BREAKING THE PARADIGM: MARINE SEDIMENTS HOLD TWO-FOLD MICROPLASTICS THAN SEA SURFACE WATERS AND ARE DOMINATED BY FIBERS

Marine compartments are often considered independent environments in studies on plastic pollution (Ali et al., 2021). Consequently, little is known about microplastic (MPs) distribution amongst those habitats closely linked. Here, we perform an interactive assessment of MPs abundance and composition from the pelagic habitat to beaches integrating shallow seafloor sediments of a coastal Mediterranean marine protected area and evaluating MPs ingestion in holothurians, echinoderms, molluscs, and fishes inhabiting the area. We observed a gradient in the accumulation of MPs from the sea surface (0.17 ± 0.39 MPs/m2) to the seafloor (76 ± 108 MPs/m2) and beach sediment (13418 ± 28787 MPs/m2), with a skip of two orders of magnitude. Microplastic abundances fit with those reported for more anthropized Mediterranean areas and suggest coastal environments as potential debris sinking areas. Fibers dominate all the studied habitats. Holothurians showed the highest general MPs and fibers ingestion occurrence (91%), with greater values (9.48 ± 8.05 MPs/individual and 8.24 ± 7.95 fibers/individual) than those reported previously (Bulleri et al., 2021). Considering ecological key role, species distribution, and MPs ingestion values, we suggest Holothuroidea as suitable bioindicators for plastic pollution, particularly for fibers. Fibers are composed primarily of cellulose acetate (29%), whereas styrofoam of polystyrene (64%), and films, fragments, and filaments of a variable percentage of polyethylene and polypropylene. Differences found in the polymer composition amongst plastics´ morphologies are reflected in the variability observed between habitats and marine organisms. Particularly the polymer composition of fibers coincides with that of one of the MPs ingested by invertebrates. Results suggest that shape is a key plastic characteristic in determining polymer distribution patterns along with habitats and in marine species. Finally, this study highlights once again the importance and urgency of local and global actions needed to mitigate plastic pollution and particularly fiber release into the marine environment

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.En prensa5,82

Assessing microplastic ingestion and occurrence of bisphenols and phthalates in bivalves, fish and holothurians from a Mediterranean marine protected area

Microplastic (MP) ingestion, along with accumulated plasticizers such as bisphenol A (BPA), bisphenol F (BPF), and bisphenol S (BPS), and phthalates represented by diethyl phthalate (DEP), dibutyl phthalate (DBP) and bis (2-ethylhexyl) phthalate (DEHP), were quantified in bivalves, fish, and holothurians collected from a coastal pristine area at the western Mediterranean Sea. MP ingestion in sediment-feeders holothurians (mean value 12.67 ± 7.31 MPs/individual) was statistically higher than ingestion in bivalves and fish (mean 4.83 ± 5.35 and 3 ± 4.44 MPs/individual, respectively). The main ingested polymers were polyethylene, polypropylene, and polystyrene. The levels of BPS, BPF, and DEHP were highest in bivalves' soft tissue; BPA and DBP had the highest levels in the holothurians’ muscle. In addition, the levels of all plasticizers assessed were lowest in fish muscle; only BPA levels in fish were higher than in bivalves, with intermediate values between those of bivalves and holothurians. This study provides data on exposure to MPs and plasticizers of different species inhabiting Cabrera Marine Protected Area (MPA) and highlights the differences in MP ingestion and levels of plasticizers between species with different ecological characteristics and feeding strategies.En prensa3,39

EXPERIMENTAL EVIDENCE OF PHYSIOLOGICAL AND BEHAVIORAL EFFECTS OF MICROPLASTICS INGESTION IN SPARUS AURATA

Increasing global research has identified microplastics (MPs) to be impacting marine organisms. The present work aimed at investigating the physiological and behavioral effects of thirty-six juvenile Sparus aurata exposed to control, virgin and weathered MPs enriched diets during a 21-day period under controlled conditions. Physiological effects were assessed in liver and brain using the following biomarkers: activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRd), the detoxifying enzyme glutathione S-transferase (GST) and malondialdehyde (MDA) as indicative of lipid peroxidation. Individuals were recorded for behavior analysis (i.e. social interactions and feeding behavior). Results revealed an increase in cellular stress from control to weathered fish groups, with the virgin group showing intermediate levels in all quantified biomarkers. Significant differences were found in the liver for all biomarkers except for MDA, suggesting that exposure time to MPs in this experiment is long enough to trigger the activation of antioxidant enzymes but not to produce cell damage by lipid peroxidation. In brain tissue samples, fish from the weathered group presented significantly higher values for CAT and SOD, highlighting its function as primary antioxidants. Regarding behavioral effects, results showed that the two MPs enriched groups were significantly bolder during social interactions and, although no significantly, tended to be more active during feeding. In conclusion, MPs which have been weathered in marine environmental conditions produces a higher physiological response than virgin MPs but also, a physiological response is variable depending on the tissue analyzed. In addition, a short period to MP exposure seems to affect overall social and feeding behavior but, further research is needed to assess long-term effects of MP ingestion and its potential consequences on fish populations

Anthropogenic particles ingestion in fish species from two areas of the western Mediterranean Sea

The Mediterranean Sea is one of the most polluted seas in terms of marine debris. To analyze the ingestion of anthropogenic particles in two areas, 197 gastrointestinal tracts from four fish species - Trachurus mediterraneus, Sardina pilchardus, Engraulis encrasicolus and Boops boops - were studied. 127 anthropogenic particles were identified in the gastrointestinal tract of 28% of the samples using visual sorting methods. Individuals from the peninsular coast showed higher ingestion occurrence (36%) than those from the Balearic Islands (12%). Significant differences in the ingestion of anthropogenic particles were found between species with Trachurus mediterraneus identified as the most affected species (43% of the individuals with mean values of 1.13 ± 0.16 particles/individual), and Engraulis encrasicolus, the least affected (2.56% and 0.03 ± 0.16 particles/individual). Moreover, the proportion of ingestion amongst species was similar in both areas, highlighting the importance of studying the same species at different locations as marine debris bioindicators