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

Microplastic ingestion and Phthalate ester levels as plastic tracers in the Mediterranean Velella velella: a candidate plastic indicator for the pelagic neustonic environment

Bioindicator species can help assess plastic pollution's impact on biodiversity by integrating spatial distribution and temporal trends, highlighting associated ecological risks. To investigate a potential indicator for pelagic neustonic environments, the holoplanktonic hydrozoan V. velella was collected in the Pelagos Sanctuary (SPAMI, NW Mediterranean Sea). A total of 460 individuals from 27 stations were collected alongside manta net trawls. Isolated organisms were digested through an alkaline solution and examined for the presence of microplastics (MPs). The correlation among the abundance of floating microplastics in the area, microplastic ingestion and levels of 11 Phthalate Acid Esters (PAEs) in V. velella have been investigated to provide a comprehensive assessment of the multiple stressors impacting this species. Over 200 MPs were isolated, with an occurrence of 93 % in the sampling stations (0.6 ± 0.7 items/individual). Polyester filamentous-shape particles (including fibres and filaments; 81 %) and polyamide, polyolefin and polystyrene fragments (17 %) were the predominant particle types. PAEs concentration averaged 313 ± 66 ng/g w.w. with Dibutyl-phthalate, Diisobutyl-phthalate, and Diethylhexyl-phthalate, listed as reprotoxic by EU regulation, comprising 95 % of total compounds. Despite no statistical correlation, a slightly positive trend between ingested plastic and total PAEs load was found shedding light on the potential direct release from particles. With its wide distribution, key trophic role, ability to capture smaller MPs fractions (<300 μm) and fibres and to accumulate the chemicals from the surrounding environment, V. velella emerges as a promising bioindicator of MPs pollution in the pelagic areas of the Mediterranean Sea and the other seas and oceans worldwide.

Assessing marine litter and its ecological impact on the seafloor of Thermaikos Gulf (NE Mediterranean Sea, Greece): Insights from ROV and diver surveys

This study investigates marine litter and its ecological impacts on the seafloor of the Thermaikos Gulf (NE Mediterranean Sea, Greece) for the first time, using data from 40 ROV dives (15-90 m depth) carried out between 2020 and 2024, and 11 scuba dives (0-5 m depth) conducted primarily at fishing ports during the same period. Plastics dominated the litter composition (80 %), with fishing-related activities contributing to 65 % of the litter at depths from 15 to 90 m, while single-use plastics comprised 46 % of the litter at nearshore locations. ROV surveys revealed litter densities decreased with depth and were likely influenced by water circulation patterns and human activities, particularly fishing. Shallow waters exhibited 50 times higher densities, highlighting the severe accumulation of litter in nearshore areas, particularly in ports. Benthic animals observed in ROV footage were identified, and their abundance was recorded, providing insights into the ecosystem's exposure to litter. Moreover, documented faunal interactions, including ghost fishing, entanglement, colonization, and the use of litter for shelter, highlight the ecological threats posed by marine litter. These findings surpass established Mediterranean litter density thresholds for the seafloor, underscoring the urgent need for stricter waste management at ports and offshore, stronger enforcement of EU directives, and targeted educational campaigns. This research establishes benchmark levels for setting environmental objectives under the Marine Strategy Framework Directive and for conducting targeted research to address litter pollution in the Thermaikos Gulf and similar coastal regions.

A best practice framework for assessing plastic ingestion in marine turtles

The ingestion of plastic debris has been reported in all seven marine turtle species, affecting vital processes throughout their entire life cycle and key habitats. Consequently, this emerging threat has been recognized as a priority conservation concern. The potential health impacts range from cryptic sublethal effects to severe injury and death. A comprehensive understanding of these impacts and the processes involved, at both the individual and population levels, is crucial for evaluating the vulnerability of marine turtles to plastic pollution. Aiming to guide researchers and stakeholders from the initial stages of project development, this study discusses essential components for establishing and achieving research on plastic ingestion in marine turtles. Drawing on diverse efforts globally, this manuscript compiles the most common approaches and established methodologies, while evaluating resource availability and capabilities, to outline a globally applicable best practice framework for designing and implementing research and monitoring initiatives on plastic ingestion impacts to marine turtles.

Anthropogenic fibers in the Mediterranean sea: Methods and monitoring of an overlooked category of microparticles in the water column

Anthropogenic particles (APs) are widespread in the marine environment, but knowledge gaps remain regarding anthropogenic fibers. This study aimed to evaluate the presence of APs, including natural and synthetic fibers, in the water column. A literature review on fibers in Mediterranean seawater revealed that current sampling methods are underdeveloped. Two sampling methods were compared to determine the best approach for collecting fibers: a new in-situ pump (20 μm mesh filter) and a WP2 plankton net (200 μm). The in-situ pump was the most effective method and was applied in three areas of the Western Mediterranean Sea (Gulf of Asinara, Capraia Island, Capo Carbonara). The predominant APs, characterized by μFTIR, were cellulose and polyester fibers, reflecting the global textile fiber production. The Asinara area was the most impacted area (average of 393.7 items/m3). This study highlights the ubiquitous presence of fibers in the water column and underscores the need for further investigation of potential impacts on marine biota.

Plastic exposure risk for costal seabirds varies seasonally with freshwater runoff

Marine litter, including Floating Marine Macro-Litter (FMML) and microplastics (MP), poses a major threat to marine ecosystems. This study investigates the seasonal distribution of FMML and MP in the Ebro Delta, a key Mediterranean wetland, and evaluates the potential risk to three tern species (family Laridae, subfamily Sterninae) that rely on the area for foraging and breeding. Seasonal surveys (October 2021-June 2022) were conducted using drone and manta trawl sampling for litter assessment, with tern densities estimated via distance sampling. Results revealed seasonal peaks in FMML and MP densities, with the highest concentrations in autumn and spring, likely influenced by river discharge and irrigation runoff. Risk assessment maps identified high-risk zones where tern densities overlapped with FMML and MP hotspots, indicating potential threats from entanglement, ingestion, and trophic transfer of pollutants. These findings underscored the relevance of seasonality and spatial risk assessment when evaluating exposure to marine litter. This study not only enhanced our understanding of marine litter impacts in the Mediterranean Sea but also provided essential data to inform evidence-based policies and management strategies aimed at protecting vulnerable species in this ecologically relevant area.

Microplastic occurrence in the digestive system and health status assessment in a commercially important cephalopod species, Sepia officinalis from the Gulf of Patti (southern Tyrrhenian Sea)

Cephalopods are ecologically and economically important species and play a key role in marine ecosystems. However, knowledge about the presence and effects of microplastic (MP) ingestion in this taxonomic group is still limited. The present research aimed to explore plastic ingestion and health status in the cuttlefish, Sepia officinalis, from the Gulf of Patti in the southern Tyrrhenian Sea, for the first time. In addition, this helps in assessing the MP pollution risks in the area. Plastic occurrence and characterization were investigated, and Le Cren's relative condition factor (Kn) calculated as an index of health status. MP concentrations and polymer hazardous were also used to preliminarily detect the environmental risk. High MP occurrence values (%O = 69) were recorded in this commercially important cephalopod species from the Mediterranean Sea suggesting that the habitat, feeding habits and digestive system (morphology and function) play an important role in affecting the occurrence and distribution of MP in S. officinalis. Absence of a clear correlation between MP ingestion and Kn in this study does not exclude the possibility of more subtle or long-term impacts of plastic on common cuttlefish health. Preliminary risk assessment confirms that the study area is subject to MP pollution and hazardous polymers. The data from this study suggests that common cuttlefish have the potential to be usefully assessed as a bioindicator for Mediterranean scale plastic pollution monitoring. We propose the addition of this species to the current monitoring programs such as the ones performed within the Marine Strategy Framework Directive.

Lanternfish as bioindicator of microplastics in the deep sea: A spatiotemporal analysis using museum specimens

We investigated MP ingestion in lanternfishes (Myctophidae), one of the most abundant vertebrates in the world, using archived specimens from museum collections from 1999 to 2017. Microplastics were detected in 55 % of the 1167 specimens analysed (0.95 ± 1.22 MP individual-1). Global plastic production has increased by about 53 % during this period. Interestingly, almost half of the lanternfishes analysed contained at least one particle in the gastrointestinal tract in the earliest data. In contrast, the incidence increased to two-thirds in the most recent data available. Although the shape and colour composition of MPs followed a similar proportion, the model considering the sampling year and migration patterns showed that specimens collected in 1999, 2000, and 2010 had a 44 %, 23 % and 20 % lower probability of MP ingestion than those collected in 2017. However, migration was the most robust predictor of MP contamination. Further analysis of specimens collected in 1999-2000 revealed that fish caught in the bathypelagic zone had the lowest number of particles, while those caught just below the thermocline had an eightfold higher probability of MP ingestion. Lanternfishes were generally more likely to ingest high-density polymers, although polyethylene had the highest concentration (445.5 ± 526.4 µg g-1 gastrointestinal tract).

Natural and Regenerated Cellulosic Microfibers Dominate Anthropogenic Particles Ingested by Commercial Fish Species from the Adriatic Sea

This study investigated the occurrence of fibrous microplastics and natural and artificial cellulose microfibers in the gastrointestinal tracts of Mullus barbatus and Merluccius merluccius specimens from the Adriatic Sea (Central Mediterranean), an important hotspot for marine litter accumulation. Red mullet and European hake were chosen due to their roles as bioindicators of marine pollution in the Mediterranean, and their economic relevance as fishery resources. Microfibers were found in 72% of M. barbatus and 68% of M. merluccius, at levels ranging from 1 to 67 particles/individual. Most of the microfibers extracted were textile fibers that were blue (33.6%), clear (26.1%), and black (20.3%) in color, while the length distribution showed the prevalence of microfibers in the size range of 350-950 µm. This visual identification, corroborated by the micro-FTIR analysis of a sub-sample of microfibers, revealed that natural and artificial cellulose microfibers were more common (80%) than fibrous microplastics. The results confirmed that both of these fish species are susceptible to microfiber ingestion and indicated the high availability of natural and artificial cellulosic fibers in the Adriatic Basin. Despite the increased evidence of microfiber pollution in the marine ecosystem, only a limited number of studies examine natural/artificial microfiber contamination and ingestion by marine biota. Therefore, greater attention should be given to this new type of contaminant, considering its implications in terms of environmental health, food security, and food safety.

Hit the target: A new experimental method to select bioindicators of microplastic ingestion by marine fish

Implementing biomonitoring programs for assessing the impact of microplastic ingestion on marine organisms is a priority to verify the effectiveness of measures adopted by legislative frameworks to deal with plastic pollution. At the European level, the Marine Strategy Framework Directive mandates Member States to establish a unified monitoring approach. However, due to the vast range and differences in marine regions, the selection of bioindicators must be tailored locally. The present study proposes a bioindication score to rapidly assess the aptitude of different species in providing an adequate description of the bioavailability of microplastics. The bioindication score is validated through the analysis of eight fish species from the Central Tyrrhenian Sea, for which a set comprising two pelagic (Scomber colias and Trachurus trachurus) and two benthopelagic/demersal species (Pagellus acarne and Mullus barbatus) is identified as the best group to obtain ecologically relevant data on microplastic ingestion in the study area.

Ocean plastic pollution: a human and biodiversity loop

This study offers an updated analysis of the effects of ocean plastic accumulation on human health and biodiversity within the food chain, covering the period from 2018 to 2023. Through a comprehensive review of relevant literature, a framework has been developed to visually illustrate the progression of plastics through the food chain. This framework emphasizes the intricate connections among four key elements: humans, plastics, biodiversity, and the food chain. By examining the cycle of challenges encountered during the phases of production, consumption, and disposal, the research reveals how these stages are interrelated. This perspective not only delineates the complexities involved but also identifies potential solutions, particularly by incorporating circular economy principles. Consequently, the study highlights the importance of understanding the impact of plastics on the food chain while proposing strategies grounded in circular economy concepts to mitigate plastic pollution throughout the three stages.

Biodiversity at risk in the SPAMI Pelagos Sanctuary: The impact of marine litter on biota

The Mediterranean basin is the second largest global biodiversity hotspot in the world, which coexists with a plethora of anthropogenic stress. This study examines the risks that marine litter poses to Mediterranean biodiversity, using the Special Protection Area of Mediterranean Importance (SPAMI) "Pelagos Sanctuary" as a case study. In this paper, a new survey method and data analysis strategies to assess the impact of marine litter, including microplastics, on Mediterranean organisms, is proposed. A total of 23 species, from invertebrates to cetaceans, were analysed using two main monitoring approaches. In the first approach, the core density distribution areas of 11 megafauna species (elasmobranchs, sea turtles, seabirds, and cetaceans) and 4 invertebrate species were evaluated through an extended field survey. Simultaneously, monitoring of floating macro- and micro-litter was performed to be overlapped with the species distribution and abundance. The second monitoring approach assessed the ingestion of marine litter, microplastics and the levels of plastic additives in 10 stranded megafauna species and in 7 invertebrate and fish species. The final data processing, merging the data on biodiversity and marine litter abundance and distribution in the environment, with the data of ingested marine litter, microplastics, and plastic additives in sentinel species, allowed to: a) create risk maps for the species inhabiting the Pelagos Sanctuary, identifying critical areas for biodiversity conservation; b) identify the most exposed species to the risk of marine litter by an "exposure score"; c) to select sentinel species for pelagic environment.

A multi-compartment monitoring approach to assess the impact of marine litter in a Mediterranean coastal area

Marine litter, particularly microplastics, is a growing threat to the Mediterranean Sea, impacting biodiversity and ecosystem health. However, most studies conducted in the Mediterranean Sea have focused on monitoring of only specific environmental compartments, and rarely have highlighted the overall impacts affecting an area. Therefore, using a new multi-compartment monitoring approach and a standardized methodology, this study investigates the abundance, distribution, composition and impact of marine litter on beaches, surface waters, fish and mussels in a coastal area of Tuscany (Italy). Concerning beach macro litter values, significant differences were found among the three beaches analysed, with the highest amount in the Feniglia beach (mean value = 1245 items/100 m). The top items found are cotton bud sticks (32.3 %), which in the winter survey at Feniglia beach, reached a remarkable density of 1983 items/100 m. Microlitter (1-5 mm), was detected in the beach sediments with a mean abundance of 130 items/m2. Regarding floating macrolitter, the transect with the highest values was the Feniglia site at 3 nautical miles in autumn (1083 items/km2) while for floating microlitter the highest concentration (832,683 MPs/km2) was found in front of Scarlino. Of the 234 fish analysed from 5 different species, 67 contained microplastics in the gastrointestinal tract (28 %) with a mean value of 0.4 items per individual. The species with the highest occurrence was the European anchovy (Engraulis encrasicolus) (53 %) followed by the bogue (Boops boops) (40 %). Through the application of the Marine Litter Impact Index (MLII), considering all the compartments analysed, the Feniglia area emerges as the ecosystem most impacted by marine litter (mean MLII = 3.5, high). This study highlights how a multi-compartment monitoring approach is crucial for understanding the complex interactions between land, sea, and biota.

Impacts of microplastic accumulation in aquatic environment: Physiological, eco-toxicological, immunological, and neurotoxic effects

The presence of microplastics (MPs) in aquatic ecosystem has become a pressing global concern. MPs pose a significant threat to aquatic ecosystems, with devastating consequences for both aquatic life and human health. Notably, freshwater ecosystems are particularly vulnerable to MPs pollution. MPs, characterized by their small size (< 5 mm), have emerged as a ubiquitous environmental pollutant. They exhibit diverse characteristics, including varying sizes, forms, polymer types, and colors. Two distinct categories of MPs exist: primary and secondary. Primary MPs are incorporated into industrial hard materials, cosmetics, and hand cleaners, whereas secondary MPs result from the breakdown of larger plastic products in both terrestrial and marine environments. They enter the environment through various sources, such as household products, clothing, industrial activities, sewage waste and plastic degradation. Aquatic organisms ingest these contaminants, facilitating the transfer of MPs into the food chain and potentially causing severe health problems. This review delves into the bioaccumulation of MPs in fish, highlighting the eco-toxicological, neurological and immunological effects. This review provides an in-depth analysis of innovative solutions for MPs removal and reduction. Finally, we delineate evidence-based strategies to mitigate impacts of MPs, offering valuable insights to inform policy formulations and accelerate the development of sustainable plastic technologies.

Microplastics in aquatic systems: A comprehensive review of its distribution, environmental interactions, and health risks

Microplastics (MPs) have become a critical pollutant, accumulating in aquatic ecosystems and posing significant environmental and human health risks. Approximately 5.25 trillion plastic particles float in global oceans, releasing up to 23,600 metric tonnes of dissolved organic carbon annually, which disrupts microbial dynamics. MPs arise from the breakdown of larger plastics, degraded by photodegradation, thermal degradation, and biological processes, which are influenced by polymer type and environmental factors. As carriers, MPs absorb and transport contaminants such as heavy metals, per- and polyfluoroalkyl substances (PFAS), and persistent organic pollutants (POPs) across trophic levels, thereby increasing toxicity within food webs. Key aquatic organisms, including microalgae, molluscs, and fish, experience cellular toxicity, oxidative stress, and disruptions in essential functions due to MP ingestion or adhesion, raising concerns about their bioaccumulation in humans through ingestion, inhalation, and dermal contact. The complex surface chemistry of MPs enhances their pollutant adsorption, a process modulated by environmental pH, salinity, and contamination levels, while aging and structural attributes further impact their bioavailability and toxicity. This review consolidates knowledge on MPs' occurrence, transformation, pollutant interactions, and methodologies for sampling and analysis, emphasizing advancements in spectroscopy and imaging techniques to improve MP detection in aquatic environments. These insights underscore the pressing need for standardized analytical protocols and comprehensive toxicological research to fully understand MPs' effects on ecosystems and human health, informing future mitigation strategies and policy development.

Spatial and temporal variation of microplastic in mussels from intertidal and subtidal banks in the Southwestern Atlantic Ocean

The objective of this study was to identify the presence of MPs in M. platensis tissues and evaluate the spatial and temporal variation of MPs in this species between different zones (Intertidal and Subtidal) and years (2012 and 2019) in Buenos Aires province Villa Gesell, Southwestern Atlantic Ocean. Our hypothesis is that the Intertidal zone will have a greater number of MPs than the Subtidal zone, and this trend will also be observed in 2019 compared to 2012. Specimens of M. platensis from the intertidal zone were hand-collected during low tide on the pier pilings in August 2012 and 2019, and the subtidal specimens were obtained by bottom trawling from a campaign with the Oceanographic ship ARA Puerto Deseado in August 2012. In general, the number of MPs varied between zones, indicating a greater number of this contaminant in the intertidal zone, whereas the same was not observed for the years. Furthermore, among the analyzed specimens, 90 % contained MPs, all of which were in the form of fibers, with blue fibers being the predominant type, and polystyrene being the most prevalent polymer. This group of organisms has significant ecological roles and commercial value. Assessing their contamination status and MPs characteristics is important to understand the potential risks to marine ecosystems and human health.

Abundance and ecological risk of microplastics in commercial fish species from northeastern Mediterranean Sea

Microplastic pollution in marine environment has attracted the attention of scientists and policy makers. A substantial number of studies have examined the microplastic content in the gastrointestinal tract (GIT) of fish to monitor microplastic (MP) pollution levels in the ambient environment. The aim of the study was to access the microplastic abundance in the commonly consumed fish species and associated ecological risk assessment for consumers. To that end, microplastic presence in the gills and GIT of Boops boops, Mullus barbatus Mullus surmuletus, Saurida undosquamis, Sardina pilchardus, Trachurus mediterraneus, Pagellus erythrinus, Oblada melanurus, Diplous annularis was investigated. The polymer analysis of extracted MPs were done using Fourier transform infrared (FTIR) spectroscopy. Including all examined specimens, mean MP abundance in the GIT and gills were found as 0.8 ± 1.2 MPs/ind and 0.3 ± 0,7 MPs/ind, respectively. Consistent with the global picture, mainly detected MPs were fiber in shape (79%), black (39%) and blue (37%) in color, and less than 500 μm in size (63%). Polyethylene (21%), polyethylene derivatives (33%) and polypropylene (26%) were the most frequently detected polymers. Ecological risk assessment was calculated by employing polymer risk index, and varied between 4,6 and 27 indicating low to medium hazard risk for examined species. Hazard risk score showed that demersal and bentopelagic fish species were more prone to MP toxicity depending on the toxicity levels of identified polymers. Results indicated that polymer distribution in the marine environment is as significant as the habitat preferences of fish in determining the ecological risk posed by microplastic toxicity.

Biomonitoring of persistent pollutants in grey seal (Halichoerus seagrypus) pups from the Gulf of Riga, Baltic Sea

We analyzed for the first time the concentration of potentially toxic trace elements Hg, As, Pb, Cr and Se and POPs (PCBs and OCPs) in tissues of 41 grey seal pups (Halichoerus grypus) stranded on the shores of the Gulf of Riga. Lanugo was the sample with the highest concentrations of all trace elements except Hg. The concentrations found in this biological matrix appeared as follows: Hg (2.50 ± 1.43 μg/g); Se (1.22 ± 0.82 μg/g); Cr (0.96 ± 1.51 μg/g); As (0.95 ± 1.03 μg/g); Pb (0.50 ± 0.60 μg/g). POPs were∑PCB (0.566 ± 0.520 μg/g), ∑DDT (0.522 ± 0.454 μg/g), ∑HCH (0.043 ± 0.045 μg/g) and Chlordane (0.041 μg/g). We detected brain Hg levels above the threshold described for neurobehavioural changes and some individuals also exceeded the toxic threshold described for PCBs. Thus, the health of grey seal pups could be affected by both groups of pollutants.

Phthalates and fatty acid markers in free-ranging cetaceans from an insular oceanic region: Ecological niches as drivers of contamination

Plastic additives, such as phthalates, are ubiquitous contaminants that can have detrimental impacts on marine organisms and overall ecosystems' health. Valuable information about the status and resilience of marine ecosystems can be obtained through the monitoring of key indicator species, such as cetaceans. In this study, fatty acid profiles and phthalates were examined in blubber biopsies of free-ranging individuals from two delphinid species (short-finned pilot whale - Globicephala macrorhynchus, n = 45; common bottlenose dolphin - Tursiops truncatus, n = 39) off Madeira Island (NE Atlantic). This investigation aimed to explore the relations between trophic niches (epipelagic vs. mesopelagic), contamination levels, and the health status of individuals within different ecological and biological groups (defined by species, residency patterns and sex). Multivariate analysis of selected dietary fatty acids revealed a clear niche segregation between the two species. Di-n-butylphthalate (DBP), diethyl phthalate (DEP), and bis(2-ethylhexyl) phthalate (DEHP) were the most prevalent among the seven studied phthalates, with the highest concentration reached by DEHP in a bottlenose dolphin (4697.34 ± 113.45 ng/g). Phthalates esters (PAEs) concentration were higher in bottlenose dolphins (Mean ∑ PAEs: 947.56 ± 1558.34 ng/g) compared to pilot whales (Mean ∑ PAEs: 229.98 ± 158.86 ng/g). In bottlenose dolphins, DEHP was the predominant phthalate, whereas in pilot whales, DEP and DBP were more prevalent. Health markers suggested pilot whales might suffer from poorer physiological conditions than bottlenose dolphins, although high metabolic differences were seen between the two species. Phthalate levels showed no differences by ecological or biological groups, seasons, or years. This study is the first to assess the extent of plastic additive contamination in free-ranging cetaceans from a remote oceanic island system, underscoring the intricate relationship between ecological niches and contaminant exposure. Monitoring these chemicals and their potential impacts is vital to assess wild population health, inform conservation strategies, and protect critical species and habitats.

Microplastic ingestion in mussels from the East Mediterranean Sea: Exploring its impacts in nature and controlled conditions

Microplastic ingestion poses a significant concern for a plethora of marine organisms due to its widespread presence in marine ecosystems. Despite growing scientific interest, the effects on marine biota are not yet well understood. This study investigates the ingestion of microplastics (MPs) by mussels from various marine environments and assesses the associated effects that can be induced by MPs and associated toxic chemicals. Biomarkers of oxidative stress (catalase, lipid peroxidation), biotransformation (glutathione S-transferase), genotoxicity (micronuclei frequency) and neurotoxicity (acetylcholinesterase) were employed. Mussels, considered reliable bioindicators of MPs pollution, were sampled by hand from diverse locations under varied anthropogenic pressures, including a highly touristic Marine Protected Area (MPA) in the Ionian Sea, a mussel farm and a fish farm in the Aegean Sea. The results revealed the highest MP ingestion in mussels from the fish farm [0.21 ± 0.04 (SE) MPs/g or 0.63 ± 0.12 (SE) MPs/Ind.], likely due to plastic aquaculture equipment use. Stereoscopic observation revealed fibers, as the predominant shape of ingested MPs across all sites, and μFTIR polymer identification revealed the presence of various types, with polyethylene (PE) and polyamide (PA) being the most abundant. Significant physiological alterations in mussels related to MP ingestion levels were observed through biomarkers indicative of oxidative stress and biotransformation, as well as the Integrated Biomarker Response (IBR index). However, laboratory experiments with mussels exposed to controlled increasing PE concentrations for four weeks, did not show significant effects triggered by the PE ingestion, possibly indicating other environmental factors, such as contaminants from aquaculture environments, may influence biomarker levels in the field. Despite the observed effects, MP ingestion rates in mussels from the field were relatively low compared to other studies. Future research should continue to investigate the interactions between MPs and marine organisms in diverse environments to better understand and mitigate their impacts.

Plastic pellet pollution in the Aeolian Islands UNESCO site (Italy, Western Mediterranean Sea): results of a comprehensive characterization and monitoring study

The archipelago of the Aeolian Islands in the Tyrrhenian Sea is a globally important natural laboratory. The archipelago, declared a UNESCO World Heritage Site for its unique geology and biodiversity, offers a unique opportunity to study plastic pollution. This study presents an initiative to assess the occurrence of plastic pellets on the beaches of five Aeolian Islands. It provides an insight into the polymer composition and the effects of degradation. Collected pellets were analyzed using stereomicroscopy and Fourier transform infrared spectroscopy (FTIR). Hierarchical cluster analysis (HCA) based on the results of the FTIR data has proved to be an effective statistical method in identifying different clusters corresponding to different degradation phases of the collected pellets. The infrared analysis identified polyethylene (80%) as the main polymer, with a small amount of polypropylene (20%). It was found that the surfaces of some pellets undergo changes during weathering that alter the polymer surfaces. By combining data on plastic pellets from the Aeolian Islands and surrounding coastal areas, we are gaining a more comprehensive understanding of the distribution patterns of microplastics. The results of the monitoring and characterization are expected to support the developing of waste management and remediation strategies for this environmentally sensitive region.

Detection of fibrous microplastics and natural microfibers in fish species (Engraulis encrasicolus, Mullus barbatus and Merluccius merluccius) for human consumption from the Tyrrhenian sea

The occurrence of natural/artificial and synthetic microfibers was assessed in three commercial fish species (Engraulis encrasicolus, Mullus barbatus, Merluccius merluccius) from the Tyrrhenian Sea sold for human consumption. The gastrointestinal tracts of n. 150 samples were analyzed, the isolated microfibers were classified applying a morphological approach, based on the analysis of their morphological features, coupled with the identification of the chemical composition of a subsample of microfibers. All the species contained microfibers at levels ranging from 0 to 49 items/individual and the number of ingested microfibers significantly differed between pelagic and demersal fishes. The evaluation of fiber morphologies highlighted that natural/artificial microfibers were the most numerous among the isolated microfibers, while the dominant colors were blue, black, and clear in all the species. Chemical characterization confirmed the morphological identification and indicated cellulose and polyester as the most common polymer types. Considering the analytical issues that may affect the evaluation of microfiber pollution, the results pointed out the importance of an accurate morphological approach that allows the distinction between different fiber types, before the spectroscopic analyses. Moreover, the implementation of fast and accessible methods to identify microfibers in fish species intended for human consumption will be beneficial also to make an adequate risk assessment to consumer health.

Rose or Red, but Still under Threat: Comparing Microplastics Ingestion between Two Sympatric Marine Crustacean Species (Aristaeomorpha foliacea and Parapenaeus longirostris)

Increasing plastic contamination poses a serious threat to marine organisms. Microplastics (MPs) ingestion can represent a risk for the organism itself and for the ultimate consumer. Through the analysis of the gastrointestinal tract, coupled with stable isotope analysis on the muscle tissue, this study provides insights into the relationship between MPs pollution and ecology in two commercial marine species caught in the Central Tyrrhenian Sea: Aristaeomorpha foliacea and Parapenaeus longirostris. Stable isotope analysis was conducted to determine the trophic position and the trophic niche width. The gastrointestinal tracts were processed, and the resultant MPs were analysed under FT-IR spectroscopy to estimate the occurrence, abundance, and typology of the ingested MPs. The trophic level of the species was similar (P. longirostris TP = 3 ± 0.10 and A. foliacea TP = 3.1 ± 0.08), with an important trophic niche overlap, where 38% and 52% of P. longirostris and A. foliacea has ingested MPs, respectively. Though species-level differences may not be evident regarding MP's abundance per individual, a high degree of dissimilarity was noted in the typologies of ingested particles. This research provides valuable insights into how MPs enter marine trophic webs, stressing that isotopic niche analysis should be combined with other methods to explain in detail the differences in MPs ingestion.

Geographical and ecological factors affect microplastic body burden in marine fish at global scale

Microplastic (MP) contamination has been identified as a worrisome environmental issue at the global level. Fish are the taxonomic group more extensively investigated to assess MP contamination in marine environment. A large variability in MP bioaccumulation (i.e., body burden) was reported in fish but to date there is a dearth of information concerning the drivers underlying this process. The present systematic review aimed at summarizing the results of the scientific literature on MP body burden in the digestive tract of marine fish to quantitatively shed light on the contribution of different geographical (i.e., latitudinal origin of the sample, distance from the coastline and field- or marked-collected) and ecological (i.e., trophic strategy, milieu, and body size) factors driving bioaccumulation. The mean (±SE) MPs/individual was 4.13 ± 2.87, and the mean MPs/ww (i.e., MPs/g) was 5.92 ± 0.94. Overall, MP abundance expressed as MPs/individual of fish from tropical areas was significantly higher compared to the other latitudinal bands, with species sampled close to the coastline that accumulated a larger number of MPs compared to those collected offshore. Neither the trophic strategy, nor the milieu and the market or field origin of fish explained the MP body burden. However, fish body size resulted as a determinant of MP body burden (as MPs/individual), with small fish accumulating a lower amount of MPs compared to larger ones. Qualitatively, but not statistically significant, similar results were generally obtained for MPs/ww, except for an opposite, and significant, variation according to species body size. Our findings showed that geographical, rather than ecological factors represent the main drivers of MP body burden in marine fish, suggesting that environmental variables and/or local pollution sources mainly contribute to explaining the large variability underlying the ingestion and bioaccumulation processes of these contaminants.

Among-colony variation in plastic ingestion by Yellow-legged gulls (Larus michahellis) across the western Mediterranean basin

The Mediterranean region is both a hotspot for biodiversity and for the accumulation of plastic pollution. Many species are exposed to this pollution while feeding, including a wide diversity of seabirds. Our objective was to investigate spatial variation in the quantity and types of plastic ingested by Yellow-legged gulls using information obtained from regurgitated pellets collected in 11 colonies. Anthropogenic debris, and particularly plastic, was found in pellets from all colonies, but the amount varied considerably. This among-colony difference was stable over the two years of study. The presence of marine prey and the proportion of agricultural area around the colonies significantly influenced the number of ingested plastics. As landfills close and garbage management improves, the availability of anthropogenic waste should decline. Following the response of gulls to these changes will be particularly useful for monitoring plastic pollution and for understanding the response of opportunistic wildlife to environmental modifications.

Optimization of a modified Captiva EMR-lipid method based on micro-matrix solid-phase dispersion coupled with gas chromatography-mass spectrometry for the determination of nine bisphenols in mussel samples

This work describes a reliable, cheap, easy and fast method for analysis of nine bisphenols in mussel samples by gas chromatography-mass spectrometry after trimethylsilylation. The modified method consisted of miniaturized matrix solid phase dispersion (micro-MSPD) in a glass Pasteur pipette using Captiva EMR (enhanced matrix removal)-lipid as the sorbent. Good linearity was obtained in the work range (1-500 μg L-1) with a correlation coefficient (R2) ≥ 0.998. The method accuracy and precision were determined at two concentration levels. The results show recoveries ranging from 55 to 111%. The precision varied from 1.95 to 11.4% (RSD). The whole quantification limits were between 0.056 and 3.42 μg per kg dry weight. The analytical procedure was applied for the analyses of five mussel samples collected from Galician Rias. The major compound was BPA, and wild mussels from Rías de Ferrol, Vigo and A Coruña had the highest levels. The proposed method is suitable for the analysis of BPA and its analogues in mussel samples.

The presence and physico-chemical properties of microplastics in seawater, sediment, and several organs of the spotted scat fish (Scatophagus argus, Linnaeus, 1766) collected from different locations along the East Java coast in Indonesia

A comprehensive study was undertaken to examine the contamination of spotted scat fish (Scatophagus argus) with microplastics (MP) in various locations along the East Java coast of Indonesia. The purpose of this study was to collect detailed information regarding the abundance, color, shape, size, type of polymer, and chemical components of the MP. The findings of this study indicated that MP exhibiting distinct attributes-including a specific fiber type, black coloration, and a size range of 1000- <5000 μm-was most abundant in the gill, stomach, and intestines of spotted scat fish of varying lengths. And MP with a size range of 100-<500 μm was prevalent in the sediment. MP with black fragments measuring less than 100 μm in diameter were found primarily in seawater. A positive correlation was identified between fish length and MP abundance in the intestines, as indicated by the Spearman correlation coefficient. Conversely, a negative correlation was detected between fish length and MP abundance in the gills. The findings of the Fourier transform infrared spectroscopy and Gas chromatography-mass spectrometry analyses, which indicate the presence of various polymers and chemical substances including plasticizers (e.g., diethyl phthalate, decane, and eicosane), stabilizers (2-piperidinone, hexadecanoic acid, mesitylene, and 2,4-Di-tert-butylphenol), and flame retardant (cyclododecene), in fish, are of the utmost importance. These substances have the potential to endanger the health of both animals and humans if they are ingested through the food chain.

Assessing biofilm formation and resistance of vibrio parahaemolyticus on UV-aged microplastics in aquatic environments

UV degradation of marine microplastics (MPs) could increase their vector potential for pathogenic bacteria and threaten human health. However, little is known about how the degree of UV aging affects interactions between MPs and pathogens and how various types of MPs differ in their impact on seafood safety. This study investigated five types of UV-aged MPs and their impact on Vibrio parahaemolyticus, a seafood pathogen. MPs exposed to UV for 60 days showed similar physicochemical changes such as surface cracking and hydrophobicity reduction. Regardless of the type, longer UV exposure of MPs resulted in more biofilm formation on the surface under the same conditions. V. parahaemolyticus types that formed biofilms on the MP surface showed 1.4- to 5.0-fold upregulation of virulence-related genes compared to those that did not form biofilms, independently of UV exposure. However, longer UV exposure increased resistance of V. parahaemolyticus on MPs to chlorine, heat, and human gastrointestinal environment. This study implies that the more UV degradation occurs on MPs, the more microbial biofilm formation is induced, which can significantly increase virulence and environmental resistance of bacteria regardless of the type of MP.

Microplastics in the Indian and South Atlantic oceans translocate to gills, digestive glands, and muscle of the chokka squid Loligo reynaudii

Comparative microplastic (MP) data for cephalopods between oceans is scarce. Our aim was to quantify, characterise, and compare MPs in gills, digestive gland, and mantle of chokka squid from the South Atlantic Ocean (SAO) and Indian Ocean (IO) off the coast of South Africa. South African squid had more MPs compared with other studies (means = 2.0 and 0.4 in SAO and IO squid mantle, respectively). Blue fibres were dominant. Identifiable MPs were polyethylene. Despite IO water having higher MP concentrations than the SAO, SAO squid had higher MP concentrations. Dilution by growth is the likely reason for the lower MP concentrations. Fibres were shorter in SAO than IO squid. However, we could not explain why fibre and mantle lengths from both oceans were positively correlated. Squid may not be the best indicator of marine MPs. The characteristics of MPs in squid can be used to track stocks and migrations.

Ten Years of Mediterranean Monk Seal Stranding Records in Greece under the Microscope: What Do the Data Suggest?

This paper presents the results of an analysis of stranding events of the Mediterranean monk seal Monachus monachus over a decade. The analysis involved categorization according to the cause of stranding and seasonality, the identification of hotspot stranding areas and an assessment of possible correlations between stranding events and environmental/climatic patterns using time series analysis. Moreover, Generalized Additive Models (GAMs) were applied to explore the effects of the size of small-scale fishing grounds, the number of species sightings, and the occurrence of reproduction sites on "human-related" strandings. Finally, special focus was put on the central part of the eastern Ionian Sea for the assessment of stranding hotspot areas by means of the Multi-Criteria Decision Analysis (MCDA) approach, based on different kinds of spatial information such as anthropogenic pressures and the location of breeding sites and feeding grounds. Time series analysis results revealed that oscillation indices, during the first half of the year, and sea surface temperature (SST) in the Mediterranean from October to December were positively correlated with monk seal stranding events. GAMs underlined that areas combining extended small-scale fishery grounds and a higher number of sightings were more likely to cause more strandings. Regarding spatial analyses, the central Aegean Sea was highlighted as a hotspot for "human-related strandings", while the MCDA approach emphasized that the southern coasts of Cephalonia and the gulf between Lefkada and mainland Greece were susceptible to subadult strandings.

A meta-analysis of potential biomarkers associated with microplastic ingestion in marine fish

Over the past decade, global reports have shown a rise in the harmful effects of microplastics (MPs) on marine fish. This study analysed marine species' biochemical biomarker responses to microplastic exposure, finding that MPs can induce oxidative stress in marine fish through meta-regression results. Overall, exposure to MPs resulted in the activation of antioxidant defence mechanisms, such as superoxide dismutase, catalase and glutathione reductase, detoxification enzymes such as glutathione-S-transferase, the detection of malondialdehyde, and inhibition of acetylcholinesterase. Moreover, results highlight oxidative stress biomarkers were activated in wild species that had ingested MPs, indicating potential harm to marine fish, as confirmed in experimental studies. Furthermore, even though MPs' exposure is better regulated in an experimental setting, it is challenging to replicate actual exposure and environmental factors. The study's findings show the need for more investigation into the hazardous consequences of exposure to environmental MPs on species surveyed in the maritime environment.

Marine litter and microplastic pollution in mangrove sediments in the Sea of Oman

Marine litter and microplastic pollution in mangroves pose significant threats. This study of litter in Omani mangroves revealed an average density of 0.83 to 21.92 items/m2. Quriyat lagoon emerged as the most contaminated area, hosting 133 items/m2, while Qurum Natural Reserve lagoon showed the least contamination at 10 items/m2. Plastics constituted 73-96 % of the litter, with microplastic levels in sediment ranging from 6 to 256 pieces/kg. Al-Sawadi's lagoon had the highest microplastic abundance (27.52 ± 5.32 pieces/kg), in contrast to Al Qurum's Marine Protected Area with the lowest (0.60 ± 1.12 pieces/kg). Microplastics, categorized as fragments, pellets, and fibers, were distributed across zones 40.05 % landward, 30.97 % seaward, and 28.98 % in the middle mangrove zones. Primary plastic polymers identified were Polyethylene (PE) at 40 % and High-Density Polyethylene (HDPE) at 28 %, along with others found in specific areas. Our findings provide essential baseline data for future monitoring efforts and management strategies in Oman and other countries.

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.

Cory's shearwater as a key bioindicator for monitoring floating plastics

The potential of using organisms as bioindicators of marine litter has been an area of general interest in multiple scientific and monitoring programs across the globe. Procellariiformes seabirds are particularly vulnerable to plastic contamination, which makes them a research focus group. This study investigated plastic ingestion in deceased fledglings and adults Cory's shearwaters (Calonectris borealis) collected over eight years (2015 to 2022) at two Atlantic archipelagos: the Azores and the Canaries. Necropsies were carried out in a total of 1,238 individuals showing a high prevalence of plastic ingestion (90%), with approximately 80% of items recovered from the gizzard. Fledglings carried greater plastic loads compared to adults, yet plastic morphologies were similar between both age classes. The temporal analyses conducted with generalised additive mixed-effect models revealed a distinct temporal trend in plastic numbers, but not in terms of plastic mass. In addition, the spatial analyses showed that Cory's shearwaters from the Canary Islands ingest a higher quantity of plastic and a greater proportion of threadlike items than the Azorean birds. These results suggest higher contamination at the NW Africa foraging grounds next to the Canaries and highlight fisheries as a potential source of marine litter in that region. On the other hand, the information gathered from the Azorean birds suggests they would be able to monitor changes in the composition of the plastic items floating in the North Atlantic Subtropical Gyre. Overall, our outcomes support the use of Cory's shearwater fledglings that are victims of light pollution as a key bioindicator of plastic contamination in the North Atlantic. For its policy application, the presented threshold value in combination with the assessment method will enable effective tracking of floating plastic litter in the framework of the MSFD and OSPAR.

Coping with current impacts: The case of Scyliorhinus canicula in the NW Mediterranean Sea and implications for human consumption

The small-spotted catshark (Scyliorhinus canicula) is a bottom-dwelling elasmobranch that represents the most discarded catch in terms of biomass in the Catalan coast (NW Mediterranean). Potential impacts affecting its population and food safety implications have been assessed in three localities along the Catalan coast. Distinct indicators were integrated, such as biological data, ingested anthropogenic items (plastic and cellulose-like items), parasitological indices, trace metal concentrations and histopathology using liver as target organ. Although high ingestion rates of fibres and levels of some heavy metals, they do not seem negatively affected by any major pathology nor by the current levels of pollutants. Small-scale differences among localities and depths were found and discussed. No zoonotic parasites were found. Encysted larvae of Grillotia adenoplusia and, above all, the levels of Hg found in the musculature, that are well over the European Commission limits, rise concerns regarding human consumption of S. canicula in this region.

Microplastic pollution in stream sediments discharging from Türkiye's eastern Black sea basin

Rivers are the principal route for terrestrial microplastics to reach the marine environment. The Black Sea exhibits a notable representation because it has a drainage zone almost six times the surface area and is semi-closed, meaning that microplastics tend to gather there. To mitigate MP pollution, it is necessary to identify the contamination sources and then raise public awareness. Thus, the current study focused on the MP presence in the sediment of streams running into the SE Black Sea. 594 MPs were observed in sediment samples from 16 stations along the 350 km coastline. The abundance of MP was higher, particularly in streams that pass through locations with high tourism and industrial activity levels. Detected MPs ranged between 0.1 and 5 mm, while the overall density was smaller than 1 mm. Fragments and fiber MPs were regularly detected, although the presence of films was rarely recorded. The polymer structures that were most commonly observed in the analyzed pollutants were PET and PE. The current study uncovered MP contamination in stream sediments originating from Türkiye's Eastern Black Sea basin and might be a baseline work for future inland water studies.

Fate of the biofilm chips overflowed from a wastewater treatment plant

In February 2018 over 100 millions of polyethylene biofilm chips overflowed from a wastewater treatment plant located at Capaccio Paestum (Italy) and due to the Thyrrhenian Sea currents, in few days they invaded the coasts of Campania, Lazio and Tuscany. During the following months the diffusion involves all the coasts of the western Mediterranean, including Spain, France and Tunisia. Samples of chips were recovered mainly along the Latium coasts (Italy) during the last 6 years. Following the exposure of the biofilm chips to the environmental conditions, the effect of natural weathering on polyethylene have been studied. The following annual decreases were evaluated: thickness 9.5 μm, diameter 18.5 μm and weight 3.7 mg while the average value of the size of all recovered items (n = 60) are: thickness = 2.936 ± 0.0406 mm, diameter = 44.349 ± 0.1266 mm and weight = 1.1593 ± 0.0248 g. Considering the weight loss, it was calculated that the complete mineralization of the disks will occur in 310 years producing about 0.5 tons of microplastics per year. FTIR analysis was used to investigate the change of chemical structure of the polyethylene. The Carbonyl index (CI), Vinyl index (VI) and Hydroxyl normalized absorbance peak were used to evaluate the polymer degradation while Scanning Electron Microscopy (SEM) was used to characterize the surface of the polymer samples. It was observed that erosion/degradation increases with time spent in the environment, above all from the last two years. The static contact angle was always >90° confirming that the surface of the biofilm chip is hydrophilic. The Oxygen/Carbon ratio increase with time: 0.18 and 0.27 has been found for 2018 and 2023 disks respectively confirming the progressive oxidative process. From TGA analysis a slightly reduction of decomposition temperature has been evaluated.

Microplastics Prevalence in Different Cetaceans Stranded along the Western Taiwan Strait

Microplastics (MPs) pollution is of global concern, which poses serious threats to various marine organisms, including many threatened apex predators. In this study, MPs were investigated from nine cetaceans of four different species, comprising one common dolphin (Delphinus delphis), two pygmy sperm whales (Kogia breviceps), one ginkgo-toothed beaked whale (Mesoplodon ginkgodens), and five Indo-Pacific humpback dolphins (Sousa chinensis) stranded along the western coast of the Taiwan Strait from the East China Sea based on Fourier transform infrared (FTIR) spectroscopy analysis. Mean abundances of 778 identified MPs items were 86.44 ± 12.22 items individual-1 and 0.43 ± 0.19 items g-1 wet weight of intestine contents, which were found predominantly to be transparent, fiber-shaped polyethylene terephthalate (PET) items usually between 0.5 and 5 mm. The abundance of MPs was found at a slightly higher level and significantly correlated with intestine contents mass (p = 0.0004*). The MPs source was mainly likely from synthetic fibers-laden sewage discharged from intense textile industries. Our report represents the first study of MPs in pelagic and deep-diving cetaceans in China, which not only adds baseline data on MPs for cetaceans in Asian waters but also highlights the further risk assessment of MPs consumption in these threatened species.

Distribution and characteristics of microplastics in 16 benthic organisms in Haizhou Bay, China: Influence of habitat, feeding habits and trophic level

Microplastics (MPs) are widely found in the ocean and cause a serious risk to marine organisms. However, fewer studies have been conducted on benthic organisms. This study conducted a case study on the pollution characteristics of MPs on 16 marine benthic organisms in Haizhou Bay, and analyzed the effects of habitat, trophic level, and feeding mode on the MPs pollution characters. The results showed that MPs were detected in all 16 organisms with an average abundance of 8.84 ± 9.14 items/individual, which is in the middle-high level in the international scale. Among the detected MPs, the main material was cellophane. This study showed that benthic organisms can be used as indicator organisms for MPs pollution. MPs in organisms can be affected by their habitat, trophic level, and feeding mode. Comprehensive analysis of MPs in benthic organisms will contribute to fully understand the characterization and source resolution of MPs pollution.

What, where, and when: Spatial-temporal distribution of macro-litter on the seafloor of the western and central Mediterranean sea

The progressive increase of marine macro-litter on the bottom of the Mediterranean Sea is an urgent problem that needs accurate information and guidance to identify those areas most at risk of accumulation. In the absence of dedicated monitoring programs, an important source of opportunistic data is fishery-independent monitoring campaigns of demersal resources. These data have long been used but not yet extensively. In this paper, MEDiterranean International Trawl Survey (MEDITS) data was supplemented with 18 layers of information related to major environmental (e.g. depth, sea water and wind velocity, sea waves) and anthropogenic (e.g. river inputs, shipping lanes, urban areas and ports, fishing effort) forcings that influence seafloor macro-litter distribution. The Random Forest (RF), a machine learning approach, was applied to: i) model the distribution of several litter categories at a high spatial resolution (i.e. 1 km2); ii) identify major accumulation hot spots and their temporal trends. Results indicate that RF is a very effective approach to model the distribution of marine macro-litter and provides a consistent picture of the heterogeneous distribution of different macro-litter categories. The most critical situation in the study area was observed in the north-eastern part of the western basin. In addition, the combined analysis of weight and density data identified a tendency for lighter items to accumulate in areas (such as the northern part of the Tyrrhenian Sea) with more stagnant currents. This approach, based on georeferenced information widely available in public databases, seems a natural candidate to be applied in other basins as a support and complement tool to field monitoring activities and strategies for protection and remediation of the most impacted areas.

Beached seabirds as plastic biomonitors in Brazil from the Beach Monitoring Project of the Santos Basin (PMP-BS)

Bioindicator species are useful to monitor wildlife exposure to plastic pollution, and responses to plastic leakage and policy interventions. Here we explore the biomonitoring potential of different seabird and shorebirds species across six years of monitoring in Brazil. Using the necropsy stranding database of the Beach Monitoring Project of the Santos Basin (PMP-BS), we evaluated i) the frequency of birds-plastic interactions in Brazil; ii) whether plastic interactions have changed through time and in different coastal regions; and iii) potential bioindicators for monitoring the exposure of seabirds to plastic in the nearshore South Atlantic Ocean. We found 37 species that had ingested plastic, including ten new records, found that the rates of tube-nosed seabirds increased through time, and suggested two potential species. We discuss the potential for biomonitoring marine pollution in the South Atlantic Ocean using PMP-BS, providing a scheme for a better plastic pollution monitoring in Brazil.

Oceanographic and anthropogenic variables driving marine litter distribution in Mediterranean protected areas: Extensive field data supported by forecasting modelling

Marine litter concentration in the Mediterranean Sea is strongly influenced both by anthropogenic pressures and hydrodynamic factors that locally characterise the basin. Within the Plastic Busters MPAs (Marine Protected Areas) Interreg Mediterranean Project, a comprehensive assessment of floating macro- and microlitter in the Pelagos Sanctuary and the Tuscan Archipelago National Park was performed. An innovative multilevel experimental design has been planned ad-hoc according to a litter provisional distribution model, harmonising and implementing the current sampling methodologies. The simultaneous presence of floating macro- and microlitter items and the potential influences of environmental and anthropogenic factors affecting litter distribution have been evaluated to identify hotspot accumulation areas representing a major hazard for marine species. A total of 273 monitoring transects of floating macrolitter and 141 manta trawl samples were collected in the study areas to evaluate the abundance and composition of marine litter. High mean concentrations of floating macrolitter (399 items/km2) and microplastics (259,490 items/km2) have been found in the facing waters of the Gulf of La Spezia and Tuscan Archipelago National Park as well in the Genova canyon and Janua seamount area. Accordingly, strong litter inputs were identified to originate from the mainland and accumulate in coastal waters within 10-15 nautical miles. Harbours and riverine outfalls contribute significantly to plastic pollution representing the main sources of contamination as well as areas with warmer waters and weak oceanographic features that could facilitate its accumulation. The results achieved may indicate a potentially threatening trend of litter accumulation that may pose a serious risk to the Pelagos Sanctuary biodiversity and provide further indications for dealing with plastic pollution in protected areas, facilitating future management recommendations and mitigation actions in these fragile marines and coastal environments.

A glimpse into the future: A suitable methodological approach for the detection and identification of micro-bioplastics in biota

In the frame of the circular economy, bioplastics are considered a good alternative to conventional plastic materials. Until recently, only a few studies have focused on the occurrence and impact of bio-microplastics (bio-MPs) in aquatic environments, and there is a lack of a methodological approach to measure their amount in marine compartments. This research aimed to identify and validate a method for bio-MPs extraction from biota. A chemical digestion protocol suitable for conventional MPs, using potassium hydroxide (KOH), was applied for the detection, in mussels, of MPs made with Mater-Bi (MBi) from socks used in mussel farming. This method was tested on virgin MBi (VMBi) and aged (AMBi) MPs, ranging from 200 to 1000 μm in presence and absence of mussel tissues. Samples were analysed in pre- and post-digestion steps to assess the recovery rate, potential visual and size changes and polymer alteration in different bio-MPs size ranges. Results showed that MBi seems to be affected by KOH under pre-production conditions (VMBi), whereas in the AMBi treatment, which represents the environmentally realistic condition, the presence of fouling due to deployment at sea preserves MBi from the action of the alkaline agent. This approach allowed the recovery of small MPs, generally difficult to extract from biota, in an optimal visual condition and without polymer alteration. Despite the fraction of organic material in the MBi, these results suggested the suitability of this method and provided the assessment of the KOH effects on MBi-MPs under different environmental conditions. Finally, validation tests proved that the KOH protocol represents a reliable approach for detecting bio-MPs in marine organisms. This study is an important starting point for assessing the impact of the bio-MPs on the marine environment and suggests future studies to improve these issues in order to fill the gaps in the field of bioplastics.

Essential and non-essential elements in tuna and billfish around the world: Distribution patterns and influencing factors

Tuna and billfish are widely distributed in oceans worldwide. Their survival is relied on a decent share of essential and non-essential elements. We conducted a comprehensive evaluation of essential and non-essential elements in livers of tuna and billfish collected from global oceans. The individual element consistently shown similar orders of magnitude in both tuna and billfish, with essential elements generally being 1-3 orders of magnitude higher than non-essential elements. Various physicochemical properties and behaviors contributed to four distinct clusters of these elements. Also, element distribution pattern indicated the presence of four sample groups based on regions and categories. Nine elements served as characteristic indicators. Among them, fish category was the most important influencing factor. Hg, Fe, Tl, Co, and Se were influenced by body size, trophic level, and feeding habits. Ni was influenced by sampling regions, while Mg, Mn and As were influenced by body size and local primary production.

Microplastic ingestion and its effects οn sea urchin Paracentrotus lividus: A field study in a coastal East Mediterranean environment

Microplastics (MPs) are recognized as an increasing threat to the marine environment, but little is known about their effects on benthic organisms, including sea urchins, when ingested. For this purpose, wild sea urchins (P. lividus) and seafloor sediment samples were investigated across three coastal areas of Zakynthos Island (Ionian Sea), each exposed to different anthropogenic pressures, revealing a consistent pattern in MP abundance, shape, and color. Biomarkers related to oxidative stress, neurotoxicity, and genotoxicity showed no significant effects of MP ingestion in the sea urchins, except for a positive correlation between GST activity and ingested MPs, suggesting a possible activation of their detoxification system in response to MP ingestion. While MP concentrations in sea urchins and sediments were within the low range reported in the global literature, it remains crucial to conduct further investigations in areas with MP pollution approaching predicted levels to fully comprehend the potential effects of MP pollution on marine organisms.

Abundance and characteristics of microplastics in a freshwater river in northwestern Himalayas, India - Scenario of riverbank solid waste disposal sites

Microplastics (MPs) are one of the challenging and established contaminants that have adverse implications on human health. The focus of this study was to quantify and analyze the contribution of unscientific municipal solid waste (MSW) disposal sites to the MPs in the Jhelum River and the risk associated with it. Quantitative analysis of our study showed a mean MP concentration of 1474 ± 1026 particles/m3 for the entire stretch of the river. All the sites confirmed the presence of MPs with the concentration ranging from 600 particles/m3 to 2500 particles/m3. The size distribution of MPs suggested that 34 % of the microplastics ranged between 300 μm to 75 μm while 66 % of the particles varied between 300 μm to 5 mm. The concentrations of MPs downstream of unscientific disposal sites were found to increase threefold to that of upstream. The Fourier Transform Infrared Spectroscopy (FT-IR) confirmed the presence of polyethylene (PE) in the majority followed by polyvinyl chloride (PVC) and polypropylene (PP). The flakes were dominant throughout the river followed by filaments, fragments, and spherules. Count based Pollution level indexing (PLI) estimated 3-14 times MP contamination in the river with respect to contamination in glacial runoffs. The risk assessment study of the MPs indicated an increase of around 10.2 % in ingestion rates of MPs due to the unscientific disposal of MSW on the banks of the freshwater body. The values of polymer hazard index (PHI) and potential ecological risk index (PERI) were in the extreme case of pollution (PHI>1000 and PERI>1200). This study manifests the adversities of unscientific municipal solid waste disposal for timely waste management.

Elder fish means more microplastics? Alaska pollock microplastic story in the Bering Sea

Marine microplastics are an increasingly big concern. We analyze the occurrence of microplastics in Alaska pollock (Gadus chalcogrammus) across 2+ to 12+ ages sampled from the Bering Sea. Results show that 85% of the fish have ingested microplastics and elder fish ingest more with over a third of microplastics in the 100- to 500-micrometer size range, indicating the prevalence of microplastics in Alaska pollock distributed in the Bering Sea. A positive linear relationship is obtained between fish age and microplastic size. Meanwhile, the number of polymer types increases in elder fish. The link between microplastic characteristics in Alaska pollock and the surrounding seawater suggests an extended spatial impact of microplastics. The impact of age-related microplastic ingestion on the population quality of Alaska pollock is still unknown. Therefore, we need to further investigate the potential impact of microplastics on marine organisms and the marine ecosystem, taking age as an important factor.

First record of plastic ingestion by a freshwater stingray

The abundance and dispersion of plastic particles in aquatic ecosystems has become pervasive resulting in the incorporation of these materials into food webs. Here we describe the first record of plastic ingestion by the freshwater white-blotched river stingray Potamotrygon leopoldi (Potamotrygonidae), an endemic and threatened species in the Xingu River, Amazon basin. Potamotrygonidae stingrays inhabit exclusively Neotropical rivers, occupying rocky substrate habitats and feeding mainly on benthic macroinvertebrates. The gastrointestinal tract of 24 stingrays were analyzed, 16 (66.6 %) of which contained plastic particles. In total, 81 plastic particles were recorded and consisted of microplastics (< 5 mm, n = 57) and mesoplastics (5-25 mm, n = 24). The plastic particles found were classified into fibers (64.2 %, n = 52) and fragments (35.8 %, n = 29). The predominant color was blue (33.3 %, n = 27), followed by yellow (18.5 %, n = 15), white (14.8 %, n = 12), black (13.6 %, n = 11), green (6.2 %, n = 5), transparent (4.9 %, n = 4), pink, grey and brown (2.5 %, n = 2, each) and orange (1.2 %, n = 1). No significant correlation was observed between the number of plastic particles and the body size. Eight types of polymers were identified in the plastic particles analyzed using 2D FTIR Imaging. The most frequent polymer was artificial cellulose fiber. This is the first report of plastic ingestion by freshwater elasmobranchs in the world. Plastic waste has become an emerging problem in aquatic ecosystems globally and our results provide an important datapoint for freshwater stingrays in the Neotropics.

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.

Multiple species ingest microplastic but few reflect sediment and water pollution on sandy beaches: A baseline for biomonitoring

Databases recording the ingestion of microplastics by marine animals are growing. This is also recurrent on sandy beaches, where different biomonitors have been proposed to monitor the impacts of plastic pollution. We aimed to record the occurrence of suspected microplastic (SMP) in the digestive tract of multiple taxa (n = 45 identified species) and test whether some macroinvertebrates and fishes ingested SMPs proportionally with the pollution level of sediment and water; thus, we aimed to depict which sandy beach species could be used as biomonitors. Among all taxa, 10 macroinvertebrates and 12 fish species were reported to ingest SMP for the first time. SMP morphotypes proportion differed between abiotic and biotic compartments. Moreover, 10 of 12 taxa did not have SMP concentration linearly related with SMP in sediment and water. Our findings suggest that few species from sandy beaches can be used as efficient biomonitors, although almost all ingest plastic polymers.