Increased plastic litter cover affects the foraging activity of the sandy intertidal gastropod Nassarius pullus

Accumulation and exposure classifications of plastics in the different coastal habitats in the western Philippine archipelago

Studies consistently ranked the Philippines as one of the top contributors of plastic wastes leaking into the ocean. However, most of these were based on probabilities and estimates due to lack of comprehensive ground-truth data, resulting also in the limited understanding of the contributing factors and drivers of local pollution. This makes it challenging to develop science-driven and locally-contextualized policies and interventions to mitigate the problem. Here, 56 sites from different coastal habitats in the western Philippine archipelago were surveyed for macroplastics standing stock, representing geographic regions with varying demography and economic activities. Clustering of sites revealed three potential influencing factors to plastic accumulation: population density, wind and oceanic transport, and habitat type. Notably, the amount and types of dominant plastics per geographic region varied significantly. Single-use plastics (food packaging and sachets) were the most abundant in sites adjacent to densely populated and highly urbanized areas (Manila Bay and eastern Palawan), while fishing-related materials dominated in less populated and fishing-dominated communities (western Palawan and Bolinao), suggesting the local industries significantly contributing to the mismanaged plastics in the surveyed sites. Meanwhile, isolated areas such as islands were characterized by the abundance of buoyant materials (drinking bottles and hygiene product containers), emphasizing the role of oceanic transport and strong connectivity in the oceans. Exposure assessment also identified single-use and fishing-related plastics to be of "high exposure (Type 4)" due to their high abundance and high occurrence. These increase their chances of encountering and interacting with organisms and habitats, thus, resulting into more potential harm. This study is the first comprehensive work done in western Philippines, and results will help contextualize local pollution, facilitating more effective management and policymaking.

Macrolitter and mesolitter in the Thames Estuary: A temporal litter assessment and brand audit of submerged and riverbed debris

Macroplastic is a growing concern for marine environments with estuaries providing a major pathway for pollution from land-based sources to the sea. In the Thames Estuary, plastic was abundant floating below the surface and on the riverbed, with an average catch per unit effort of 0.57 ± 0.42 and 2.75 ± 2.44 item per minute respectively. Whilst the abundance of litter differed between midwater and benthic zones, the types of products recovered did not. These were identified through visual examination and use of a unique citizen science engagement protocol, allowing for the item age, brand and countries of origin to be established. The majority of litter from the present study (n = 1335) was packaging (40%), some of which was over 30-years old and may have originated from landfill run off. Also abundant was sewage-related debris, the inputs of which was related to heavy or prolonged rainfall. Peaks in this material were recorded in September 2020 following the greatest volume of rain recorded in a single day and in June 2019 after the longest period of continuous rainfall. The Covid-19 pandemic did not influence the abundance or diversity of plastic recovered between December 2018 and September 2020. The durability of plastic ensures it has high potential for harm through entanglement, deoxygenation of sediment and ingestion. The retention in the environment also increases opportunities to fragment into micro- or nanoplastics and, therefore, it is important to monitor plastics at both a macro- and micro-scale.

Spatio-temporal distribution of microplastic pollution in surface sediments along the coastal areas of Istanbul, Turkey

Microplastics (MPs) have become prevalent in various environmental compartments, including air, water, and soil, attracting attention as significant pollutant parameters. This study investigated the prevalence of MP pollution in surface sediments along Istanbul's Marmara Sea, encompassing the megacity and the Bosphorus. A comprehensive sampling approach was employed, covering 43 stations across four seasons and depths ranging from 5 to 70 m. The objective was to assess the impact of terrestrial, social, and industrial activities on MPs. The average concentrations varied per season, with fall, winter, spring, and summer values recorded as 2000 ± 4100, 1600 ± 3900, 4300 ± 12,000, and 9500 ± 20,300 particles/kg-DW. The study identified river stations in the Golden Horn and sea discharge locations as hotspots for high concentrations. Notably, the dominant shape shifted from fibers in fall, winter, and spring to fragments during summer, coinciding with mucilage occurrences. The study identified 11 different polymers, with polyethylene (44 %) and polypropylene (31 %) being the most common.

Behavioural and biochemical responses of the sea snail Tritia reticulata to lithium concentration gradient

Lithium (Li) is present in many modern technologies, most notably in rechargeable batteries. Inefficient recycling strategies for electronic waste containing this element may result in its release into aquatic systems, which may induce harmful effects on wildlife. The present study evaluated the effect of Li contamination on the gastropod Tritia reticulata exposed to different concentrations of Li (100, 200, 500 and 1000 µg L-1) for 21 days. Biochemical analyses showed that this species was not significantly affected by this contaminant at the cellular level, as no significant differences were observed in terms of metabolism, oxidative stress, and neurotoxicity. Results further revealed that snails attempted to avoid Li accumulation by burying in the sediment at a faster rate when exposed to the highest concentrations (500 and 1000 µg L-1). More research is needed to fully assess the response of T. reticulata to Li contamination, such as investigating longer exposure periods or other endpoints.

Habitual feeding patterns impact polystyrene microplastic abundance and potential toxicity in edible benthic mollusks

That increasing microplastics (MPs, <5 mm) eventually end up in the sediment which may become a growing menace to diverse benthic lives is worthy of attention. In this experiment, three edible mollusks including one deposit-feeding gastropod (Bullacta exarate) and two filter-feeding bivalves (Cyclina sinensis and Mactra veneriformis) were exposed to polystyrene microplastic (PS-MP) for 7 days and depurated for 3 days. PS-MP numbers in the digestive system and non-digestive system, digestive enzymes, oxidative stress indexes, and a neurotoxicity index of three mollusks were determined at day 0, 3, 7, 8 and 10. After seven-day exposure, the PS-MP were found in all three mollusks' digestive and non-digestive systems. And PS-MP in M. veneriformis (9.57 ± 2.19 items/individual) was significantly higher than those in C. sinensis (3.00 ± 2.16 items/individual) and B. exarate (0.83 ± 1.07 items/individual) at day 7. Three-day depuration could remove most of the PS-MP in the mollusks, and higher PS-MP clearance rates were found in filter-feeding C. sinensis (77.78 %) and M. veneriformis (82.59 %) compared to surface deposit-feeding B. exarate (50.00 %). The digestive enzymes of B. exarate significantly reacted to PS-MP exposure, while oxidative responses were found in C. sinensis. After three-day depuration, the changes of digestive enzymes and the oxidative states were fixed, but neurotoxicity induced by PS-MP was not recoverable. Besides, it is noteworthy that changes of digestive enzymes and acetylcholinesterase are related to feeding patterns.

The occurrence, speciation, and ecological effect of plastic pollution in the bay ecosystems

Bay is a unique part of the ecosystem, acting as the intersection for marine and terrestrial systems and hosting diverse biological organisms. The ubiquitous application of plastics has resulted in a massive amount of plastic waste released and accumulated in the bay ecosystem, posing significant ecological effects. Thus, thoroughly understanding plastic pollution's occurrence, speciation, and ecological effect in the bay ecosystems is of vital importance. We conducted a comprehensive review on the sources and distribution of plastics in the bay ecosystem, and the associate ecological effects, from individual toxicity to trophic transfer in ecosystems. Among bay areas around the world, the concentrations of microplastics vary from 0.01 to 3.62 × 10⁵ item/m³ in seawater and 0 to 6.75 × 10⁵ item/kg in sediment. Small-sized plastic particles (mostly <2 mm) were widely reported in bay organisms with the concentration range of 0 to 22.5 item/ind. Besides, the toxicity of plastics on marine organisms has been documented in terms of mortality, growth, development, reproduction, enzyme activity and transcription. Since abundance of small plastic particles (e.g., micro- and nano-scale) is far greater than large plastic debris in the bay ecosystems, in-depth risk assessment of small-sized plastics needs to be conducted under environmentally realistic conditions. Our review could provide a better understanding on the occurrence, speciation, and ecological effect of plastic pollution in the bay ecosystems.

Mission impossible: Reach the carrion in a lithium pollution and marine warming scenario

In this study we investigated the independent and synergistic effects of lithium (Li, 0.08 mM) contamination and the rising seawater temperature (21 °C; control- 15 °C) on survival and trophic interactions (foraging behaviour, success, search time, carrion preference, feeding time, and tissue consumption-the dry weight basis) of the opportunistic intertidal scavenger Tritia neritea. Trophic interactions were assessed in a two-choice test using a Y-maze design using the same amount of two carrion species (Solen marginatus and Mytilus galloprovincialis) given to all snails simultaneously. Lithium pollution and synergestic warming have the effect of reducing the survival rate of T. neritea, triggering potential global change scenarios. The foraging behaviour of T. neritea under Li-contaminated conditions was characterised by a decrease in the snail's effectiveness in finding a carrion. Lithium changes the feeding behaviour as well as increasing the time it takes for snails to reach their food. T. neritea did not show preference for any of the carrion species offered in controls, but a shift in feeding behaviour towards more energetic carrion under Li contamination which may indicate a strategy to compensate for the greater energy expenditure necessary to survive. There were no differences in feeding time at the different treatments and regardless of the treatment tested T. neritea consumed more mussels tissue probably due to its greater palatability. Results showing foraging modifications in an intertidal scavenger mollusc in global change scenarios indicate potential changes in complex trophic interactions of marine food webs.

The nexus of macroplastic and microplastic research and plastic regulation policies in the Philippines marine coastal environments

The Philippines was reported as one of the top plastic polluters (macroplastics and microplastics (MPs)) to the marine coastal environment, which necessitated the development and enforcement of plastic regulation policies. However, the nexus between the growing research on macroplastic/MP and the plastic regulation policies in the country is unexplored. Current review suggests that macroplastic/MP research in the Philippines is still in its infancy owing to methodological and technological constraints to apportion the sources and fluxes, characterize macroplastics/MPs, and identify influencing socio-environmental factors. While government efforts are underway, it is also unclear if local researches on macroplastics/MPs were the basis in institutionalizing the existing plastic regulation policies. Therefore the nexus between the researches carried out on this problem and the policies enforced cannot be concluded. Overall, this review presents gaps on the macroplastic/MP research needing more work on the problem to establish a sound science plastic regulation policy.

Mangroves as unique but understudied traps for anthropogenic marine debris: A review of present information and the way forward

Marine debris and plastic pollution affect all coastal habitats, however coastal debris studies are predominantly performed on sandy beaches. Other coastal habitats, such as mangroves, remain understudied. Eighteen of the top twenty rivers that contribute the most plastic to the ocean are associated with mangroves, but very few of those forests were investigated in terms of plastic debris pollution. Here we discuss the results of the few available studies on macrodebris conducted in mangroves, which show that mangrove debris research is still in its early stages, with many areas of study to be further investigated. Indeed, the distinct structural complexity of mangroves increases their ability to trap debris from both terrestrial, freshwater and marine sources, resulting in impacts unique to the mangrove ecosystem. Our review highlights a significant lack in standardisation across the performed surveys. Here we suggest standardised guidelines for future integrated macrodebris and microplastic studies in mangroves to facilitate comparisons between studies. Such standardisation should prioritize the use of stratified random sampling, the measurement of the area covered by the debris and the abundance and type of macrodebris and microplastics found, in order to assess the ecological impact of macrodebris and its role as source of microplastics for adjacent ecosystems. We also advocate the use of standard categories across studies, based on those identified for surveying other coastal habitats. This review highlights an alarming knowledge gap in extent, sources and overall impacts of marine macrodebris, mainly constituted by plastic, on mangrove forests, which hinders policy making to address this issue. Standardised, reliable and extended research on this aspect of mangrove pollution is needed to manage and protect these endangered vegetated coastal ecosystems.

Transport of floating litter within Manila Bay, Philippines

The increasing amount of marine litter is a global issue that is also being experienced within the Manila Bay Philippines. To better understand the behavior of litter within the bay, particle tracking simulations of floating litter released from several sources were conducted. Forward-in-time (PTM-FIT) simulation of particle movements showed that during the southwest monsoon season, litter particles released by river sources tend to accumulate toward five hotspots located along the northeastern coastline of the bay. Backward-in-time (PTM-BIT) simulation of particles released from the identified hotspots showed coastal and foreign sources contributing to the litter collected within these areas. PTM-FIT simulations during the southwest monsoon season showed that particles tend to circulate locally within the bay before being transported toward the hotspots. By contrast, PTM-FIT simulations during the northwest monsoon season showed that litter particles tend to travel toward the mouth of the bay, an implication for global marine litter pollution.

The effects of wet wipe pollution on the Asian clam, Corbicula fluminea (Mollusca: Bivalvia) in the River Thames, London

The aim of the present study was to evaluate "flushable" and "non-flushable" wet wipes as a source of plastic pollution in the River Thames at Hammersmith, London and the impacts they have on the invasive Asian clam, Corbicula fluminea, in this watercourse. Surveys were conducted to assess whether the density of wet wipes along the foreshore upstream of Hammersmith Bridge affected the distribution of C. fluminea. High densities of wet wipes were associated with low numbers of clams and vice versa. The maximum wet wipe density recorded was 143 wipes m^-2 and maximum clam density 151 individuals m^-2. Clams adjacent to the wet wipe reefs were found to contain synthetic polymers including polypropylene (57%), polyethylene (9%), polyallomer (8%), nylon (8%) and polyester (3%). Some of these polymers may have originated from the wet wipe reefs.

Plastic pollution in the marine environment

Plastic pollution is recognized as a severe anthropogenic issue in the coastal and marine ecosystems across the world. Unprecedented and continuous accumulation of growing plastic contaminants into any respective aquatic ecosystem by the anthropogenic sources causes direct and/or indirect interruption to ecosystem structure, functions, and consequently, services and values. Land-based and sea-based sources are the primary sources of these contaminants in various modes that enter the ocean. In this review paper, we focused on highlighting different aspects related to plastic pollution in coastal and marine environments. Plastic pollutants are distributed in the ecosystems in different forms, with different size variations as megaplastic, macroplastic, mesoplastic, and microplastic. Microplastics in primary and secondary forms reveal a widespread distribution in the water, sediment, and biota of the marine and coastal habitats. The microplastic level of different coastal and marine ecosystems nearly ranged from 0.001-140 particles/m3 in water and 0.2-8766 particles/m3 in sediments at different aquatic environments over the world. The microplastic accumulation rate of coastal and marine organisms varied at 0.1-15,033 counts. Accordingly, plastic pollution creates several kinds of negative consequences combined with ecological and socio-economic effects. Entanglement, toxicological effects via ingestion of plastics, suffocation, starvation, dispersal, and rafting of organisms, provision of new habitats, and introduction of invasive species are significant ecological effects with growing threats to biodiversity and trophic relationships. Degradation (changes in the ecosystem state) and modifications of marine systems are associated with loss of ecosystem services and values. Consequently, this emerging contaminant affects the socio-economic aspects through negative impacts on tourism, fishery, shipping, and human health. Preventing accumulation sources of plastic pollutants, 3Rs (Reduce-Recycle-Reuse), awareness & capacity building, and producer/manufacturer responsibility are practical approaches toward addressing the issue of plastic pollution. Existing and adopted policies, legislations, regulations, and initiatives at global, regional, and national level play a vital role in reducing plastic debris in the marine and coastal zones. Development of proposals/solutions on key research gaps can open a novel pathway to address this environmental issue in an effective scientific manner. In conclusion, this paper demonstrates the current status of plastic pollution in the marine ecosystem to make aware people of a plastic-free, healthy blue ocean in the near future.

Impacts of plastic debris on biota and implications for human health: A South African perspective

Entanglement and ingestion of plastics are the main ecological impacts of marine plastic debris on marine biota, but indirect effects such as the transport of alien species and benthic smothering are also important to note. Entanglement of invertebrates, sharks, turtles, birds and marine mammals is mainly caused by macroplastics (>5 mm), and leads to reduced mobility, ineffective foraging and subsequent mortality. The main plastic types associated with entanglement are improperly discarded fishing nets, lines, ropes and straps. In South Africa and surrounding waters, plastic ingestion has been reported in a number of marine species: sharks (n=10), fish (n>=7), turtles (n=1) and birds (n=36). Lethal (macroplastic) and sub-lethal effects (microplastic ≤5 mm) of marine debris on biota have been noted, but at the time of this review there were no published reports on impacts at the population level. Consumed shellfish are possible vectors for the introduction of microplastics into humans. The specific impacts of microplastic ingestion on human health are largely unknown, but additives associated with plastics represent a threat. The research infrastructure in South Africa is insufficient to monitor and characterise marine plastic debris and, in many cases, not in line with global standards. More research effort is needed to understand the impacts of marine plastic debris on humans and marine biota in South Africa, particularly at the population level. Significance • Macroplastics affect marine biota mainly via entanglement and microplastics largely through ingestion. • Macro- and microplastic interactions with biota can result in sub-lethal effects and mortality but no population effects have been reported for South Africa. • Consumed shellfish are a potential source of microplastics for humans but their potential effects in humans remain unknown. • Better infrastructure is needed for improved monitoring and research on the effects of marine debris in South Africa.

Slime travelers: Early evidence of animal mobility and feeding in an organic mat world

Mobility represents a key innovation in the evolution of complex animal life. The ability to move allows for the exploration of new food sources, escapes from unfavorable environmental conditions, enhanced ability to exchange genetic material, and is one of the major reasons for the diversity and success of animal life today. The oldest widely accepted trace fossils of animal mobility are found in Ediacaran-aged rocks (635-539 Ma). The earliest definitive evidence for movement associated with exploitation of resources for feeding occurs in the White Sea assemblage of the Ediacara Biota-macroscopic, soft-bodied fossils of Ediacaran age. Here, we evaluate potential support for mobility in dickinsoniomorphs, presenting new data regarding abundant Dickinsonia and associated trace fossils from the Ediacara Member, South Australia. Results quantitatively demonstrate that Dickinsonia was capable of mobility on relatively short, ecological timescales. This organism was bilaterally symmetrical, likely moved via muscular peristalsis, and left trace fossils due to active removal of the organic mat related to feeding. Analogous structures associated with Yorgia indicate that it was also mobile and fed in a similar manner. Morphological evidence suggests that two other modular taxa, Andiva and Spriggina, were able to move but did not feed in a manner that impacted the organic mat. Together, these data suggest that mobility was present in multiple disparate bilaterally symmetrical Ediacaran taxa.

The effects of plastic bags presence on a macrobenthic community in a polluted estuary

The damaging effects of marine debris on wildlife are often noted through the observation of animals that ingest and/or become entangled in debris. Yet, few studies have evaluated the effects of marine litter on benthic habitats. The aim of this study was to investigate if the presence of plastic bags has any effect on benthic macrofauna in an estuary located in an urban area in North-eastern Brazil. Biogeochemical and macrofauna samples were obtained from 10 different deposition locations (location factor), under, border and distant (treatment factor) from plastic bags. The results did not show any significant alterations in the biogeochemical parameters of the sediment due to treatment effect except for summed microphytobenthic pigments. The macrobenthic community structure responded to treatment. The greatest dissimilarity (34%) was between samples that were under and distant. Effects occurred despite the high dynamics of deposition-resuspension of plastic bags and the dominance of opportunistic species. Changes in community structure are a complex result of plastic bags effects on species ecological interactions in the polluted estuarine environment, attracting deposit feeders, diminishing suspension feeders and providing mechanical protection against predation by seabirds.

Marine litter disrupts ecological processes in reef systems

Marine litter (ML) contaminates essentially all global coastal and marine environments and drives multiple ecosystem-level effects. Although deleterious effects of ML on several organisms have been investigated in the last years, this information tends to be dispersed or underreported, even in marine biodiversity hotspots such as reef ecosystems. Two are the main goals of this paper: (i) to integrate and synthesize current knowledge on the interactions of ML and reef organisms, and (ii) to evaluate the multiple disruptions on the ecological processes in reef systems. We report here ML-driven ecological disruptions on 418 species across eight reef taxa, including interactions that were previously not addressed in detail, and evaluate their major conservation implications. These results can help raise awareness of global impacts on the world's reefs by highlighting ML associations in different reef systems around the world, and can aid in ML input reduction and marine management.

Baseline evaluation of sediment contamination in the shallow coastal areas of Saudi Arabian Red Sea

Despite the growing recognition of the importance of water and sediment quality there is still limited information on contamination levels in many regions globally including the Red Sea. This study provides a comprehensive assessment of three classes of contaminants (Polycyclic Aromatic Hydrocarbons - PAH; metals; plastics) in coastal sediments along the Saudi Arabian Red Sea mainly collected using grabs. Background concentrations are provided for metals in the region. Concentrations of metals and PAH were generally low in comparison to international guidelines. A clear relationship between the concentration of metals and anthropogenic sources was not always apparent and dust and vegetation may be relevant players in the region. Microplastic items (mainly polyethylene) were abundant (reaching up to 1gm^-2 and 160piecesm^-2) and in general associated with areas of high human activity. This study provides critical information for future monitoring and the development of national policies within the Red Sea region.

Linking effects of anthropogenic debris to ecological impacts

Accelerated contamination of habitats with debris has caused increased effort to determine ecological impacts. Strikingly, most work on organisms focuses on sublethal responses to plastic debris. This is controversial because (i) researchers have ignored medical insights about the mechanisms that link effects of debris across lower levels of biological organization to disease and mortality, and (ii) debris is considered non-hazardous by policy-makers, possibly because individuals can be injured or removed from populations and assemblages without ecological impacts. We reviewed the mechanisms that link effects of debris across lower levels of biological organization to assemblages and populations. Using plastic, we show microplastics reduce the 'health', feeding, growth and survival of ecosystem engineers. Larger debris alters assemblages because fishing-gear and tyres kill animals and damage habitat-forming plants, and because floating bottles facilitate recruitment and survival of novel taxa. Where ecological linkages are not known, we show how to establish hypothetical links by synthesizing studies to assess the likelihood of impacts. We also consider how population models examine ecological linkages and guide management of ecological impacts. We show that by focusing on linkages to ecological impacts rather than the presence of debris and its sublethal impacts, we could reduce threats posed by debris.

Impacts of discarded plastic bags on marine assemblages and ecosystem functioning

The accumulation of plastic debris is a global environmental problem due to its durability, persistence, and abundance. Although effects of plastic debris on individual marine organisms, particularly mammals and birds, have been extensively documented (e.g., entanglement and choking), very little is known about effects on assemblages and consequences for ecosystem functioning. In Europe, around 40% of the plastic items produced are utilized as single-use packaging, which rapidly accumulate in waste management facilities and as litter in the environment. A range of biodegradable plastics have been developed with the aspiration of reducing the persistence of litter; however, their impacts on marine assemblages or ecosystem functioning have never been evaluated. A field experiment was conducted to assess the impact of conventional and biodegradable plastic carrier bags as litter on benthic macro- and meio-faunal assemblages and biogeochemical processes (primary productivity, redox condition, organic matter content, and pore-water nutrients) on an intertidal shore near Dublin, Ireland. After 9 weeks, the presence of either type of bag created anoxic conditions within the sediment along with reduced primary productivity and organic matter and significantly lower abundances of infaunal invertebrates. This indicates that both conventional and biodegradable bags can rapidly alter marine assemblages and the ecosystem services they provide.

The impact of debris on marine life

Marine debris is listed among the major perceived threats to biodiversity, and is cause for particular concern due to its abundance, durability and persistence in the marine environment. An extensive literature search reviewed the current state of knowledge on the effects of marine debris on marine organisms. 340 original publications reported encounters between organisms and marine debris and 693 species. Plastic debris accounted for 92% of encounters between debris and individuals. Numerous direct and indirect consequences were recorded, with the potential for sublethal effects of ingestion an area of considerable uncertainty and concern. Comparison to the IUCN Red List highlighted that at least 17% of species affected by entanglement and ingestion were listed as threatened or near threatened. Hence where marine debris combines with other anthropogenic stressors it may affect populations, trophic interactions and assemblages.

Identifying species at extinction risk using global models of anthropogenic impact

The International Union for Conservation of Nature Red List of Endangered Species employs a robust, standardized approach to assess extinction threat focussed on taxa approaching an end-point in population decline. Used alone, we argue this enforces a reactive approach to conservation. Species not assessed as threatened but which occur predominantly in areas with high levels of anthropogenic impact may require proactive conservation management to prevent loss. We matched distribution and bathymetric range data from the global Red List assessment of 632 species of marine cone snails with human impacts and projected ocean thermal stress and aragonite saturation (a proxy for ocean acidification). Our results show 67 species categorized as 'Least Concern' have 70% or more of their occupancy in places subject to high and very high levels of human impact with 18 highly restricted species (range <100 km(2)) living exclusively in such places. Using a range-rarity scoring method we identified where clusters of endemic species are subject to all three stressors: high human impact, declining aragonite saturation levels and elevated thermal stress. Our approach reinforces Red List threatened status, highlights candidate species for reassessment, contributes important evidential data to minimize data deficiency and identifies regions and species for proactive conservation.

The incidence of plastic ingestion by fishes: from the prey's perspective

One of the primary threats to ocean ecosystems from plastic pollution is ingestion by marine organisms. Well-documented in seabirds, turtles, and marine mammals, ingestion by fish and sharks has received less attention until recently. We suggest that fishes of a variety of sizes attack drifting plastic with high frequency, as evidenced by the apparent bite marks commonly left behind. We examined 5518 plastic items from random plots on Kamilo Point, Hawai'i Island, and found 15.8% to have obvious signs of attack. Extrapolated to the entire amount of debris removed from the 15 km area, over 1.3 tons of plastic is attacked each year. Items with a bottle shape, or those blue or yellow in color, were attacked with a higher frequency. The triangular edges or punctures left by teeth ranged from 1 to 20 mm in width suggesting a variety of species attack plastic items. More research is needed to document the specific fishes and rates of plastic ingestion.

Marine debris: a proximate threat to marine sustainability in Bootless Bay, Papua New Guinea

Surveys of stranded marine debris around Motupore Island, a small island in Bootless Bay, Papua New Guinea, revealed exceptionally high loads (up to 78.3 items m(-2)), with major concentrations in mangrove-dominated, depositional areas. The worst affected, 50-m stretch of shore was estimated to contain >37.000 items with a combined weight of 889 kg. Consistent with studies elsewhere, plastics comprised by far the majority of debris across all sites (89.7%). The lack of centralised waste collection and limited village-based resources, coupled with an increasing population, suggests that this issue is a long way from solution. High debris loads thwart attempts to rehabilitate depleted mangrove forests through smothering of seedlings, perpetuating run-off and water quality issues in the bay. Addressing marine debris is thus of fundamental importance for the sustainability of Bootless Bay and its resources, and a critical step in promoting ecosystem resilience.

Microplastics in the marine environment: a review of the methods used for identification and quantification

This review of 68 studies compares the methodologies used for the identification and quantification of microplastics from the marine environment. Three main sampling strategies were identified: selective, volume-reduced, and bulk sampling. Most sediment samples came from sandy beaches at the high tide line, and most seawater samples were taken at the sea surface using neuston nets. Four steps were distinguished during sample processing: density separation, filtration, sieving, and visual sorting of microplastics. Visual sorting was one of the most commonly used methods for the identification of microplastics (using type, shape, degradation stage, and color as criteria). Chemical and physical characteristics (e.g., specific density) were also used. The most reliable method to identify the chemical composition of microplastics is by infrared spectroscopy. Most studies reported that plastic fragments were polyethylene and polypropylene polymers. Units commonly used for abundance estimates are "items per m(2)" for sediment and sea surface studies and "items per m(3)" for water column studies. Mesh size of sieves and filters used during sampling or sample processing influence abundance estimates. Most studies reported two main size ranges of microplastics: (i) 500 μm-5 mm, which are retained by a 500 μm sieve/net, and (ii) 1-500 μm, or fractions thereof that are retained on filters. We recommend that future programs of monitoring continue to distinguish these size fractions, but we suggest standardized sampling procedures which allow the spatiotemporal comparison of microplastic abundance across marine environments.