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

Monitoring microplastics in coastal waters of a biosphere reserve: a case study in Menorca (Spain)

This study provides with evidence of the presence of sea surface microplastics in a UNESCO marine biosphere reserve: the island of Menorca in the north-western Mediterranean Sea. From a total of 90 samples, in 100% of the samples, microplastics were observed with a mean value of 0.18 ± 0.01 items/m2. According to data, no significant differences were observed for sampling period with very similar values between 2021 (0.17 ± 0.02 items/m2) and 2022 (0.18 ± 0.02 items/m2). However, significant differences were observed regarding sampling area (both site and locality) suggesting that sea surface plastics in the study area might be more dependent of the spatial scale rather than on the temporal scale. Fibre type microplastics predominated over fragments, films, pellets, and foams, but in the commercial Port de Maó, almost 50% of the identified items were foams which could be related to the transportation of packed goods to this port. Results from the model applied to study the relation between waste management indicators and microplastic abundance indicate that when considering all marine litter categories, the explanatory variables are plastic waste generated by residents population (tonnes/year/km2) and waste collection rate (%), whereas if only plastics are considered, the indicator regarding waste per capita (kg/hab/year) is also included. Data in this study is obtained through a harmonized protocol which can be used to define baseline and threshold values to evaluate good environmental status regarding descriptor 10 of the Marine Strategy Framework Directive.

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.

Ingestion of microplastics and microfibers by the invasive blue crab Callinectes sapidus (Rathbun 1896) in the Balearic Islands, Spain

The blue crab Callinectes sapidus Rathbun, 1896 is native to the western coasts of the Atlantic Ocean and is currently considered an invasive species in the Mediterranean Sea. In this study, we examined the stomach contents of C. sapidus to determine the frequency of occurrence of microplastics (MPs) and microfibers (MFs) in the Balearic Islands archipelago in the western Mediterranean Sea. A total of 120 individuals were collected from six locations between 2017 and 2020. Overall, 65.8% of the individuals had MPs and/or MFs particles with an average of 1.4 ± 1.6 particles ind.-1 of which an average of 1.0 ± 1.3 items ind.-1 were MFs and an average of 0.4 ± 0.8 items ind.-1 were MPs. In terms of type, fragments were the dominant type of MPs and the most common size of items ranged from between 0.5 and 1 mm (40%) followed by 1-5 mm (31%). The most prevalent polymers were low-density polyethylene (39%) and high-density polyethylene (26%). In terms of links to human activities, MP ingestion was positively correlated with an increase in drain pipes, whereas MF ingestion was positively correlated with an increase in sewage pipelines, providing evidence of potential sources and the bioavailability of these particles in various environments. This study confirms the widespread presence of MP and MF particles, even in areas that are currently managed under different protection statuses, in the stomach contents of invasive blue crab species throughout coastal communities.

The hyperbenthic environment: A forgotten habitat for plastic pollution

This study investigates the abundances and composition of microplastics (MP) among the shallow layers of a coastal Mediterranean Marine Protected Area (Cabrera MPA), seafloor sediments, hyperbenthic environment, and the water column. The mid waters samples were collected mid-way between the sea surface and the seafloor and hyperbenthic samples at the water layer adjacent to the seafloor. Sampling was carried out on patchiness seafloor of Posidonia oceanica meadows. The seafloor sediments showed a mean abundance of 378,769.20 ± 508,109.11 MPs/m3, three orders of magnitude higher than the hyperbenthic (209.17 ± 117.07 MPs/m3), and the mid waters layer (106.48 ± 107.17 MPs/m3). An increasing vertical gradient in MP abundances, mainly composed of fibers was observed. Fibers were made-up mainly of polystyrene (PS, 25 %), expanded polystyrene (EPS, 18 %) and cellulose acetate (CA, 16 %). The results stress the need to increase efforts to find solutions to mitigate fiber pollution in the marine environment.

Sea surface surveys for microplastic and floating marine macro litter items in coastal waters of Cabrera Archipelago Maritime Terrestrial National Park

This study is aimed at identifying and comparing microplastics and floating marine litter along the sea surface in the marine protected area of Cabrera Archipelago Maritime Terrestrial National Park (Cabrera MPA) in the Balearic Islands. A total of 52 net surveys and 22 visual surveys were carried out between July and August in 2019 and 2020. The abundance of microplastic (MP) items was highest in the southern and eastern regions, with an average of 381,244.4 ± 1,031,082.8 items/km² weighing an average of 927.1 ± 2731.4 g/km². Most of these items were < 5 mm (81%) in size and were mainly composed of polyethylene and polypropylene (98%). In terms of floating marine macro litter (ML) from visual surveys, an average of 2028 ± 2084 items/km² were observed. In this case, the majority of the ML items were plastic pieces (69%) measuring 2.5 to 50 cm. Furthermore, ML quantified by visual surveys was an order of magnitude higher than in similar studies carried out on large vessels, highlighting the importance of vessel height and speed for identifying the smallest size fractions (81%). The results of this study document the intensity of MPs and ML, primarily plastic, in coastal waters, and provide a baseline for management efforts to mitigate floating litter, in addition to raising awareness of the transferability of marine litter from other regions.

Breaking the paradigm: Marine sediments hold two-fold microplastics than sea surface waters and are dominated by fibers

We conducted one of the first studies to integrate the quantification and characterization of microplastics (MPs), including fibers, in different habitats (sea surface, seafloor and beach sediments) of a coastal Mediterranean marine protected area, analyzing their ingestion in several marine species. The objectives of the study were to evaluate the distribution of MPs according to shape and polymer, to assess the contribution of fibers to local plastic pollution and to evaluate their ingestion in fish and invertebrates species that inhabit the study area (Pagrus pagrus, Serranus scriba, Spondyliosoma cantharus, Diplodus vulgaris, Oblada melanura, Holothuria forskalii, Holothuria tubularis, Holothuria polis, Arbacia lixula, Paracentrotus lividus, Modiolus barbatus, Mytilus galloprovincialis and Arca noae). A total of 111 environmental samples were analyzed. The mean abundance of MPs (excluding fibers) quantified in beach sediments (13,418.86 ± 28,787.99 MPs/m²) was two orders of magnitude higher than that found in seafloor sediments (76.92 ± 108.84 MPs/m²), which in turn was two orders of magnitude higher than sea surface samples (0.17 ± 0.39 MPs/m²). The fibers were the most abundant shape of MPs identified in all habitats. Variability in MPs ingestion was detected between species, with ingestion rates ranging from 43 % to 100 % for general MPs and ranging from 7 % to 100 % for fibers. The highest ingestion was observed in Holoturians, representing suitable bioindicators for plastic pollution. The composition of the polymer varies weakly depending on habitats and biota, but the result is strongly correlated with the morphology of the plastic. Fibers were mainly composed of cellulose acetate (29 %), styrofoam of polystyrene (18 %), and filaments, films and fragments of polyethylene and polypropylene. The results highlighted the need to expand integrated approaches to effectively study marine plastic pollution and to undertake efficient actions to limit the input of plastics, particularly fibers, into the marine environment.

Sources, sinks and transformations of plastics in our oceans: Review, management strategies and modelling

Currently, 60-80 % of litter is plastic, and almost 10 % ends up in the ocean directly or indirectly. Plastics often suffer from photooxidation producing microplastics and these microplastics derived from the breakdown of larger plastics are called secondary microplastics. These compounds simply cannot be extracted from the oceans, and once mixed, they enter the food chain and may have toxic effects. This work reviews the current existing information on the topic in the scientific literature. Then, the current plastic management strategies in the marine environment are analysed, with the objective of identifying possible needs and improvements from a sustainable point of view, and to define new approaches. Simultaneously, a material flows analysis in different media of the marine environment is carried out using system dynamics. A preliminary model of plastics mobilization into the ocean to other media of the marine environment (like sediments and biota) is developed and validated with the existing data from the previous steps of the work. This work expands the current knowledge on the plastics management, their transformations and accumulation in the marine environment and the harmful effects on it. Likewise, preliminary dynamic model of mobilization of plastics in the ocean is implemented, run, and validated. The developed model can be used to predict trends in the distribution of the plastics in the ocean with time. In addition, the most important reservoirs of plastics in the ocean can be observed. Although plastics undergo transformations in the marine environment, it is not a means of disposal since most of them are non-biodegradable. Most plastics accumulate on the seabed. The proportion of microplastics found in sediments is higher than that of macroplastics.

Toward a long-term monitoring program for seawater plastic pollution in the north Pacific Ocean: Review and global comparison

Through a literature survey and meta-data analysis, monitoring methods and contamination levels of marine micro- and macroplastics in seawater were compared between the North Pacific and the world's other ocean basins. The minimum cut-off size in sampling and/or analysis of microplastics was crucial to the comparison of monitoring data. The North Pacific was most actively monitored for microplastics and showed comparatively high levels in the global context, while the Mediterranean Sea was most frequently monitored for macroplastics. Of the 65 extracted mean abundances of microplastics in seawater from the North Pacific, two (3.1%) exceeded the lowest predicted no-effect concentration (PNEC) proposed thus far. However, in the context of business-as-usual conditions, the PNEC exceedance probability may be expected to reach 27.7% in the North Pacific in 2100. The abundance of marine plastics in seawater, which reflects the current pollution status and marine organisms' waterborne exposure levels, is a useful indicator for marine plastic pollution. For regional and global assessments of pollution status across space and time, as well as assessment of ecological risk, two microplastic monitoring approaches are recommended along with their key aspects. Although microplastic pollution is closely linked with macroplastics, the monitoring data available for floating macroplastics and more extent to mesoplastics in most ocean basins are limited. A more specific framework for visual macroplastic survey (e.g. fixed minimum cut-off size, along with survey transect width and length according to survey vessel class) is required to facilitate data comparison. With the implementation of standardised methods, increased efforts are required to gather monitoring data for microplastics and-more importantly-floating macroplastics in seawater worldwide.

Multispecies Assessment of Anthropogenic Particle Ingestion in a Marine Protected Area

We have applied a multispecies ecosystem approach to analyse the ingestion of anthropogenic particles (AP) in the gastrointestinal tract of 313 individuals (17 fish species and 8 invertebrate species) from pelagic, demersal and benthic habitats in a marine protected area off the Western Mediterranean (Cabrera National Park). We have quantified and characterized the ingestion at several taxonomic levels of fish, sea urchins, sea cucumbers, bivalves, and jellyfish in relation to biotic/abiotic factors based on taxonomic groups, trophic guilds (functional groups) and habitats. AP ingestion occurrence ranged from 26 to 100% with no significant differences among taxonomic groups. The fish within the MPA showed an overall ingestion occurrence ranging from 0 to 100%, the echinoderms from 29 to 100%, the bivalves from 72 to 96% and the jellyfish 36% ingestion. The ecosystem approach applied to evaluate overall AP ingestion within the species reported that for trophic guilds, the omnivorous species ingested the highest amounts of anthropogenic items, while herbivores ingested significantly fewer items than all other trophic guilds. Moreover, no significant differences were found amongst habitats, indicating a homogeneous spatial distribution of APs at all studied habitats. The multispecies approach provided insight into the high APs exposure to species within Cabrera MPA, highlighting the potential harm linked with marine litter that threatens marine biodiversity.

The coastal waters of the south-east Bay of Biscay a dead-end for neustonic plastics

Numerical models point to the south-east Bay of Biscay as a convergence area for floating particles, including plastics. The few existing studies on plastic abundance in the area mainly focus on open waters and yet information on the coastal area is limited. To fill this gap, neustonic samples were taken along the coastal waters of the south-east Bay of Biscay (2017-2020) to define the spatial distribution of plastic abundances and composition. Results show an average plastic abundance of 739,395 ± 2,625,271 items/km² (998 ± 4338 g/km²). French waters were more affected, with five times higher plastic abundances than Spanish coasts. Microplastics represented 93 % of the total abundance of plastic items (28 % in weight), mesoplastics 7 % (26 %) and macroplastics 1 % (46 %). This study demonstrates that this area is a hotspot for plastic with levels in coastal waters similar to those in the Mediterranean Sea or other litter aggregation areas.

Marine plastics in Mediterranean islands: Evaluating the distribution and composition of plastic pollution in the surface waters along four islands of the Western Sea Basin

To study the spatial distribution of sea surface plastics in marine protected and non-protected areas, 65 sea surface trawls were carried out using a Hydro-bios manta net coupled with a 335-μm mesh. A total of 19 sampling sites along the coastal waters of Mallorca, the "Parque Nacional Marítimo-Terrestre del Archipiélago de Cabrera" and Menorca in the Balearic Islands as well as along coastal waters of The Natural Park of Columbretes Islands (NW Mediterranean Sea) were sampled. A total of 10,637 plastic items were identified and a subset of these items was categorized by shape, color, size and polymer composition. Plastic particles were found at each sampling site and in all samples. No microscale nor mesoscale variability in floating marine plastics abundance (particles/m²) was encountered throughout the study area where similar values were found in protected areas with no local land-based contamination sources, such as Columbretes [0.04 (±0.03) particles/m²], and in high anthropized areas, such as the island of Mallorca [0.04 (±0.07) particles/m²]. However, differences were found in characteristics of plastic items (shape, polymer, and size range), with the protected area of Columbretes characterized by the presence of the highest density of very small plastic items composed mainly of fragments (93%). Quantified plastics from the marine environment were composed mainly of polyethylene (PE, 63.3%), polypropylene (PP; 24.9%), polycarbonate (PC; 4.6%) and polystyrene (PS, 3.3%). The polymer composition showed a homogenous composition between islands and differences were detected only amongst Columbretes and the other islands. Results from this study provide further evidence of the ubiquity of plastics in the marine environment and highlight that remote and protected areas, such as Columbretes, are not exempt from plastic pollution, but receptor areas for small and aged floating plastics composed mainly by fragments, which might have potentially harmful effects on protected ecosystems.

Are the seafloors of marine protected areas sinks for marine litter? Composition and spatial distribution in Cabrera National Park

The seafloors of oceans and seas are becoming major sinks for marine litter (ML) at a global scale and especially within the Mediterranean Sea. Within global oceans and seas, Marine Protected Areas (MPAs) have been established to protect and conserve marine habitats and increase marine biodiversity. In this study, extensive coastal shallow scuba diving surveys were conducted in 2019 and 2020 to identify the distribution of ML in the MPA of Cabrera Marine-Terrestrial National Park (Cabrera MPA) in the Balearic Islands. Approximately 900 items weighing 70.1 kg were collected throughout the MPA during the underwater surveys. Glass bottles, including pieces (25-30%) and glass or ceramic fragments >2.5 cm (8-19%) were the most common identified items followed by plastic food containers and plastic bags (~8%). Overall, 75% of the abundance of collected ML was observed during the first year. In terms of the protection status of the different locations, similar abundances of ML were found in public access areas and no-take areas. Additionally, no significant differences were identified according to location indicating that ML on the seafloor was homogeneous within the studied shallow coastal areas. Overall, the results indicate that Cabrera MPA is a hotspot for ML and mitigation actions and measures, such as annual cleaning efforts, can help to prevent and minimize ML accumulation on the seafloor.

Microplastic abundance and biodiversity richness overlap: Identification of sensitive areas in the Western Ionian Sea

Plastic pollution in the Mediterranean Sea has been widely reported, but its impact on biodiversity has not been fully explored. Simultaneous sampling of microplastics (MP) with a manta net and surveys of large marine vertebrates were conducted along the coastal waters of Sicily (Western Ionian Sea). A total of 17 neustonic samples have been collected and 17 marine species (cetaceans, sea turtles, seabirds, and fish) have been sighted in the target area. Kernel density estimation was evaluated to highlight a possible overlap between the presence of large marine fauna and MP densities to provide a preliminary risk assessment. The highest biodiversity and MP concentration (0.197 ± 0.130 items/m²) were observed in the southernmost part of the studied area. The overlap between biodiversity hotspots and the occurrence of MP, potential contribute to the identification of sensitive areas of exposure in a poorly studied region.

Mathematical modeling of microplastic abundance, distribution, and transport in water environments: A review

Microplastic pollution in marine and riverine environments is a threat not only for the aquatic ecosystem itself but also for human activity and life. Although there are reviews regarding microplastic debris in environments, most of them focus on the studies on their type, occurrence, and distribution. Only a limited number of these studies focus on the modeling methods, usually concentrating on particular aspects, such as settling or bioaccumulation. In this paper, physically-based existing microplastics modeling studies are classified and reviewed according to the environment, modeling methodology, and input-output relationships. Considering the strengths and weaknesses of all modeling methodologies, it is deduced that more reliable results are obtained using hybrid methods, especially the coupling of hydrodynamic and process-based models, and hydrodynamics and statistical models. The significance of having much more consideration and knowledge on the microplastics' physical properties and the environmental processes affecting their fate and transport in the aquatic environments is revealed for future research. It has also been recommended that a standardized method for data calibration, validation, and verification is necessary to be able to compare the modeling results with field investigations more efficiently than it is currently.

Neustonic microplastics and zooplankton in coastal waters of Cabrera Marine Protected Area (Western Mediterranean Sea)

The high abundance of microplastics in marine environments is becoming a growing threat for Marine Protected Areas (MPAs). Recent studies have identified microplastics (MP) as having multiple effects on biota, and it is of special interest to highlight their effects on zooplanktonic organisms. These organisms play a key role on local food web structures and there is a need to better understand the accumulation of MPs and associated contaminants within the food web. The present study addresses MP distribution and composition within Cabrera MPA as well as its effects on local zooplanktonic community composition. Neustonic microplastic and zooplankton abundance and composition were determined in the shallow coastal waters of Cabrera MPA during the summer season of 2019. Samples were taken using a sea surface manta-net, with a mesh size of 335 μm. MPs were found in all manta trawl samples for a total of 7047 MP with an overall mean abundance (± SD) of 3.52 (± 8.81) items/m³, a value higher than those reported for the majority of Western Mediterranean Sea basins. Qualitative and semi-quantitative analyses of the local zooplankton community suggest that its composition could be sensitive to MP abundances. Although no correlation was found between overall mean abundance of MP and zooplankton, a positive correlation was found between MP abundance and the abundance of the planktonic stage of the foraminifer Rosalina globularis (Tretomphalus). This species seems to be able to use MP for its dispersion. On the other hand, a negative correlation between MP abundance and Copepoda abundance was detected. This work confirms that the coastal zooplankton community composition within the MPA of Cabrera are not exempt from MP pollution and suggests important and complex interactions between MP and zooplankton organisms in coastal waters.

Modelling the distribution of fishing-related floating marine litter within the Bay of Biscay and its marine protected areas

Sea-based sources account for 32-50 % of total marine litter found at the European basins with the fisheries sector comprising almost 65 % of litter releases. In the south-east coastal waters of the Bay of Biscay this figure approaches the contribution of just the floating marine litter fraction. This study seeks to enhance knowledge on the distribution patterns of floating marine litter generated by the fisheries sector within the Bay of Biscay and in particular on target priority Marine Protected Areas (MPAs) to reinforce marine litter prevention and mitigation policies. This objective is reached by combining the data on geographical distribution and intensity of fishing activity, long-term historical met-ocean databases, Monte Carlo simulations and Lagrangian modelling with floating marine litter source and abundance estimates for the Bay of Biscay. Results represent trajectories for two groups of fishing-related items considering their exposure to wind; they also provide their concentration within 34 MPAs. Zero windage coefficient is applied for low buoyant items not subjected to wind effect. Highly buoyant items, strongly driven by winds, are forced by currents and winds, using a windage coefficient of 4 %. Results show a high temporal variability on the distribution for both groups consistent with the met-ocean conditions in the area. Fishing-related items driven by a high windage coefficient rapidly beach, mainly in summer, and are almost non-existent on the sea surface after 90 days from releasing. This underlines the importance of windage effect on the coastal accumulation for the Bay of Biscay. Only around 20 % of particles escaped through the boundaries for both groups which gives added strength to the notion that the Bay of Biscay acts as accumulation region for marine litter. MPAs located over the French continental shelf experienced the highest concentrations (>75 particles/km²) suggesting their vulnerability and need for additional protection measures.

Microplastic intake and enzymatic responses in Mytilus galloprovincialis reared at the vicinities of an aquaculture station

Aquaculture is a potential source of microplastics (MPs) that could be strong stressors for marine organisms. In this study, we evaluated the effects of MPs derived from aquaculture in antioxidant defences and oxidative stress markers in gills of Mytilus galloprovincialis. Mussels were distributed in three areas with different impacts: inside aquaculture cages, Control 1 (located inside Andratx harbour) and Control 2 (located in a no-anthropized area). Samples were obtained along three different time periods in May (T₀), July (T₆₀) and in September (T₁₂₀). At each sampling period, mussels' biometric measurements were taken, and tissue samples were kept frozen for biochemical determinations and to determine the intake of MPs. An increase in MPs intake was detected throughout the study, and this increase was significantly higher in samples from the aquaculture cages. Similarly, antioxidant enzyme activities (catalase, superoxide dismutase, glutathione reductase and glutathione peroxidase) were significantly higher in samples from cages at T₁₂₀. Additionally, a similar tendency was observed in glutathione-s-transferase, with a higher activity in the aquaculture cages at T₆₀ and T₁₂₀. Malondialdehyde and carbonyl protein derivates as a marker of oxidative damage were also measured and samples from aquaculture cages presented higher oxidative stress markers, mainly in T₁₂₀. In conclusion, living in environments exposed to aquaculture activities at sea may imply a higher intake of MPs which in turn might cause an antioxidant response in M. galloprovincialis which is not enough to avoid oxidative damage.

Plastic litter pollution along sandy beaches in the Caribbean and Pacific coast of Colombia

Plastic pollution is a global problem that poses a threat to coastal and marine ecosystems and human livelihoods and requires effective solutions adaptable to local conditions. In Colombia, the knowledge about marine plastic pollution is still limited and the development of effective strategies for managing marine and coastal environments is crucial. Therefore, plastic pollution was assessed on 43 Colombian sandy beaches on the Caribbean and Pacific coasts. Amounts of macroplastic ranged from 35 ± 15 to 81 ± 23 items 100 m^-1, being product's packaging the most common. Microplastic densities ranged from 3 to 1387 items m^-2. The highest microplastic concentrations were found on the beaches from Caribbean cities and in rural areas of Pacific municipalities. Fragments and polyethylene were the most commonly observed shape and polymer categories, respectively. Tourism and poor waste management practices are the primary plastic sources on the studied beaches. Plastic litter on Colombian beaches are a problem that requires prevention, mitigation, and control actions to help conserve this ecosystem.

Comprehensive phenotyping and multi-omic profiling in the toxicity assessment of nanopolystyrene with different surface properties

There is a growing concern regarding the toxic effects of terrestrial nanoplastic contaminants. However, an all-encompassing phenotyping- and omics-based strategy for the toxicity assessment of nanoplastics with different surface properties on soil living organisms remains to be established. Herein, we devised a comprehensive phenotyping and multi-omic profiling method to examine the molecular disturbance of nanopolystyrene (PS)-exposed Caenorhabditis elegans. The exposure time was 24 h with either 1 μg/mL or 10 μg/mL of PS. We found that PS considerably affected the reproduction and locomotion, as well as increased the oxidative stress of worms regardless of their surface properties. Nevertheless, each type of PS affected the metabolome and lipidome of the nematodes differently. Uncharged PS (PS-N) triggered significant metabolic disturbances, whereas the metabolic influences from PS-NH₂ and PS-COOH were subtle. The dysregulated transcriptome profiles of PS-N were strongly associated with the metabolic pathways. Besides, the altered expression of several genes associated with autophagy and longevity was observed. Collectively, we demonstrated that comprehensive phenotyping and omics-based profiling establish a practical framework that allows us to gain deeper insights into the maladaptive consequences of PS in nematodes. It can be utilized for the evaluation of other environmental contaminants in the terrestrial ecosystem.

Nearshore spatio-temporal sea surface trawls of plastic debris in the Balearic Islands

Nearshore sea-surface manta trawls were carried out monthly at seven sites along the coastline of Mallorca in the Balearic Islands in the Western Mediterranean Sea. Plastic marine debris was present in all trawls (n = 63) with an overall average abundance of 858,029 ± 4,082,964 items/km² (mean ± standard deviation) and weight of 4,520 ± 22,806 g(DW)/km² and the micro-plastic fraction (74%) dominating the size class. Polyethylene (LDPE and HDPE) was the most common polymer (70%) with high spatial heterogeneity, especially along the north-western coast. August showed almost two-fold as much plastic as the other months, and the number of items decreased significantly with distance from the coastline. A positive correlation was found with the fractal dimension of the coastline indicating higher coastal plastic debris retention in areas with a higher fractal dimension and backtracking simulations indicated that marine litter was mainly locally sourced. Overall results indicate a significant small scale variability of nearshore coastal marine plastic in the Balearic Islands.

Surface water circulation develops seasonally changing patterns of floating litter accumulation in the Mediterranean Sea. A modelling approach

Marine litter and, particularly, plastics are a growing concern at global scale. The Mediterranean Sea is among the zones in the world with the highest concentration of floating plastic debris. However, our knowledge remains limited on the spatial distribution of litter across this basin. Here, a set of different numerical model simulations were conducted to examine the dynamic conditions of the surface layer of the Mediterranean and how this drives the circulation and accumulation of floating litter. Seasonal dynamics of surface water circulation led to contrasting distribution patterns of floating litter along the year. Multiple hot spots of litter zones appeared across the basin in summer, while litter disperses and moves towards the Eastern Mediterranean and nearshore waters in winter. Taking into account such seasonal variability in the spatial patterns of litter in the Mediterranean seems to be key in the design of further sampling surveys and management strategies.

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Surface current dynamics shows marked seasonality in the Mediterranean.

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Accumulation and distribution of floating particles follow currents patterns.

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Floating litter accumulates in diverse areas during different seasons.

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Lagrangian model helps to identify beaches impacted by floating litter.