividing them into average noise values and peak noise values.

Bird captures were made using the standard procedure for birds’ ringing. The nets were opened before sunrise and monitored six times in the following hours. Ancillary data were collected including time of the catch, ring code, recapture, species name, Euring specific code, status, molt, plumage, weight, age, sex, fat, muscle, measurements of tarsus, chord, and third remiges’ length. The equipment included a bird identification guide, rings of various sizes, banding pliers, different rules, and a portable scale. Data has then been transferred to electronic datasets.

The statistical analysis, performed with the software R and ggplot package (R Core Team 2016 ), included the calculation of the AED index ( Absolute Effective Diversity ), to estimate the number of species observed in an area, including those not detected (Cazzolla Gatti et al. 2020 ). We also compared temporal trends, during years and seasons, between the three areas. To understand whether the acoustic disturbance affects species diversity and abundance Wilcoxon’s test (Wilcoxon 1992 ) was applied.

In the three sampling nets, 41 different species of birds were captured and ringed, and their relative abundance was recorded (Table 1 ). The three sampling sites showed differences in their richness and abundance, with higher values always for the Far net (Table 2 ). Some of the species protected under the Bird Directive 2009/147/CE have been ringed and collected in this study: the marsh warbler ( Acrocephalus palustris ), the pied flycatcher ( Ficedula hypoleuca) , the red-backed shrike ( Lanius collurio ), the nightingale ( Luscinia megarhynchos ), and the song thrush ( Turdus philomelos ).

To better analyze the contribution of resident and migratory species to the total richness and abundance in the three sampling areas, we separate species collected in Spring from those collected in Autumn (Figure 2 ). In terms of species richness, the Far net shows higher values for both periods ( p = 0.021 between Near and Far sampling points), whereas Spring abundance shows lower values in the Far net compared to the other sampling sites ( p = 0.036).

Bird species richness (S) and total abundance (N) in the whole study period (a and d, respectively), in Spring (b and e), and Autumn (c and f). The median (central line in the box) represents the values that fall between the second (lower quartile value) and the third quartile (upper quartile value). The whiskers include data that lie between the 10th percentile (lower bound) and the lower quartile value, and between the upper quartile and the 90th percentile. Points outside the lower and upper bounds are outliers

Time series of noise pollution recordings show a clear separation of the three sampling nets, with higher values (in dB) at the Near sampling point (Figure 3 ). Then, the time series were separated into peak noise values and average noise values. This separation of noise pollution allowed us to clearly show that the disturbance caused by the passage of high-speed trains (Fig. 3 b) is scattered (because each recorded peak corresponded to a monitored time of train arrival), whereas the disturbance caused by the noise of motor vehicles on the highway is constant (Fig. 3 c). In both cases, the Near sampling point recorded the highest noise pollution, which was higher than at the Intermediate and Far nets both for railways and highways (Fig. 4 ).

Time series of acoustic disturbances (in dB) ( a ) separated as peaks noise values ( b ) and average noise values ( c ). To separate the noise pollution caused respectively by railway and highway infrastructure, acoustic recordings were separated by calculating, for each sampling point, the value corresponding to the 95th percentile, dividing them into average noise values and peak noise values

Noise pollution (in dB) distribution ( a ) separated into peak values distribution ( b ) and average values distribution ( c ). The median (central line in the box) represents the values that fall between the second (lower quartile value) and the third quartile (upper quartile value). The whiskers include data that lie between the 10th percentile (lower bound) and the lower quartile value, and between the upper quartile and 90th percentile. Points outside the lower and upper bounds are outliers

We analyzed the impact of a highway and a high-speed railway on the species diversity of a protected area in Italy, from autumn 2019 to autumn 2022.

Species richness decreases in the proximity of the sources of disturbance. In fact, bird diversity near the infrastructures is lower than the one observed in the more distant point, as confirmed also by previous studies: bird species richness is strongly affected by human disturbance such as agriculture, forest harvesting, roads, and urban and industrial areas in the surroundings of a habitat (Zhang et al. 2013 ). The significant differences between the nearest and farthest sampling points confirm our hypothesis of a higher impact due to high-speed ways, although the intermediate sampling net shows contrasting results attributable to the mid-domain effect that may lead to a higher abundance and diversity in the core of a reserve and a decrease of them at its edge (Colwell and Lees 2000 ).

In our study, bird abundance was significantly higher in the central area compared to the sampling point near the disturbance source. This is probably due to the mid-domain and edge effects, which lead the specimens to concentrate at the core of the Reserve, seeking protection in a less disturbed habitat. Bird diversity in the center of the Reserve was even a bit higher than at the farthest sampling point from noise pollution, and this may be because this point is close to the limit of the protected area and to the agricultural fields in which hunting seasonally takes place.

Total abundance shows a significant growing trend moving away from the source of disturbance, confirming the hypothesis that infrastructures represent the major reason for differences in bird species. Although a general increase is evident, it is not always linear and may reflect the different distribution of species within the reserve and their different behaviors. Birds that vocalize more could live further away from the source of noise pollution, which would interfere with the correct communication of individuals and consequently with their reproductive strategies, often based on an elaborate execution of the song, as already confirmed by different studies: with increasing background noise levels, males of European robin proved to be more likely to move away from the noise source and changed their singing behavior gradually (McLaughlin and Kunc 2013 ), and the number of birds per study area was shown to increase with the distance from the roads (Polak et al. 2013 ). Generally, highway noise has an impact on birds within several hundred meters (up to 1 km) from the source, despite visual disturbance and vehicular pollutants extended for a shorter distance from highways (Dooling and Popper 2016 ; Benítez-López A. et al. 2010 ).

In our sampling sites, we found a significantly higher bird abundance during autumn than spring and this may be due to migratory species that are probably less affected by anthropic noise while sedentary species are the most impacted. Anthropogenic noise pollution has been observed in other studies to play stronger effects on breeding birds than, in opposition to our results, wintering species, assuming these different responses may reflect species differences in acoustic communications (Wang et al. 2013 ; Catchpole et al. 2003 ). Breeding birds often need an elevated number of frequencies and types of acoustic contacts to complete the entire breeding cycle, such as mate attraction, territorial advertisement, or parent-offspring communication (Wang et al. 2013 ).

The absolute and effective diversity index (AED), which provides a comparable estimation of species missed from the sampling, confirms an important increase in the number of species moving away from high-speed ways. Some of these species could have different habitat preferences, while others, probably present in the reserve, have never been captured for random reasons. The index provided a value of potentially 50.81 living in the Reserve, which seems reliable as many species have been identified besides the 41 species detected in this study. The continuation of monitoring will certainly improve this work, allowing a higher bird species detection.

The highway A1 Milan–Naples and high-speed railway Milan–Bologna are highly busy causing a strong acoustic disturbance as measured by our phonometers. This may also be the reason why the reserve is rarely visited by people, as nature appreciation is enhanced by natural sounds and decreased by extraneous noises produced by road traffic, for instance (Chau et al. 2010 ).

Noise peaks in correspondence with the scattered passage of high-speed and regional trains seem to be less impacting for bird communication than the constant noise produced by the highway although both may importantly contribute to the acoustic disturbance.

It has been documented how the background acoustic disturbance — which grows exponentially in combination with the transit of high-speed trains or with the use of car horns — has repercussions on birdlife (Pickett et al. 1989 ; Parris and Schneider 2009 ; Lucas et al. 2017 ).

Reijnen et al. ( 1995 ) showed evidence that, in woodland, noise is probably the most critical factor in causing reduced densities close to roads. In regression analysis, using vehicle noise and visibility as response variables, the noise seemed to be the best and, in many species, the only predictor of observed depressed densities in the proximity of the road. Similarly, in open agricultural fields, several species of breeding birds showed a density reduction of almost 100% due to dense traffic, possibly causing an important loss of species richness (Reijnen et al. 1997 ), with total population density reduced by 39% in open agricultural grasslands and 35% in woodlands. Several studies also on non-bird species support the finding that, generally, animals change their distributions in response to anthropogenic noise, as the observation of Sonoran pronghorn’s behavior in avoiding loud areas due to military jet overflights (Barber et al. 2009 ). High levels of noise have been shown to affect wildlife physiological aspects, including temporary and permanent hearing loss (Barber et al. 2009 ).

In light of our findings and previous studies, to better protect birdlife and wildlife in general, it would be important to limit the extent of the disturbance by setting anti-noise barriers alongside the infrastructures. Most of the scientific literature is in line in acknowledging that anti-noise walls can reduce acoustic pollution of 5-15 dB: the volume of the sound pressure which a wall can absorb is directly proportional to the size of the sound pressure of the incoming source, considering that the decibel scale is logarithmic, even a small numeric variations translate into a major changes in sound perception (Hranický et al. 2016 ). According to Adamec et al. ( 2011 ), on average, well-designed barriers reduce noise by approximately 4 or more dB, depending on the geometry of traffic noise propagation.

Different types of noise barriers can be considered a valid help: reflecting walls with a smooth surface or absorbing walls with rugged folds are useful not only for the reflection of sound waves but also for their direct limitation; however, it is important to note that reflective barriers are often made with transparent materials and may be a danger for birds if not appropriate visual deterrent is placed (Hranický et al. 2016 ). Another related issue can occur where noise barriers are built only on one side of the track and animals can remain trapped on the infrastructure, but a simple solution can be the placement of stickers with dark contours of predatory birds for deterrence and further the integration of these structures with elevated ecological corridors (Hranický et al. 2016 ). In this specific case, noise barriers should reach a maximum height equivalent to the height of the tree crowns, as they could otherwise create an additional obstacle to the passage of moving birds.

Overall, our study was conducted in a relatively longer timespan (4 years) than most of the previous studies (Reijen et al. 2006 ; Wiacek et al. 2015 ) and, therefore, provides reliable evidence that road and rail traffic, particularly on high-speed ways, is one of the main causes of the loss of bird diversity, even in protected areas.

Data Availability

The data that support the findings of this study are available from the corresponding author, SP, upon reasonable request.

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Ester Bergamini and Sofia Prandelli equally contributed and shared the first authorship.

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Department of Biology, University of Pisa, Pisa, Italy

Ester Bergamini

Department of Biological, Geological, BIOME-Biodiversity and Macroecology Lab, and Environmental Sciences (BiGeA), University of Bologna, Bologna, Italy

Ester Bergamini, Sofia Prandelli & Roberto Cazzolla Gatti

Ente di Gestione per i Parchi e la Biodiversità-Emilia Centrale, Modena, Italy

Fausto Minelli

Biological, Geological and Environmental Sciences Department (BiGeA), BIOME Lab, University of Bologna, Bologna, Italy

Roberto Cazzolla Gatti

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All authors contributed to the study’s conception and design. Material preparation, data collection, and analysis were performed by Ester Bergamini, Sofia Prandelli, Fausto Minelli, and Roberto Cazzolla Gatti. The first draft of the manuscript was written by Ester Bergamini with the supervision of Roberto Cazzolla Gatti, and all authors worked on manuscript revision and finalization with the lead of Sofia Prandelli. All authors read and approved the final manuscript.

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Bergamini, E., Prandelli, S., Minelli, F. et al. Impacts of noise pollution from high-speed rail and road on bird diversity: a case study in a protected area of Italy. Environ Sci Pollut Res (2024). https://doi.org/10.1007/s11356-024-33372-0

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Received : 20 June 2023

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DOI : https://doi.org/10.1007/s11356-024-33372-0

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