Search Results (259)

Filter-feeding bivalves can accumulate fecal bacteria and antimicrobial resistance determinants, yet routine regulatory monitoring relies mainly on quantitative Escherichia coli criteria. This study provides a whole-genome characterization of an ExPEC-like E. coli ST536 (O21) isolate recovered from commercially depurated retail mussels originating from a Class B harvesting area in Portugal. The isolate was phenotypically identified by MicroScan WalkAway Plus and subjected to antimicrobial susceptibility testing and Oxford Nanopore long-read sequencing, followed by genome assembly, annotation, antimicrobial resistance and virulence screening, plasmid and prophage detection, and phylogenomic analysis. Phenotypically, only resistance to tobramycin was detected using the MicroScan WalkAway system. Genomic analysis revealed a complex mobile element-rich architecture, including multiple resistance-associated determinants, 116 virulence-associated loci, prophage regions, and a mobilizable IncY plasmid carrying CTX-like class A β-lactamase-associated hits detected by ABRicate. Despite its ST536 assignment and ExPEC-associated traits, phylogenomic analysis placed the isolate within a phylogroup A/commensal-like background rather than among classical B2 ExPEC lineages, suggesting acquisition of pathoadaptive modules by an atypical environmental lineage. These findings highlight the potential utility of WGS as a complementary tool and suggest that depurated bivalves may serve as sentinels, warranting further investigation. Full article

The concentrations of 18 metal(loid)s were measured in five marine invertebrate species (Oxystele tigrine and sinensis, Marthasterias glacialis, Cymbula oculus and granatina, Parechinus angulosus, and Mytilus galloprovincialis) and five macroalgae/seaweed species (Aeodes orbitosa, Gelidium pristoides, Caulerpa filiformis, Ulva sp., and Bifurcaria brassicac formis) collected from eight sites within the marine environment of False Bay, Cape Town, South Africa. To assess the potential human health hazards associated with consumption, samples were acid digestion and analysed using inductively coupled plasma optical emission spectrometry (ICP-OES). The analysed elements included trace metals (Fe, Mn, Zn) toxic metals (Pb, Cd, As), transition metals (Ta, Ti), alkali metals (Li), and metalloid (Se, As). Metal concentration varied widely among species and locations, with values ranging from Zn: not detected (nd)—3836.04 mg/kg dry weight (dw); As: nd—77.98 mg/kg dw; Pb: nd—301.15 mg/kg dw; Li: nd—97.28 mg/kg dw, indicating diverse metal accumulation patterns. Human health risk was evaluated using the target hazard quotient (THQ) and hazard index (HI). Arsenic consistently exceeded the THQ threshold of one across all sites, and all the HI values were greater than one for all edible species, suggesting potential non-carcinogenic health risks associated with the consumption, except for M. glacialis, which is not commonly consumed. The HI metrics demonstrate the adverse impacts of metal concentration in marine biota. The observed spatial and biological variability in metal accumulation highlights the limitations of relying solely on metal concentrations for assessing health risks, food safety or anthropogenic contamination, and therefore more frequent and comprehensive monitoring is recommended. Full article

Nuclear receptors (NRs) of the NR1J1 group have been described in aquatic invertebrates and proposed as the evolutionary counterparts of vertebrate NR1I receptors, known for their role in xenobiotic-sensing and detoxification. In bivalves, previous studies have shown that NR1J1 activity and gene expression are modulated by pharmaceuticals, toxins, natural compounds, and algal extracts. However, their functional properties and diversification remain poorly understood. Here, we investigated the function and evolution of NR1J1 receptors in the bivalves Mytilus galloprovincialis and Ruditapes decussatus. We first identified four nr1j1 paralogs in R. decussatus and then integrated phylogenetic analysis, domain identity comparisons, tissue distribution profiling, and luciferase-based transactivation assays to characterize NR1J1 paralogs from both species. The receptors displayed distinct but partially overlapping transactivation profiles in response to confirmed ligands of NR1I and NR1H receptors, natural compounds, plant extracts, and fish bile, indicating paralog- and species-specific differences in ligand responsiveness. Allocholic acid emerged as the most consistent agonist across paralogs, whereas curcumin, carnosic acid, and Ptychopetalum olacoides extract showed more selective response patterns. Tissue profiling revealed broad but non-uniform expression of nr1j1 paralogs across bivalve tissues. Together, these findings underscore that bivalve NR1J1 receptors constitute a functionally diversified chemical-sensing system and provide a framework for future studies addressing ligand-dependent regulation and detoxification pathways. Full article

Carbon-based materials like activated carbon (AC) are frequently applied for water treatments and remediation. The increasing use and functionalization of AC, especially with the recent mandate to implement quaternary treatments to remove organic micropollutants (Directive 2024/3019), may inadvertently introduce AC or leachate products to aquatic bodies. Such occurrences pose potential risks to inhabiting organisms, which have been understudied. This study assessed the environmental safety of an AC obtained from spent brewery grains (SBG)—a lignocellulosic biomass—through microwave pyrolysis with potassium carbonate activation. The resulting AC (SBG-AC) was washed, sieved (powder, particle size ≤ 180 µm), and tested for its ecotoxicological effects on the marine mussel Mytilus galloprovincialis at doses of 5, 25, and 50 mg/L. After 28 days of exposure (with weekly water renewal), biochemical parameters related to the mussels’ metabolic capacity and oxidative status were evaluated. Exposure to SBG-AC stimulated the energy metabolism in M. galloprovincialis, at the expense of internal energy reserves (such as glycogen). Although SBG-AC exposure induced antioxidant responses, the significant increase in lipid peroxidation and protein carbonylation at the higher doses (particularly 50 mg/L) suggests that these protective mechanisms were insufficient to prevent oxidative damage. Overall, while SBG-AC offers an effective alternative for water treatment, its ecotoxicity at higher doses raises concerns, emphasizing the need for careful risk assessment and containment measures. Full article

Marine bivalves represent promising experimental models for the development of in vitro approaches in environmental biology, ecotoxicology, and bioactive compound screening. However, their application remains limited compared with that of more established vertebrate and mammalian cell systems, mainly due to the lack of standardized and reproducible protocols for maintaining primary cell cultures. This study aimed to establish and optimize a short-term primary cell culture protocol using gill and digestive gland tissues from the marine mussel Mytilus galloprovincialis. Primary cultures were prepared at four initial cell densities, ranging from 2.5 to 10 × 10⁶ cells mL⁻¹, and monitored over 72 h through cell density evaluation and metabolic activity assessment. Cells from both tissues were successfully maintained in short-term culture, predominantly showed rounded to spheroidal morphologies. Nevertheless, tissue-specific responses were observed. Gill-derived cultures displayed greater morphological homogeneity and stability across the tested densities, whereas digestive gland cultures showed greater cellular heterogeneity, aggregation, and stronger density-dependent responses. Metabolic activity remained stable during the first 24 h, while more evident differences among cell densities emerged after 48 and 72 h. Overall, intermediate cell densities, particularly 5 × 10⁶ and 7.5 × 10⁶ cells mL⁻¹, provided the most suitable balance between cell maintenance and metabolic performance. This optimized methodological framework supports the further development of mussel primary cell cultures as reproducible and ecologically relevant in vitro models for studying early cellular responses and for preliminary environmental safety assessment. Full article

Microplastics pose a growing threat to marine ecosystems as they can accumulate in aquatic organisms, interfering with essential physiological processes including reproduction. This study analyzed the effects of short-term exposure (48 h) to two concentrations (0.5 and 1 µg/mL) of 5 µm diameter polystyrene microplastic bead particles in female Mytilus galloprovincialis mussels, a bioindicator species of the Mediterranean Sea. Histological analyses revealed progressive oocyte degeneration and the development of hypertrophic PAS-positive mucous cells, indicative of a stress response, in a dose-dependent manner. Changes in hemocyte classes, which are major effectors of bivalve immunity, were evidenced by the May–Grünwald Giemsa reaction. Biochemical data showed that microplastics increased levels of stress proteins, such as HSP70 and p53, and altered the composition of ovarian glycoproteins. Metabolomic analysis based on ¹H NMR spectrometry revealed significant alterations in metabolites involved in energy (glucose, glycogen, and malonate) and amino acid (branched-chain amino acids arginine, glycine, glutamate, histidine, betaine, and choline) metabolism, suggesting impairment to bioenergetic and antioxidant pathways. Overall, these results suggest that even short-term exposure to polystyrene microplastic beads can alter the ovarian function and metabolism of female M. galloprovincialis, highlighting their vulnerability. Full article

The seasonal distribution of microplastics, as a representative case, was examined in Mytilus galloprovincialis from a pilot farm in the Gulf of Naples (Italy). The influence of marine parameters on microplastic uptake rate was assessed. A destructive patented method was used, and two microplastic size classes (<10 µm; >10 µm) were defined. Estimated Daily Intakes were calculated for different age groups. Results showed a significant abundance of small microplastics (9683.92 ± 6911 vs. 41.85 ± 13.98). In mussels, the highest levels (19,738.13 ± 3406.04) were detected in summer, and the lowest in autumn (4145.56 ± 2364.93). Summer variations in seawater temperature, oxygen, and pH were significantly different from those in winter and spring. High exposure levels, mainly of microplastics < 10 µm, were observed in the elderly (318.08 ± 227.00), followed by adults (225.29 ± 160.78) and children (212.29 ± 151.50), with the lowest in teenagers (127.51 ± 91.00). Despite the high variability of factors influencing mussel filtration and microplastic uptake, the study provided data on the seasonal microplastic distribution pattern and a size-based screening exposure level. Results highlight the importance of geographic and seasonal conditions, and particle size in assessing microplastic exposure through farmed mussel consumption. Full article

Spatial and temporal variability of macrozoobenthic communities were investigated around three offshore gas structures with different architecture (a subsea well-site, a four-leg platform, and a one-leg platform) in the NW Adriatic Sea. Four post-installation surveys (two per year over two years) were conducted by sampling sediments at increasing distances from each structure (approximately 0, 30, 60, 120 and 1000 m from the structure edge). A total of 233, 271 and 260 taxa were recorded around Structures A, B and C, respectively, with polychaetes representing the dominant taxonomic group at all sites. Across all structures, community composition showed significant variability both among surveys and along the distance gradient. Near-structure stations (0–60 m) most frequently accounted for spatial dissimilarities, whereas communities at 120 and 1000 m were generally more similar. Early surveys around the well-site and the four-leg platform were characterised by low diversity and high dominance of the opportunistic polychaete Ditrupa arietina, suggesting a short-term disturbance related to installation. Post-installation trajectories differed among structures: community descriptors stabilized faster around the subsea well-site, while changes near the platforms extended for at least two years. At the one-leg and four-leg platforms, the progressive development of a bivalve mound (specimens of Mytilus galloprovincialis and/or Neopycnodonte cochlear fell from the submerged parts of the platforms) coincided with increased abundance, species richness and occurrence of hard-bottom associated taxa at 0 m stations. Overall, the results indicate that offshore gas structures can locally influence macrozoobenthic assemblages by modifying habitat heterogeneity and promoting site-specific community responses. Although based on post-installation observations only, this study provides site-specific evidence useful for future decommissioning planning in soft-bottom shelf areas. Full article

Coastal ecosystems are increasingly threatened by human activities, highlighting the need for sensitive tools to assess environmental risk. An active biomonitoring approach, using the Mediterranean mussel (Mytilus galloprovincialis), was employed to evaluate anthropogenic chemical contamination in the North Ionian Sea, a still poorly studied area, by comparing mussel health status before (PrePT) and after (PostPT) the peak tourist season. Bioaccumulation of metal(loid)s was quantified in whole organisms. Oxidative stress was assessed in the gills and digestive gland through catalase (CAT), superoxide dismutase (SOD), lipid peroxidation (LPO), and oxidized carbonyl proteins (OMP). Neurotoxicity was evaluated via acetylcholinesterase (AChE) activity, while gene expression of stress-related biomarkers was analysed for metallothioneins (mt10, mt20), sod, cat, Glutathione S-transferase (gst), and Heat Shock Protein 70 (hsp70). Results suggest a progressive contaminant accumulation likely associated with intensified summer anthropogenic activity. Biomarker responses revealed clear activation of oxidative stress, with tissue-specific patterns. The findings confirm the effectiveness of active biomonitoring and multibiomarker approach in assessing coastal water quality and provide valuable baseline data for the management of marine ecosystems. Full article

Glitter is a distinctive and largely overlooked form of primary microplastic. Unlike more commonly studied microplastics, glitter particles are typically flat, highly reflective, multi-layered, and are composed of polymers such as polyethylene terephthalate, polyvinyl chloride with metallic coatings and a wide range of additives. In response to regulatory restrictions on intentionally added microplastics and increasing consumer demand, “eco-friendly” alternatives based on modified regenerated cellulose, cellulose nanocrystals, or mica have been introduced, although their environmental safety remains insufficiently characterized. This review synthesizes current knowledge on the environmental occurrence and ecotoxicological effects of both conventional and biodegradable glitters. A systematic literature search in Scopus identified 15 peer-reviewed experimental studies meeting predefined inclusion criteria. Evidence spans a wide range of taxa, including bacteria (i.e., Aliivibrio fischeri), microalgae and cyanobacteria (i.e., Phaeodactylum tricornutum, Raphidocelis subcapitata, Microcystis aeruginosa), aquatic plants (i.e., Lemna minor, Egeria densa), marine and freshwater invertebrates as crustaceans (i.e., Daphnia magna), bivalves (i.e., Mytilus galloprovincialis), sea urchins (i.e., Paracentrotus lividus), brine shrimp (Artemia sp.) and terrestrial soil fauna (Eisenia fetida, Folsomia candida). Results indicate that glitter cannot be treated as a uniform stressor: biological responses vary markedly with particle size, shape, colour, polymer type, additive composition, and weathering time, and leachates often exert stronger effects than intact particles. Reported impacts include impaired photosynthesis and growth, oxidative stress, developmental abnormalities, altered energy metabolism, and reduced reproduction. Substantial gaps remain regarding environmental concentrations, ageing processes, mixture effects, and long-term ecological consequences, particularly for biodegradable glitters. Addressing these gaps will require realistic exposure scenarios, mesocosm and field studies, and integrated chemical–biological approaches to support robust risk assessment and safer material design. Full article

Bivalve mollusks efficiently bioaccumulate human enteric viruses, posing significant food safety risks. This study assessed the prevalence of Norovirus (NoV GI and NoV GII), Hepatitis A virus (HAV), and Hepatitis E virus (HEV) in 59 samples of live mussels (Mytilus galloprovincialis) collected from the Bulgarian Black Sea coast between July 2022 and July 2023. Viral detection was performed using one-step real-time reverse transcription-polymerase chain reaction (RT-qPCR) following ISO 15216-2 standards, with a mean extraction efficiency of 4.06%. Norovirus GII was the most prevalent pathogen, with detection peaks following intense rainfall events in July 2023. In contrast, all samples tested negative for HAV and HEV. The analysis showed no significant correlation between E. coli contamination levels and the presence of NoV (Mann–Whitney U test, p = 0.565). The viral RNA was detected in several samples that otherwise complied with regulatory bacterial standards for direct consumption (≤230 MPN/100 g). In conclusion, within the limitations of the evaluated sample size and the specific geographically unbalanced sampling design, NoV GII was the predominant genogroup detected. These results suggest that current bacterial indicators may be insufficient to ensure viral safety in these products. In this regard, national control authorities need to undertake timely policies and measures for better and adequate surveillance, control and prevention of viruses in the different parts of the food chain. Full article

The population of the blue crab Callinectes sapidus is rapidly expanding in the Mediterranean Sea, where it is causing increasing ecological and economic impacts. However, biological information from recently colonised areas remains limited. This study combined controlled experiments and reproductive analyses to investigate the key biological traits of C. sapidus in the northern Adriatic Sea. Feeding trials were conducted under controlled conditions to assess prey consumption and feeding behaviours using Manila clams (Ruditapes philippinarum) and Mediterranean mussels (Mytilus galloprovincialis), offered as monospecific and mixed diets. The results showed that, while the number of prey items consumed did not differ markedly between species, mussels provided a significantly higher edible biomass, indicating greater energetic profitability. Handling and consumption times were comparable between prey types, suggesting compensatory differences between opening and feeding phases. Food intake was strongly influenced by temperature, with peak consumption observed between 25 and 28 °C and reduced feeding at both lower and higher temperatures. Reproductive analysis of ovigerous females revealed high fecundity, with a mean of 1.63 ± 0.53 million eggs per individual and a positive relationship between fecundity and body size. Overall, the results confirm that C. sapidus combines trophic flexibility with high reproductive output—traits that support its invasive success. These findings improve the understanding of the blue crab’s ecological role in the northern Adriatic, providing useful insights for assessing its impact on shellfish aquaculture and developing management strategies. Full article

Systematic surveillance of World Organization for Animal Health (WOAH)-listed protozoan parasites is essential for maintaining the sanitary status of seafood exports and detecting the introduction of exotic pathogens into coastal ecosystems. In 2023, we examined wild Mediterranean mussels Mytilus galloprovincialis and Pacific oysters Crassostrea gigas collected from small harbors adjacent to ten major trading ports along the west and south coasts of Korea to assess the occurrence of WOAH-listed protozoan parasites and emerging Perkinsus species. A total of 1080 mussels and 1080 oysters from 18 sites were sampled in spring and autumn, and gill and digestive gland tissues were pooled from six individuals for DNA extraction. Species-specific PCR assays targeting Perkinsus marinus, P. olseni, P. beihaiensis, Bonamia ostreae, B. exitiosa, and Marteilia refringens were performed using previously validated primer sets and positive controls. All PCR assays were negative for the six protozoan parasite species in both host species across all sampling sites, indicating no detectable infections in port-adjacent wild mussel and oyster populations during the survey period. These negative results contrast with recent reports of P. marinus in wild C. gigas and B. ostreae in Ostrea denselamellosa on the west coast of Korea, suggesting that infections may currently be focal, transient, and host-specific rather than widespread in port-associated M. galloprovincialis and C. gigas populations. The present study provides baseline data on the distribution of protozoan parasites in bivalves inhabiting high-risk harbor environments and underscores the need for continued surveillance of transboundary shellfish diseases that is closely coupled with environmental monitoring. Full article

The presence of endocrine-disrupting compounds (EDCs) in aquatic environments has raised significant concerns, particularly regarding their impact on marine biota. Among these compounds, 17α-ethinylestradiol (EE2), a synthetic estrogen widely used in oral contraceptives, is highly persistent and biologically active at very low concentrations. This study evaluated the effects of EE2 exposure on oxidative stress responses and endocrine disruption in Mytilus galloprovincialis, exposed for 28 days to three EE2 concentrations (10, 30, and 300 ng·L⁻¹). Biomarkers of oxidative stress, including the enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST), as well as Lipid Peroxidation (MDA levels), total ubiquitin (UBI) and the endocrine disruption marker, vitellogenin-like protein (VTG) were assessed. Results showed significant increase in GST and a decrease in CAT activities followed by an elevation at 300 ng·L⁻¹, slightly higher than control values. Overall, results suggest an enhanced oxidative challenge. No significant changes were detected in MDA and UBI levels. VTG-like protein levels increased according to the EE2 concentrations tested, suggesting an effect on the mussel’s endocrine system. These results show the activation of detoxification and antioxidant defense mechanisms in exposed mussels as a response to mitigate oxidative stress damage. Furthermore, it highlights the importance of using biomarkers in pollution monitoring studies and environmental risk assessment. Full article

Marine biofouling is a major global concern affecting the marine industry, the environment, and public health. The accumulation of organisms on submerged surfaces causes significant economic losses, including increased fuel consumption, higher pollutant emissions, and accelerated corrosion. Antifouling (AF) coatings with biocides are widely used to prevent this problem. However, many conventional biocides have been banned due to toxicity, creating an urgent need for environmentally friendly alternatives. In previous studies, we synthesized a gallic acid derivative and three flavonoids that showed AF activity against the settlement of mussel larvae (Mytilus galloprovincialis) together with low ecotoxicity. In the present work, to further assess their potential in marine coatings and exploit the advantages of nanocarriers in protecting and prolonging bioactive effects, these compounds were loaded into halloysite nanotubes (HNTs) and incorporated into epoxy coatings. Coatings containing the same AF compounds in free form were also prepared for comparison. HNTs were characterized by scanning electron microscopy (SEM), and compound loading was quantified by thermogravimetric (TG) analysis. The resulting composites were analyzed by SEM and dynamic water contact angle measurements. Laboratory bioassays with M. galloprovincialis larvae showed that coatings containing HNT-loaded synthetic compounds generally reduced larval settlement more effectively than the corresponding coatings containing the same compounds directly dispersed in the epoxy matrix, with values below 20% after both 15 and 40 h of exposure for the best-performing formulation. These findings highlight the novelty of the proposed HNT-based delivery strategy for nature-inspired synthetic antifoulants and support its potential for the development of effective and environmentally safer AF coatings. Full article