PCBs contamination in water and Mytilus edulis along the north Portuguese Atlantic Ocean coastline and analysis of potential carcinogenic risk to human health.

Seven seawater polychlorinated biphenyls (PCBs) were measured in water (DAP), suspended particulate matter (SPM), and blue mussels (Mytilus edulis) collected from four beaches in northwest Portugal. PCBs were extracted using solid-phase-extraction, ultrasound-extraction and QuEChERS before GC-MS analysis. The two-year annual average concentrations of PCBs in DAP, SPM and the four-year analysis in mussels were âˆ¼ 4.4 ng/L, ∼15.9 µg/kg, and âˆ¼ 56.0 µg/kg. The results suggest higher concentrations of PCBs in summer for SPM and in spring for mussels, mainly those collected close to the Ave River estuary. The origins of PCBs remain uncertain. Risk assessment shows that PCBs in water are unlikely to harm local biota due to their low thyroid hormone toxicity equivalents (TEQ-TH; ∼1.4E-04 ng/L and âˆ¼ 4.1E-04 µg/kg) and on WHO toxicity equivalents (TEQ-WHO; ∼2.1E-05 ng/L and âˆ¼ 4.9E-05 µg/kg). However, the lifetime carcinogenic risk (LCR) for humans consuming local bivalves is concerning, as it exceeds 1.0E-06.

Description of Conchophthirus sinanodontae n. sp. (Ciliophora: Scuticociliatia), a new endocommensal ciliate of the freshwater mussel Sinanodonta woodiana from Korea.

The morphology and molecular phylogeny of a new ciliate, Conchophthirus sinanodontae n. sp., which was discovered in the freshwater mussel Sinanodonta woodiana (Lea, 1834) from the Chilsancheon River, Buyeo-gun, South Korea, were investigated. The new species was characterized and could be distinguished from congeners by a combination of characters including the ovate body outline, four to six oral polykinetids deeply embedded in the upper wall of the buccal cavity, six to ten vestibular kineties, 34-49 ventral and 36-53 dorsal somatic kineties. The genetic differences among C. sinanodontae n. sp. and other congeners with available 18S rDNA sequences further support its distinctness. Moreover, the phylogenetic analyses based on the 18S rDNA sequences show that the new species clusters with other congeners, corroborating the monophyly of the genus Conchophthirus. The Conchophthirus clade nests within the cluster of Dexiotricha spp., Loxocephalus luridus, and Haptophrya spp.

Technical specifications for a EU-wide baseline survey of antimicrobial resistance in bacteria from aquaculture animals.

The European Commission requested scientific and technical assistance in the preparation of a EU-wide baseline survey of antimicrobial resistance (AMR) in bacteria from aquaculture animals. It is recommended that the survey would aim at estimating the occurrence of AMR in Aeromonas spp. isolated from Atlantic Salmon (Salmo salar), European seabass (Dicentrarchus labrax) and trout (Salmo trutta, Salvelinus fontinalis, Oncorhynchus mykiss) intended to consumption, at harvesting (at farm/slaughter), at the EU level and in addition, at estimating the occurrence and diversity of AMR of Escherichia coli, Enterococcus faecium, Enterococcus faecalis, Vibrio parahaemolyticus and Vibrio alginolyticus in blue mussel (Mytilus edulis) and Mediterranean mussel (Mytilus galloprovincialis) from production areas and at dispatch centres at the EU level. These technical specifications define the target populations, the sample size for the survey, sample collection requirements, the analytical methods (for isolation, identification, phenotypic susceptibility testing and further genotypic analysis of some of the bacteria targeted) and the data reporting requirements. The data to be reported by the EU Member States to support this baseline survey are presented in three data models. The results of the survey should be reported using the EFSA reporting system.

Nationwide seasonal monitoring of lipophilic marine algal toxins in shellfish and causative microalgae along the coasts of South Korea.

In this study, lipophilic marine algal toxins (LMATs)-producing microalgae were identified at 23 sites along the coasts of Korea, and distribution characteristics of LMATs in phytoplankton and mussels were investigated. The causative microalgae, including Gonyaulux spinifera, Dinophysis acuminata, D. caudata, and D. fortii, were observed in the study area, with notably higher densities during the summer. Significant correlations were found between the densities of these microalgae and the water temperature. Seasonal distribution patterns of LMATs in phytoplankton closely matched those observed in mussels. Notably, LMAT concentrations in mussels from the Yellow Sea were relatively high. PTX2 was detected predominantly in phytoplankton, and homo-yessotoxin was found mainly in mussels. Overall, LMAT concentrations were elevated in the summer, raising concerns about biotoxin contamination in shellfish. These results provide important insights into the dynamics of unmanaged marine biotoxins in Korea and offer baseline data for future safety management policies and inflow surveillance.

First investigation of the temporal distribution of neurotoxin ß-N-methylamino-L-alanine (BMAA) and the candidate causative microalgae along the South Sea Coast of Korea.

The neurotoxin ß-N-methylamino-L-alanine (BMAA), produced by cyanobacteria and diatoms, has been implicated as an environmental risk factor for neurodegenerative diseases. This study first investigated the occurrence and monthly distributions of BMAA and its isomers, 2,4-diaminobutyric acid (DAB) and N-2-aminoethylglycine (AEG), in phytoplankton and mussels from 11 sites along the South Sea Coast of Korea throughout 2021. These toxins were quantified using LC-MS/MS, revealing elevated BMAA concentrations from late autumn to spring, with phase lags observed between phytoplankton and mussels. The highest concentration of BMAA in phytoplankton was detected in November (mean: 1490 ng g-1 dry weight (dw)), while in mussels, it peaked in December (mean: 1240 ng g-1 dw). DAB was detected in phytoplankton but was absent in mussels, indicating limited bioaccumulation potential. In February, the peak mean DAB concentration in phytoplankton was 89 ng g-1 dw. AEG was not detected in any samples. Chlorophyll-a concentrations consistently showed an inverse correlation with BMAA concentrations in mussels throughout the year. Through correlation analysis, four diatom genera, Bacillaria, Hemiaulus, Odontella, and Pleurosigma, were identified as potential causative microalgae of BMAA. This study offers insights into identifying the causative microalgae for BMAA and informs future regulatory efforts regarding unmanaged biotoxins.

Microplastics and arsenic speciation in edible bivalves from the coast of China: Distribution, bioavailability, and human health risk.

Bivalves, such as oysters and mussels, are exposed to environmental pollutants, like microplastics (MPs) and arsenic (As). This study investigated co-existence and interaction of MPs and As (total As and As species) in two bivalve species from the Chinese coastline. Smaller MPs (20-100 µm) averaged 30.98 items/g, while larger MPs (100-500 µm) averaged 2.98 items/g. Oysters contained more MPs (57.97 items/g) in comparison to mussels (11.10 items/g). In Contrast, mussels had a higher As concentrations (8.36-23.65 mg/kg) than oysters (4.97-11.02 mg/kg). The size and composition of MPs influenced As uptake and speciation in bivalves, with inorganic arsenic (iAs) and methylated arsenic (MMA and DMA) correlating with larger-sized MPs. Polyethylene (PE) may interact with the formation of arsenobetaine (AsB) in oyster. This study provides valuable insights into the interaction of MPs and As in marine ecosystems and highlights their implications for food safety.

Rare earth elements and warming: Implications for adult mussel health and sperm quality.

The present study aimed to investigate the effects of europium (Eu) exposure (10 µg/L), warming (a 4 °C increase), and their combination on Mytilus galloprovincialis. Biochemical and histopathological changes in adult mussels were evaluated after a 28-day exposure period. Additionally, biochemical and physiological alterations in sperm were measured following a 30-min exposure period. The overall responses to each treatment were assessed using the Integrated Biological Response index version 2 (IBRv2). In adult mussels, warming elevated metabolism and activated glutathione S-transferases (GSTs), leading to redox imbalance and cellular damage. Europium exposure alone slightly enhanced metabolism and GSTs activity, resulting in cellular damage and histopathological injuries in digestive tubules. The combined exposure to Eu and warming was the most detrimental treatment for adults, as indicated by the highest IBRv2 value. This treatment slightly increased metabolism and uniquely elevated the activity of antioxidant enzymes, as well as GSTs and carboxylesterases. Despite these responses, they were inadequate to prevent redox imbalance, cellular damage, and histopathological injuries in digestive tubules and gills. Regarding sperm, warming reduced reactive oxygen species (ROS) production but raised lipid peroxidation levels. Sperm exposed to this treatment also increased their oxygen consumption and exhibited reduced velocity. The IBRv2 indicated that Eu was the most harmful treatment for sperm, significantly increasing ROS production and notably decreasing sperm velocity. When combined with warming, Eu elevated superoxide anion (O2-) production, lowered sperm velocity, and increased oxygen consumption. This study underscores the importance of investigating the effects of rare earth elements and their interaction with climate change-related factors.

A case study on microlitter and chemical contaminants: Assessing biological effects in the southern coast of the Gulf of Finland (Baltic sea) using the mussel Mytilus trossulus as a bioindicator.

Chemical and microlitter (ML) pollution in three Estonian coastal areas (Baltic Sea) was investigated using mussels (Mytilus trossulus). Polycyclic aromatic hydrocarbons (PAH) in mussel tissues were observed in moderate levels with high bioaccumulation factors for the more hydrophilic and low molecular weight PAH (LMW PAH), namely anthracene and fluorene. Tissue concentrations of polybrominated diphenyl ethers (PBDE) and cadmium within mussel populations exceeded the Good Environmental Status thresholds by more than 200% and 60%, respectively. Multiple contamination at the Muuga Harbour site by tributyltin, high molecular weight PAH, including the highly toxic benzo[c]fluorene and PBDE, coincided with the inhibition of acetylcholinesterase activity and a lower condition index of the mussels. The metabolization and removal of bioaccumulated LMW PAH, reflected in the dominance of oxy-PAH such as anthracene-9,10-dione, is likely associated with the increased activity of glutathione S-transferase in caged mussels. Only a few microplastic particles were observed among the ML in mussel tissues, with coloured cellulose-based microfibers being the most prevalent. The average concentration of ML in mussels was significantly higher at the harbour area than at other sites. The integrated biomarker response index values allowed for the differentiation of pollution levels across studied locations representing high, intermediate, and low pollution levels within the studied area.

The complete female mitogenome of Potomida semirugata (Lamarck, 1819).

Freshwater mussels perform important ecological functions in ecosystems, such as water filtration and energy cycling. Unlike marine bivalves, freshwater mussels have unique characteristics including internal fertilization and parental care. Some freshwater mussels are facing a high risk of extinction due to several factors such as climate change and habitat loss. Potomida semirugata (Lamarck, 1819) is one of the freshwater mussel species with a high risk of extinction and listed as Endangered in the Red List of the International Union for Conservation of Nature. Here, we present the first F-type mitogenome sequence of P. semirugata. The genome was sequenced on an Illumina high-throughput platform from a P. semirugata specimen collected from the Tersakan River (Turkey). The 16,093 bp mitochondrial genome sequence contains 13 protein-coding genes, 22 transfer RNAs, and two ribosomal RNAs. Phylogenetic analysis placed P. semirugata in the Lamprotulini clade with Potomida littoralis, as expected. Potomida semirugata is a poorly studied species and the genomic resource provided here will contribute to a better understanding of its biological characterization.

Differential effects of antidepressant sertraline in glochidia-fish interactions involving drug transfer from parasite to host.

This study examined the impact of sertraline, an antidepressant common in treated wastewater, on the host-parasite dynamics between parasitic freshwater mussel (Unio tumidus, Unionidae) larvae (glochidia) and their host fish (Squalius cephalus, Cyprinidae). Employing a full-factorial design, both fish and glochidia were subjected to sertraline at the combinations of 0 µg L-1 (control), 0.2 µg L-1 (environmentally relevant concentration), and 4 µg L-1 (elevated concentration, short-term exposure of the parasite). The results showed that long-term host exposure (involving intensive sertraline accumulation in the fish brain) marginally increased subsequent glochidia attachment success by 2 %, while parasite exposure at the same environmentally relevant concentrations had no detectable effect. There was also no effect of exposure of glochidia to 0.2 µg L-1 of sertraline on their viability and encapsulation success during the initial parasitic stage. However, a significant alteration in attachment behavior, marked by a 3.3 % increase in attachment success and changes in the glochidia spatial distribution on the host body, was noted after 24 h of glochidia exposure to 4 µg L-1 of sertraline. Importantly, this study provides the first evidence of sertraline transfer from exposed glochidia to nonexposed host fish, as indicated by elevated levels of sertraline (12.8 ng g-1) in the brain tissue of nonexposed hosts. These findings highlight the subtle yet significant effects of pharmaceutical pollutants on freshwater ecosystems but also underscore the importance of understanding the unexpected dynamics of such contamination to predict and address future ecological changes.

Mussel Culture Farming Systems in the Northern Gargano Coast (Adriatic Sea): Changes in the Nutritional Profile of the Mytilus galloprovincialis.

The objective of this study was to investigate the nutritional characteristics of Mytilus galloprovincialis cultivated in three sites of the Northern Coastal Area of Gargano. The mussel farms were characterized by different distances of dropper ropes (extensive dropper ropes: EDR; intensive dropper ropes: IDR; semi-intensive dropper ropes: SIDR). Mussels' chemical composition, fatty acids, and amino acids profiles were investigated at monthly intervals, from April to June. The fat content of mussels from EDR and SIDR sites was lower than values observed for mussels of the IDR in both the April and June sampling months. An increase in the main saturated fatty acids (C15:0; C16:0; C17:0 and C18:0; p < 0.001) and polyunsaturated fatty acids (C18:2c9c12, C18:3n3, C20:2n6, C20:4n6, and C22:6n3; p < 0.001) was found in the mussels collected in June from all farms analyzed. In terms of farming systems, mussels from the EDR and SIDR sites exhibited the greatest content of beneficial molecules like conjugated linoleic acids isomers (p < 0.001), glutamic acid (p < 0.05), serine (p < 0.05), tryptophan (p < 0.001), hydroxyproline (p < 0.05) and proline (p < 0.01). This study revealed that the farming system can affect the nutritional composition of mussels and evidenced that EDR and SIDR are the most effective cultured farming methods in the Gargano area.

Dietary exposure experiments on the migration of chemical pollutants from microplastics to bivalves.

Plastics can contain two types of organic contaminants; absorbed from ambient water, and already contained as additives. To investigate the bioaccumulation of these substances, we conducted two types of exposure experiments using mussels and polyethylene microplastics with absorbed PCBs and containing four types of additives (BDE209, DBDPE, UV327 and UV234). After dietary exposure for 15 days, significantly higher concentrations of total PCBs, UV327 and UV234 were detected in the gonad of exposed groups than in the control groups, respectively. However, no significant differences in BDE209 or DBDPE levels were observed between the control and exposure groups. Although a higher transfer ratio was shown for PCB congeners with octanol-water partition coefficients (logKow) below 7, the ratio was lower for higher-hydrophobic PCBs with logKow above 7. This suggests that higher hydrophobic compounds (not only highly chlorinated PCBs, but also BDE209 and DBDPE) tend not to desorb or leach from plastics.

Assessing marine ecosystem health using multi-omic analysis of blue mussel liquid biopsies: A case study within a national marine park.

Marine ecosystems are under escalating threats from myriad environmental stressors, necessitating a deeper understanding of their impact on biodiversity and the health of sentinel organisms. In this study, we carried out a spatiotemporal multi-omic analysis of liquid biopsies collected from mussels (Mytilus spp.) in marine ecosystems of a national park. We delved into the epigenomic, transcriptomic, glycomic, proteomic, and microbiomic profiles to unravel the intricate interplay between ecosystem biodiversity and mussels' biological response to their environments. Our analysis revealed temporal fluctuations in the alpha diversity of the circulating microbiome associated with human activities. Analysis of the hemolymphatic circulating cell-free DNA (ccfDNA) provided information on the biodiversity and the presence of potential pathogens. Epigenomic analysis revealed widespread hypomethylation sites within the mitochondrial (mtDNA). Comparative transcriptomic and glycomic analyses highlighted differences in metabolic pathways and genes associated with immune and wound healing functions. This study demonstrates the potential of multi-omic analysis of liquid biopsy in sentinel to provide a holistic view of human activities' environmental impacts on marine coastal ecosystems. Overall, this approach has the potential to enhance the effectiveness and efficiency of various conservation efforts, leading to more informed decision-making and better outcomes for biodiversity and ecosystem conservation.

Proposed validation stages for MPs extraction from edible mussels (Mytilus galloprovincialis).

The potential presence of microplastics (MPs) in seafood products presents significant health concerns, demanding the adoption of standardized and validated methodologies. In this study, we introduce a validated method and an innovative technique for extracting MPs from mussels using an oxidizing agent, Corolase enzyme, and a surfactant, thus eliminating the need for mechanical agitation. Evaluation of the extraction process focused on three critical parameters: recovery percentage, repeatability, and chemical integrity, along with color stability. To ensure precision and reliability, low-density infrared spectroscopy (LDIR) was employed to analyze the effect of spectrum quality (Q). Ultimately, this methodology was applied to identify MPs in commercial mussels, with results showcasing the viability of the proposed validation stages for MPs extraction, maintaining MPs integrity with high recovery percentages.

Plastic Analysis with a Plasmonic Nano-Gold Sensor Coated with Plastic-Binding Peptides.

Contamination with plastics of small dimensions (<1 µm) represents a health concern for many terrestrial and aquatic organisms. This study examined the use of plastic-binding peptides as a coating probe to detect various types of plastic using a plasmon nano-gold sensor. Plastic-binding peptides were selected for polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS) based on the reported literature. Using nAu with each of these peptides to test the target plastics revealed high signal, at 525/630 nm, suggesting that the target plastic limited HCl-induced nAu aggregation. Testing with other plastics revealed some lack of specificity but the signal was always lower than that of the target plastic. This suggests that these peptides, although reacting mainly with their target plastic, show partial reactivity with the other target plastics. By using a multiple regression model, the relative levels of a given plastic could be corrected by the presence of other plastics. This approach was tested in freshwater mussels caged for 3 months at sites suspected to release plastic materials: in rainfall overflow discharges, downstream a largely populated city, and in a municipal effluent dispersion plume. The data revealed that the digestive glands of the mussels contained higher levels of PP, PE, and PET plastic particles at the rainfall overflow and downstream city sites compared to the treated municipal effluent site. This corroborated earlier findings that wastewater treatment could remove nanoparticles, at least in part. A quick and inexpensive screening test for plastic nanoparticles in biological samples with plasmonic nAu-peptides is proposed.

From Personal Care to Coastal Concerns: Investigating Polyethylene Glycol Impact on Mussel's Antioxidant, Physiological, and Cellular Responses.

Pharmaceutical and personal care products (PPCPs) containing persistent and potentially hazardous substances have garnered attention for their ubiquitous presence in natural environments. This study investigated the impact of polyethylene glycol (PEG), a common PPCP component, on Mytilus galloprovincialis. Mussels were subjected to two PEG concentrations (E1: 0.1 mg/L and E2: 10 mg/L) over 14 days. Oxidative stress markers in both gills and digestive glands were evaluated; cytotoxicity assays were performed on haemolymph and digestive gland cells. Additionally, cell volume regulation (RVD assay) was investigated to assess physiological PEG-induced alterations. In the gills, PEG reduced superoxide dismutase (SOD) activity and increased lipid peroxidation (LPO) at E1. In the digestive gland, only LPO was influenced, while SOD activity and oxidatively modified proteins (OMPs) were unaltered. A significant decrease in cell viability was observed, particularly at E2. Additionally, the RVD assay revealed disruptions in the cells subjected to E2. These findings underscore the effects of PEG exposure on M. galloprovincialis. They are open to further investigations to clarify the environmental implications of PPCPs and the possibility of exploring safer alternatives.

Characterization of NR1J1 Paralog Responses of Marine Mussels: Insights from Toxins and Natural Activators.

The pregnane X receptor (PXR) is a nuclear hormone receptor that plays a pivotal role in regulating gene expression in response to various ligands, particularly xenobiotics. In this context, the aim of this study was to shed light on the ligand affinity and functions of four NR1J1 paralogs identified in the marine mussel Mytilus galloprovincialis, employing a dual-luciferase reporter assay. To achieve this, the activation patterns of these paralogs in response to various toxins, including freshwater cyanotoxins (Anatoxin-a, Cylindrospermopsin, and Microcystin-LR, -RR, and -YR) and marine algal toxins (Nodularin, Saxitoxin, and Tetrodotoxin), alongside natural compounds (Saint John's Wort, Ursolic Acid, and 8-Methoxypsoralene) and microalgal extracts (Tetraselmis, Isochrysis, LEGE 95046, and LEGE 91351 extracts), were studied. The investigation revealed nuanced differences in paralog response patterns, highlighting the remarkable sensitivity of MgaNR1J1γ and MgaNR1J1δ paralogs to several toxins. In conclusion, this study sheds light on the intricate mechanisms of xenobiotic metabolism and detoxification, particularly focusing on the role of marine mussel NR1J1 in responding to a diverse array of compounds. Furthermore, comparative analysis with human PXR revealed potential species-specific adaptations in detoxification mechanisms, suggesting evolutionary implications. These findings deepen our understanding of PXR-mediated metabolism mechanisms, offering insights into environmental monitoring and evolutionary biology research.

Biomarker responsiveness in Norwegian Sea mussels, Mytilus edulis, exposed at low temperatures to aqueous fractions of crude oil alone and combined with dispersant.

Biological effects of aqueous fractions of a crude oil, alone or in combination with dispersant, were investigated in mussels, Mytilus edulis, exposed at three temperatures (5, 10 and 15 °C). Polycyclic aromatic hydrocarbons (PAHs) tissue concentrations were determined, together with genotoxicity, oxidative stress and general stress biomarkers and the Integrated Biological Response (IBR) index. The bioaccumulation of individual PAHs varied depending on the exposure temperature, with relevant bioaccumulation of phenantrene and fluoranthene at 5 °C and heavier (e.g. 5-rings) PAHs at 15 °C. The values and response profiles of each particular biomarker varied with exposure time, concentration of the oil aqueous fraction and dispersant addition, as well as with exposure temperature. Indeed, PAH bioaccumulation and biomarker responsiveness exhibited specific recognizable patterns in mussels exposed at low temperatures. Thus, genotoxicity was recorded early and transient at 5 °C and delayed but unremitting at 10-15 °C. Catalase activity presented a temperature-dependent response profile similar to the genotoxicity biomarker; however, glutathione-S-transferase responsiveness was more intricate. Lysosomal membrane stability in digestive cells decreased more markedly at 5 °C than at higher temperatures and the histological appearance of the digestive gland tissue was temperature-specific, which was interpreted as the combined effects of PAH toxicity and cold stress. It can be concluded that the profile and level of the biological effects are definitely different at low temperatures naturally occurring in the Arctic/Subarctic region (e.g. 5 °C) than at higher temperatures closer to the thermal optimum of this species (10-15 °C).

Detection of Toxoplasma gondii in wild bivalves from the Kerguelen and Galapagos archipelagos: influence of proximity to cat populations, exposure to marine currents and kelp density.

Oocysts of the protozoan Toxoplasma gondii are found in felid feces and can be washed into coastal waters, where they persist for months, attaching to algae and accumulating in invertebrates. We used wild bivalves to assess contamination of coastal waters of the Kerguelen and Galapagos archipelagos by this zoonotic parasite. Additionally, we leveraged the contrasting situations of these archipelagos to identify some potential drivers of contamination. In the Galapagos, with a cat density reaching 142 per km2, 15.38% of the sampled oysters (Saccostrea palmula) tested positive for T. gondii by quantitative real-time PCR (qPCR) (n = 260), and positive samples were found in all eight sampling sites. In Kerguelen, with 1-3 cats per km2, 40.83% of 120 tested mussels (Mytilus edulis platensis) were positive, and positive samples were found in four out of the five sampling sites. These findings provide evidence of T. gondii contamination in the coastal waters of these archipelagos. Furthermore, T. gondii-positive bivalves were found on islands located 20 km away (Galapagos) and 5 km away (Kerguelen) from the nearest cat population, indicating that T. gondii oocysts can disperse through waterborne mechanisms over several kilometers from their initial deposition site. In the Galapagos, where runoff is infrequent and all sites are exposed to currents, the prevalence of qPCR-positive bivalves did not show significant variations between sites (p = 0.107). In Kerguelen where runoff is frequent and site exposure variable, the prevalence varied significantly (p < 0.001). The detection of T. gondii in Kerguelen mussels was significantly correlated with the site exposure to currents (odds ratio (OR) 60.2, p < 0.001) and the on-site density of giant kelp forests (OR 2.624, p < 0.001). This suggests that bivalves can be contaminated not only by oocysts transported by currents but also by consuming marine aggregates containing oocysts that tend to form in kelp forests.

Photoaging Elevated the Genotoxicity of Polystyrene Microplastics to Marine Mussel Mytilus trossulus (Gould, 1850).

Micro-sized particles of synthetic polymers (microplastics) are found in all parts of marine ecosystems. This fact requires intensive study of the degree of danger of such particles to the life activity of hydrobionts and needs additional research. It is evident that hydrobionts in the marine environment are exposed to microplastics modified by biotic and abiotic degradation. To assess the toxic potential of aging microplastic, comparative studies were conducted on the response of cytochemical and genotoxic markers in hemocytes of the mussel Mytilus trossulus (Gould, 1850) after exposure to pristine and photodegraded (UV irradiation) polystyrene microparticles (µPS). The results of cytochemical tests showed that UV-irradiated µPS strongly reduced metabolism and destabilized lysosome membranes compared to pristine µPS. Using a Comet assay, it was shown that the nuclear DNA of mussel hemocytes showed high sensitivity to exposure to both types of plastics. However, the level of DNA damage was significantly higher in mussels exposed to aging µPS. It is suggested that the mechanism of increased toxicity of photo-oxidized µPS is based on free-radical reactions induced by the UV irradiation of polymers. The risks of toxic effects will be determined by the level of physicochemical degradation of the polymer, which can significantly affect the mechanisms of toxicity.