Induction of detoxification systems in wild red mullet Mullus surmuletus after microplastic ingestion

Marine litter greatly affects marine species and ecosystems (1), however there is little evidence of physiological responses of vertebrates to plastic exposure. In this study, wild mullets Mullus surmuletus were obtained from fishing vessels operating in Mallorca Island (W Mediterranean). Stomach content analyses and identification under microscope determined that 28% of the samples had ingested microplastics. Liver samples of surmullets with and without microplastic ingestion were analysed to determine physiological effects. Results suggest an induction of the detoxification system in M. surmuletus Linnaeus, 1758 but no oxidative stress or cellular damage

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

Reduced Antioxidant Response of the Fan Mussel Pinna nobilis Related to the Presence of Haplosporidium pinnae

The endemic fan mussel (Pinna nobilis) in the Mediterranean Sea is at high risk of disappearance due to massive mortality events. The aim of the study was to evaluate the antioxidant response of P. nobilis collected in the Balearic Islands (Western Mediterranean) before and after the mass mortality event. Individuals collected before (between 2011 and 2012) and after (between 2016 and 2017) the event were analyzed by histological, molecular, and biochemical methods to compare pathogenic loads and biochemical responses. All the individuals collected during 2016–2017 presented symptoms of the disease and were positive for Haplosporidium pinnae, while acid-fast bacteria or/and Gram-negative bacteria were detected in some individuals of both sampling periods. The activities of the antioxidant enzymes catalase and superoxide dismutase in the gills were significantly lower in P. nobilis a ected with the parasite compared to those in the asymptomatic ones, while levels of malondialdehyde, as an indicator of lipid peroxidation, were higher in infected individuals. When analyzing the di erential e ects of H. pinnae and Mycobacterium sp. on P. nobilis, it was observed that significant e ects on biomarkers were only observed in the presence of H. pinnae. Co-infection of P. nobilis by H. pinnae with other pathogens such as Mycobacterium sp. constitutes a serious problem due to its high mortality rate in the Balearic Island waters. This concerning situation for P. nobilis is favored by a reduction in antioxidant defenses related to H. pinnae infection that induces oxidative stress and cell damage.En prens

Oxidative status assessment of the endemic bivalve Pinna nobilis affected by the oil spill from the sinking of the Don Pedro

Several biomarkers were determined to evaluate the effects of the Don Pedro spillage on the digestive gland of the fan mussel Pinna nobilis (Linnaeus, 1758). Two areas in the southeast of Ibiza Island (Western Mediterranean) were selected; one affected by the oil spill (Talamanca) and one did not affected (Espardell). Mussels were sampled one, six and twelve months after the accident. PAH levels were elevated in P. nobilis from the affected area one month after the accident and, although they were decreasing gradually, they were always higher than in the control area. An increase in enzyme activities, reduced glutathione and lipid peroxidation were evidenced one month after the spillage, with no changes in acetylcholinesterase. All biomarkers progressively returned to basal levels one year after the oil spill. In conclusion, the Don Pedro oil spill induced an acute situation of oxidative stress on P. nobilis that were recovered twelve months later.Publicado1,953

Microplastic ingestion by Mullus surmuletus Linnaeus, 1758 fish and its potential for causing oxidative stress

A total of 417 striped red mullet, Mullus surmuletus, were analyzed to study microplastic ingestion and livers of fish were assessed to study effects of microplastics. Nearly one third (27.30%) of the individuals were quantified to ingest microplastics although there was no evidence of oxidative stress or cellular damage in the liver of fish which had ingested microplastics. A small increase in the activity of glutathione S-transferase (GST) of M. surmuletus was detected which could be suggesting an induction of the detoxification systems but these findings should be tested in laboratory conditions under a controlled diet and known concentration of microplastics. Fish from trammel fisheries, operating closer to land and targeting larger individuals, showed higher mean ingestion values than fish from trawling fisheries, and were related to body size, as microplastics ingested increased with total fish length. Consequently, ingestion values of microplastics were not related to sampling distance from land giving further evidence of the ubiquity of microplastics in the marine environment. Finally, Fourier Transform Infrared Spectroscopy (FTIR) analysis showed that the vast majority of microplastics were filament type and polyethylene terephthalate (PET) was the main identified componentVersión del edito

Assessment of the effect of long-term exposure to microplastics and depuration period in Sparus aurata Linnaeus, 1758: Liver and blood biomarkers

The constant increase in plastic pollution has attracted great attention in recent years due to its potential detrimental effects on organisms and ecosystems.While the consequences of ingestion of large plastic litter aremostly understood, the impacts resulting from a long-term exposure and a recovery period of microplastics (MPs) are still limited. The aims were to monitor oxidative stress, detoxification and inflammatory biomarkers in liver, plasma and erythrocytes of Sparus aurata exposed during 90 days to low-density polyethylene (LDPE)-MPs enriched diet (10% by weight) followed by 30 days of depuration. Exposure to LDPE-MPs progressively activates the antioxidant and detoxification systemand induces an inflammatory response in liver and plasma,whereas no significant changes were observed in erythrocytes. The plasma activities of catalase, myeloperoxidase (MPO), lysozyme and the levels of malondialdehyde (MDA) as maker of lipid peroxidation significantly increased after exposure to LDPE-MPs for 90 days compared to the control group. The activities of all antioxidant enzymes – catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase-, the detoxification enzyme glutathione s transferase,MPO, the production of reactive oxygen species and the levels ofMDA were also significantly increased in liver after MPs exposure. Additionally, all these biomarkers tended to recover during the depuration period,most of themreaching similar levels to those of the control group. In conclusion, the ingestion of a diet containing LDPE-MPs for 90 days induced a progressive increase in oxidative stress and inflammation biomarkers in liver and plasma of S. aurata but not in erythrocytes, which tended to regain control valuesEn prensa3,25

Long-term exposure to microplastics induces oxidative stress and a pro-inflammatory response in the gut of Sparus aurata Linnaeus, 1758

Environmental pollution from plastic debris is a major global concern, being a potential threat to marine organisms and ecosystems. The accumulation of microplastics (MPs) in the oceans has notable ecological implications due to their long persistence, their potential ecotoxicity, and their ability to adsorb other pollutants and act as vectors of pathogens. Nevertheless, whereas the number of investigations documenting the presence of MPs in wild fish has increased, less studies have addressed the toxicological effects associated with the ingestion of MPs in long-term laboratory conditions. The aim of the present study was to assess the physiological response of gilthead seabream (Sparus aurata) exposed to low-density polyethylene (LDPE) MPs during a 90-day exposure followed by an extra 30 days of depuration through the application of oxidative stress biomarkers in the gut. No changes were observed in the Fulton condition factor of fish associated with MP intake. The activities of antioxidant enzymes and glutathione s-transferase and the levels of reduced glutathione progressively increased throughout the study in the MPs-fed group compared to the control group, reaching the highest values at 90 days. Similarly, the activity of the pro-inflammatory enzyme, myeloperoxidase, and the levels of oxidative damage markers -malondialdehyde and protein carbonyls-also increased after 90 days of exposure to an enriched diet with MPs. During the 30-day depuration period, all the biomarkers analysed tended to normalize, with the majority recovering values similar to those of the control group. In conclusion, MPs exposure during 90 days to S. aurata induced oxidative stress and a pro-inflammatory response in gut, and were able to recover after the exposure to MPs was removed

Long-term exposure to virgin and seawater exposed microplastic enriched-diet causes liver oxidative stress and inflammation in gilthead seabream Sparus aurata, Linnaeus 1758

Plastics accumulation in marine ecosystems has notable ecological implications due to their long persistence, potential ecotoxicity, and ability to adsorb other pollutants or act as vectors of pathogens. The present work aimed to evaluate the physiological response of the gilthead seabream (Sparus aurata) fed for 90 days with a diet enriched with virgin and seawater exposed low-density polyethylene microplastics (LDPE-MPs) (size between 100 and 500 μM), followed by 30 days of depuration, applying oxidative stress and inflammatory markers in liver homogenates. No effects of LDPE-MPs treatments on fish growth were observed throughout this study. A progressive increase in antioxidant enzyme activities was observed throughout the study in both treatments, although this increase was higher in the group treated with seawater exposedMPs. This increase was significantly higher in catalase (CAT), glutathione reductase (GRd), and glutathione-s-transferase (GST) in the seawater exposedMPs group, with respect to the virgin group. In contrast, no significant differenceswere recorded in superoxide dismutase (SOD) and glutathione peroxidase (GPx) between both groups. Exposure to MPs also caused an increase in the oxidative damage markers (malondialdehyde and carbonyls groups). Myeloperoxidase activity significantly increased because of MPs treatments. After 30 days of depuration, antioxidant, inflammatory enzyme activities and oxidative damage markers returned to values similar to those observed in the controlEn prensa3,25