Biodiversity knowledge gaps undermine biogeographical analyses, leading to biased interpretations with direct consequences for research, conservation and management. In Mexico, marine invertebrate diversity remains poorly documented due to historical physical, economic and social limitations. We quantified the taxonomic, spatial and temporal coverage of digitally accessible records for Mexican marine invertebrates to identify biases, gaps and priorities for future surveys. We compiled 121,502 records representing 4642 species of sponges, cnidarians, echinoderms and molluscs from two open-access repositories (GBIF and OBIS). Taxonomic coverage was evaluated based on the historical accumulation of documented species and the annual number of records, providing a temporal perspective on taxonomic knowledge. Inventory and taxonomic completeness were estimated across 50 × 50 km grid cells to identify well-surveyed areas and temporal coverage was examined relative to 2024. Ignorance maps combining the above metrics were generated to highlight priority areas for sampling. Knowledge of marine invertebrates in Mexico has expanded since the 1930s, yet biodiversity data cover less than 35% of the study area and only a small fraction of cells qualifies as well-surveyed. Records remain strongly biased towards coastal and reef systems, while deep-sea and offshore environments are largely unsampled. Temporal gaps are also evident with many areas lacking recent records. These patterns reveal persistent and uneven knowledge shortfalls. Addressing them requires targeted surveys in poorly sampled marine-coastal and deep-sea environments, as well as re-surveys in sites not visited for decades where new discoveries and updated biodiversity baselines are most likely to be found.

Unveiling the mechanisms of oxidative stress-mediated multi-pathway programmed cell death in Ruditapes philippinarum exposed to butylated hydroxytoluene (BHT).

Ascidians, a class of tunicates, are marine invertebrates with valveless, tubular hearts. Recent experiments suggest that the hearts of Ciona robusta have two distinct pacemakers, one at each end of the heart tube. Variations in the pacing intervals of these two pacemakers are implicated as being responsible for an unusual phenomenon: after minutes of sustained pumping of blood in one direction, the heart can suddenly reverse the direction of blood flow, pumping blood in the opposite direction for several minutes. In this article, we explore possible electrophysiological bases for these reversals and the roles that different ionic currents might play. We model the heart tube as an excitable, one-dimensional medium using the standard cable equation. For cells within the interior of the cable, we use a three-current model for the membrane potential, the three currents representing the total transmembrane currents associated with sodium, potassium, and calcium. As the two pacemakers consist of cells that exhibit automaticity, cells at the cable boundaries are simulated using an adaptation of a sinoatrial node model.

Envenomations, stings, and traumas caused by marine invertebrates: from scientific facts to a forensic vision towards sustainable health and conservation strategies:a review.

• Enamel(oid) δ 66 Zn values are well preserved in Late Cretaceous marine vertebrates. • Zinc isotopes reveal significant resource partitioning among Cretaceous marine taxa. • Late Cretaceous sharks occupied top trophic positions comparable to today. Food web structures and trophic interactions among Late Cretaceous marine taxa remain largely ambiguous due to the challenges in reconstructing ecological interactions in the deep-time fossil record. Here we analyse enamel(oid) δ 66 Zn values, a trophic-level proxy, across 16 marine vertebrate taxa from two Turonian–Coniacian boundary localities in New Mexico and Kansas, USA, deposited in what was then the Western Interior Seaway (WIS). Our results demonstrate well-preserved enamel(oid) δ 66 Zn values in both localities, but locality-specific differences in the diagenetic modification of dentine δ 66 Zn values. We highlight significant resource partitioning among the analysed taxa within the WIS, including sharks. For example, Archaeolamna , Cretodus and Cretoxyrhina occupied very high trophic positions, whereas Cretalamna was likely foraging opportunistically across several trophic levels. Our study expands the use of enamel(oid) δ 66 Zn analysis to Mesozoic fossils for the first time and demonstrates that robust reconstructions of food web dynamics and trophic interactions are possible in deep time as far back as 90 million years ago, providing new avenues for palaeobiological and evolutionary research.

Advances and perspectives of in vitro cell toxicology in aquatic animals.

Marine invertebrates harbor diverse bacterial communities that contribute to host defense by producing antibacterial compounds. In this study, 258 cultivable bacterial isolates from corals (Porites panamensis, P. lobata), the sea urchin Echinometra vanbrunti, and the ctenophore Mnemiopsis leidyi were screened against aquaculture and human pathogens. 14% (37 isolates) exhibited antibacterial activity, predominantly from E. vanbrunti and M. leidyi. Multiple assays revealed strong, broad-spectrum inhibition, particularly against aquaculture pathogens such as Listonella anguillarum, Photobacterium damselae, and Vibrio parahaemolyticus, whereas human pathogens showed limited sensitivity. Notably, isolates MT26 and MT43 displayed the widest inhibitory spectra, and EV78 and MM7 demonstrated high inhibition rates in growth assays. Taxonomic analysis showed that Bacillus was the dominant genus (65%), followed by Vibrio and Pseudoalteromonas. These findings highlight marine invertebrate-associated bacteria as promising sources of bioactive compounds with potential applications in aquaculture and biotechnology.

Targeting microglial dysfunction: The antioxidant potential of and the regulation of microglial responsiveness by dermatan sulfate from a marine invertebrate.

Museum specimens are widely used for PCR-based pathogen detection, yet their potential for metagenomic discovery of beneficial microbes remains underexplored, largely due to difficulties in distinguishing true symbionts from contaminants. Here, we use metagenomics of museum specimens to uncover symbioses in endangered or difficult-to-collect animals, such as nudibranchs. To date, Doriopsilla is the only nudibranch demonstrated to harbor an uncultured symbiont involved in chemical defense, leaving it unclear whether comparable associations occur in other nudibranchs. We hypothesized that bona fide symbionts should belong to abundant, uncultured lineages consistently present across individuals of the same host taxon collected across space and time. Using ethanol-preserved specimens archived for up to 30years, we doubled the number of available nudibranch microbiome datasets and found that dominant uncultured symbionts are rare, with most nudibranchs likely relying on alternative chemical defense mechanisms. An exception were Polycera and Felimare that contained two previously unknown symbionts, Candidatus Polyceribacter and Candidatus Felimaribacter, from distinct uncultured orders that are globally rare in marine metagenomes. These symbionts encode diverse biosynthetic gene clusters exhibiting strain- and species-level microdiversity consistent with metabolites previously reported from their hosts. Their restricted host distribution, phylogenetic distinctiveness, and phylogenetic similarity to symbionts of sponges or corals that are not nudibranch prey, support long-term evolutionary specialization and functional convergence. Fine-scale diversification further suggests host-driven microbial adaptation following symbiosis establishment. Overall, this study establishes museomics as a robust framework for symbiosis research and advances understanding of the evolutionary and chemical ecology of host-microbe interactions in rare marine invertebrates. Video Abstract.

Functional analysis of IRF1/2 homolog in immune regulation of the sea urchin Strongylocentrotus intermedius.

Climate change and ocean acidification outweigh local stressors in Mediterranean mussels: a multi-method convergence analysis.

Bioaccumulation assessment is a key component of chemical regulations, with fish-based bioconcentration factors (BCFs) serving as the standard metric. Because conventional fish BCF tests (OECD TG 305) require many vertebrates, alternative tests such as the amphipod Hyalella azteca BCF test (OECD TG 321, HYBIT) have been developed. However, physiological and ecological differences between fish and aquatic invertebrates affect chemical uptake and elimination, raising uncertainty when applying fish-based BCF thresholds directly to invertebrate data. In this study, empirical and model-based approaches were combined to compare bioaccumulation potential in H. azteca and fish. An evaluation of empirical BCFs showed consistent categorizations between H. azteca and fish for non-bioaccumulative chemicals (log KOW ≤ 4.5) and for recalcitrant organochlorines categorized as (very) bioaccumulative. In contrast, for biotransformed chemicals, H. azteca BCFs frequently exceeded fish BCFs and often surpassed regulatory thresholds, reflecting the amphipod's lower metabolic capacity. A food-chain bioaccumulation model was used to assess the influence of chemical (e.g.,, KOW, biotransformation rate constant) and biological (e.g.,, metabolic capacity) parameters. At log KOW 5, amphipod BCFs were lower than fish BCFs for poorly biotransformed chemicals. However, at log KOW ≥ 5, moderately to highly biotransformed chemicals showed higher BCFs in amphipods than both fish BCFs and biomagnification metrics (BMF, TMF), indicating potential overestimation of bioaccumulation potential. These findings highlight potential misalignment in bioaccumulation assessment outcomes when amphipod BCFs substitute fish data. Applying tiered, weight-of-evidence assessment frameworks that integrate multiple bioaccumulation metrics with biotransformation information can strengthen the scientific robustness of assessments and contextualize HYBIT results.

Quantitative passive acoustic monitoring in benthic settings requires conversion of recorded amplitudes into absolute sound pressure levels (SPL, dB re 1 µPa). We tested whether HydroMoth (HM) recorders can provide sufficiently accurate SPL estimates in the low-frequency band relevant to benthic marine invertebrates and ship noise. Nine units were calibrated by a single-point offset using a 1000 Hz reference tone in an anechoic chamber and subsequently compared to a factory-calibrated SoundTrap ST600 in a controlled playback experiment (100-1000 Hz). In the pool dataset (HM1-HM5), deviations ranged from -2.6 to +1.8 dB with mean absolute errors typically within ~1-3 dB across frequencies; field measurements (HM6-HM9) showed deviations of similar magnitude, with mean deviations ranging from -0.5 to +1.0 dB across frequencies and mean absolute errors between 0.9 and 2.4 dB. Device orientation was fixed and identical across setups, reflecting benthic use cases where orientation is constrained and orientation related sensitivity differences act as a constant factor within deployments. These results show that HydroMoth recorders, under defined benthic conditions and within 100-1000 Hz, can provide SPL estimates with deviations comparable to those observed between commercial reference systems. This enables quantitative use of low-cost recorders in applications where absolute accuracy within a few decibels is sufficient.

Metamorphosis is an obligate developmental transition for most marine invertebrates with a biphasic life cycle, representing a critical ontogenetic phase. This process involves extensive morphological and physiological changes that incur high mortality, thereby regulating population dynamics. This study establishes a single-cell transcriptomic atlas of larval and juvenile Heliocidaris crassispina, providing a comprehensive analysis at single-cell resolution. eight distinct cell types were identified: digestive, epithelial, germ, immune, muscle, nerve, proliferating, and skeletogenic cells. These findings establish a foundation for future research into invertebrate metamorphosis at the single-cell level.

Representative species weight is a critical ecological index for modeling, vulnerability assessment, and toxicity prediction, yet scientifically validated data for aquatic invertebrates remain limited. To address this gap, we present the first literature-based strategy to estimate and validate representative dry weights of freshwater invertebrate species in Korean rivers using Length-Weight Relationships (LWRs). Species length and dry weight records were compiled from domestic field guides, while dry weight records were compiled from both domestic and global literature. LWR coefficients (a and b) were then calculated at genus, family, and order levels and preprocessed under control conditions. Among the taxonomic levels tested, averaging genus-level coefficients yielded the highest concordance with field-measured dry weights (R2 = 0.6633, n = 240), outperforming broader taxonomic levels. Furthermore, a logarithmic correlation analysis confirmed that greater numbers of LWR sources improve predictive accuracy, particularly at the genus level. Based on this optimal strategy, representative dry weights were estimated for 563 taxa. This methodology fills a critical data gap by leveraging existing literature to generate reliable species-specific weight indices without additional field measurements. Our approach provides a quantitative foundation for biomass estimation in data-limited freshwater ecosystems and supports improved ecological modeling, conservation planning, and machine learning-based impact prediction.

Elevated invertebrate methylmercury concentrations across functional feeding groups in a eutrophic bog post-flooding.

Clorsulon is highly toxic to aquatic organisms, including fish and invertebrates, and can have long-term adverse effects on the environment. It is commonly used in cattle, and residues excreted in dung can negatively affect dung-dependent insects. Direct contamination of waterways, such as ponds, streams, or ditches, should be strictly avoided. Therefore, clorsulon detection is pivotal. In this study, density functional theory (DFT) and semiempirical metadynamics are used to investigate the properties of polypyrrole-based molecularly imprinted polymer (MIP-PPy) as a receptor targeting clorsulon detection. To address this aim, the electronic and physicochemical properties of PPy are studied, and the optimal imprinting conditions are calculated. The novelty of this study lies in the in silico characterization of the effects of PPy conformers on its electrochemical properties under different couplings. Next, the sensing mechanism via binding sites formed in the modeled imprinted polymer is described. The ratio of pyrrole monomers needed to form the optimal imprinted PPy for clorsulon drug detection is determined, and the solvent effect is evaluated. A water-based solvent was selected as the best medium and solvent for preparing the polymerization mixture, since it does not interfere with the optimized monomers and template molecules at a 16:1 ratio. Moreover, the αβ- and ββ-coupling present in PPy chains was considered and compared with the ideal configuration of all αα-coupled chains. Finally, the sensing mechanism and electrochemical properties of the in silico-designed MIP-PPy are discussed.

Polar marine invertebrate giants are proposed to have emerged from the greater availability of environmental oxygen, overcoming the viscosity of cold water and avoiding oxygen poisoning. However, molecular evidence on their metabolic adaptations is lacking to date. Consequently, we characterised the metabolome profiles of a number of marine Antarctic giants and their regular-size relatives exposed acutely in the laboratory either under mean seasonal conditions or elevated temperature. Giants from very distinct taxa share the differential utilisation of metabolic pathways involved in energy production, suggesting an adaptive convergence of metabolic reprogramming to meet the challenge of possessing larger bodies and facing harsh polar conditions. Further, we show that giants are not just larger regular-size species, as indicated by a breakpoint in the allometric relationship for metabolomics scores. Finally, giants do not appear to be more sensitive to ocean warming when compared to their regular-size relatives, all species tested showing no short-term metabolomics reprogramming under elevated temperatures.

Many marine invertebrate larvae are influenced by environmental factors during development, with diatom biofilms playing a crucial role in the settlement and metamorphosis of bivalve larvae. This study found that Navicula sp. biofilms alter the larval microenvironment by increasing dissolved oxygen levels through photosynthesis and decreasing nitrate, ammonium, and phosphate levels in the surrounding water. Exposure to Navicula sp. biofilms induced directional swimming in larvae and significantly shortened the time required for settlement and metamorphosis. Biofilms formed by Navicula sp. contained effective substances and key infochemicals that promoted the settlement and metamorphosis of Mizuhopecten yessoensis larvae. Soluble polysaccharides containing β-1,4-glycosidic bonds secreted by the biofilm were recognized by the larvae, triggering settlement and metamorphosis signaling. Untargeted and targeted metabolomic analyses revealed increased levels of cGMP (Cyclic guanosine monophosphate), and GMP (Guanosine monophosphate), suggesting that larval settlement and metamorphosis may be associated with cGMP regulation. Based on these results, cGMP was selected for subsequent functional analyses. Treatments with the NO donor SNAP, the cGMP analog 8-Br-cGMP, and the sGC activator BAY 41-2272 significantly promoted metamorphosis, whereas the sGC inhibitor ODQ suppressed metamorphosis in a dose-dependent manner. These findings demonstrate that the NO-sGC-cGMP pathway positively regulates the settlement and metamorphosis of M. yessoensis larvae, with cGMP serving as a key effector. This study provides new insights into the mechanisms underlying larval settlement and metamorphosis in bivalves.

IntroductionThe increasing use of resin-based dental materials has prompted questions about their environmental footprint. During clinical procedures, small amounts of unpolymerized monomers may enter wastewater systems, and their possible effects on aquatic invertebrates remain insufficiently explored. We hypothesized that commonly used resin-based dental monomers could exert developmental and cellular effects in an aquatic invertebrate model.Materials and MethodsThe acute and sublethal effects of five monomers associated with dental composites, namely – BPA (bisphenol A), Bis-DMA (bisphenol A dimethacrylate), Bis-GMA (bisphenol A-glycidyl methacrylate), Bis-EMA (bisphenol A ethoxylate dimethacrylate), and TEG-DMA (triethylene glycol dimethacrylate) – were evaluated in Artemia salina at both cyst and naupliar stages. The effects on naupliar survival, body length, and Lactate dehydrogenase (LDH) activity were measured to assess compound-specific biological responses.ResultsBis-GMA, Bis-DMA, and BPA significantly reduced survival, while Bis-EMA caused modest mortality, and TEG-DMA had no effect. Despite these differences in survival, most monomers affected naupliar growth, with greater developmental sensitivity observed following cyst-stage exposure. However, growth responses were compound specific and not uniformly dose-dependent across all monomers. LDH responses were monomer specific: Bis-GMA and Bis-DMA increased LDH activity, although Bis-DMA showed no consistent effect on growth, whereas BPA and TEG-DMA showed reductions in LDH activity, despite observed growth inhibition, and Bis-EMA showed no significant change.ConclusionTaken together, our findings show that dental resin monomers differ in their developmental and metabolic impacts, highlighting the importance of considering safety alongside clinical performance when designing and selecting dental biomaterials. As the concentrations used were for hazard screening, these results indicate possible biological effects under controlled conditions but do not necessarily reflect environmental exposure scenarios or ecological risk. Additional studies at environmentally relevant exposure levels are needed to better evaluate ecological safety and support the development of more sustainable dental materials.