Search Results (341)

Haplosporidium edule is a haplosporidian parasite originally described in the common edible cockle (Cerastoderma edule) along the European Atlantic coast. In this study, we report the first detection of H. edule in the olive-green cockle (Cerastoderma glaucum) from the northern Adriatic Sea, representing both a novel host record and a new geographic occurrence. During a cross-sectional study conducted in May 2019, 90 C. glaucum specimens were collected from three lagoon sites in northeastern Italy. Histological examination of soft tissues revealed haplosporidian developmental stages, including plasmodia, sporoblasts and mature spores, within connective tissues of the mantle, digestive gland, gills and between gonadal tubules in eight individuals from the Goro Lagoon. Molecular characterization based on a fragment of the small subunit ribosomal DNA showed high similarity with the previously published H. edule sequence. Host identification was confirmed through cytochrome c oxidase subunit I barcoding together with morphological and histological analyses. These findings indicate that H. edule has a broader host range than previously recognized. Although prevalence was relatively low, the detection of this parasite in a new host species and geographic area highlights the importance of continued surveillance, particularly in the context of climate change, shellfish translocations and the expansion of aquaculture activities. Full article

The periostracum is the outermost shell layer and the first produced during shell formation in molluscs. This organic layer isolates the extrapallial space from the external environment and provides a scaffold for subsequent calcification. In cephalopods with an internal shell, some organic shell structures are putatively homologous to the periostracum of other molluscan groups. However, neither their detailed structure nor their mode of formation has been described, leaving the extent of this homology unresolved. To address this issue, we investigated the morphology and formation of the organic layer of the dorsal shield and the gladius in embryos of the cuttlefish Sepia officinalis Linnaeus, 1758, and the squid Loligo vulgaris Lamarck, 1798, respectively, using light microscopy and transmission electron microscopy. In both species, the periostracum forms within a periostracal groove located along the lateral and anterior margins of the shell sac. As in other molluscs, secretions from columnar cells at the bottom of the groove produce a dense layer, while a translucent layer is subsequently added beneath it through secretions from cuboidal cells. The main difference is the absence of both a pellicle and of the specialized glandular cells that typically secrete it at the bottom of the periostracal groove. Full article

The Chi River Basin in northeastern Thailand is the country’s second-largest basin and a major tributary of the Mekong River, which is a regional hotspot for freshwater mollusc diversity. However, many of its sub-tributaries remain poorly studied. This study investigated molluscan diversity in the upper Chi River and examined relationships between assemblage structure and physicochemical habitat factors. Quantitative quadrat sampling was conducted at 11 stations along a 100 km reach, and community–environment linkages were analyzed using cluster analysis and canonical correspondence analysis (CCA). A total of 2734 individuals representing 25 taxa (12 gastropods, 13 bivalves) were recorded. Three distinct assemblages—Upstream, Midstream, and Downstream—were identified along the longitudinal gradient. CCA indicated that flow velocity, total dissolved solids (TDS), and dissolved oxygen (DO) were the primary predictors of assemblage structure (p < 0.01), jointly explaining 59.5% of community variation. Upstream reaches were dominated by Thiaridae (Tarebia, Brotia), midstream sections by Corbicula, and downstream areas exhibited the highest diversity, characterized by large unionid mussels. This study provides the first quantitative evidence of clear longitudinal zonation in the upper Chi River and establishes essential baseline data for conservation and management in this overlooked, biodiversity-rich basin. Full article

Freshwater ecosystems in arid and semi-arid zones of the East European Plain are characterized by severe habitat degradation, which negatively impacts their biodiversity. This study attempts to comprehensively examine the species richness of molluscs and determine the influence of abiotic factors on their spatial distribution using the example of one of the river basins in southern Eastern Europe—the Yeruslan River basin (a tributary of the Volga River). Fifteen watercourses in the Yeruslan basin were surveyed, with 72 samples collected from the littoral and deepwater zones. A total of 28 mollusc species were identified in the samples, predominantly those with broad ranges (Holarctic, Palearctic, and Euro-Siberian). Estimating true species richness using nonparametric methods revealed that the collected samples contained at least 90% of the expected number of species. In the small tributaries of the Yeruslan River, the dominant species were the lymnaeids Lymnaea stagnalis (Linnaeus, 1758) and Radix auricularia (Linnaeus, 1758). The Yeruslan River is dominated by the non-native species Dreissena polymorpha (Pallas, 1771). The low values of the Shannon diversity index recorded in the rivers of the Yeruslan basin are typical of desert and semi-desert riverine ecosystems with low stability and productivity, caused by the constant reduction in habitats due to periodic and/or permanent drying. It was established that the most significant abiotic factors determining the distribution of molluscs are the bottom substrate and the concentrations of nitrites and phosphates. Moreover, non-critical concentrations of the latter in the water likely had a beneficial effect on the productivity of streams in an arid climate. Full article

Aquaculture of molluscs and crustaceans represents an important and expanding sector within global food production. The intensification of these systems has been accompanied by an increased prevalence and severity of infectious diseases, which continue to constrain productivity and sustainability. Current disease management approaches include biosecurity measures, husbandry practices, therapeutics, and selective breeding, which have shown limited efficacy against many emerging pathogens affecting invertebrate species. Unlike finfish, aquatic invertebrates lack adaptive immunity and rely exclusively on innate immune mechanisms, limiting the effectiveness of traditional vaccine strategies. There is growing interest in immunostimulants that enhance innate defenses and support immune priming or trans-generational immune priming (TGIP). This review summarises the current understanding of immune defence mechanisms in molluscs and crustaceans and examines recent progress in the development of immunomodulators and prophylactic interventions aimed at improving health outcomes and disease resilience in invertebrate aquaculture. Full article

Coastal lakes are highly vulnerable transitional systems in which sedimentological processes and benthic ecological conditions jointly control contaminant accumulation and preservation, particularly in densely urbanized settings. A robust understanding of the physical and ecological characteristics of bottom sediments is therefore essential for the correct interpretation of contaminant distributions, including those of potentially toxic metals. In this study, an integrated sedimentological–ecological approach was applied to Lake Ganzirri, a Mediterranean shallow coastal lake located in northeastern Sicily (Italy), where recent investigations have identified localized heavy metal anomalies in surface sediments. Sediment texture, petrographic and mineralogical composition, malacofaunal assemblages, and lake-floor morpho-bathymetry were systematically analysed using grain-size statistics, faunistic determinations, GIS-based spatial mapping, and bivariate and multivariate statistical methods. The modern lake bottom is dominated by bioclastic quartzo-lithic sands with low fine-grained fractions and variable but locally high contents of calcareous skeletal remains, mainly derived from molluscs. Sediments are texturally heterogeneous, consisting predominantly of coarse-grained sands with lenses of very coarse sand, along with gravel and subordinate medium-grained sands. Both sedimentological features and malacofaunal death assemblages indicate deposition under open-lagoon conditions characterized by brackish waters and relatively high hydrodynamic energy. Spatial comparison between sedimentological–ecological parameters and previously published heavy metal distributions reveals no significant correlations with metal hotspots. The generally low metal concentrations, mostly below regulatory threshold values, are interpreted as being favoured by the high permeability and mobility of coarse sediments and by energetic hydrodynamic conditions limiting fine-particle accumulation. Overall, the integration of sedimentological and ecological data provides a robust framework for interpreting contaminant patterns and offers valuable insights for the environmental assessment and management of vulnerable coastal lake systems, as well as for the understanding of modern lagoonal sedimentary processes. Full article

Limpets are marine gastropod molluscs well adapted to intertidal rocky environments, yet their taxonomic resolution remains challenging due to extensive morphological convergence and the presence of cryptic species. In this study, we applied an integrative taxonomic framework combining multi-locus DNA barcoding and fine-scale morphological characterization to clarify species boundaries within three families of limpets—Nacellidae, Lottiidae, and Siphonariidae. A total of 132 individuals collected from six coastal sites in Shenzhen and adjacent areas of southern China were analyzed using four markers Cytochrome c oxidase subunit I (COI), 16S ribosomal RNA (16S rRNA), Cytochrome b (Cytb) and 28S ribosomal RNA (28S rRNA), together with scanning electron microscopy (SEM) observations of radular morphology. Molecular analyses identified nine distinct species across five genera. Kimura two-parameter distance analyses revealed clear barcode gaps in 16S rRNA, Cytb, and 28S rRNA genes, particularly among Cellana and Nipponacmea, whereas COI exhibited stronger discriminatory power within Siphonaria. Moreover, our study provides newly 16S, 28S references for Nipponacmea formosa and Cytb references for Nipponacmea formosa, Lottia luchuana, Siphonaria atra, Siphonaria sirius, Siphonaria sp. and Siphonaria sirius, enriching the public references and explaining the lack of corresponding records in previous BLAST searches. In addition, we identified misannotated COI references in NCBI which were labelled as Nipponacema schrenckii but belong to Cellana toreuma, highlighting inconsistencies in existing reference data rather than issues with our samples. SEM-based radular features displayed consistent interspecific variation that corroborated molecularly defined clades, offering comprehensive search of the NCBI reliable morphological evidence for species delimitation. Collectively, our findings highlight the value of integrating lineage-specific molecular markers with detailed morphological analyses to resolve taxonomic ambiguities in morphologically conservative marine gastropods. Furthermore, this approach strengthens molecular reference resources essential for future biodiversity and evolutionary research on intertidal limpets. Full article

Background: Clostridium perfringens is an infectious agent of concern in wild/farmed shellfish. Hence, this study assessed shellfish-borne Clostridium perfringens (ShbCp) prevalence. Methods: A total of 1469 ShbCp from 2336 shellfish were modelled using hierarchical generalized linear and 1000-permutation-based-mixed-effects, meta-regression models. Results: The overall ShbCp prevalence was 54.12% (19.73–84.99) with a 32.02% (14.52–56.64) toxigenic rate and a higher estimate in 2020–2025 (41.01%, 17.00–70.23) versus 1970–2019 (20.01%, 4.49–57.08). Culture media significantly affect ShbCp recovery, with cooked meat medium and thioglycollate medium registering higher estimates (77% and 25.15%, respectively) than selective agars (<7%). The molluscans had a higher ShbCp rate (60.68%) than crustaceans (1.57%) and cephalopods (0.14%); oysters (85.97%) than mussels (71.81%), clams (50.38%), slug/snails (48.23%), scallops (16.24%), crabs (11.91%), shrimps (1.05%), and squids (0.42%); and Crassostrea gigas (89.27%) versus Ruditapes philippinarum (45.92%) versus Mytilus galloprovincialis (30.14%). ShbCp differed significantly by nations but not by continent with Spain (87.79%) having the highest rate, then China (47.01%), Japan (43.91%), the USA (10.44%), and Greece (0.00%); South America (51.36%), then Asia (44.77%), Europe (21.97%), and North America (10.44%). Sample size, growth medium, nation, and shellfish class significantly explained 27.58%, 72.30%, 67.52%, and 28.51% ($R^2$) variance in ShbCp prevalence, respectively. Conclusions: The present study estimated a high ShbCp prevalence, suggesting a significant public health risk. It recommends that C. perfringens should be incorporated as a supplemental indicator into shellfish safety/shellfish water quality monitoring alongside traditional indicators. Also, geographical data gaps from Africa, Latin America, the Middle East, and Oceania underline the need for national and global monitoring attention and priority on C. perfringens in shellfish/shellfish beds. Full article

The Metaponto coastal plain (Ionian margin, Southern Italy) records the Late Pleistocene–Holocene evolution of a foredeep coastal system shaped by relative sea-level change, vertical land motion, and compaction. We analyze a 22 m continuous core (Meta 1) using lithofacies logging, grain size statistics and cumulative curves, multivariate analysis of grain size distributions (PCA and k-means clustering), and three AMS 14C ages, and we compare the record with a nearby borehole (MSB) and a global eustatic curve. Four depositional units document a shift from lower-shoreface–offshore deposition to lagoon–barrier/aeolian systems, culminating in late Holocene near-surface progradation. Textural end members (mud-rich offshore/lagoonal, traction-dominated, and sand-rich) are coherent across classical parameters, Visher-type curves, PCA, and k-means clusters. Depth–age comparisons suggest net uplift during the Late Glacial, followed by near-present relative sea level and a Late Holocene onset of modest net subsidence; a compaction contribution is plausible but unquantified. Subsidence/uplift rates therefore remain upper-bound estimates owing to sparse chronological control and the lack of glacio-isostatic and compaction modeling. Together with the MSB emerged-beach tie-point, the record constrains shoreline position and progradation. The inferred Mid- to Late-Holocene stabilization and progradational trends are consistent with other Italian and wider Mediterranean coastal plains. Additional dating and quantitative paleoecological proxies (e.g., foraminifera/ostracods/molluscs) are key to independently constrain salinity and water-depth changes and to refine the partitioning between subsidence and compaction. Full article

The sustainability of mollusc aquaculture relies, in part, on overcoming the challenges of spat production in captivity, particularly during the metamorphosis and settlement stages. The optimization of rearing technologies at these stages would ensure possible solutions for sustainably producing mollusc spat while simultaneously improving stock performance. The current work represents a large-scale trial examining the effect of biological and chemical inducers on larval settlement in Mytilus galloprovincialis. For this purpose, one batch of pediveliger larvae was directly transferred to settlement on microalgae-based biofilm (mature cylinders), while another batch was pretreated with gamma-aminobutyric acid GABA (10⁻⁴ M, 10⁻⁵ M and 10⁻⁶ M) and potassium chloride KCl (20 mM and 30 mM) according to two different exposure times (6 h and 24 h), before being transferred for settlement (immature cylinders). The impact of different treatments on larval performance was evaluated in terms of larval settlement rate (Sr), post-larval growth rate (Gr), and spat production rate (Pr). The biofilm treatment had the highest settlement rate and spat production (Sr = 65% and Pr = 46.4 spat/cm²) compared to chemical treatments. The highest settlement rate among chemical treatments occurred under short exposure times (6 h) to low GABA concentrations, i.e., Sr 40% and 45% at GABA 10⁻⁵ M and 10⁻⁶ M, respectively). GABA and KCl treatments ensured a faster post-larval growth rate than the biofilm, i.e., 15.54 ± 7.67 µm/day, 18.26 ± 9.39 µm/day, and 11.35 ± 6.73 µm/day, respectively, while control trials showed the lowest growth rate (6.80 ± 4.39 µm/day). These findings reveal a key trade-off: biofilm is the most effective measure for promoting spat production, while a targeted use of GABA and KCl at short exposure times (6 h) appears to significantly enhance post-larvae growth. Full article

A combination of stomach contents analysis (SCA) and nitrogen (δ¹⁵N) and carbon (δ¹³C) stable isotope analysis (SIA) was used to assess the trophic structure of nine fish species (two belonging to the family Mullidae, Mullus barbatus and Mullus surmuletus, and seven belonging to the family Sparidae, Diplodus sargus, Diplodus vulgaris, Pagellus acarne, Pagellus erythrinus, Pagrus auriga, Pagrus pagrus, and Sparus aurata) with high commercial value in the Bay of Cádiz, Southern Spain. A total of 91 different food items were identified in the stomachs, mainly belonging to four animal phyla (Arthropoda, Mollusca, Annelida, and Echinodermata). Crustaceans (primarily decapods and amphipods) were the most common prey consumed by the species of Mullus, Pagrus, and Pagellus, whereas macroalgae, polychaetes, and molluscs were dominant in D. sargus, D. vulgaris, and S. aurata stomachs, respectively. Diet composition and isotopic signature differed among fish species, indicating food partitioning among coexisting species. Some discrepancies appeared when comparing fish trophic level using SCA versus SIA, since SCA provides information on recently consumed items, while SIA generates data about source utilization over a period of several months. Integration of both approaches offers a more comprehensive understanding of feeding strategies. Dietary studies shed light on the trophic ecology of commercial fish species, being the baseline for future ecological modelling and long-term management of marine resources. Full article

The Isles of Scilly are an archipelago of islands in the far southwest of the UK which contain numerous beds of wild bivalve molluscs which are recreationally harvested for local consumption. However, the islands have never previously been assessed for the presence of harmful algae and their shellfish toxin metabolites which can cause serious human health impacts. This study sought to address these knowledge gaps through the analysis of seawater and shellfish tissues for microalgae and toxins utilizing portable and lab-based microscopy, nanopore sequencing, chemical analysis and immunoassay kits. The study design was affected by the national COVID-19 lockdown which enforced implementation of citizen-led sampling and in-field microscopy. Microscopy and sequencing approaches led to the confirmation of multiple HAB species of concern, including those potentially responsible for production of neurotoxic and diarrhetic shellfish toxins. A portable microscope was successfully utilized in the field for recognition of microalgae and for early warning of potential shellfish toxicity events. Chemical analysis of cockle, clam and mussel samples confirmed the detection of paralytic, diarrhetic and amnesic shellfish toxins, with an unusual okadaic acid group toxin profile reaching a maximum toxicity of approximately half the regulatory limit as defined by EU law. The Sensoreal Alert Lateral Flow Assay was used to screen and highlight samples containing higher concentrations of DSP toxins. Furthermore, Tetrodotoxin was detected for the first time in the UK in cockle and grooved carpet shells. Multiple saxitoxin analogues were also detected in two echinoderm species, with this providing the first ever report of paralytic shellfish toxins in the spiny starfish, Marthasterias glacialis. The toxin profiles in the two species varied significantly with a dominance of GTX4 in Luidia ciliaris as opposed to a dominance of STX in Marthasterias glacialis. Overall, the study showed that a multi-method assessment of a previously unexplored region within the UK territory contained microalgae and toxins of concern to human health, and that a citizen-led programme could be instigated using portable microscopy and rapid toxin testing to assess the early warning for potentially harmful microalgae and toxins in the region, with confirmatory analysis being conducted to establish actual levels of risk for local consumers of seafood. Full article

Antidepressant drugs (ADDs) are one of the most widely prescribed pharmaceuticals globally and are widely detected in the environment. They are designed to target monoamine neurotransmission—a highly conserved pathway between humans and animal species. Monoamines are particularly involved in the regulation of a wide array of key biological functions in molluscs, an ecologically important group of animals. Despite this, the target-specific effects of environmental concentrations of different classes of ADDs in molluscs remain poorly understood. The present study seeks to understand the target-specific effects of environmental concentrations of different classes of ADDs in molluscs through a systematic review of the literature. This study, following our published systematic review protocol, analyzed 51 studies after deduplication and screening of 1156 identified records. Included studies reported on a range of outcomes, including reproductive, (loco)motor, developmental, behavioral, immuno-modulating and neurophysiological effects. Data synthesis was performed with a harvest plot of exposures, effect direction and risk of bias. We found evidence (weak to moderate) for (i) immunosuppression, resulting from tissue serotonin level elevation, (ii) larval development impairment, and (iii) acetylcholinesterase inhibition, at environmental concentrations of ADDs. Most study outcomes, in addition to data-deficient outcomes, were inconclusive due largely to methodological limitations such as the use of wild-derived species with minimal or no acclimation (65.38% of included studies), lack of proper controls and replicates, and unrealistic exposures, affecting the reliability of existing data. Although the observed effects—particularly immunosuppressive ones—provide critical insight into the ecological risks posed by ADDs, their impacts at environmentally relevant concentrations remain poorly characterized for most endpoints. Given the ecological importance of molluscs, further studies addressing the identified methodological and research gaps are urgently needed to better characterize the hazards posed by environmental concentrations of ADDs. Full article

The study assesses water-filled subsidence basins in the Karviná region using ecological and faunistic characteristics, with freshwater molluscs as bioindicators. Two sites—subsidence lake Kozinec and Doubrava basins—differing in size, salinity, and vegetation, were examined. A malacological survey identified 16 mollusc species, with invasive species dominating Kozinec due to high salinity from mine water discharge, while native species prevailed in Doubrava basins. The study analysed the impact of shoreline zones on mollusc communities, measured physicochemical water parameters (e.g., salinity, pH, nitrites), and evaluated anthropogenic influences. Proposed measures include raising the dam to prevent salinisation of Kozinec’s isolated section, supporting ecological succession, and protecting littoral zones, highlighting the potential for revitalising post-mining sites. Full article

Microplastic contamination in seafood has emerged as a significant concern for public health and food safety. Bivalve molluscs are especially vulnerable because of their filter-feeding behaviour, leading to the accumulation of different substances in seawater, including contaminants like microplastics. This study examines microplastic contamination by comparing commercially available ready-to-cook frozen and deep-frozen clams, assessing particle morphologies, dimensions, colours, and chemical identities. The Polymer Hazard Index (PHI) derived from the proportions of polymers in the samples and their hazard scores, whereas the Estimated Average Daily Intake (EADI) was determined based on per capita consumption and microplastic counts. The results indicated a significantly higher prevalence of microplastics in deep-frozen clams compared to frozen clams, with 2.58 ± 0.87 and 0.43 ± 0.13, respectively. EADI was estimated at 0.47 and 0.76 MP/kg(bw)/day for deep-frozen clams and frozen clams, respectively (before cooking). Our findings highlight the influence of industrial processing on microplastic contamination, other than the environmental contribution, with considerable implications for human exposure, underscoring the necessity for monitoring initiatives and regulatory policies to reduce microplastic exposure in seafood, thereby safeguarding food safety and public health. Full article