Fin whales and microplastics: The Mediterranean Sea and the Sea of Cortez scenarios

Knowledge about Microplastic in Mediterranean Tributary River Ecosystems: Lack of Data and Research Needs on Such a Crucial Marine Pollution Source

Plastic debris occurring in freshwater environments, which can either come from the surrounding terrestrial areas or transported from upstream, has been identified as one of the main sources and routes of plastic pollution in marine systems. The ocean is the final destination of land- based microplastic sources, but compared to marine environments, the occurrence and effects of microplastics in freshwater ecosystems remain largely unknown. A thorough examination of scientific literature on abundance, distribution patterns, and characteristics of microplastics in freshwater environments in Mediterranean tributary rivers has shown a substantial lack of information and the need to apply adequate and uniform measurement methods.

Adverse effects of plastic ingestion on the Mediterranean small-spotted catshark (Scyliorhinus canicula)

Plastics are widely diffused in the oceans and their ingestion by marine organisms is raising concern for potentially adverse effects. The risk of harmful interactions with marine plastic pollution depends on the biology of the species as well as the distribution and abundance of the different plastic types. The aim of this study was to assess the occurrence of plastic ingestion by the small-spotted catshark (Scyliorhinus canicula), one of the most abundant elasmobranchs in the Mediterranean Sea. The expression levels of genes indicative of total immune system function were analyzed to gather preliminary data for further investigation of any potential correlations between plastic presence and immune activation. One hundred catsharks were collected during the Spring 2018 in two geographic locations in the southern region of the central Mediterranean Sea: 1) near Mazara del Vallo, SW Sicily and 2) near Lampedusa island, Italy's southernmost. Standard measurements were recorded for each specimen and its organs and sex was determined. The gastrointestinal tract (GIT) was preserved for plastic detection and identification. Where present, plastics (macro- and micro-) were characterized in terms of size, shape and polymer typology through microscopy and μ-Raman spectroscopy. Spleen from a subset of thirty samples was preserved for RNA extraction, then used to quantify by real time PCR the transcripts of T cell receptor beta (TCRB), T cell receptor delta (TCRD) and IgM genes. The results indicated that ingestion of plastic is widespread, with microplastics (MP, from 1 μm to <1 mm) abundantly present in nearly all samples and macroplasticplastic (MaP, > 1 cm) in approximately 18% of the specimens collected. A significant increase in the expression of TCRB, TCRD and IgM was observed in the spleen of MaP + specimens from Mazara del Vallo waters, in parallel with 67% increase in liver weight. While the presence of MP alone is not enough to induce a strong activation of the immunity, some type of plastics falling into the MaP category may be more toxic than others and crucial in the activation of the immune response. The results of this study represent a first evidence that plastic pollution represents an emerging threat to S. canicula, the Mediterranean food web and human consumers.

Microplastics: Sources and distribution in surface waters and sediments of Todos Santos Bay, Mexico

Microplastics (MPs) are ubiquitous and a threat to marine and freshwater environments. Effluent waters from secondary wastewater treatment plants (WWTPs) into Todos Santos Bay (TSB) were investigated as sources of MPs. MPs were detected in all analyzed matrices and presented variable morphologies. MPs from surface water samples (n = 18) varied from 0.01 to 0.70 plastic particles/m³ (pp/m³). Fragments (47 ± 23%) and fibers (47 ± 23%) were the most abundant particles found in the surface water samples. In sediment samples (n = 11), MPs varied from 85 to 2494 pp/0.1 m². Sediment samples showed fragments of 70 ± 19%, fibers 28 ± 18% in mean. The range of MP values from WWTP effluents (n = 24) was 81 to 1556 pp/m³, and fibers (65 ± 28%) were the most abundant MP particles. Several synthetic polymers (polypropylene, polyethylene, polyethylene-propylene, polyvinyl chloride, cellophane), and natural fibers (cotton and wood) were identified. The surface currents and the parameters that modulate them, are the main factors that dominate the distribution of MPs in surface waters. While in the sediments the parameters such as bathymetry and grain size distribution have more influence on their distribution in the marine environment, where the effluent waters from WWTPs only contributes MPs to the TSB.

Microplastic ingestion cause intestinal lesions in the intertidal fish Girella laevifrons

We exposed juvenile intertidal fish to different amounts of Poly(styrene-co-divinylbenzene) microplastics in their diet. We fed ten individuals with pellets containing 0.01 g, another ten fish with pellets containing 0.1 g of PS, and ten fish without plastic as control. After 45 days of treatment, the whole intestine was removed, and the histological evaluation started immediately. We evaluated inflammation due to leukocyte infiltration (Lk), circulatory disorders like Hypermeia (Hyp), and regressive changes in the intestinal tissue, assessing Crypt cell loss (Ccl) and Villi cell loss (Vcl). The severity of the lesions increased according to the microplastic concentration. In the fish group feeding on microplastics, we found that leukocyte infiltration and hyperemia were more severe in the higher exposure group compared to the lower exposure; and crypt cell loss and villi cell loss increased significantly due to Poly(styrene-co-divinylbenzene) microplastic physical abrasion.

Micro- and nano-plastics in marine environment: Source, distribution and threats - A review

Plastic litters have become the predominant components of marine debris due to extensive consumption plastics and mismanagement of plastic wastes. As part of the problem, microplastics (MPs) and nanoplastics (NPs) have generated special concerns due to their unique features that make them easy to transfer among oceans in the marine ecosystem, across different trophic levels inside the food web, and even across different tissues inside contaminated animals. Studies have demonstrated the almost omnipresence of MPs in the marine ecosystem, which present serious threats to the health of marine animals, causing symptoms such as malnutrition, inflammation, chemical poisoning, growth thwarting, decrease of fecundity, and death due to damages at individual, organ, tissue, cell, and molecule levels. The information on NPs in the marine ecosystem has been scarce due to the challenges in sampling and detecting these nano-scaled entities. In vitro and in vivo experiments have demonstrated that NPs have the potential to penetrate different biological barriers including the gastrointestinal barrier and the brain blood barrier and have been detected in many important organs such as brains, the circulation system and livers of sampled animals.

Microplastics pollution along the Lebanese coast (Eastern Mediterranean Basin): Occurrence in surface water, sediments and biota samples

The Mediterranean Sea is the largest semi-enclosed sea and one of the worst affected regional seas with sub-basin scale heterogeneity in plastics concentration. Few studies on microplastics (MPs) pollution have been conducted in the Eastern part of the Mediterranean basin. This study aims to evaluate, for the first time, the MPs pollution of the Lebanese coast (Levantine Basin) as well as the most common polymers found, and to assess the potential role of coastal landfills in this pollution. Two important seafood species that are wholly consumed by the Lebanese community: the European anchovy, Engraulis encrasicolus, and the spiny oysters, Spondylus spinosus, were sampled in three different sites englobing the littoral (Tripoli, Beirut and Sidon). Sea water and sediment samples were also collected from the same sites. Results showed different patterns of MPs concentration in the analyzed matrices: Sidon water sample was highly contaminated in MPs (6.7 MPs/m³) while Tripoli had the highest MPs in sediments (4.68 MPs/g). The occurrence of MPs in the biota was high (83.4% and 86.3% in anchovies and spiny oysters, respectively). Both anchovies and oysters from Beirut region had the highest ingested MPs/individual (2.9 ± 1.9 and 8.3 ± 4.4 MPs/individual, respectively). This study is the first that investigated microplastics ingestion by Spondylus spinosus while indicating the most common polymers found in the three matrices (water, sediments and biota) in the Eastern Mediterranean. These results highlighted the high MPs pollution found in the Levantine Basin in comparison to other Western Mediterranean regions. In addition, the obtained results indicate a potential contribution of coastal landfills to this pollution.

Current practices and future perspectives of microplastic pollution in freshwater ecosystems in China

The pollution of marine and freshwater environments by plastic waste has attracted increasing public attention worldwide in recent years. China is the world's second largest economy and contributes the largest mass of mismanaged plastic waste. In this review, we collected accessible data on the abundance of microplastics in China's freshwater ecosystems, analyzing this pollutant in the samples of waters, sediments and biota. The results showed that microplastics are pervasive in surveyed freshwater environments, and a high abundance of microplastics was found in estuaries and inland waters located in populated urban areas. Moreover, many freshwater bivalve and fish have been found to uptake microplastics. Although similar sampling and laboratory processing methods were applied for microplastic research in different aquatic ecosystems, methods of investigation and units reported by different authors should be standardized. The characteristics of the detected microplastics showed that small size (<1 mm), fibers and transparency were the most common features in China's freshwater ecosystems and that PP and PE were the most common types of microplastics. The current situation of microplastic pollution in China is largely caused by inefficient administration and lack of applicable legislation and regulations. Therefore, we suggest that the Chinese government need to be more active in dealing with the plastic pollution issues, and increase education and publicity to promote people's awareness of environmental pollution caused by microplastics.

Vertical Distribution of Microplastics in the Water Column and Surficial Sediment from the Milwaukee River Basin to Lake Michigan

Microplastic contamination was studied along a freshwater continuum from inland streams to the Milwaukee River estuary to Lake Michigan and vertically from the water surface, water subsurface, and sediment. Microplastics were detected in all 96 water samples and 9 sediment samples collected. Results indicated a gradient of polymer presence with depth: low-density particles decreased from the water surface to the subsurface to sediment, and high-density particles had the opposite result. Polymer identification results indicated that water surface and subsurface samples were dominated by low-density polypropylene particles, and sediment samples were dominated by more dense polyethylene terephthalate particles. Of the five particle-type categories (fragments, films, foams, pellets/beads, and fibers/lines), fibers/lines were the most common particle-type and were present in every water and sediment sample collected. Fibers represented 45% of all particles in water samples and were distributed vertically throughout the water column regardless of density. Sediment samples were dominated by black foams (66%, identified as styrene-butadiene rubber) and to a lesser extent fibers/lines (29%) with approximately 89% of all of the sediment particles coming from polymers with densities greater than 1.1 g cm^-3. Results demonstrated that polymer density influenced partitioning between the water surface and subsurface and the underlying surficial sediment and the common practice of sampling only the water surface can result in substantial bias, especially in estuarine, harbor, and lake locations where water surface concentrations tend to overestimate mean water column concentrations.

Evaluation of the infiltration of polystyrene nanobeads in zebrafish embryo tissues after short-term exposure and the related biochemical and behavioural effects

One of the current main challenges faced by the scientific community is concerning the fate and toxicity of plastics, due to both the well-known threats made by larger plastic items spreading in ecosystems and their fragmentation into micro- and nanoparticles. Since the chemical and physical characteristics of these smaller plastic fragments are markedly different with respect to their bulk product, the potential toxicological effects in the environment need to be deeply investigated. To partially fill this gap of knowledge, the aim of this study was to evaluate the polystyrene nanobead intake in the tissues of zebrafish (Danio rerio) embryos and their related toxicity. Embryos at 72 h post fertilization (hpf) were exposed for 48 h to 0.5 μm fluorescent polystyrene nanobeads at a concentration of 1 mg L^-1. Confocal microscopy was employed to investigate nanoplastic ingestion and tissue infiltration, while potential sub-lethal effects were evaluated by measuring several endpoints, which covered the adverse effects at the molecular (protein carbonylation), cellular (P-glycoprotein, activity of several antioxidant/detoxifying enzymes) and organism levels by evaluating of possible changes in the embryos' swimming behaviour. Imaging observations clearly highlighted the nanoplastics' uptake, showing nanobeads not only in the digestive tract, but also migrating to other tissues through the gut epithelium. Biomarker analyses revealed a significant decrease in cyclooxygenase activity and an induction of superoxide dismutase. The behavioural test highlighted a significant (p < 0.05) variation in the turn angle between the control and exposed embryos. This study points out the capability of nanoplastics to infiltrate zebrafish embryo tissues, even after a short exposure, thus suggesting the need for deeper investigations following longer exposure times, and highlighting the potential of nanoplastics to cause toxicological effects on freshwater organisms, at the organism level.

Microplastics in the environment: A critical review of current understanding and identification of future research needs

Microplastics (plastic particles <5 mm) are a contaminant of increasing ecotoxicological concern in aquatic environments, as well as for human health. Although microplastic pollution is widespread across the land, water, and air, these environments are commonly considered independently; however, in reality are closely linked. This study aims to review the scientific literature related microplastic research in different environmental compartments and to identify the research gaps for the assessment of future research priorities. Over 200 papers involving microplastic pollution, published between 2006 and 2018, are identified in the Web of Science database. The original research articles in 'Environmental Sciences', 'Marine/Freshwater Biology', 'Toxicology', 'Multidisciplinary Sciences', 'Environmental Studies', 'Oceanography', 'Limnology' and 'Ecology' categories of Web of Science are selected to investigate microplastic research in seas, estuaries, rivers, lakes, soil and atmosphere. The papers identified for seas, estuaries, rivers and lakes are further classified according to (i) occurrence and characterization (ii) uptake by and effects in organisms, and (iii) fate and transport issues. The results reveal that whilst marine microplastics have received substantial scientific research, the extent of microplastic pollution in continental environments, such as rivers, lakes, soil and air, and environmental interactions, remains poorly understood.

Microparticles in Table Salt: Levels and Chemical Composition of the Smallest Dimensional Fraction

This study evaluates the chemical composition of microplastic materials (MPs) and non-synthetic particles in different table salts of marine origin by the µFT-IR technique. This research focuses on the microparticles fraction within 10–150 µm of size. Eleven commercial trademarks coming from Italy (IT = 6) and Croatia (CRO = 5) were grouped in two different cost ranges, cheap (n = 5) and expensive (n = 6) and were analysed in replicates (n = 3). Levels and chemical composition of microparticles measured in commercial products were correlated on a statistical basis to some factors of variability of potential scientific interest (geographical origin of marine salt, cost of commercial products, etc.). Results of analyses performed on the tested size fraction of microparticles (10–150 µm) evidence that: (i) levels of MPs are within 0.17–0.32 items/g (IT) and 0.07–0.20 items/g (CRO); (ii) non-synthetic particles detected are mostly made by fibres made of cellulose acetate; (iii) Nations show a different chemical composition of MPs recovered in analysed trademarks (PET and PVC from Italy; PA, PP, and nylon from Croatia); (iv) the annual amount ingested by humans from marine salt consumption ranges between 131.4–372.3 items/y (CRO) and 306.6–580.35 items/y (IT) considering a dose of 5 g of salt per day; (v) statistics performed on factors of interest evidenced that the geographical origin of marine salt do not affect neither levels nor chemical composition of MPs in tested trademarks; while slight correlations are recorded with non-synthetic particles. Further studies are needed to better explore on statistical basis if both levels and chemical composition of MPs in table salts of marine origin can be used or not as good indicators of marine pollution.

Quarterly variability of floating plastic debris in the marine protected area of the Menorca Channel (Spain)

Plastic pollution is widespread in all the oceans and seas, representing a significant threat to most of their ecosystems even in marine protected areas (MPAs). This study determines the floating plastic distribution in four different periods between 2014 and 2015 in the recently approved Menorca Channel MPA (Balearic Islands). Plastic debris were persistent during all sampling periods on the surface of the Channel, composed mainly by the microplastic sizes. Average particle abundances ranged from 138,293 items⋅km^-2 in autumn to 347,793 items⋅km^-2 during the spring, while weight densities varied from 458.15 g(DW)⋅km^-2 in winter to 2016.67 g(DW)⋅km^-2 in summer. Rigid plastics were the most frequent particles in all the periods analysed (from 89.40%-winter to 94.54%-spring). The high-resolution and particle distribution models corroborated that the oceanographic variability shapes different patterns of presence of plastics, and in particular the existence of areas with almost no plastics.

Recent advances in toxicological research of nanoplastics in the environment: A review

Nanoplastics have attracted increasing attention in recent years due to their widespread existence in the environment and the potential adverse effects on living organisms. In this paper, the toxic effects of nanoplastics on organisms were systematically reviewed. The translocation and absorption of nanoplastics, as well as the release of additives and contaminants adsorbed on nanoplastics in the organism body were discussed, and the potential adverse effects of nanoplastics on human health were evaluated. Nanoplastics can be ingested by organisms, be accumulated in their body and be transferred along the food chains. Nanoplastics showed effects on the growth, development and reproduction of organisms, and disturbing the normal metabolism. The toxic effects on living organisms mainly depended on the surface chemical properties and the particle size of nanoplastics. Positively charged nanoplastics showed more significant effects on the normal physiological activity of cells than negatively charged nanoplastics, and smaller particle sized nanoplastics could more easily penetrate the cell membranes, hence, accumulated in tissues and cells. Additionally, the release of additives and contaminants adsorbed on nanoplastics in organism body poses more significant threats to organisms than nanoplastics themselves. However, there are still knowledge gaps in the determination and quantification of nanoplastics, as well as their contaminant release mechanisms, degradation rates and process from large plastics to nanoplastics, and the transportation of nanoplastics along food chains. These challenges would hinder the risk assessment of nanoplastics in the environment. It is necessary to further develop the risk assessment of nanoplastics and deeply investigate its toxicological effects.

Abundance, morphology and chemical composition of microplastics in sand and sediments from a protected coastal area: The Mar Menor lagoon (SE Spain)

This paper presents the abundance and ubiquitous presence of microplastics in a protected coastal zone located in the southeast of Spain: The Mar Menor lagoon, an important tourist destination in this region. Seventeen sampling sites, corresponding to both intertidal and backshore points, were collected during winter 2017 and 2018, being situated in different protected areas according to international, European and Spanish environmental policies. The main objectives of the study were to examine microplastics in both protected and non-protected areas, and to test the importance of local activities on their presence. Northwest samples reported higher average microplastic concentrations than samples collected in the southeastern part of the coastal lagoon, likely due to the extensive use of sludge from wastewater treatment plants besides the fragmentation of low density polyethylene from plastic greenhouses, being microplastic films also higher for northwest than for southeast samples. Moreover, large inter-site differences observed in microplastic concentrations also demonstrated that local activities, mainly tourism and fishery, may play an important role as microplastic sources. The extensive amount of 17 different polymer types identified in this paper, much higher than most reported in similar studies, together with the variety of colors of microplastics most of them in a fragmented form (59.4%) and mainly detected in urban beaches, should be related to the geographical situation of this coastal lagoon, together with enormous environmental passives accumulated over the past 50 years. Only polyvinyl ester resins proved to be statistically higher in non-protected than in protected zones, probably related to their use in manufacturing boat hulls, although sources and pathways for microplastics are always difficult to assess. Measures to avoid microplastic pollution should be taken through educational programs, with also a clear commitment from plastic producers and transformers.

Adverse outcome pathways potentially related to hazard identification of microplastics based on toxicity mechanisms

Increasing concern over microplastics has recently brought increased attention to studies on microplastic toxicity. Here, we conduct a systematic review on toxicity of microplastics that focuses on identifying data gaps in the mechanisms of microplastic toxicity. We observe that microplastic toxicology research thus far has focused on ecotoxicity using apical endpoints and only a few studies deal with toxicity mechanisms. Based on this review, we propose putative Adverse Outcome Pathways (AOPs) applicable to microplastic management to understand microplastic toxicity. We matched toxicity mechanisms and apical endpoints to a key event (KE) and adverse outcome (AO) information from the AOP Wiki. Overall, our results suggest that the molecular initiating event (MIE) was reactive oxygen species (ROS) formation and the AO was increased mortality, decreased growth and feeding, and reproduction failure. However, there are a limited number of studies on toxicity mechanisms of microplastics and, therefore, evidence concerning the relationship between KEs is not sufficient. Clearly, more studies on toxicity mechanisms are required to fill these gaps in data. This study also suggests that the AOP framework is a suitable tool to integrate existing data from various literature sources and can identify data gaps in microplastic toxicity mechanisms.

Long-term isolation at a low effective population size greatly reduced genetic diversity in Gulf of California fin whales

The Gulf of California, Mexico is home to many cetacean species, including a presumed resident population of fin whales, Balaenoptera physalus. Past studies reported very low levels of genetic diversity among Gulf of California fin whales and a significant level of genetic differentiation from con-specifics in the eastern North Pacific. The aim of the present study was to assess the degree and timing of the isolation of Gulf of California fin whales in a population genetic analysis of 18 nuclear microsatellite genotypes from 402 samples and 565 mitochondrial control region DNA sequences (including mitochondrial sequences retrieved from NCBI). The analyses revealed that the Gulf of California fin whale population was founded ~2.3 thousand years ago and has since remained at a low effective population size (~360) and isolated from the eastern North Pacific (Nem between 0.89-1.4). The low effective population size and high degree of isolation implied that Gulf of California fin whales are vulnerable to the negative effects of genetic drift, human-caused mortality and habitat change.

Persistent organic pollutants in blubber of fin whales (Balaenoptera physalus) from the Southern Ocean

Persistent organic pollutants (POPs) were analyzed in eighteen blubber samples biopsied from fin whales (Balaenoptera physalus) during the feeding season near the Antarctic Peninsula in the summer of 2013. POP content (in ng g^-1 lipid weight) ranged from 46.4 to 708 for polychlorinated biphenyls (∑PCBs), 6.77 to 123 for hexachlorobenzene (HCB), 10.1 to 489 for dichlorodiphenyltrichloroethane and derivatives (∑DDTs), 5.38 to 52.8 for hexachlorocyclohexanes (∑HCH) and <0.40 to 2.54 for polybrominated diphenyl ethers (∑PBDEs). The presence of those compounds in Southern Ocean fin whales is related to long-range transport and their diet based mainly on euphausiids (krill). Their contents were much lower compared to the same species in other locations, especially in the Northern Hemisphere, presumably due to differences in trophic position and the proximity of POP sources and contamination of prey items.

Ingestion, egestion and post-exposure effects of polystyrene microspheres on marine medaka (Oryzias melastigma)

Microplastics (MPs) are of environmental concern due to their bioavailability and potential impacts on a wide range of marine biota. In this study, we investigated the ingestion, bioaccumulation and egestion of fluorescent polystyrene (PS) micospheres (10 μm) in both larvae and adults of marine medaka (Oryzias melastigma), with or without food supply. The post-exposure effects of non-fluorescent PS (10 μm) on the survival, growth and reproduction of medaka larvae were also explored. Results showed that the PS microspheres could be ingested by both larvae and adults during the 48 h-exposure. Notably, feeding status was found to significantly affect the ingestion in medaka adults, which was not observed in the larvae. The egestion process of PS was rapid during the first recovery day but there was still certain percent of particles retained in digestive tracts at the end of 7 d recovery for either larvae or adults. After a 14 d pre-exposure with the non-fluorescent PS microspheres, the subsequent survival, growth and reproduction of medaka larvae were all significantly affected at the end of 120 d of experiment without PS. Overall, these results indicate that fishes might ingest or retain more MPs if the environmental abundance of MPs continues to increase while the available food decreases. Medaka fishes in larval stage have no capacity to select natural food sources like the adults. The chronic and "legacy effect" of MPs might also be a problem worthy paid more attention in future research instead of acute and immediate effect studies.

A whale of a tale: A One Environmental Health approach to study metal pollution in the Sea of Cortez

Marine metal pollution is an emerging concern for human, animal, and ecosystem health. We considered metal pollution in the Sea of Cortez, which is a relatively isolated sea rich in biodiversity. Here there are potentially significant anthropogenic inputs of pollution from agriculture and metal mining. We considered the levels of 23 heavy metals and selenium in seven distinct cetacean species found in the area. Our efforts considered two different periods of time: 1999 and 2016/17. We considered the metal levels in relation to (1) all species together across years, (2) differences between suborders Odontoceti and Mysticeti, (3) each species individually across years, and (4) gender differences for each of these comparisons. We further compared metal levels found in sperm whale skin samples collected during these voyages to a previous voyage in 1999, to assess changes in metal levels over a longer timescale. The metals Mg, Fe, Al, and Zn were found at the highest concentrations across all species and all years. For sperm whales, we observed decreased metal levels from 1999 to 2016/2017, except for iron (Fe), nickel (Ni), and chromium (Cr), which either increased or did not change during this time period. These results indicate a recent change in the metal input to the Sea of Cortez, which may indicate a decreased concern for human, animal, and ecosystem health for some metals, but raises concern for the genotoxic metals Cr and Ni. This work was supported by NIEHS grant ES016893 (J.P.W.) and numerous donors to the Wise Laboratory.

Ingestion of microplastics by fish and other prey organisms of cetaceans, exemplified for two large baleen whale species

Knowledge on microplastic (MP) ingestion by cetaceans is difficult to obtain. We infer the potential for MP uptake by cetaceans from the occurrence of MP in prey species. First, we reviewed information on whale prey species, focussing on common minke (Balaenoptera acutorostrata) and sei whale (B. borealis), for which the most comprehensive quantitative datasets exist. Second, evidence of MP ingestion by their prey species was reviewed. We found common minke whales forage opportunistically on fish from various families: Ammodytidae, Clupeidae, Gadidae, Engraulidae and Osmeridae. Sei whales mostly feed on copepods, Engraulidae, Clupeidae and Scombridae. High levels of MP contamination are reported for Scombridae in the Atlantic and Engraulidae in the Northwest Pacific Ocean. Copepods exhibit low levels of MP ingestion in the Northeast Pacific Ocean. Species-specific prey preferences and feeding strategies imply different cetaceans have varied potential for MP uptake, even if they feed in similar geographic areas.

Microplastic pollution in the rivers of the Tibet Plateau

The Tibet Plateau, the so-called Third Pole of the world, is home to the headstreams of many great rivers. The levels of microplastic pollution in those rivers, however, are unknown. In this study, surface water and sediment samples were collected from six sampling sites along five different rivers. The surface water and sediment samples were collected with a large flow sampler and a stainless steel shovel, respectively. The abundance of microplastics ranged from 483 to 967 items/m³ in the surface water and from 50 to 195 items/kg in the sediment. A large amount of small, fibrous, transparent microplastics were found in this study. Five types of microplastics with different chemical compositions were identified using micro-Raman spectroscopy: polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyamide (PA). These results demonstrate that rivers in the Tibet Plateau have been contaminated by microplastics, not only in developed areas with intense human activity but also in remote areas, where microplastic pollution requires further attention.

Hyperspectral Imaging Based Method for Rapid Detection of Microplastics in the Intestinal Tracts of Fish

Microplastics (MPs) in aquatic organisms are raising increasing concerns regarding their potential damage to ecosystems. To date, Raman and Fourier transform infrared spectroscopy techniques have been widely used for detection of MPs in aquatic organisms, which requires complex protocols of tissue digestion and MP separation and are time- and reagent-consuming. This novel approach directly separates, identifies, and characterizes MPs from the hyperspectral image (HSI) of the intestinal tract content in combination with a support vector machine classification model, instead of using the real digestion/separation protocols. The procedures of HSI acquisition (1 min) and data analysis (5 min) can be completed within 6 min plus the sample preparation and drying time (30 min) where necessary. This method achieved a promising efficiency (recall >98.80%, precision >96.22%) for identifying five types of MPs (particles >0.2 mm). Moreover, the method was also demonstrated to be effective on field fish from three marine fish species, revealing satisfying detection accuracy (particles >0.2 mm) comparable to Raman analysis. The present technique omits the digestion protocol (reagent free), thereby significantly reducing reagent consumption, saving time, and providing a rapid and efficient method for MP analysis.

Identification of marine microplastics in Eastern Harbor, Mediterranean Coast of Egypt, using differential scanning calorimetry

Microplastic pollution has gained significant attention, and there are growing concerns about its potential effects on aquatic environments. The lack of proper solid waste management in Egypt has resulted in the accumulation of plastic litter and its deposition in waterways. However, no attempts have been made to identify or assess marine plastic litter in Egypt. We provide, for the first time, a precise, simple, and cost-effective method to identify microplastics in Eastern Harbor by using differential scanning calorimetry (DSC). This screening revealed the presence of ten polymers in seawater and shoreline sediments. Most of the extracted microplastics are secondary microplastics, as they appear to be remnants of larger plastic fragments.

Using opportunistic sightings to infer differential spatio-temporal use of western Mediterranean waters by the fin whale

The fin whale (Balaenoptera physalus) is a cosmopolitan species with a resident population in the Mediterranean Sea. Due to its habitat, open seas often far from ports and airfields, and its long-distance migratory behaviour, studying and monitoring its distribution is costly. Currently, many opportunistic sightings (OS) reports are available, which provide a source of potentially useful, low-cost information about the spatio-temporal distribution of this species. Since 1993, the Spanish Institute of Oceanography has compiled a dataset comprising 874 records of OS of nine species of cetaceans in the western Mediterranean Sea and adjacent waters. The aim of this study was to use this dataset to investigate the differential use of these waters by the fin whale when compared with other cetaceans. We compared the presence of fin whales with the presence of any other cetacean species in the dataset. Binary logistic regression was then used to model these occurrences according to several spatio-temporal variables expected to reflect their habitat use. Several significant models reveal that fin whales are more prone than other cetaceans to use the waters over the slope of the Gulf of Lion in summer. This finding confirms that the Gulf of Lion is an area of importance for this species and suggests that the slope of the continental shelf could be particularly important. Our study shows how OS can be a source of useful information when appropriately analyzed.

Marine litter: One of the major threats for marine mammals. Outcomes from the European Cetacean Society workshop

Marine litter is a pollution problem affecting thousands of marine species in all the world's seas and oceans. Marine litter, in particular plastic, has negative impacts on marine wildlife primarily due to ingestion and entanglement. Since most marine mammal species negatively interact with marine litter, a first workshop under the framework of the European Cetacean Society Conference, was held in 2017 to bring together the main experts on the topic of marine mammals and marine litter from academic and research institutes, non-governmental organisations, foundations and International Agreements. The workshop was devoted to defining the impact of marine litter on marine mammals by reviewing current knowledge, methodological advances and new data available on this emerging issue. Some case studies were also presented from European waters, such as seals and cetaceans in the North, Baltic, and Mediterranean Seas. Here, we report the main findings of the workshop, including a discussion on the research needs, the main methodological gaps, an overview of new techniques for detecting the effects of marine litter (including microplastics) on marine mammals and, also, the use of citizen science to drive awareness. The final recommendations aim to establish priority research, to define harmonised methods to detect marine litter and microplastics, enforce networking among institutions and support data sharing. The information gathered will enhance awareness and communication between scientists, young people, citizens, other stakeholders and policy makers, and thereby facilitate better implementation of international directives (e.g., the Marine Strategy Framework Directive) in order to answer the question about the actual status of our oceans and finding solutions.

Ingestion and effects of micro- and nanoplastics in blue mussel (Mytilus edulis) larvae

It is well known that mussels are exposed to microplastics but ingestion and potential effects on mussel larvae are not well understood. We quantified ingestion and egestion of 100 nm and 2 μm polystyrene beads in blue mussel larvae after 4 h exposure and 16 h depuration using different plastic-to-microalgae ratios. Effects on growth and development of mussel larvae were investigated at 0.42, 28.2 and 282 μgL^-1 within 15 days of exposure. We found that, on a mass basis, larvae ingested a higher amount of 2 μm than 100 nm beads, while egestion was independent of particle size and the plastics-to-algae ratio. Although particle egestion occurred readily, microplastics remained inside the larvae. Larval growth was not affected but abnormally developed larvae increased after exposure to polystyrene beads. Malformations were more pronounced for 100 nm beads, at higher concentration and after longer exposure time.

Microplastic ingestion ubiquitous in marine turtles

Despite concerns regarding the environmental impacts of microplastics, knowledge of the incidence and levels of synthetic particles in large marine vertebrates is lacking. Here, we utilize an optimized enzymatic digestion methodology, previously developed for zooplankton, to explore whether synthetic particles could be isolated from marine turtle ingesta. We report the presence of synthetic particles in every turtle subjected to investigation (n = 102) which included individuals from all seven species of marine turtle, sampled from three ocean basins (Atlantic [ATL]: n = 30, four species; Mediterranean (MED): n = 56, two species; Pacific (PAC): n = 16, five species). Most particles (n = 811) were fibres (ATL: 77.1% MED: 85.3% PAC: 64.8%) with blue and black being the dominant colours. In lesser quantities were fragments (ATL: 22.9%: MED: 14.7% PAC: 20.2%) and microbeads (4.8%; PAC only; to our knowledge the first isolation of microbeads from marine megavertebrates). Fourier transform infrared spectroscopy (FT-IR) of a subsample of particles (n = 169) showed a range of synthetic materials such as elastomers (MED: 61.2%; PAC: 3.4%), thermoplastics (ATL: 36.8%: MED: 20.7% PAC: 27.7%) and synthetic regenerated cellulosic fibres (SRCF; ATL: 63.2%: MED: 5.8% PAC: 68.9%). Synthetic particles being isolated from species occupying different trophic levels suggest the possibility of multiple ingestion pathways. These include exposure from polluted seawater and sediments and/or additional trophic transfer from contaminated prey/forage items. We assess the likelihood that microplastic ingestion presents a significant conservation problem at current levels compared to other anthropogenic threats.

Phthalate Release from Plastic Fragments and Degradation in Seawater

Plastic debris in the environment contains plasticizers, such as phthalates (PAEs), that can be released during plastic aging. Here, two common plastic materials, an insulation layer of electric cables (polyvinyl chloride, PVC-cables) and plastic garbage bag (polyethylene, PE-bags), were incubated in natural seawater under laboratory conditions, and the PAE migration to the seawater phase was studied with varying light and bacterial conditions over a 90-day time course. Free PAEs diluted in seawater were also studied for bacterial degradation. Our results showed that, within the first month of incubation, both plastic materials significantly leached out PAEs into the surrounding water. We found that di-isobutyl phthalate (DiBP) and di- n-butyl phthalate (DnBP) were the main PAEs released from the PE-bags, with the highest values of 83.4 ± 12.5 and 120.1 ± 18.0 ng g^-1 of plastic, respectively. Furthermore, dimethyl phthalate (DMP) and diethyl phthalate (DEP) were the main PAEs released from PVC-cables, with mass fractions as high as 9.5 ± 1.4 and 68.9 ± 10.3 ng g^-1, respectively. Additionally, we found that light and bacterial exposure increased the total amount of PAEs released from PVC-cables by a factor of up to 5, whereas they had no influence in the case of PE-bags.

Using solitary ascidians to assess microplastic and phthalate plasticizers pollution among marine biota: A case study of the Eastern Mediterranean and Red Sea

The interaction of microplastic (MP) with marine organisms is crucial for understanding the significant effect that MP and its additives may have on marine environments. However, knowledge regarding the magnitude of these pollutants in the Eastern Mediterranean Sea and the tropical Red Sea is still scarce. Here we examined the levels of phthalate acid esters (PAEs) and MP in Herdmania momus and Microcosmus exasperatus sampled along the Mediterranean and Red Sea coasts of Israel. High levels of dibutyl phthalate (DBP) and bis (2‑ethylhexyl) phthalate (DEHP) were found in ascidians at the majority of sampling sites, and MP particles were found in ascidians at all sites. As efficient filter-feeders and being widely-distributed, invasive ascidians present fundamental opportunities for the environmental monitoring of microplastic and its additives worldwide. The high levels of pollutants revealed emphasize the need for further research into the magnitude and effects of MP and PAEs in these regions.

Marine litter in sediments related to ecological features in impacted sites and marine protected areas (Croatia)

This study estimates levels of marine litter including plastics (macro-, meso- and microplastics) in sediments collected in shallow marine water from Croatia (Central Adriatic Sea). Selected sampling areas are characterized by different human pressure: Silba is highly stressed by tourism while Grebena is listed as marine protected area (MPA) of future institution. Obtained results on marine litter in sediments are correlated to ecological features recorded in each sampling site. Marine litter in collected sediments ranged within 180-528 items/kg d.w. Macroplastics were not recorded while mesoplastics were 1.3-4.8%. On a general basis, fibres are higher than microplastics. In Južni Greben, level of fragments higher than fibres was recorded. A slight significance of the factor "water depth" was evidenced by the statistical analyses exploring relationships among marine litter and ecological features. Furthermore, Silba and Grebena Islands showed a significant different assessment of size, shape and colour features. These results suggest different sources/dynamics affecting marine litter recorded in marine areas stressed by tourism compared to MPA.

Abundance and composition of floating marine macro litter on the eastern sector of the Mediterranean Sea

Floating marine litter is known to be currently a widespread pollution problem, especially in the Mediterranean basin, but records on the levels of floating debris in the eastern part are less known. By using an observation platform (32 days, 137 transects, 1784 km), this study provides evidence of a high amount of floating debris in the Levantine sub-basin, within the eastern Mediterranean Sea. The density of floating litter varied between 18 and 1593 items km^-2 (average 232 ± 325 items km^-2), and small plastic debris accounted for >90% of the items surveyed. These values tend to be higher than densities reported for the central and western Mediterranean areas, which may be related to the circulation patterns and inputs from coastal sources. Significant correlations of floating macro litter density with wind force and sea state were found, thus strengthening the need to standardise protocols (including oceanographic variables) of visual surveys of floating debris.

Retrospective study of foreign body-associated pathology in stranded cetaceans, Canary Islands (2000-2015)

Marine pollution, overrepresented by plastic, is a growing concern worldwide. However, there is little knowledge on occurrence and detrimental impacts of marine debris in cetaceans. To partially fill in this gap of knowledge, we aimed to investigate the occurrence and pathologies associated with foreign bodies (FBs) in a large cohort of cetaceans (n = 465) stranded in the Canary Islands. The Canary Islands shelter the greatest cetacean biodiversity in Europe, with up to 30 different species, of which nine are regularly present year around. We found at least one ingested FB in 36 out of 465 (7.74%) studied cetaceans, involving 15 different species, including eight out of the nine (80%) cetacean species present year-round in the Canary Islands. Risso's dolphin was the species most affected, followed by sperm whale, beaked whale and mysticetes. Plastic FB were the most common item found (80.56%). FB was directly associated with death in 13/36 (36.11%) animals. Poor body condition and deep diving behavior were found to be risk factors for FB ingestion, whereas the adult age was a protective factor. To the authors knowledge this is the first study that use statistical analysis to investigate risk and protective factors for FB ingestion. This study also provides insights of the potential impact caused by ingested FBs on the animal's health and mortality. This knowledge is critical to better understand and assess the impact of FB in cetaceans setting the scientific basis for prospective impact monitoring and future conservation policies.

Occurrence, sources, human health impacts and mitigation of microplastic pollution

The presence and accumulation of plastic and microplastic (MP) debris in the natural environment is of increasing concern and has become the focus of attention for many researchers. Plastic debris is a prolific, long-lived pollutant that is highly resistant to environmental degradation, readily adheres hydrophobic persistent organic pollutants and is linked to morbidity and mortality in numerous aquatic organisms. The prevalence of MPs within the natural environment is a symptom of continuous and rapid growth in synthetic plastic production and mismanagement of plastic waste. Many terrestrial and marine-based processes, including domestic and industrial drainage, maritime activities agricultural runoff and wastewater treatment plants (WWTPs) effluent, contribute to MP pollution in aquatic environments. MPs have been identified in food consumed by human and in air samples, and exposure to MPs via ingestion or inhalation could lead to adverse human health effects. Regulations in many countries have already been established or will soon be implemented to reduce MPs in aquatic environments. This review focuses on the occurrence, sources, and transport of MPs in terrestrial and aquatic environments to highlight potential human health effects, and applicable regulations to mitigate impacts of MPs. This study also highlights the importance of personality traits and cognitive ability in reducing the entry of MPs into the environment.

Microplastic in marine organism: Environmental and toxicological effects

Microplastics are tiny ubiquitous plastic particles present in marine environments. They are not an individual entity, but constitute a cocktail of polymers and additives that can absorb substances from the surrounding environment, including living substances, nutrients and marine pollutants. Given their small size (< 5 μm), microplastics can be ingested by a wide range of marine organisms with the potential to cause harms. Microplastics are a growing threat for marine biota and ecosystem. For organisms, the risks associated with microplastic ingestion are not only due to the material itself, but also to its ability to absorb and concentrate environmental contaminants in seawater and subsequently transfer them through food chains. Moreover, microplastics could influence ecological processes. Recently, plastic debris are recognized as emerging pollutants and represent a great risk for marine biodiversity worldwide. Here, we summarize the main effects of plastics and microplastics on some marine organisms and ecosystem.

Perspectives on using marine species as bioindicators of plastic pollution

The ever-increasing level of marine pollution due to plastic debris is a globally recognized threat that needs effective actions of control and mitigation. Using marine organisms as bioindicators of plastic pollution can provide crucial information that would better integrate the spatial and temporal presence of plastic debris in the sea. Given their long and frequent migrations, numerous marine species that ingest plastics can provide information on the presence of plastic debris but only on large spatial and temporal scales, thus making it difficult to identify quantitative correlations of ingested plastics within well-defined spatio-temporal patterns. Given the complex dynamics of plastics in the sea, the biomonitoring of marine plastic debris should rely on the combination of several bioindicator species with different characteristics that complement each other. Other critical aspects include the standardization of sampling protocols, analytical detection methods and metrics to evaluate the effects of ingested plastics in marine species.

Microplastics in the intestinal tracts of East Asian finless porpoises (Neophocaena asiaeorientalis sunameri) from Yellow Sea and Bohai Sea of China

The direct evidences for the ingestion of microplastics by cetaceans, especially the cetaceans in Asian marine areas are limited. In this study, residue of microplastics in the intestinal tracts of East Asian finless porpoises (Neophocaena asiaeorientalis sunameri) was investigated. Microplastics were detected in all specimens, with mean abundance of 19.1 ± 7.2 items/individual. With respect to microplastics properties, fibers, blue items, and polypropylene were predominant in shapes, colors, and plastic materials, respectively. Trophic transfer and unintentional ingestion might be the potential pathways for microplastics ingested by finless porpoise. The specific intestinal structure might account for the predominance of fibers and the accumulation of microplastics at the beginning portion of intestines. This study indicates that cetaceans in Chinese marine areas also suffer from microplastics pollution. Further studies on the fate and ecological effects of microplastics should be conducted to reveal their potential risks to cetaceans.

Microplastics in mussels and fish from the Northern Ionian Sea

Microplastic ingestion by marine organisms presents an emerging threat to marine ecosystems; microplastics in different marine species are currently reported worldwide. This study aims to assess microplastic ingestion in four, highly commercial, marine species from Greek waters in the Northern Ionian Sea (Mediterranean Sea). Microplastics were found in mussels (Mytilus galloprovincialis) and all three fish species (Sardina pilchardus, Pagellus erythrinus, Mullus barbatus) examined. The frequency of occurrence of ingested microplastics was 46.25% in mussels, while among fish species, S. pilchardus showed the highest frequency of microplastic ingestion (47.2%). Microplastic abundance ranged from 1.7-2 items/individual in mussels and from 1.5-1.9 items/individual in fish. The majority of ingested microplastics were fragments, while their color and size varied. Fourier Transform Infrared Spectroscopy (FT-IR) indicated polyethylene as the most common polymer type in mussels and fish. Results can be used to set baseline levels for the assessment of microplastic pollution in the Ionian Sea.

Plastic litter transfer from sediments towards marine trophic webs: A case study on holothurians

This study estimates for the very first time plastic litter levels in sea cucumbers (Echinodermata, Holothuroidea) sampled in situ and their intakes from sediments in three different rocky bottom habitats (slides, cliff, banks) settled in Salina Island (Aeolian Archipelago). Macroplastic were never recorded while meso- and microplastics were identified in all sediment (81-438 items/kg d.w.) and animal samples (1.8-22 items/ind.). Plastic intakes by sea cucumbers resulted frequently associated to the size range included within 100-2000 μm. Over than 70% of ingested plastic litter is represented by the size fraction >500 μm. Sediment/animals ratios % are included 2.7 ± 2.0% in studied habitats with a selective intake of fragments occurring in slides. Furthermore, results support the occurrence of selective ingestion of plastic litter by holothurians in natural environments underlining the role of these species in microplastic transfer from abiotic towards biotic compartments of the marine trophic web.

Litter & microplastics features in table salts from marine origin: Italian versus Croatian brands

This study estimates litter content, including microplastics, mesoplastic, and macroplastic in marine table salts coming from Italy and Croatia. Both high (HC) and low (LC) costs commercial brands easily found at the supermarket were analysed. Any macroplastic or mesoplastic were recovered while microplastics and other litter impurities significantly affect table salts of all tested brands. Average microplastic values ranged within 1.57 (HC) - 8.23 (LC) (Italy) and 27.13 (HC) - 31.68 (LC) items/g (Croatia). Microplastics sizes (min-max) ranged within 4-2100 μm (Italy) and 15-4628 μm (Croatia). In samples from both Nations, a significant general positive correlation between the average number of items/g recorded and the total amount of general impurities was recorded. Concerning microplastic shapes, in Italy, fragments dominated even if fibres, granules, films, and foams are frequently recorded. On the contrary, clear PP fibres dominated in Croatian brands even if also other shape classes were recorded.

Microplastics in Sediment and Surface Water of West Dongting Lake and South Dongting Lake: Abundance, Source and Composition

Microplastic pollution was investigated in sediment and surface water in West Dongting Lake and South Dongting Lake for the first time. The abundance of microplastics ranged from 616.67 to 2216.67 items/m³ and 716.67 to 2316.67 items/m³ in the lakeshore surface water of West Dongting Lake and South Dongting Lake, respectively. The highest levels of microplastic pollution were found in the lakes' outlets. In the lake center sites of the West Dongting Lake and South Dongting Lake, the abundance of microplastics ranged from 433.33 to 1500 items/m³ and 366.67 to 1566.67 items/m³, respectively. Meanwhile, the study found that in lakeshore sediment of West Dongting Lake and South Dongting Lake, microplastic concentrations ranged from 320 to 480 items/m³ and 200⁻1150 items/m³. Polystyrene (PS) and polyethylene terephthalate (PET) were most common in the surface water and sediment samples, respectively. In addition, we suggest that the effects of polymer types in microplastics should be taken into account when considering abundance. This study can provide valuable points of reference to better understanding microplastic pollution in inland freshwater areas.

Plastic levels in sediments closed to Cecina river estuary (Tuscany, Italy)

This study focuses on plastic distribution levels (shape, size, colour, type) in sediments from the coastal area of Cecina (Tuscany, Italy). Samples are collected in three sampling stations along six transect settled randomly along the shoreline and along the final tract of the Cecina river. Recorded plastic size ranges within 62.51-13,462 μm (average values 1591 ± 837 μm). Microplastics (<5000 μm) represent over than 97% of the total even if mesoplastics (5000-25,000 μm) are also recorded (2%). Over than 60% of recorded plastic items are higher than 500 μm. Measured levels range within 72 (ST2)-191 (ST4) items/kg d.w. Fragment > Fiber > Granule in each of the tested sampling site. Plastic litter levels recorded in study evidence low pollution compared to the existing literature supporting the occurrence of good environmental levels in Cecina coastline for the "Marine litter" descriptor.

Abundance and characterization of microplastics in the coastal waters of Tuscany (Italy): The application of the MSFD monitoring protocol in the Mediterranean Sea

Monitoring efforts are required to understand the sources, distribution and abundance of microplastic pollution. To verify the abundance of microplastics along the Tuscan coastal waters (Italy), water-column and surface samples were collected in two seasons across four transects at different distances to the coast (0.5, 5, 10 and 20 km), within the implementation of the European Marine Strategy Framework Directive. The results show an average concentration of 0.26 items/m³ in the water-column samples and 41.1 g/km² and 69,161.3 items/km² of floating microplastics, with an increase with the distance to the coast The seasonality and the sampling area do not affect the abundance of microplastics. The most abundant size class is 1-2.5 mm as fragments and sheets suggesting that fragmentation of larger polyethylene and polypropylene items could be the main source of microplastics. These data represent the application of a harmonized protocol to make the data on microplastics comparable and reliable.

Bioindicators for monitoring marine litter ingestion and its impacts on Mediterranean biodiversity

The Mediterranean Sea has been described as one of the most affected areas by marine litter in the world. Although effects on organisms from marine plastic litter ingestion have been investigated in several oceanic areas, there is still a lack of information from the Mediterranean Sea. The main objectives of this paper are to review current knowledge on the impact of marine litter on Mediterranean biodiversity, to define selection criteria for choosing marine organisms suitable for use as bioindicator species, and to propose a methodological approach to assessing the harm related to marine litter ingestion in several Mediterranean habitats and sub-regions. A new integrated monitoring tool that would provide the information necessary to design and implement future mitigation actions in the Mediterranean basin is proposed. According to bibliographic research and statistical analysis on current knowledge of marine litter ingestion, the area of the Mediterranean most studied, in terms of number of species and papers in the Mediterranean Sea is the western sub-area as well as demersal (32.9%) and pelagic (27.7%) amongst habitats. Applying ecological and biological criteria to the most threatened species obtained by statistical analysis, bioindicator species for different habitats and monitoring scale were selected. A threefold approach, simultaneously measuring the presence and effects of plastic, can provide the actual harm and sub-lethal effects to organisms caused by marine litter ingestion. The research revealed gaps in knowledge, and this paper suggests measures to close the gap. This and the selection of appropriate bioindicator species would represent a step forward for marine litter risk assessment, and the implementation of future actions and mitigation measures for specific Mediterranean areas, habitats and species affected by marine litter ingestion.

Microplastic contents from maricultured and natural mussels

Results of this research focuses on microplastic contents (levels, type, size, colour) in maricultured and natural mussels (Mytilus galloprovincialis) from different Italian stocks. No significant differences were found among maricultured and natural stocks. All recovered MPs are filaments ranging within 750-6000 μm of maximum length (average values 1150-2290 μm). Feeding raw mussel could produce median MP intakes of 6.2-7.2 items/g w.w. Concerning human exposure by diet, both raw and cooked values are important. Some preliminary tests performed in this study evidenced that the cooking process determined lower MPs levels (-14%) in cooked tissues compared to raw ones, MPs were recorded in cooking water and were characterized by a lower size than in raw mussels. Results obtained by this study represent an important baseline on MPs level to evaluate environmental and human exposure risks by diet.

Single and combined effects of microplastics and mercury on juveniles of the European seabass (Dicentrarchus labrax): Changes in behavioural responses and reduction of swimming velocity and resistance time

Microplastics and mercury are environmental pollutants of great concern. The main goal of the present study was to investigate the effects of these pollutants, both individually and in binary mixtures, on the swimming performance of juvenile European seabass, Dicentrarchus labrax. Microplastics alone, mercury alone and all the mixtures caused significant reduction of the swimming velocity and resistance time of fish. Moreover, changes in behavioural responses including lethargic and erratic swimming behaviour were observed. These results highlight that fish behavioural responses can be used as sensitive endpoint to establish the effects of contamination by microplastics and also emphasizes the need to assess the combined effects of microplastics and other environmental contaminants, with special attention to the effects on behavioural responses in fish and other aquatic species.