Microplastic ingestion by pelagic and benthic fish and diet composition: A case study in the NW Iberian shelf

How do fish consume microplastics? An experimental study on accumulation pattern using Nile tilapia (Oreochromis niloticus)

The aim of this study was to investigate microplastic (MP) exposure by Nile tilapia (Oreochromis niloticus) in laboratory conditions. A total of 150 tilapia fishes were equally distributed randomly in 15 different glass tanks with five experimental conditions. Observed results depicted that the presence of MPs in different organs was mainly accumulated from the fish feed rather than externally added MPs in the culture tanks. It was also revealed that the gastrointestinal tract (GIT) was found to be the most susceptible to MPs accumulation followed by gills and muscles in order. However, muscle contained the least size of MPs followed by GITs and gills. A statistical test showed significant correlations among the average length and weight of fish with MP exposure. A filamentous shape was found to be dominant in both GITs and gills while fragment shape was dominant in muscles. FTIR results revealed a total of 12 different polymers in the fish of which two polymers (polyvinyl alcohol and ethylene vinyl acetate) were not detected in the feed-only tanks. Polypropylene (PP) and polyethylene terephthalate (PET) were found to be dominant polymers in all the experimental GIT, gills, and muscle organs. FESEM results indicated the presence of different textures including cracks, edges, flakes, scratches, grooves, and adhering particles. EDX results exhibited the presence of Na, Si, K, Ni, Cu, Zn, As, and Cd in the analyzed samples that may pose additional health risks. Thus, this study could act as baseline data for laboratory-based studies of aquaculture species in future research.

Assessment of the impact of microplastic ingestion in striped red mullets from an Eastern Mediterranean coastal area (Zakynthos Island, Ionian Sea)

Monitoring microplastics (MPs) in the marine environment is an ongoing process, and our understanding of their impact on marine organisms is limited. The present study evaluates the effects of ingested MPs on the marine MP pollution bioindicator fish species Mullus surmuletus. The study follows a three-fold approach to assess the impact of MPs on marine organisms by investigating: 1) the ingestion of MPs, 2) the bioaccumulation of phthalate compounds as plastic additives, and 3) the evaluation of toxicological biochemical and cellular biomarkers. Striped red mullets were sampled in the marine protected area (MPA) of the National Marine Park of Zakynthos and coastal sites with high touristic pressure in Zakynthos Island in the Ionian Sea, Greece. Fewer ingested MPs and lower phthalate concentrations were found in fish inside the MPA compared to those sampled outside the marine park. However, no relationship was found between either phthalate concentrations or biomarker levels with the ingested MPs in the red striped mullets. Biomarker levels were influenced by season and site, but no effect could be attributed to the ingested MPs. The lack of association of biomarker responses and plasticizer bioaccumulation to MP ingestion can be explained by the low number of ingested MPs in the fish from Zakynthos coastal area as MP abundance ranged from 0.15 to 0.55 items per individual fish.

Plastic webs, the new food: Dynamics of microplastics in a Mediterranean food web, key species as pollution sources and receptors

In the context of global environmental change, this study presents a novel approach to evaluating microplastic (MP) fluxes and probabilities of pollution within marine food webs. A topological model was built to understand the dynamics of MP pollution in the Mediterranean food webs. The analysis involves two approaches: the first approach includes centrality measures to understand the key role of species in the transmission of trophic effects regarding MPs, and the second approach incorporates MP data by developing the Interaction Pollution Indices (IPIs) at multiple levels to identify species being sources and receptors of MP pollution in the new concept of a plastic-food web. The trophic network consisted of 356 nodes representing not only species, but also aggregations in higher taxa, for a total of 3517 interactions, with 108 species having information on MP frequency of occurrence (FO). The mean probability of dietary MP transference was 0.087 %, and the maximum was 18 %. Species such as the rose shrimp A. antennatus, the catshark S. canicula, the sole S. solea, the sardine S. pilchardus, the Norway lobster N. norvegicus, and the forkbeard P. phycis were found to be significant sources of pollution and played crucial roles in the transmission of effects within the network. By incorporating the IPIs, a deeper understanding of the pollution dynamics at multiple levels was gained, highlighting the value of combining feeding and MP pollution data to develop effective management and conservation strategies. The application of the IPIs holds immense potential for studying bioaccumulation and biomagnification through MP pollutant transferences in marine ecosystems. Its flexibility in incorporating different types of information and units enables its transversal application throughout the field of ecology. This research provides a crucial step towards developing effective tools for MP pollution mitigation strategies and the preservation of marine ecosystems integrity.

Microplastics in the stomach content of the commercial fish species Scomber colias in the Gulf of Cadiz, SW Europe

Concerning microplastics (MPs) contamination is increasing due their negative impacts on marine food webs and their potential toxicity to wildlife and humans. In this study, we analyze the presence of MPs in the stomachs of the commercial fish species Scomber colias (Atlantic chub mackerel) in the Gulf of Cadiz (GoC). Out of the 104 analyzed stomachs, 90.4 % contained some type of MPs, with an average of 5.4 MPs per individual. Of the 1152 MPs analyzed, 91.1 % were fibers, and 8.9 % fragments type. Fourier Transformation Infrared Spectrometry analysis was performed on 152 items, revealing that 73.6 % were MPs. The most common synthetic polymers found were polyamide (64 %), polypropylene (15 %), polystyrene (12 %), polyvinyl chloride (5 %), and polyethylene (4 %). The consistent ingestion of synthetic polymers by the individuals of Atlantic chub mackerel across different zones might suggest an even distribution of MP contamination throughout the GoC.

Trophic transfer and biomagnification of microplastics through food webs in coastal waters: A new perspective from a mass balance model

Since the 1950s, plastic pollution and its risk have been recognized as irreversible and nonnegligible problems as global plastic production has increased. In recent years, the transport and trophic transfer of microplastics (MPs) in biotic and abiotic environment have attracted extensive attention from researchers. In this study, based on the Ecotracer module from Ecopath with Ecosim (EwE) model, the marine ranching area of Haizhou Bay, Jiangsu Province, China, was taken as a case study by linking the environmental plastic inflow with MPs in organisms to simulate the variation of MPs in the marine food web for 20 years, as well as its potential trophic transfer and biomagnification. We found that the concentration of MPs in top consumers first increased when the concentration of MPs in the environment increased, while that in primary consumers first decreased when the concentration of MPs in the environment decreased. Moreover, high TL consumers had a stronger ability to accumulate MPs, and pelagic prey fishes was the opposite. From the perspective of the food web, all functional groups showed significant trophic magnification along with the trophic level and no biodilution. Generally, there is a direct relationship between the MPs in marine organisms and environmental inflow. If the pollutants flowing into the environment can be reduced, the MP pollution problem in coastal waters will be effectively alleviated. Our research can further provide a scientific basis for ecological risk assessment and management of MPs and biodiversity protection in marine ecosystems.

Microplastic distribution in different tissues of small pelagic fish of the Northeast Atlantic Ocean

The accumulation of microplastics (MP) by marine species of ecological and commercial interest represents a major concern, particularly for those present in human diet. This study analysed the accumulation of MP in three species of coastal pelagic fish with high commercial value, European sardine (Sardina pilchardus), European anchovy (Engraulis encrasicolus) and horse mackerel (Trachurus trachurus), collected along the Western coast of the Iberian Peninsula. The gastrointestinal tract (GT), gills and muscle were analysed and a total of 504 particles were observed. MP were found in all target tissues of the studied species. Horse mackerel exhibited significantly higher concentrations of microplastics in GT compared to other tissues. On the other hand, anchovies and sardines had significantly lower microplastic concentrations in their muscle tissue. The accumulation of microplastics in the gills showed a significant difference between species, with anchovy having significantly higher concentrations compared to horse mackerel. Horse mackerel had the highest percentage of individuals with microplastics in their GT (92 %), followed by sardine (75 %) and anchovy (50 %). Horse mackerel was also the species that registered the highest percentage of individuals with particles in the muscle (63 %), followed by anchovy (40 %) and finally sardine (39 %). MP in the gills of European sardines and anchovies were similar to those found in water samples. The majority of MP found measured <0.5 mm and were blue fibers. Furthermore, the presence of MP in the GT showed a weak and moderated significant negative correlation with the Fulton Condition Index in horse mackerel and European sardine. Our study confirms the ubiquitous extent of MP contamination in the ocean and provides baseline evidence of MP tissue distribution in three small pelagic fish species with distinct feeding behaviour, while correlating this with the presence of MP in water. Importantly, the results of this study contribute to improve the understanding of biological partitioning of MP in open sea fish species with high commercial relevance, and the potential deleterious effects of our increasingly MP contaminated world.

Microplastics in the River Ganga and its fishes: Study of a Himalayan River

The River Ganga has been explored for microplastics (MPs) majorly in the lower or middle course, while the upper course from where the river starts its journey remains untouched. This study investigates the occurrence and distribution of MPs in the river environment (water and sediment) and common fishes inhabiting the upper stretch of River Ganga in the Uttarakhand state of India. A volume-reduce method by using sieve filtration was used to take water and sediment samples from the study area while fish samples were collected using net method. The samples underwent alkali digestion, microscopic examination, and chemical analysis using Fourier Transformed Infrared Spectroscopy (FTIR). An average of 118.5 ± 49.65 particles per 1000 L and 131.5 ± 53.60 particles/kg dry weight were found in water and sediment respectively. While in the fishes, Tor tor, Schizothorax richardsonii, Labeo dero and Gara gotyla gotyla MPs were 53.13 ± 63.77, 36.33 ± 22.34, 15.42 ± 9.33 and 12.63 ± 5.93 particles/individual respectively. A positive correlation was observed between the number of MPs in fish and their body length, weight, and gut weight, while no correlation was found between feeding habit and MP accumulation. The majority of MPs detected were fibers ranging from 100 μm to 1 mm in size. Polymer types varied among water, sediment, and fish samples, with polyethylene (PE) predominant in water, polypropylene (PP) dominant in sediment, and polyethylene terephthalate (PET) and polystyrene (PS) most abundant in fish samples.

Microplastics in stomach contents of juvenile Patagonian blennies (Eleginops maclovinus)

Microplastics are one of the major environmental issues that need to be addressed because they are starting to impact food chains and are also affecting human populations. The size, colour, form, and abundance of microplastics in young blennies of the species Eleginops maclovinus were examined in the current study. While the stomach contents of 70 % of the studied individuals contained microplastics, 95 % of them included fibres. Individual size and the largest particle size that can be eaten, which ranges between 0.09 and 1.5 mm present no statistical correlation. The quantity of particles taken in by each individual does not change with size. The most present microfibers colours were blue and red. Sampled fibres were analysed with FT-IR and no natural fibres were detected, proving the synthetic origin of the detected particles. These findings suggest that protected coastlines create conditions that favour the encounter of microplastics increasing local wildlife exposure to microplastics, raising the danger of their ingestion with potential physiological, ecological, economical and human health consequences.

Trophic niche influences ingestion of micro- and mesoplastics in pelagic and demersal fish from the Western Mediterranean Sea

Plastic pollution has been extensively documented in the marine food web, but targeted studies focusing on the relationship between microplastic ingestion and fish trophic niches are still limited. In this study we investigated the frequency of occurrence and the abundance of micro- and mesoplastics (MMPs) in eight fish species with different feeding habits from the western Mediterranean Sea. Stable isotope analysis (δ13C and δ15N) was used to describe the trophic niche and its metrics for each species. A total of 139 plastic items were found in 98 out of the 396 fish analysed (25%). The bogue revealed the highest occurrence with 37% of individuals with MMPs in their gastrointestinal tract, followed by the European sardine (35%). We highlighted how some of the assessed trophic niche metrics seem to influence MMPs occurrence. Fish species with a wider isotopic niche and higher trophic diversity were more probable to ingest plastic particles in pelagic, benthopelagic and demersal habitats. Additionally, fish trophic habits, habitat and body condition influenced the abundance of ingested MMPs. A higher number of MMPs per individual was found in zooplanktivorous than in benthivore and piscivorous species. Similarly, our results show a higher plastic particles ingestion per individual in benthopelagic and pelagic species than in demersal species, which also resulted in lower body condition. Altogether, these results suggest that feeding habits and trophic niche descriptors can play a significant role in the ingestion of plastic particles in fish species.

The pervasiveness of microplastic contamination in the gastrointestinal tract of fish from the western coast of Bangladesh

This study investigated the prevalence of microplastics (MPs) in the gastrointestinal tract (GIT) of fish from the western coast of Bangladesh, the world's largest mangrove ecosystem. Altogether, 8 different species of fish (5 demersal and 3 pelagic) were examined. Microplastics were detected in every individual fish with an average abundance of 7.1 ± 3.14 particles per specimen. The demersal species were observed to consume more microplastics (7.78 ± 3.51) than the pelagic species (5.92 ± 2.06). Moreover, small-sized fish was found to accumulate higher MPs/body weight than large-sized fish. Polypropylene was the most abundant polymer type (45 %) and fiber was the most prevalent shape (71 %). SEM analysis revealed cracks, pits, and foreign particles on the microplastics' surface, representing their ability to bear organic pollutants and heavy metals. This study will be a source of information for future research and a guide for policy-makers to take better actions to protect and restore marine resources.

Investigating the impacts of biofouled marine plastic debris on the olfactory behaviour of juvenile yellowtail kingfish (Seriola lalandi)

Marine microplastics are rapidly colonised by a microbial community which form a biofilm unique from the surrounding seawater that often contains infochemical-producing species associated with food sources. Here, we investigated whether juvenile kingfish (Seriola lalandi) were more attracted to biofouled plastics compared to clean plastics. Plastics were exposed to unfiltered seawater for one month to cultivate a microbial community. An olfactory behavioural experiment showed little difference in their response to the biofilm compared to clean plastic and control treatment. Further, ingestion experiments demonstrated that S. lalandi ingested fewer biofouled microplastics compared to clean microplastics. However, this was likely due to the bioavailability of the biofouled microplastics. This study highlights that while juvenile kingfish will ingest microplastics, they are not more attracted to those with a naturally acquired biofilm.

Microplastics accumulation in pelagic and benthic species along the Thoothukudi coast, South Tamil Nadu, India

Microplastics contamination poses a serious threat to marine biota, so the current study was carried out to assess the incidence of microplastics in the gastrointestinal tracts of pelagic and benthic species collected from the six sampling sites along Thoothukudi region from January 2021 to December 2021. In the present study, benthic species (0.67 ± 0.14 MPs/indiv) showed a higher abundance of microplastics than pelagic species (0.53 ± 0.11 MPs/indiv). The dominance of microplastic shapes, sizes, colours and polymers found were comparable among both pelagic and benthic species, this being fibre (27.56% and 48.33%), 0.5-1mm (39.78% and 42.94%), blue (50% and 40.85%), and PE (46.24% and 48.18%), respectively. The present study showed that microplastics are ubiquitous in both habitats, which raises serious concerns for public health. Hence, measures focusing on reducing local emissions and plastic waste disposal should be implemented to control microplastic pollution in the marine environment.

Detection methods of micro and nanoplastics

Plastics and related contaminants (including microplastics; MPs and nanoplastics; NPs) have become a serious global safety issue due to their overuse in many products and applications and their inadequate management, leading to possible leakage into the environment and eventually to the food chain and humans. There is a growing literature reporting on the occurrence of plastics, (MPs and NPs) in both marine and terrestrial organisms, with many indications about the harmful impact of these contaminants on plants and animals, as well as potential human health risks. The presence of MPs and NPs in many foods and beverages including seafood (especially finfish, crustaceans, bivalves, and cephalopods), fruits, vegetables, milk, wine and beer, meat, and table salts, has become popular research areas in recent years. Detection, identification, and quantification of MPs and NPs have been widely investigated using a wide range of traditional methods, such as visual and optical methods, scanning electron microscopy, and gas chromatography-mass spectrometry, but these methods are burdened with a number of limitations. In contrast, spectroscopic techniques, especially Fourier-transform infrared spectroscopy and Raman spectroscopy, and other emerging techniques, such as hyperspectral imaging are increasingly being applied due to their potential to enable rapid, non-destructive, and high-throughput analysis. Despite huge research efforts, there is still an overarching need to develop reliable analytical techniques with low cost and high efficiency. Mitigation of plastic pollution requires establishing standard and harmonized methods, adopting holistic approaches, and raising awareness and engaging the public and policymakers. Therefore, this chapter focuses mainly on identification and quantification techniques of MPs and NPs in different food matrices (mostly seafood).

Contamination from microplastics and other anthropogenic particles in the digestive tracts of the commercial species Engraulis encrasicolus and Sardina pilchardus

Fragments of microplastics (<5 mm) found in commercial species of fish, crustaceans, and bivalves, are an issue of global concern. The bioaccumulation of microplastics and other anthropogenic particles in different levels of the food web may provoke unwanted impacts on marine ecosystems and cause pernicious effects on human health. Here, we study the presence of anthropogenic particles and the fraction of microplastics in the target organs of two representative commercial fish species in Spain; the European anchovy (Engraulis encrasicolus) and the European pilchard (Sardina pilchardus). The individuals were sampled along the continental shelf of the Gulf of Cádiz, from the Bay of Cádiz to Cape Santa Maria. The isolation of the microplastics (MPs) was carried out with a complete alkaline-oxidant organic digestion (KOH-H₂O₂) of the digestive tract, including both the contents ingested and the muscle tissues. Anthropogenic particles were found in all individuals of both species with an average of 8.94 ± 5.11 items·ind^-1. Fibres made up 93 % of the items while fragments and films were represented by the remaining 7 %. The average size of the anthropogenic particles was 0.89 ± 0.82 mm. In addition to the fragment and film particles identified as microplastics, 29 % of the fibres were estimated to be microplastics by Fourier-transform infrared spectroscopy (FTIR) analysis. The main polymer found in both species was nylon. No significant correlation was found between the abundance and size of anthropogenic particles ingested and individual size or other body variables. The analysis of similarities (ANOSIM) and the distanced-based multiple linear regression model showed a high homogeneity in anthropogenic particle contamination in both species throughout the study area along the continental shelf of the Gulf of Cádiz.

Microplastics in different fish and shellfish species in the mangrove estuary of Bangladesh and evaluation of human exposure

The water bodies in Bangladesh thrive from plastic pollution. Estuaries are pools of environmental contaminants, and the world's largest mangrove forest, Sundarbans' estuary, is no exception. Thus, for the first time, we investigate MPs abundance in the muscle and gastrointestinal tract (GIT) of twenty estuarine species of fish and shellfish of the Sundarbans, as well as the human health risk. MPs abundance was evident in all the samples ranging from 5.37 ± 1.07 to 54.30 ± 16.53 MP items/g wet body weight (dw) in muscle samples and 7.33 ± 1.89 to 205.61 ± 136.88 MP items/g (dw) in GIT samples. The estimated health risk from MPs is substantial, where the average human intake will be 85,710.08 items of MPs per year per capita for the population of Bangladesh. The dominant polymer types observed using ATR-FTIR are PP and PE (17.5 %), PA (17.5 %) in the muscle tissues, and PP and PE (11.11 %), and EVA (11.11 %) in the GITs. Bottom-feeding species, such as demersal and benthic species, are more contaminated. However, the level of MPs in the species shows a negative correlation with the length and weight of the species. This study reveals that MP pollution is widespread and concerning in Bangladesh's Sundarban mangrove estuarine zone.

The different ways microplastics from the water column and sediment accumulate in fish in Haizhou Bay

Global microplastic (MP) pollution is a serious environmental problem that has been found in various ecosystems, especially marine ecosystems. In this study, the water (surface, middle and bottom water), sediment and fish (pelagic, demersal and benthic fish) in the artificial reef area and adjacent waters in Haizhou Bay were collected, and the mechanism of MP transmission among the three media was analyzed. The results showed that >96 % of the plastics in the region were MPs. The shape of MPs was mainly fibrous (water (73.3 %), sediment (56 %), fish (95.3 %)), color was mainly blue (water (49.3 %), sediment (47 %), fish (72.3 %)), and the material was mainly PET (water (39.6 %), sediment (33 %), fish (86.6 %)). We found that, except for the natural deposition of MPs, MPs could be ingested by pelagic fish and transmitted through vertical movement in the water, while there was an interaction between MPs in benthic fishes and the middle-bottom waters. In addition, as relevant variables, body length and body weight were more likely to explain the number of MPs ingested by fishes than were δ13C and δ15N. Therefore, based on the linear relationship between δ15N and body length, we concluded that there was a weak trophic magnification effect of MPs ingested by fish in this region. This study provides unique information for further exploring the factors influencing the spatial distribution of MPs and the transmission mechanism of MPs in fish.

Microplastics in fish and sediments from the Montenegrin coast (Adriatic Sea): Similarities in accumulation

The accumulation of microplastics (MPs) in the biotic and abiotic components of the marine environment poses a major threat to marine ecosystems worldwide. The objective of this study was to document, for the first time, differences in MP accumulation in the gastrointestinal tract of two commercially important fish species and to evaluate the possible correlation between MP accumulation in the biotic (fish) and abiotic (sediment) components of the marine environment of the Montenegrin coast (Adriatic Sea). Samples were collected from two areas of the Montenegrin coast, Boka Kotorska Bay and the coastal part of the open sea. The frequency of MP ingestion was 58.6 % for Mullus barbatus and 54 % for Merluccius merluccius, while the average number of ingested MPs was 2.9 ± 0.5 and 3.2 ± 1.0 items/individual, respectively. Average MP abundance in surface sediments from Boka Kotorska Bay and the coastal part of the open sea was 315 ± 45 and 435 ± 258 MPs/kg of dry sediment, respectively. Most MPs identified were filaments, followed by fragments and films, while the most abundant polymers found in fish and sediments samples were polypropylene and polyethylene. The present results indicate that MP pollution in the study area is reflected in the accumulation of MPs in the biotic (fish) and abiotic (sediment) components of the marine environment. Measures need to be taken to reduce the input of plastics/MPs into the marine environment.

A Biomarker Approach as Responses of Bioindicator Commercial Fish Species to Microplastic Ingestion: Assessing Tissue and Biochemical Relationships

Plastic debris is a growing environmental problem on a global scale, as plastics and microplastics (MPs) can be ingested by marine organisms, inducing toxic effects. The aim of this study was to assess MP intake and antioxidant responses in three bioindicator species: red mullet, bogue, and anchovy (Mullus surmuletus, Boops boops, and Engraulis encrasicolus, respectively) for plastic contamination in the Mediterranean Sea. MP intake was assessed in the gastrointestinal tract of the fish. Further, several enzymes from both the liver and brain were analysed. The antioxidant defences, catalase (CAT) and superoxide dismutase (SOD), as well as the detoxifying enzyme glutathione-S-transferase (GST), were measured in both tissues. The acetylcholine esterase (AchE), as an indicator of neuronal damage, was measured in the brain. Malondialdehyde (MDA) was analysed as a marker of oxidative damage in the brain and liver samples. Total MP intake and MP typology differed between the three species, with M. surmuletus showing the lowest intake of MPs, while B. boops showed the highest intake of MPs. An increase in both antioxidant enzymes was evidenced in E. encrasicolus liver activity with respect to MP intake. In brain samples, an increase in CAT activity was found in M. surmuletus and B. boops as a consequence of MP ingestion. SOD activity in the brain increased in B. boops and E. encrasicolus that had ingested MPs. GST activity increased in the liver of M. surmuletus' and in brains of B. boops that had ingested MPs. The intake of MPs is species related, as well as being inherently linked to the habitat they live in and being able to induce a light activation of species-specific detoxifying and antioxidant mechanisms.

Hazard index of microplastics contamination in various fishes collected off Parangipettai, Southeast coast of India

The authors of the present research aimed to assess microplastics (MPs) contamination in the gills and gut of selected fishes from various aquatic zones and also to bring out the risks of the identified polymers. Accordingly, about 200 fish specimens of 10 different species were collected from the landing center at Parangipettai, southeast coast of India. The fishes were dissected to investigate MPs contamination in their gills and gut. The dissected tissues were acid digested and filtered to observe its microplastic contamination using a stereozoom microscope. In gills, Cynoglossus arel had the least contamination (0.4 ± 0.01 particles/ind) and Mugil cephalus had highest microplastic contamination (1.7 ± 0.01 particles/ind). In gut, C. arel had the minimum contamination (0.7 ± 0.09 particles/ind) and Rastrelliger kanagurta had maximum contamination (2.3 ± 0.26 particles/ind). The size of microplastics isolated from the present study ranged from 100 to 1000 μm. Among microplastic shapes, fibers (97%) and pellets (3%) were observed. About eight colours of microplastics were observed in the fishes among which black was dominant. Three polymers such as LDPE, PP and PS were identified by μFTIR, among which LDPE (57%) was dominant. Polymer Hazard Index denotes that LDPE (6.27), PP (3.4) and PS (2.7) have a PHI score of 1-10 classifying them in the hazard category II which has a medium risk. These polymers may directly enter the human body when consumed and cause health implications which require further investigation.

Large size (>100-μm) microplastics are not biomagnifying in coastal marine food webs of British Columbia, Canada

Microplastics (MPs) contamination in marine environments is of increasing concern, as plastic particles are globally ubiquitous across ecosystems. A large variety of aquatic taxa ingest MPs, but the extent to which animals accumulate and transfer MPs through food webs is largely unknown. In this study, we quantified MP uptake in bivalves, crabs, echinoderms, and fish feeding at different trophic levels at three sites on southern Vancouver Island. We paired stable-isotope food web analysis with MP concentrations in digestive tracts across all trophic levels and in fish livers. We then used Bayesian generalized linear mixed models to explore whether bioaccumulation and biomagnification were occurring. Our results showed that MPs (100-5000 μm along their longest dimension) are not biomagnifying in marine coastal food webs, with no correlation between the digestive tract or fish liver MP concentrations and trophic position of the various species. Ecological traits did, however, affect microplastic accumulation in digestive tracts, with suspension feeder and smaller-bodied planktivorous fish ingesting more MPs by body weight. Trophic transfer occurred between prey and predator for rockfish, but higher concentrations in full stomachs compared with empty ones suggested rapid excretion of ingested MPs. Collectively, our findings suggested the movement of MP through marine food webs is facilitated by species-specific mechanisms, with contamination susceptibility a function of species biology, not trophic position. Furthermore, the statistical methods we employ, including machine learning for classifying unknown particles and a probabilistic way to account for background contamination, are universally applicable to the study of microplastics. Our findings advance understanding of how MPs enter and move through aquatic food webs, suggesting that lower-trophic-level animals are more at risk of ingesting >100-μm MPs, relative to higher-trophic-level animals. Our work also highlights the need to advance the study of <100-μm MPs, which are still poorly understood and may need to be considered separately in ecological risk assessments.

Occurrence of microplastics in gastrointestinal tract of fish from the Gulf of Guinea, Ghana

Over the past decades, there has been a growing concern about microplastics pollution in global aquatic habitats and its potential impact on human health. This study was carried out to determine the presence of microplastics in fish of economic importance in Ghana. Microplastics were found to be abundant in all investigated samples, with 68 % of the fishes contaminated with microplastics and a total of 133 plastic items identified in the fish. The presence of fibers, black coloured particles, and microplastics in the size range of 0.5-1.0 mm was the most abundant in the samples examined. Three polymers specifically, polyethylene, polyvinyl acetate, and polyamide were identified in the study. The presence of microplastics in the fishes investigated may pose severe ecological and health concerns, and hence comprehensive policies targeted at preventing plastic pollution of Ghana's maritime environment is warranted.

Microplastic occurrence in deep-sea fish species Alepocephalus bairdii and Coryphaenoides rupestris from the Porcupine Bank (North Atlantic)

Microplastic occurrence in marine biota has been reported in a wide range of animals, from marine mammals and seabirds to invertebrates. Commercial and shallow-water fish have been the subject of numerous works on microplastic ingestion, given their importance in human diet and accessibility. However, little is known about microlitter occurrence in fish species inhabiting the dark ocean, in the bathyal zone and there is a high degree of uncertainty about microplastic distribution in offshore areas and the deep sea. In this study, bathydemersal species Alepocephalus bairdii and Coryphaenoides rupestris from the Porcupine Bank caught between 985 and 1037 m depth were inspected for microdebris. The stomach contents were digested by the alkaline method plus ethanol addition to avoid clogging. A filament of Polyethylene Terephthalate (PET) was found in the stomach of a specimen of A. bairdii, representing 4% of the total sampled specimens of this species (i.e. prevalence in n = 25). However, when considering potential microplastics, the prevalence increased to 28% in both, A. bairdii and C. rupestris. This work provides the first baseline study of microplastic items in fish from such depths in the Atlantic and suggests these species might be used as biomonitors in future research.

Optimization of an Analytical Protocol for the Extraction of Microplastics from Seafood Samples with Different Levels of Fat

Marine organisms are affected by the ubiquitous occurrence of microplastics (MPs) in the environment. Several protocols have been described to extract and quantify MPs in seafood, although their complex matrices, with high level of fat, can compromise the efficiency of MPs extraction. To solve this issue, the present study aimed to develop a detailed methodology suitable to process seafood samples with different levels of fat, namely fish and molluscs, from fresh and canned sources, including the immersive liquids from the cans. Sample digestion was tested using different solutions (10% KOH, 30% H₂O₂), temperatures (40 °C, 65 °C) and incubation times (24, 48, 72 h). For fat removal, three detergents (two laboratory surfactants and a commercial dish detergent) and 96% ethanol were tested, as well as the manual separation of fat. The methodology optimized in this study combined a digestion with 30% H₂O₂ at 65 °C, during 24 to 48 h, with a manual separation of the fat remaining after the digestion. All steps from the present methodology were tested in six types of polymers (PE-LD, PET, PE, AC, PS, and lycra), to investigate if these procedures altered the integrity of MPs. Results showed that the optimized methodology will allow for the efficient processing of complex seafood samples with different fat levels, without compromising MPs integrity (recoveries rate higher than 89% for all the polymers tested).

Microplastics in fillets of Mediterranean seafood. A risk assessment study

Microplastics (MPs) are considered as emergent threat to human health. No complete data still exists on MPs presence in fish tissue and their transmission to humans. The present study aims to detect and quantify the presence of MPs (<3 μm) in several edible seafood (Sardina pilchardus, wild and farmed Sparus aurata, Mullus surmuletus, Solea solea and musselMytilus galloprovincialis) from the south coast of Mediterranean Sea. MPs were detected through an innovative extraction method coupled to the SEM-EDX technology. The Estimated Daily Intakes (EDIs) for adults and children for each species were calculated. The higher median level (IQR) of MPs (9.09E+04) was found inM. surmuletus. Conversely, the lower median (IQR) level was observed in S. pilchardus (7.04E+04). The smallest and biggest median (IQR)diameter of MPs (1.8 and 2.5 μm) were identified in M. galloprovincialisand S. solea, respectively. The highest EDIs (25.50E+03; 48.09E+03) arefor ingestion of farmedS. auratarespectively for adults and children. Instead, the lowest EDIs (2.37E+02; 4.48E+02) are due to M. galloprovincialisingestion for adults and children, respectively. Our data should be carefully considered in view of the direct exposure of humans to plastic particles under 3 μm through seafood consumption to better manage the related risks.

Microplastic uptake and gut retention time in Japanese anchovy (Engraulis japonicus) under laboratory conditions

To explore the impact of microplastic (MP) pollution on planktivorous fish, we examined the uptake and retention of MPs by Japanese anchovy (Engraulis japonicus) under laboratory conditions. MP uptake was size selective in adult anchovy-0.3-mm MPs were taken up in significantly larger amounts than 0.85-mm MPs-but not in juveniles. There were no significant differences in the uptake of MPs of three different colors, suggesting that anchovy do not select for MP coloration. More than 90% of the MPs were excreted within 20 h of ingestion, indicating that MP retention time is similar to the processing time of food items. Our findings suggest that Japanese anchovy tend to take up MPs that are equivalent in size to prey items, but that the impacts of MP ingestion are likely to be limited under the current state of oceanic MP contamination.

Can the toxicity of polyethylene microplastics and engineered nanoclays on flatfish (Solea senegalensis) be influenced by the presence of each other?

Microplastics and nanomaterials are applied in a myriad of commercial and industrial applications. When leaked to natural environments, such small particles might threaten living organisms' health, particularly when considering their potential combination that remains poorly investigated. This study investigated the physiological and biochemical effects of polyethylene (PE; 64-125 μm in size, 0.1, 1.0, and 10.0 mg·L^-1) single and combined with an engineered nanomaterial applied in antifouling coatings, the copper-aluminium layered double hydroxides (Cu-Al LDH; 0.33, 1.0, and 3.33 mg·L^-1) in the flatfish Solea senegalensis larvae (8 dph) after 3 h exposure, in a full factorial design. Particles ingestion, histopathology, and biochemical biomarkers were assessed. Fish larvae presented <1 PE particles in their gut, independently of their concentration in the medium. The histological health index showed minimal pathological alterations at PE combined exposure, with a higher value observed at 1 mg LDH·L^-1 × 0.1 mg PE·L^-1. Gut deformity and increased antioxidant defences (catalase), neurotransmission (acetylcholinesterase), and aerobic energy production (electron transport system) were observed at PE ≥ 1.0 mg·L^-1. No oxidative damage (lipid peroxidation) or alterations in the detoxification capacity (glutathione-S-transferase) was observed on single and combined exposures. PE, combined or not with Cu-Al LDH, does not seem to compromise larvae's homeostasis considering levels reported so far in the marine and aquaculture environments. However, harsh effects are expected with MP contamination rise, as projections suggest.

Spatial distribution of microplastics in Chinese freshwater ecosystem and impacts on food webs

Over the past two decades, there has been a lot of discussion about the rapid increase of microplastics (MPs) due to their persistence, ubiquity, and toxicity. The widespread distribution of MPs in various freshwater ecosystems makes them available for different trophic levels biota. The ingestion and trophic transfer of MPs may induce potential impacts on freshwater food webs. Therefore, this systematic review is an in-depth review of 51 recent studies to confirm the spatial distribution of MPs in the Chinese freshwater ecosystem including water, sediment and biota, exposure pathways, and impacts on freshwater food webs. The result suggested the white, transparent and colored, Polypropylene (PP) and Polyethylene (PE) of <1 mm fibers were dominant in Chinese freshwaters. The uptake of MPs by various freshwater organisms as well as physiological, biological and chemical impacts on food webs were also elucidated. At last, some limitations were discussed for future studies to better understand the effects of MPs on food webs.

Microplastic contamination of fish gills and the assessment of both quality assurance and quality control during laboratory analyses

Microplastic pollution has received substantial international attention in terrestrial and marine environments and in the atmosphere. In this study, we assessed microplastic pollution and analyzed the accumulation of microplastics in the gills of fish caught in the Zhoushan fishing ground from September 2017 to March 2018. The average abundance of microplastics was 0.49 ± 0.54 particles/gill and frequently found chemical polymers was polyethylene terephthalate. We also conducted experiments on microplastic pollution in the water and the working solutions used during the analytical process and found that the source of microplastic contamination was the solutions used. Moreover, we evaluated and scored experimental quality control and quality assurance adapted from the 'Total Accumulated Score' method. Valuable steps are recommended in order to produce reliable results and improve the quality of results in microplastic analyses.

The utility of jellyfish as marine biomonitors

Jellyfish are abundant in coastal waters across broad latitudinal ranges and are often considered pests and a group that can cause phase shifts in marine ecosystems. Recent studies have highlighted their potential as biomonitors of contaminants including metals, herbicides and nutrients. Traditionally, sedentary organisms like molluscs and annelid worms have been used, but some jellyfish have similar characteristics of localised distributions and in some cases sedentary behaviour. Broad gradients in contaminant accumulation have been shown for a number of planktonic jellyfish species. An alternative biomonitoring candidate is the tropical/sub-tropical upside-down jellyfish (Cassiopea spp.). In laboratory and field deployments, Cassiopea accumulate measurable contaminants over days to weeks, making them ideal for detecting short-term pulses. Furthermore, the decay curve of contaminants varies temporally post-exposure and contaminant type. This can provide an estimate of the timing of exposure. Cassiopea, along with other jellyfish, have the potential to be an interesting and valuable group of organisms for monitoring coastal impacts.

The fishing and seafood sector in the time of COVID-19: Considerations for local and global opportunities and responses

This article provides an overview of the impact of the COVID-19 pandemic on the fishing sector over the world, including several economic, social, environmental, and health challenges that the fisheries have had to face during the early days of the health crisis, and some of them still continue today. These problems, in short, are translated into a decrease in seafood demand, loss of jobs, changes in food consumption habits, economic losses, or increased vulnerability of the industry. As a consequence, governments have been forced to implement regulations and measures in support of this sector. However, a positive aspect of the pandemic also stands out, the opportunity to transform the food system to be greener, more inclusive, and resilient against future shocks.

Microplastics in Tissues (Brain, Gill, Muscle and Gastrointestinal) of Mullus barbatus and Alosa immaculata

The researches on MPs in commercial marine fish are very limited although in marine environments microplastic (MPs) pollution is a global problem. In this study, the presence, composition, and characterization of MPs in different tissues (brain, gill, muscle, and gastrointestinal tract) of commercial fish species [red mullet (Mullus barbatus) and pontic shad (Alosa immaculata Bennett 1835)] from the Black Sea were investigated. M. barbatus (demersal) and A. immaculata (pelagic) fish were preferred in the selection of fish species in order to represent demersal and pelagic environments. After dissected the fish, MPs were obtained from the tissues by extraction using the flotation method; then the MPs were counted and categorized according to shape, size, and color. The composition of the MPs was determined via ATR-FTIR spectroscopy. In terms of microplastic abundance in fish tissues, the gastrointestinal tract (40.0%) ranked first in both fish species, while the lowest MPs density was determined in brain tissues (7.0%). After the gastrointestinal tissue, gills were identified as the second tissue with the highest MPs density. Regardless of fish species, MPs characterization was mainly fibrous (51.0%), black colored (49.0%), and 50-200 µm in size (55.0%). Among the nine different polymers determined, polychloroprene (18.8%) and polyamide (15.0%) were found most frequently. This research provides data for tissue-based assessment of MPs in fish. The obtained data showed that MPs (one of the anthropogenic pollutants) are quite high in all tissues regardless of fish species. Moreover, it has emerged that these two fish species are suitable for monitoring microplastics in the study area.

Big eyes can't see microplastics: Feeding selectivity and eco-morphological adaptations in oral cavity affect microplastic uptake in mud-dwelling amphibious mudskipper fish

Microplastic contamination is a widespread global problem. Plastic pollution in the oceans has received a lot of news coverage, but there is a significant gap in our knowledge about its effect in estuarine areas and a profound regional bias in available information. Here, we estimated the degree of microplastic pollution, its impact on a selected fish, and its function as a vector for heavy metals in the Ulhas River estuary, which is one of the most fragile, polluted, and anthropogenically impacted estuaries in India. Using mudskipper fish, we have also assessed how the feeding guild and ecomorphological adaptations in the feeding apparatus affected the microplastic intake and life history traits of the fish. Sediment, water and fish samples were collected from three sampling localities (S1, S2 and S3) in the Ulhas River estuary and analysed. Findings showed an increase in microplastic abundance from S1 (suburban) to S3 (urban industrial belt) in sediment (96.67-130.0 particles kg^-1), water (0.28-0.41 particles L^-1) and fish (3.75-6.11 particles per fish). Fragments, followed by pellets and filaments largely contribute to the plastic morphotypes in sediment and water. FTIR analysis revealed polymers of anthropogenic and industrial origin such as polypropylene, Surlyn ionomer, low-density polyethylene, and polyethylene or polybutylene terephthalate. Only filaments were found in the guts of 74% of the mudskippers examined, which may be due to their filter-feeding habit and unique anatomical arrangement of oral structures that effectively filter large microplastic particles. Microplastic abundance showed a strong negative correlation with condition factor, fullness index and hepatosomatic index of fish. SEM-EDS analysis revealed that the microplastic surface topography played an important part in adsorbing heavy metals from a water body containing these contaminants. Results highlight the contamination of vulnerable estuarine habitats, harmful effects on resident biota, and health threats to dependent populations.

Twitter data analysis to assess the interest of citizens on the impact of marine plastic pollution

Few studies have mined social media platforms to assess environmental concerns. In this study, Twitter was scraped to obtain a ~140,000 tweet dataset related specifically to marine plastic pollution. The goal is to understand what kind of users profiles are tweeting and how and when they do it. In addition, topic modelling and graph theory techniques have allowed us to identify main concerns on this topic: i) impact on wildlife, ii) microplastics/water pollution, iii) estimates/reports, iv) legislation/protection, and v) recycling/cleaning initiatives. Results reveal a scarce influence of organizations involved in research and marine environmental awareness, so some guidelines are depicted that could help to adjust their communication plans. This is relevant to engage society through reliable information, change habits and reinforce sustainable behaviour. A visualization tool has been created to analyze the results over time.

Plastic waste: Status, degradation and microbial management options for Africa

This paper presents a review of synthetic polymer (notably plastic) wastes profiles in Africa, their current management status, and better options. Data revealed that of the approximated 86.14 million metric tonnes and 31.5 million metric tonnes of primary polymers and plastics, respectively, and an estimated 230 million metric tonnes of plastic components imported between 1990 and 2017, about 17 million metric tonnes are mismanaged. Leading African nations on the plastic wastes generator table in increasing order are Tunisia (6.9%), Morocco (9.6%), Algeria (11.2%), South Africa (11.6%), Nigeria (16.9%), and the chief is Egypt (18.4%). The volume of plastic wastes generated in Africa directly correlates with her increasing population status, however, the current treatment options have major drawbacks (high energy and technological input, high demand for space, and creation of obnoxious by-products). Ineffective regulations, poor monitoring, and slow adoption of veritable practices by governments are responsible for the steady increase in plastic volume in the African landscapes and environments. In Nigeria, only about 9% and 12% of the total generated wastes are recycled and incinerated. The remainder bulk is either discarded into waste dumps (and a few available landfills) or natural environments. There is a paucity of standard plastic biodegradative work by African scientists, and only a few works show detection of competent synthetic plastic degrading microbes globally. Asides from the ills of possible omission of core degraders, there is a need for researchers to follow standard degradation procedures to arrive at efficient, reproducible, and generally accepted outcomes utilizable on a larger scale. Thus, metagenomic search on the vast African urban and rural plastisphere is the best isolation option.

A Bayesian analysis of the factors determining microplastics ingestion in fishes

Microplastic particles (MPs) occur widely in aquatic ecosystems and are ingested by a wide range of organisms. While trophic transfer of MPs is known to occur, researchers do not yet fully understand the fate of MPs in food webs. We explored the factors influencing reported ingestion of MPs in marine and freshwater fishes by conducting a literature review of 123 studies published between January 2011 and June 2020. We used Bayesian generalized linear mixed models to determine whether MP ingestion by fishes varies by Food and Agricultural Organization fishing area, trophic level, body size, taxa, and study methodology. After accounting for methodology, strong regional differences were not present, although ingested MP concentrations were slightly different among some FAO areas. According to the reviewed studies, MP concentrations in fish digestive tracts did not increase with either trophic level or body size, suggesting that biomagnification of MPs did not occur, although larger fish were more likely to contain MPs. Researchers reported higher concentrations of MPs in clupeids compared with other commonly studied taxonomic families, which could be due to their planktivorous feeding strategy. Methodology played an influential role in predicting reported concentrations, highlighting the need to harmonize methods among studies.

Commercial Gilthead Seabream (Sparus aurata L.) from the Mar Menor Coastal Lagoon as Hotspots of Microplastic Accumulation in the Digestive System

This paper presents the results on the presence and characterization of microplastics (MP) in the gastrointestinal tract of gilthead seabream (Sparus aurata L.), a species of commercial interest from the Mar Menor coastal lagoon in Southeast Spain. This is the first time that microplastic ingestion is recorded in any species from this semi-enclosed bay. Stomach and intestine from a total of 17 specimens captured by local fishermen were processed, and microplastic particles and fibers found in all of them were displayed. Overall, 40.32% (279/692) of total isolated microparticles proved to be microplastics; i.e., <5 mm, as identified by FTIR spectroscopy. The average value by fish was 20.11 ± 2.94 MP kg^-1, corresponding to average concentrations of 3912.06 ± 791.24 and 1562.17 ± 402.04 MP by kg stomach and intestine, respectively. Four MP forms were isolated: fiber (71.68%), fragment (21.15%), film (6.81%), and microbead (0.36%), with sizes ranging from 91 µm to 5 mm, an average of 0.83 ± 0.04 mm, and no statistically significant differences between mean sizes in stomach and intestine samples (F-test = 0.004; p = 0.936). Nine polymer types were detected, although most of fibers remained unidentified because of their small size, the presence of polymer additives, or closely adhered pollutants despite the oxidizing digestion carried out to eliminate organic matter. No significant correlation was found between main biological parameters and ingested microplastics, and high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene polypropylene (PEP), and polyvinyl (PV) were identified as the most abundant polymers. The average microplastic ingestion in this study area was higher than those reported in most studies within the Mediterranean Sea, and closely related to microplastic pollution in the surrounding area, although with a predominance of fiber form mainly due to fishery activities.

Preliminary Assessment on the Histological Changes in Juvenile Siganus guttattus (Bloch, 1787) Exposed to Plastic Debris

Plastic debris is ubiquitous in the marine environment and many of this is polyethylene based plastic bags. Its potential effect on marine organisms is still understudied. Hence, this study determined the histological changes induced in the intestine and liver of the juvenile rabbit fish, Siganus guttatus. S. guttatus (N = 150) were sub chronically exposed to plastic bag debris suspensions (0, 0.01, 0.1, 1.0 and 10 mg L^-1) for 10 days. In addition to histological changes, the condition factor (CF) index of the fishes were assessed. Results showed that there was no significant difference in the CF index of the fishes exposed to varying concentrations of plastic suspensions, there was however histological changes in fishes exposed to 10 mg L^-1. The histological changes in the intestine were hyperemia, necrosis, goblet cells hyperplasia, and shortening of the villi. Histological changes in the liver were hyperemic blood vessels and vacuolization. Fishes exposed to 10 mg L^-1 exhibited a higher proximal, distal, liver and total organ index as compared to those unexposed (p < 0.05).

Microplastics in freshwater and wild fishes from Lijiang River in Guangxi, Southwest China

Microplastics (MPs) are ubiquitous contaminants of emerging concern that have gained great attention recently due to their widespread appearance in the environment and potential adverse effects on living biota. Lijiang in Guangxi in China is a world-famous place of tourist attraction and attracted thousands of visitors every year. However, little is known regarding occurrence and distribution of MPs in freshwater and wild fishes in the Lijiang River. In this study, we used stereoscopy and micro Fourier transform infrared spectrometry (μ-FTIR) methods to investigate the abundance, morphotype, size distribution, and polymer type of MPs in freshwater collected by plankton nets and bulk sampling by pumping and filtration. Results showed that abundance of MPs in freshwater with bulk sampling by pumping (67.5 ± 65.6 items/m³) was significantly higher than those using plankton nets (0.67 ± 0.41 items/m³ and 0.15 ± 0.15 items/m³ for mesh sizes of 75 μm and 300 μm, respectively). An average abundance of MPs detected in wild fishes was 0.6 ± 0.6 items/individual, of which, a majority was found in the gastrointestinal tracts. Large-sized (>0.3 mm) and colored MPs in morphotypes of flakes and fibers dominated in both freshwater and wild fishes. Polypropylene-polyethylene copolymer and polyethylene were the top two abundant polymer types of MPs in freshwater, while polyethylene terephthalate dominated in wild fishes. This study provides evidences for our better understanding of pollution status of MPs in the Lijiang River.