An overview of the contaminant mixtures present in key consumed fish and seafood species along the Portuguese territory.

Understanding the effects of recent atmospheric heatwaves on seagrass-inhabited intertidal shellfish beds: a mesocosm experiment.

Bioactive peptides have recently emerged as promising candidates for cancer treatment due to their selective cytotoxicity toward cancer cells. The bivalve mollusk Ruditapes decussatus contains bioactive compounds that have not been thoroughly investigated for their potential anticancer properties. In this study, isolation and purification of peptide mixtures from R. decussatus were performed using FPLC chromatography followed by de novo sequence analysis. Using de novo peptide sequencing, a total of 135 peptides (ranging from 2681.6 to 5925.12 Da) were identified, of which 57 peptides (42%) were predicted to exhibit anticancer potential upon analysis with AntiCP 2.0, highlighting their possible therapeutic utility (Data are available via ProteomeXchange with identifier PXD067801). Additionally, fractions were tested against liver (HepG2) and colorectal (HT-29) cancer cell lines, as well as normal human hepatocytes and VERO (obtained from kidney) cells, to evaluate their cytotoxic effects. Fractions 2 and 3 showed significant anticancer activity against both cancer cell lines, while exhibiting minimal cytotoxicity toward normal cells. These fractions induced apoptosis, as evidenced by the downregulation of Bcl-2 and upregulation of caspase-3, and also activated autophagy, marked by increased Beclin-1 expression. Flow cytometry analysis revealed enhanced apoptotic cell death and G1/S phase cell cycle arrest in the treated cancer cells. Morphological analysis further confirmed the presence of apoptotic changes. Overall, the peptides derived from R. decussatus demonstrated the ability to induce apoptosis and cell cycle arrest in cancer cells, with a highly selective effect on colorectal carcinoma, suggesting their potential as anticancer agents for further investigation.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-20094-7.

Comparative transcriptomics reveals different grades of susceptibility to a bacterial infection in bivalves.

This pilot research focused on investigation of the parasites infecting carpet shell clam ( Ruditapes decussatus L.) from İzmir Bay. The sampling material consisted of randomly selected 360 carpet shell clams collected from İzmir Bay during the period between October 2023 and September 2024. Rich parasite fauna was unveiled consisting of one protozoan and five metazoans, respectively a protozoan Ancistrum spp. and metazoans Cercaria tapidis ( Monorchis parvus Looss 1902), Urastoma cyprinae , symbiotic copepod, nematode larva and cestode larva. The most severe pathological impact was observed in the tissues infected with the nematode larvae. There was discernable pattern in seasonal abundances, more parasites encontered in warmer months except the symbiotic copepod which preffered clams as its host in cooler months.

ABSTRACTIn Italy, the consumption and the production of shellfish, including clams, is considerable and has a significant impact on human health. In the lagoon of Capo Peloro (Sicily), three native clam species, Cerastoderma glaucum, Ruditapes decussatus, and Polititapes aureus, are traditionally farmed, locally commercialized, and highly appreciated by consumers. The fatty acid (FA) profile of these Sicilian species collected in 2023 and 2024 was evaluated and compared with the non‐commercial samples from the reserve of Oliveri‐Tindari (Sicily) and the extensively commercial R. decussatus from Sardinia. The results confirmed a low‐fat product, rich in C16:0 (22.37%–31.88%) and DHA (9.59%–17.48%). Samples from Capo Peloro are characterized by the highest content of saturated FAs (42.78%–50.88%) while samples from Sardinia have the highest content of polyunsaturated FAs (37.26%–40.83%). However, the fat in all samples demonstrated high nutritional quality, supported by good nutritional indexes and significant levels of EPA and DHA. Statistical analysis, used to differentiate the samples according to location, sampling year, and species, highlights the influence of environmental factors, seasonal variation, and genetic diversity on the FA composition. Among these, climatic temperature appears to be the most influential factor in regulating the balance between saturated and unsaturated FAs.

Energy metabolism under thermal stress in Mytilus galloprovincialis and Ruditapes decussatus: Insights from gene expression and enzyme activity profiles.

Assessing the vulnerability of commercial bivalves to intensifying atmospheric heatwaves in coastal ecosystems.

The research focused on uptake and accumulation of Toxoplasma gondii and Cryptosporidium parvum oocysts in carpet shell clams (Ruditapes decussatus L.) from İzmir Bay. Molecular identification of T. gondii and C. parvum oocysts was carried out by conventional PCR method. The rate of positiveness of C. parvum was 3.33 % and of T. gondii 4.16 % in 120 pools examined. Statistical analysis revealed slight positive correlation between the monthly rate of positiveness of C. parvum and the clam length. However no statistically significant correlation between clam length and T. gondii monthly rate of positiveness was detected. Shellfish farming in non polluted seawater, depuration before consumption and strict food safety control for emerging enteric protozoan parasites such as T. gondii and C. parvum are recommended.

IntroductionThis study showcases how the end-users of Ria de Aveiro coastal lagoon (Portugal), perceive the threat of invasive alien species (IAS), as well as biodiversity loss, and how it relates to their local activities, environmental identity and risk perception. Previous studies in the region and elsewhere have demonstrated that invasive species might have an impact at the habitats and at the species levels, both with potential negative socio-economic implications for end-users, i.e., for citizens who rely on the ecosystem for their livelihoods. However, this relation is still not well understood.MethodsData drew on face-to-face questionnaires run in situ at the lagoon intertidal flats. Supported by maps, participants were invited to identify the presence of the habitat Zostera noltei (also known as Zostera noltii), and the species Diopatra neapolitana, Hediste diversicolor and Arenicola spp., as well as Ruditapes decussatus, Venerupis corrugata and Ruditapes philippinarum, and inquired about the extraction, preference, and preferred areas. Of the 174 participants, 83% were male, and 68% were private citizens. Their main reason to be in situ at the time of the questionnaire relates to local traditional activities. This study is driven by three main research questions focusing on the perspective of the Ria de Aveiro local community that rely on the lagoon for their livelihoods: i) How is the threat of IAS to native species perceived? ii) How are the relations between local activities and IAS perceived? iii) What is the impact of environmental perceptions on marine biological resources?ResultsThe research questions that drove this study enabled us to conclude that the threat posed by IAS and biodiversity loss is moderate and individuals perceive that most of the species have decreased in the past and/or will decrease in the future. End-user’s evidence spatial-distinct preferences in the lagoon area for species-specific harvesting, including alien species, mainly related to market demand and financial gain.DiscussionThe impact of environmental perceptions on marine biological resources, indicate that the inter-relations between environmental identity and risk perception might have unexpected effects that need to be better understood.

Aquaculture in the crossroad of microplastic contamination.

Abstract The continuous decline in size (age)-specific growth rate over the life span is an important feature of the life history of many animal populations. Differential size scaling of physiological rates has been invoked to account for such negative allometry in most currently available growth models. In this study, both feeding rates (for energy gain) and metabolic rates (for energy expenditure) were determined in two congeneric clam species using specimens spanning a wide size range covering the ontogenetic growth phases following spat settlement. Mass-scaling allometric functions were fitted to these measurements, both for interspecific comparisons and for intraspecific comparisons between age groups, and the results were incorporated into Scope for Growth models. Overall, growth simulations show nearly isometric trends in the juvenile (seed) phase, which become clearly allometric in the adult, while growth of the grooved carpet shell (GCS) clam appears to be more size constrained than that of the Manila clam, especially in the seed phase. The GCS clam was a more efficient filter feeder, exhibiting higher gill pumping performance (clearance rates per unit gill area) compared to the Manila clam, which instead had a more suitable gill to labial palp ratio, allowing for better pre-ingestive selection of high food value particles.

Abstract In the present study, rare earth gadolinium elements doped high‐active ZnS semiconductor nanoparticles (NPs) were developed. The nanomaterial was prepared via a facile aqueous route using zinc acetate as Zn source and cetyltrimethylammonium bromide (CTAB) as ligand and stabilizer agent. The microstructure of the obtained NPs was characterized using XRD and TEM techniques. Elemental analysis was performed to prove the purity of the sample using EDX measurement. The optical response of the Gd‐doped ZnS NPs was performed via a UV–visible spectrophotometer to further characterize the gap energy of the nanomaterials. A photocatalytic test was also performed to evaluate the photodegradation activity of the doped semiconductor. According to the preliminary results, we found that Gd‐doped ZnS NPs exhibited high photocatalytic activity after the doping process compared to bare ZnS. The other purpose of this work is to study the physiological response and the induction of oxidative stress in different organs of the Mediterranean clams (Ruditapes decussatus). Considered NPs do not induce a significant impact on clams' response following exposure to Gd‐doped ZnS NPs with 3 and 5%. In contrast, Gd‐doped ZnS with 10% content enhances the enzymatic activities.

Global warming significantly impacts coastal zones, particularly affecting ectothermic inhabitants such as bivalve mollusks. This study evaluates the response of the grooved carpet shell clam Ruditapes decussatus (Linnaeus, 1758) to increasing temperatures (22.5°C, 24.5°C, 26.5°C) over 25 days through the transcription of key genes involved in antioxidant defense [Cu-Zn superoxide dismutase (Cu-Zn sod), catalase, metallothionein], anti-apoptotic procedures [b-cell lymphoma 2 (bcl2)], and energy metabolism [pyruvate kinase (pk), phosphoenolpyruvate carboxykinase (pepck)]. Additionally, the genes catalase and Cu-Zn sod were characterized for the first time, and along with the metallothionein gene, were sequenced in heat-resilient and heat-susceptible individuals to identify polymorphisms potentially associated with thermal tolerance. At 22.5°C, clams showed a delayed increase in glycolytic flux and a gradual up-regulation of antioxidant and anti-apoptotic mechanisms. At 24.5°C and 26.5°C, a strong initial stress response resulted in equally high mortality during the early days of exposure. Subsequently, clams appeared to shift toward a reduced energy metabolism, with mildly upregulated antioxidant defenses and anti-apoptotic activity. With prolonged exposure, there was evidence of enhanced aerobic glycolysis, antioxidant, and anti-apoptotic responses at these temperatures. However, increased pepck transcription on days 12 and 25 suggests that metabolic demands may have exceeded aerobic capacity, potentially triggering apoptotic processes at 26.5°C. Clams at 24.5°C maintained aerobic capacity upon the final day, also engaging anaerobic pathways to meet energy demands. Eventually, three SNPs were statistically correlated with heat resilience. These included one non-synonymous SNP in catalase, one SNP in the 3' untranslated region (3'UTR) of metallothionein, and one synonymous SNP in Cu-Zn sod. These findings underscore the sensitivity of R. decussatus populations from the northeastern Mediterranean to persistent thermal stress and reveal several polymorphisms in antioxidant genes with potential adaptive significance. However, the limited sample size and the weak correlations observed in some cases highlight the need for further research to clarify the relationship between these polymorphisms and thermal resilience.

The grooved carpet shell clam (Ruditapes decussatus) is a bivalve of high commercial value distributed throughout the European coast. Its production has suffered a decline caused by different factors, especially by the parasite Perkinsus olsenii. Improving production of R. decussatus requires genomic resources to ascertain the genetic factors underlying resistance/tolerance to P. olsenii. In this study, the first reference genome of R. decussatus was assembled through long- and short-read sequencing (1677 contigs; 1.386 Mb) and further scaffolded at chromosome level with Hi-C (19 superscaffolds; 95.4% of assembly). Repetitive elements were identified (32%) and masked for annotation of 38,276 coding- and 13,056 non-coding genes. This genome was used as a reference to develop a 2bRAD-Seq 13,438 SNP panel for a genomic screening on six shellfish beds distributed across the Atlantic Ocean and Mediterranean Sea. Beds were selected by perkinsosis prevalence and the infection level was individually evaluated in all the samples. Genetic diversity was significantly higher in the Mediterranean than in the Atlantic region. The main genetic breakage was detected between those regions (FST = 0.224), being the Mediterranean more heterogeneous than the Atlantic. Several loci under divergent selection (394 outliers; 261 genomic windows) were detected across shellfish beds. Samples were also inspected to detect signals of selection for resistance/tolerance to P. olsenii by using infection-level and population-genomics approaches, and 90 common divergent outliers for resistance/tolerance to perkinsosis were identified and used for gene mining. Candidate genes and markers identified provide invaluable information for controlling perkinsosis and for improving production of the grooved carpet shell clam.

ABSTRACT Tebufenpyrad (TUBF) is classified as a pyrazole acaricide and insecticide and is extensively utilized in greenhouse environments in several countries. Nevertheless, limited data exists regarding the potential reproductive toxicity of TUBF, particularly in non-target species. In this study, the fatty acid (FA) composition, the histopathology aspects, and redox status were assessed in the digestive gland of the clam Ruditapes decussatus following short-term exposure (96 h) to a series of concentrations (50, 100, and 200 µgL−1) of TUBF. Our findings indicated that TUBF induced oxidative stress, as evidenced by elevated levels of hydrogen peroxide (H2O2), malondialdehyde (MDA), and lipid peroxides (LOOH) in the treated groups. TUBF was also found to disrupt the enzymatic (catalase) and non-enzymatic (reduced glutathione) antioxidant defense systems. Additionally, TUBF was found to disrupt the FA composition. Overall, alterations in saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids, including certain essential FAs (such as LA, ARA, EPA, and DHA), exhibited differential compensatory/adaptive processes in R. decussatus depending on the concentration of TUBF. Furthermore, both examined organs showed various histological impairments, such as lipofuscin accumulation, infiltrative inflammations, and changes in digestive tubules, which provide additional evidence of TUBF toxic effects.

The heavy metals were measured in edible parts and shells of five edible bivalve species; Venerupis corrugata, Venerupis sp., Venerupis aurea, Ruditapes decussatus, and Paratapes undulatus collected from Timsah Lake, Suez Canal, Egypt. Ruditapes decussatus showed the highest average of flesh weight and exhibited the highest accumulation averages of Mn, Ni, and Pb. Paratapes undulatus recorded the highest averages of Fe, Zn, Cu, Cd, and Co in their flesh. According to the WHO guidelines, Fe levels in the edible parts of V. corrugata, R. decussatus and P. undulatus exceed the permissible limit of 100 µg/g. In contrast, Cu and Zn metals concentrations are below the permissible limits of 30 and 1000 µg/g, respectively. The levels of Pb and Ni surpass the permissible limits (0.2 and 0.35 µg/g) in all the studied species. Meanwhile, Cd levels are below the permissible limit (0.07 µg/g) in all species, except for P. undulatus. Furthermore, P. undulatus had the highest shell weight average and the highest averages of the mineralized; Fe, Mn, Zn, Cu, Ni, Pb, and Cd. Zn recorded the highest mineralization ratio (metal shell/metal flesh) in the shells of R. decussatus, P. undulates, and V. corrugata (11.38, 6.26, and 5.18, respectively). However, Cd and Fe showed high mineralization ratios in the shell lattices of P. undulatus (7.17, 6.22), suggesting that some bivalve species have demonstrated differential abilities to mineralize certain metals within their shells.

Widespread use of pesticides in agriculture has the potential to harm non-target creatures diffusely and contaminate aquatic habitats through leaching and runoff events. Triazoles are among the fungicides used extensively worldwide due to their efficacy against fungal crop diseases and their broad spectrum of action. In this study, the impact of Topas on the antioxidant defence system, fatty acid composition and histopathological injuries was experimentally examined under three concentrations (4, 40, and 400 µg L-1) over 96 hours in Ruditapes decussatus siphons. Our results showed that Topas exposure induced a significant decrease in the levels of saturated fatty acids. However, an increase of monounsaturated fatty acids and polyunsaturated fatty acids, mainly the eicosapentaenoic (C20:5n-3), docosahexaenoic (C22:6n-3) and arachidonic (C20:4n-6) acids. Topas exposure enhanced the levels of hydrogen peroxide, malondialdehyde and protein carbonyls and altered enzymatic and non-enzymatic antioxidant status in all treated clams. Acetylcholinesterase activity was inhibited with the increase of Topas concentrations. Eventually, histopathological changes detected in treated animals varied in a concentration-dependent manner and were herein consistent with the biochemical outcomes. Our findings shed new light on the relationship between redox state and fatty acid composition changes, allowing us to understand Topas-triggered toxicity.

Comparative study of Ruditapes philippinarum and Ruditapes decussatus in Ria de Aveiro, Portugal: Invasive species management and marine resource conservation

ABSTRACT Penconazole is a widely used fungicide to control critical fungal diseases of crops. This study aimed to elucidate the effects of PEN exposure, for 96 h, on fatty acids composition, redox status, and histopathological injuries in Ruditapes decussatus gills under different concentrations (4, 40, and 400 µg/L). Compared to the control group, our results showed an increase in saturated and monounsaturated fatty acids. However, the levels of polyunsaturated fatty acids were diminished, mainly those of eicosapentaenoic, docosahexaenoic, and arachidonic acids upon exposure to PEN. Depletion of PUFAs’ levels, particularly the long-chain and double-bond-rich ones, can affect membrane fluidity, and disrupt membranes’ biological functions, such as cell signalling, membrane transport, and protection against other environmental stresses. Herein, PEN uptake also results in enhanced oxidative stress by increasing levels of the ferric-reducing antioxidant power, hydrogen peroxidase, malondialdehyde, advanced oxidation protein products, and protein carbonyls. Moreover, changes in both enzymatic and non-enzymatic antioxidants were noticeable, indicating the stimulation of the antioxidant defense system. Adverse histological alterations were detected in PEN-treated specimens’ gill tissues, supporting our biochemical findings. Overall, in the current study, redox status was related to changes in fatty acid composition, contributing to a better understanding of the PEN-toxicity mechanism in clams.