Search Results (385)

Certain sacoglossan sea slugs, often known as “solar-powered sea slugs”, are a group of marine gastropods that have the unique ability to photosynthesize by stealing functional chloroplasts from algae. The sacoglossan Elysia papillosa can maintain functional chloroplasts for up to two weeks after feeding. The microbiome of these slugs may play a crucial role in their metabolism, immunity, development, but more importantly their photosynthesis. Shotgun metagenomic sequencing was conducted on four samples of E. papillosa in order to characterize their microbiome. Sequences were classified and relative abundance was quantified with Centrifuger and functional data was examined using SqueezeMeta. Bacteria were analyzed by taxonomic groups and hypothesized function to the sea slug was determined with literature analysis. All samples were dominated by phyla Actinomycetota, Bacillota, Patescibacteriota, and Pseudomonadota. The presence of the phyla Bacteroidota and Bacillota was notable in all samples, which contain species known to produce enzymes that break down polysaccharides. It is possible that these bacteria could assist in degradation of the polysaccharide xylan found in the cell walls of Penicillus, the algal food source of E. papillosa. One species that was found in all samples was Cutibacterium acnes which has been shown to be an important component of the gut microbiota in other marine invertebrates and may provide the host with vitamin B12 and other beneficial nutrients. Many of these bacteria may be opportunistic rather than commensal. As a result, more research is required to describe the interactions between the slug and its microbiome, but this preliminary report provides a valuable starting point for identifying the microbiome make-up to further understanding of these relationships. Full article

Potentially toxic elements (PTE) are persistent contaminants in coastal systems and may accumulate in marine organisms, with relevance for both environmental monitoring and seafood safety assessment. This study provides an exploratory cross-biota assessment of Cd, Cr, Cu, Ni, and Pb in fishery resources from the Romanian Black Sea in 2024. The dataset included 24 composite samples and 120 analyte-level observations across bivalves, gastropods, pelagic fish, and demersal fish. Tissue concentrations were integrated with regulatory maximum levels, bioconcentration factors (BCF), biota–sediment accumulation factors (BSAF), and adult dietary risk indices, including estimated daily intake (EDI), target hazard quotient (THQ), and total target hazard quotient (TTHQ). Within the limits of this single-year dataset, Cd and Pb concentrations were generally higher in bivalves than in fish and gastropods, whereas Cr showed higher values in several fish samples, particularly pelagic fish. Cd was the main element of concern, with regulatory exceedances occurring mainly in bivalves and fewer exceedances in pelagic fish, while Pb exceedance was isolated. BCF and BSAF supported the relevance of Cd as a priority element but were interpreted only as descriptive tissue–water and tissue–sediment ratios, not as evidence of specific uptake pathways. Low abiotic Cd concentrations may have inflated some ratio-based values, and Cr interpretation remains limited by the absence of Cr speciation and dissolved/particulate partitioning data. The adult dietary risk assessment did not indicate substantial non-carcinogenic concern, as all individual THQ values and cumulative TTHQ values remained below 1. Overall, the findings support continued PTE monitoring in the Romanian Black Sea, using sessile bivalves as indicators of local environmental contamination and including gastropods and representative pelagic and demersal fish species of ecological and fisheries relevance to capture contaminant patterns across benthic and mobile fishery resources. Future monitoring should improve species-level replication, integrate metal partitioning in abiotic matrices, and include additional contaminants of seafood safety relevance, particularly Hg and As. Full article

Caffeine (CAF) is a widely consumed psychostimulant known to modulate adenosine receptors and neurotransmitter systems, although its effects in invertebrates remain poorly understood. Environmentally relevant concentrations (5, 30, and 50 µg/L) are associated with altered behavior, including locomotion, exploration, and feeding, in the freshwater gastropod Physella acuta. This study examined molecular responses underlying these effects. Adult snails were exposed to CAF for 24 h and 7 days. Gene expression related to the nervous system and stress pathways was analyzed by RT-PCR, including A1AR, ADORA2B, AChE, GLRA2, DRD2, RYR, HSD11β, HSP70, SLC6A2, and SLC6A1. After 24 h, exposure to 50 µg/L CAF altered A1AR expression and caused downregulation of AChE, GLRA2, and DRD2, associated with observed behavioral changes. A1AR upregulation may indicate compensatory adjustment in adenosine signaling. After 7 days, A1AR remained upregulated, while genes linked to inhibitory neurotransmission showed partial recovery. Increased expression of genes involved in dopamine regulation and steroid metabolism suggested physiological adaptation. Overall, CAF induced dose- and time-dependent molecular responses in P. acuta, linking neurochemical disruption with behavioral changes and highlighting its ecological risk as an emerging freshwater contaminant. Full article

The increasing fragmentation of plastic debris into nanosized particles represents a threat to freshwater ecosystems, yet the biological effects of nanoplastics (NPs) on freshwater invertebrates remain poorly understood. This study investigated tissue distribution, cellular effects and immune responses following acute exposure to polyethylene terephthalate nanoplastics (PET-NPs) in the freshwater gastropod Pomacea canaliculata, a species of high ecological relevance and physiological resilience. Adult snails were injected with PET-NPs at 5 or 10 mg/L and sampled after 24 and 72 h. PET-NPs accumulation in the anterior and posterior kidneys was assessed by fluorescence imaging and tissue morphology was evaluated. Stress- and inflammation-related genes (Pc-Heat Shock Protein (HSP)70, Pc-HSP90 and Pc-Allograft inflammatory factor 1) expression was quantified by RT-qPCR. PET-NPs uptake and phagocytic activity were analyzed in circulating hemocytes in vivo and ex vivo. PET-NPs were accumulated in renal tissues, persisting up to 72 h without histopathological alterations. Gene expression analyses revealed non-linear and dose/time-dependent responses. Hemocytes of different morphologies internalized PET-NPs in a dose-dependent manner and showed intercellular particle transfer. Overall, acute PET-NP exposure determines rapid immune handling and tissue sequestration with limited short-term physiological impact, underscoring the potential involvement of immune processes in NPs fate and highlighting the need for chronic exposure studies. Full article

Monacha cartusiana (O. F. Müller, 1774), native to the Mediterranean region and Europe, is a terrestrial gastropod recognized as a highly destructive agricultural pest that causes significant damage to crop plants, fruit trees, vegetables, ornamentals, and natural ecosystems. Despite its broad geographic distribution, the evolutionary history and phylogeographic relationships of M. cartusiana populations remain globally unexplored. This study reports the first molecularly confirmed record of M. cartusiana in Pakistan and investigates its genetic diversity and phylogeographic structure within a global context using mitochondrial markers. After morphological identification, genomic DNA was extracted from collected specimens using the CTAB method, followed by amplification and sequencing of the mitochondrial COI and 16S rRNA genes. The resulting sequences were subsequently analyzed using DnaSP and PopART software to estimate genetic diversity, perform neutrality tests, and construct haplotype networks. Published sequences of M. cartusiana retrieved from GenBank were incorporated to provide a global comparative framework. The COI dataset (555 bp) revealed 52 haplotypes, whereas the 16S rRNA dataset (269 bp) identified 14 haplotypes across global populations. High haplotype diversity (Hd = 0.946 for COI; Hd = 0.831 for 16S rRNA) and moderate nucleotide diversity (π = 0.010 for COI; π = 0.01253 for 16S rRNA) indicated substantial genetic variability within the species. Neutrality tests produced negative and insignificant values for Tajima’s D for COI and significant values for 16S rRNA (−1.428 for COI; −0.20586 for 16S rRNA) and Fu’s Fs (−29.776 for COI; −1.263 for 16S rRNA), suggesting historical population expansion. Phylogenetic reconstruction and haplotype network analyses identified two major clades (Clade A and Clade B), reflecting genetic relationships among populations from different geographic regions. AMOVA based on COI and 16S rRNA sequences revealed significant population structuring, with 29.98–51.30% of the total genetic variation occurring among populations and high fixation indices (FST = 0.299–0.51398, p = 0.001), indicating pronounced genetic differentiation and restricted gene flow. Pairwise FST analyses indicated that the Pakistani population is most closely related to populations from Italy and Central Europe, suggesting a closer genetic affinity with Southern or Central European populations. However, FST alone does not allow definitive inference of introduction directionality, and additional analyses would be required to robustly identify the source population. Overall, this study provides the first comprehensive molecular and phylogeographic assessment of the M. cartusiana species from Pakistan within a global context. These findings contribute important baseline data for understanding the evolutionary dynamics, dispersal history, and population connectivity of this economically important pest species. The pronounced genetic differentiation among populations and the suggested genetic affinity of the Pakistani population with European lineages have direct implications for biosecurity monitoring, invasion pathway tracing, and targeted pest management strategies. Future research integrating nuclear markers with the mitochondrial data presented here will be essential for a more complete understanding of gene flow and local adaptation in this species. Full article

V. alginolyticus (VAlg) is one of the three Vibrio species causing human vibriosis. Its presence in shellfish constitutes a potential health risk. Thus, this investigation aimed to determine the prevalence and distribution of VAlg in 18,544 shellfish across geographies using standard protocols and random intercepts/mixed-effects regressions. The global VAlg prevalence in shellfish was 19.70% (95% CI: 13.54–27.75). VAlg pooled prevalence was significantly different (p < 0.0001) by shellfish type (${\chi }_{20}^2$ = 238.48), species (${\chi }_{74}^2$ = 440.34), genus (${\chi }_{51}^2$ = 414.37), VAlg detection methods (${\chi }_{10}^2$ = 150.43), nation (${\chi }_{30}^2$ = 632.27), and continent (${\chi }_4^2$ = 33.81). Europe and South America showed the highest pooled VAlg contaminated rates in shellfish (27% and 32%, respectively) but Asia had a low rate (~4%). By shellfish type, gastropods (snails) topped the list with 50%, followed by bivalves (29%). Among shellfish species, the VAlg rate declined from 67% to 5% (k ≤ 6), but with a more stable prevalence in Litopenaeus vannamei (19.02%, k = 11) and Crassostrea gigas (15.18%, k = 9). Edible oysters and clams had lower VAlg pooled rates (4–15%). Targeted culture with MALDI-TOF or species-specific qPCR detected VAlg in 100% of tested shellfish samples. By contrast, conventional phenotypic tests detected less VAlg in shellfish yielding 20% by general biochemical/API tests, 8.8% by generic PCR, and near-zero (0.3–3%) by multiplex PCR or MALDI-TOF/PCR. Both the multiplicative (${\beta }_0=-3.28\pm 3.76, F_{54;125}$ = 3.01, p = 0.001) and additive (${\beta }_0=-1.89\pm 1.47, F_{31;148}$ = 3.83, p = 0.001) interactions of nation and sample size explained 73.14% and 58.04% of the true variance in VAlg prevalence in shellfish. Other factors include detection techniques ($R^2$ = 46.59%, ${\beta }_0=-1.63\pm 0.83, F_{10;169}=11.16$, p = 0.001), nation ($R^2=37.72$ = 1.89, p = 0.006), medium $R^2$ = 19.42%, ${\beta }_0=2.24\pm 1.85, F_{15;164}$ = 1.69, p = 0.03), shellfish type ($R^2$ = 16.99%, ${\beta }_0=-3.90\pm 1.32, F_{20;159}$ = 1.34, p = 0.12), and continent ($R^2$ = 15.29%, ${\beta }_0=-1.81\pm 0.41, F_{4;175}$ = 5.90, p = 0.001). In conclusion, the study reveals substantial occurrence of VAlg in shellfish worldwide, with notable regional and species-specific hotspots. Harmonized and molecular-based surveillance of VAlg in shellfish linked to food safety criteria will be essential to manage its emerging threat. Full article

This study presents the results of monitoring the endangered gastropod Patella ferruginea within a Marine Protected Area in Sardinia. A detailed map of the species distribution was created, and individual density and population structure were analysed by comparing data collected during monitoring campaigns in 2014, 2018, and 2023. A total of 206, 203, and 109 individuals were recorded in 2014, 2018, and 2023, respectively. In 2014 and 2018, 24 and 26 specimens with a maximum diameter of ≥6 cm were observed, while in 2023, only 11 individuals reached this size, with a single specimen measuring 6.5 cm. Linear density showed an average reduction of approximately 37% in the latest campaign compared to the previous one. The coastline under analysis was divided into five sectors based on the degree of protection and exposure to prevailing winds. The overall decline of approximately 50% in the population indicates a decrease affecting all size classes, although it is more pronounced in the larger size classes. Furthermore, analyses of spatial structure using the Minimum Spanning Tree (MST), Clark and Evans’ R index, and Nearest Neighbour Distance (NND) indicate a dispersed distribution already in 2018, which became more pronounced in 2023. These results indicate that current protection measures within the MPA may not be sufficient to ensure long-term population stability, suggesting that conservation strategies for this species should be assessed on a site-specific basis. Full article

A new intracellular parasite of the phylum Apicomplexa is described infecting the digestive gland of the gastropod Bulla striata from the south coast of Portugal. Only merogonial stages enclosed within parasitophorous vacuoles were observed by light and electron microscopy. The meront cytoplasm contained lipid droplets, rough endoplasmic reticulum cisternae, and several round or oval electron-dense microbodies closely associated with amylopectin granules, suggesting that these microbodies may represent glycosomes. Mitochondria or related organelles were not identified. A reticulum of branched tubules extending from the parasitophorous vacuole membrane was observed, likely increasing the surface available for metabolite exchange between parasite and host cell. Merozoites resulting from meront division were present within the parasitophorous vacuoles. They were elongated and slightly curved, measuring 7–8 µm in length and about 2 µm in width, and possessed an apical complex comprising numerous rod-shaped micronemes, rhoptries, and a conoid. Phylogenetic analyses based on a partial 18S rDNA sequence placed this parasite within the coccidian lineage, at the base of the ichthyocolid clade, a recently recognized group of apicomplexans previously known from fish blood cells. This finding expands the host range of ichthyocolids to gastropods and provides the first ultrastructural observations of this lineage, although only of merogonic stages. Full article

Understanding how geometry governs interfacial contact and material removal is central to designing efficient bioinspired surface systems. Gastropod radular teeth form natural arrays of microscale cutting elements optimized for repeated interaction with compliant and semi-rigid substrates, yet experimentally validated shape–performance relationships remain limited. Here, we isolate geometric effects on interfacial mechanics using stereolithography-printed biomimetic tooth arrays inspired by the taenioglossan radula of the hard-substrate grazer Spekia zonata. Two morphologically distinct tooth types (central and marginal) were systematically varied in cusp and stylus geometry (four variants each), while array configuration, material, and boundary conditions were kept constant. Tooth stiffness was quantified in bending tests as load-induced height reduction. Interfacial performance was assessed using a controlled pull-through assay in agarose substrates of two stiffness levels (0.4% and 0.8%), with continuous force recording and measurement of removed mass. Marginal-tooth geometries were stiffer and consistently removed more substrate than central variants. Although work increased substantially in stiffer gels, removal did not scale proportionally and declined for central teeth, revealing a decoupling between mechanical input and yield. Performance correlated with active engagement rather than work alone, indicating geometry-limited contact regimes. These findings establish geometry-controlled stiffness and engagement as key parameters for efficient abrasive interfaces. Full article

The Cândești necropolis is currently the largest excavated Bronze Age necropolis in Romania, with approximately 800 graves. Notably, one grave from an earlier phase of the Monteoru culture (c. 2200–1850 BC) contained a remarkable necklace composed of 22 perforated gastropod shells and a metal pendant. Our investigation adopted an integrated approach, including taxonomic identification, taphonomic, technological and functional analyses, experimental studies, and physico-chemical investigations (Fourier Transform Infrared Spectroscopy and Raman spectroscopy) of the pigment traces present on the shells’s surface. For the metal pendant, X-Ray Fluorescence analysis was conducted to ascertain its elemental composition. The combined analysis yielded unexpected insights: the shells, belonging to the genus Conus, originated from the Mediterranean region. The perforations were not the result of anthropic intervention; rather, they were the result of natural processes, indicating that the shells were collected from thanatocoenoses. The shells were assembled into the necklace using a thread colored with a red pigment. The perforations show signs of prolonged use, suggesting that the necklace was not only a funerary offering. In conclusion, our study indicated that these exotic shells were collected post-mortem already perforated through a rubbing process in the seashore sediments, transported to the site from a distance, and prior to the death of the owner, had been previously worn as personal adornment before being deposited as grave goods. Full article

Pomacea canaliculata, a pervasive invasive gastropod, inflicts significant ecological and economic damage in Chinese rice ecosystems. With the limitations of chemical molluscicides, sustainable biological control solutions are urgently required. This study presents a comprehensive investigation into the biocontrol potential of larvae of the endemic aquatic firefly, Aquatica leii, against Pomacea canaliculata. Through controlled laboratory experiments, we evaluated the feeding preference of larvae when offered a choice between Pomacea canaliculata and a native snail (Cipangopaludina chinensis), and systematically quantified the predatory efficiency (lethal time and consumption amount) across the 3rd to 6th larval instars. Furthermore, the lethal activity of crude extracts from distinct anatomical regions of the larval digestive tract (mouthpart, foregut, midgut, and hindgut) was assayed via injection into Pomacea canaliculata. The larvae accepted Pomacea canaliculata as a viable prey source. Predatory performance varied markedly among instars; 4th-instar larvae exhibited optimal efficacy, characterized by the shortest mean lethal time (7.37 min) and the highest mean consumption (1.23 g). Midgut extract was identified as the principal causative agent of mortality, inducing a 96.7% mortality rate in Pomacea canaliculata, which was significantly superior to the minimal effects observed from other extract types. This points to the midgut secretion as a likely source of potent bioactive compounds responsible for rapid snail lethality, warranting further investigation. responsible for rapid snail lethality. Our results conclusively demonstrate, from both behavioral and physiological vantage points, the feasibility of Aquatica leii larvae as a highly effective native biocontrol agent. This work establishes a critical foundation for future research aimed at the isolation and characterization of the midgut-specific active substances, paving the way for the development of novel, target-selective biogenic molluscicides. Full article

Pearl oyster aquaculture is severely constrained by biofouling organisms, particularly fouling oysters, which substantially impair pearl oyster growth and farming efficiency. This study investigated the selective oyster-feeding behavior of the predatory gastropod Thais luteostoma and evaluated its potential as an ecological biofouling control agent in pearl oyster culture. Field co-culture experiments showed that T. luteostoma did not adversely affect the survival of Pinctada fucata martensii, while effectively reducing biofouling loads and significantly improving pearl oyster growth performance. Laboratory behavioral assays and quantitative analyses revealed a pronounced feeding preference for oysters in T. luteostoma, as evidenced by a higher number of feeding individuals, longer total feeding duration, and greater spatial overlap between feeding hotspots and oyster locations. In addition, digestive enzyme assays indicated marked post-feeding physiological responses in T. luteostoma, with a stronger induction of digestive activity in the digestive gland than in the stomach. Collectively, these findings suggest that T. luteostoma represents a promising and sustainable biological option for managing biofouling in pearl oyster aquaculture, with potential applicability to other high-value bivalve farming systems. Full article

The identification of species complexes in freshwater snails remains challenging due to limited diagnostic morphological characters and incomplete taxonomic knowledge in many taxa. Within the family Bithyniidae, species have traditionally been classified using shell morphology and genital anatomy to distinguish intraspecific variation from interspecific differences. However, extensive morphological plasticity has hindered reliable species delimitation, and the presence of cryptic diversity further complicates taxonomy. Recent DNA barcoding studies of Hydrobioides have provided evidence of such cryptic diversity, highlighting the need for taxonomic reassessment within the genus. In the present study, we examined morphological variation in Hydrobioides nassa from Thailand in conjunction with mitochondrial DNA sequence data. Molecular phylogenetic analyses based on cytochrome c oxidase subunit I (cox1) sequences revealed three well-supported genetic lineages within H. nassa, accompanied by high levels of pairwise genetic divergence. Morphological comparisons of shell, operculum, and radular characters further supported differentiation among these lineages, although some characters showed overlap. While Hydrobioides has previously been regarded as comprising a single morphologically defined species, our results demonstrate that H. nassa represents a complex of genetically distinct lineages with subtle but consistent morphological differences. This study highlights the importance of integrating molecular approaches with traditional morphological analyses to improve taxonomic resolution and to better understand biodiversity within freshwater snail groups exhibiting cryptic diversity. 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

This study assesses the diversity, distribution, and ecological interactions of freshwater gastropod communities across eight sites in southern Iraq, spanning marshes, rivers, and canal systems within the Tigris-Euphrates basin. Diversity indices (Shannon–Wiener H′ and Pielou’s evenness J) were calculated to evaluate community structure, and a revised stacked bar chart of relative abundances revealed widespread dominance by species such as Melanoides tuberculata and Physella acuta, which frequently exceeded 50% of local assemblages. While P. acuta is an established invasive species, M. tuberculata is now considered native or long-established in the region. Species interactions were examined using Pianka’s niche overlap index, and null model testing (999 permutations) revealed only a few statistically significant overlaps (p < 0.05), suggesting that species co-occurrence is shaped more by environmental filtering than direct competition. To directly examine the influence of environmental drivers on species composition, Multiple Factor Analysis (MFA) was performed. MFA revealed patterns of association between dissolved oxygen, salinity, and species assemblages, suggesting these abiotic factors may influence community structure. To our knowledge, this study is the first in Iraq to use null models, constrained ordination, and MFA to investigate community assembly of freshwater gastropods, ultimately producing novel insights regarding the interactions between environmental stressors and aquatic biodiversity patterns. The results of this study highlight the need for long-term ecological monitoring and conservation in marshland habitats important for the resiliency of native species. Full article