Search Results (720)

Plastic pollution has emerged as one of the most pervasive environmental challenges, with microplastics (MPs) widely distributed across marine ecosystems worldwide. This study aimed to assess the uptake of MPs by key fish and invertebrate species from different locations in the coastal zone of the Bulgarian Black Sea. Fish were collected during routine monitoring surveys in September–November 2024, while invertebrates were obtained via scuba diving. The presence of MPs in fish stomachs and invertebrate soft tissues, and their polymer composition, shape and size were analyzed using an Agilent 8700 LDIR Chemical Imaging System. Potential biological effects of ingested MPs were evaluated by an integrated Specific Oxidative Stress (SOS) index. The results revealed MP uptake levels comparable to those reported globally. Small-sized particles (<50 µm) with rounded shapes were most abundant across studied taxa. Polymer composition varied considerably depending on species and sampling region, indicating differences in exposure sources and environmental conditions. Oxidative stress levels in both fish and invertebrates showed substantial interspecific variation, and clear differences between the northern and southern region of the Bulgarian Black Sea. Overall, elevated uptake of MPs appears to contribute to oxidative stress in marine organisms, potentially affecting their health status, resilience, and adaptive capacity, as reflected by increased SOS index values. Full article

Marine invertebrates are characterized by high species diversity, a wide distribution, ease of culture, low cost, short life cycles and high sensitivity to pollutants, which makes them excellent models for observing toxic effects and elucidating underlying mechanisms. This paper reviews representative species from three phyla—Arthropoda, Mollusca, and Echinodermata—under both single emerging contaminant exposure and combined exposure scenarios, and analyzes the reproductive and neurotoxic impacts of these contaminants on marine invertebrates. Neurotoxicity is mediated by several key mechanisms: inhibition of acetylcholinesterase activity; disruption of neurotransmitter balance, oxidative stress; and cellular damage, interference with embryonic neural development and axis specification, and impairment of neural cell differentiation and migration. Reproductive toxicity impairs reproductive development by disrupting endocrine signaling, inducing oxidative stress, downregulating reproduction-related genes and damaging gonadal structure. Studies have shown that, besides environmental factors, contaminant concentration is closely correlated with toxic potency and differing concentration ratios can lead to either antagonistic or synergistic effects in combined toxicity. Current research has largely focused on single or binary contaminant systems, whereas studies on multi-contaminant mixtures and their interactions with multiple environmental factors remain limited. Future research should prioritize combined exposure to multiple contaminants, long-term multigenerational observations and the development of comprehensive ecological risk assessment models and monitoring standards, thereby providing a scientific basis for marine ecological conservation. Full article

The marine benthic invertebrate Urechis unicinctus exhibits extraordinary tolerance to hypoxic environments, making its coelomic fluid a unique and promising biological source for discovering novel stress-adapting macromolecules. Polysaccharides derived from the coelomic fluid of U. unicinctus were systematically extracted, fractionated, and characterized to investigate their structural features and associated biological activities. Gradient ethanol precipitation (30–80%) combined with DEAE-52 ion exchange chromatography yielded twelve fractions with distinct physicochemical properties. Significant variations were observed in molecular weight (10³–10⁵ Da), sulfate content (3.77–24.26%), and monosaccharide composition. High-ethanol fractions, particularly U68P and U18P (extracted at 60 °C and 100 °C, respectively, and both precipitated with 80% ethanol), were enriched in low-molecular-weight, highly sulfated heteropolysaccharides composed of galactose, fucose, glucosamine, and ribose. These fractions exhibited superior antioxidant activities, including strong scavenging effects against DPPH, ABTS, and hydroxyl radicals. Moreover, they demonstrated pronounced neuroprotective effects in the oxygen–glucose deprivation/reoxygenation (OGD/R) model using SH-SY5Y cells, significantly improving cell viability. Structure–activity relationship analysis revealed that reduced molecular weight, increased sulfation degree, and more diverse monosaccharide composition (e.g., more diverse monosaccharide composition) synergistically contribute to improved bioactivity by facilitating cellular uptake and exposing functional groups. In contrast, high-molecular-weight homoglucan fractions showed relatively weak effects. Overall, this study identifies U. unicinctus coelomic fluid as a promising source of bioactive polysaccharides and provides a theoretical basis for the development of marine-derived anti-hypoxic and antioxidant agents. Full article

Many filter-feeding invertebrates consume microplastics (MP) under laboratory conditions, but little is known about newly settled, field-collected juveniles. To address this information gap, we collected 3439 juvenile invertebrates in the Indian River Lagoon (IRL), FL, USA. Previous studies suggest that the IRL is a MP hotspot. A total of 70% of IRL adult oysters (Crassostrea virginica) contained MP (mean: 2.3 MP/individual), and MP number and MP length were positively correlated with animal size. We predicted that juvenile C. virginica and other sessile invertebrates would contain MP with a positive correlation to animal size. Five species were examined; 51% were C. virginica (mean shell length ± SD: 6.3 ± 4.7 mm). Overall, 117 (3.4%) animals contained potential MP (fibers: 90.7%). Of these particles that matched FTIR databases with a score of 70% or greater, 51% were plastic and 49% were anthropogenically modified particles. No correlations to animal size were found for particle presence (logistic regressions: p ≥ 0.20 for all species) or particle length (linear regressions: p ≥ 0.23 for all species). Thus, even though found in a MP hotspot, our extrapolated results suggest few juveniles (<1%) contained MP. This information is important for understanding the relationship between MP and the life histories of filter-feeding animals, especially for species considered biological indicators of MP. Full article

Ascidians are a group of marine invertebrates, most of which are sessile and soft-bodied. Their lack of an adaptive immune system makes them rely on innate immune responses to detect and eliminate invading microbes. Antimicrobial peptides (AMPs) play an essential part in this process. In this paper, we present the isolation, structure elucidation, and bioactivities of two new cysteine-rich peptides (CRPs) from the Arctic marine ascidian Synoicum turgens. The sequences and structures of the peptides were determined by Edman degradation sequencing, mass spectrometry, and NMR analysis. This revealed two novel 2 kDa peptides, St-CRP-1 and St-CRP-2, with neutral net charge and C-terminal amidation. St-CRP-1 consisted of 18 amino acids and displayed selective and moderate growth inhibition of two Gram-positive bacterial strains (Bacillus subtilis and Corynebacterium glutamicum) at 24.6 µM, whereas St-CRP-2 consisted of 19 amino acids and inhibited the growth of B. subtilis at 49.2 µM. St-CRP-1 had no effect on two mammalian cell lines or the brine shrimp Artemia salina at the highest concentration tested. Structural analysis of the St-CRPs indicated a Cys1–Cys6, Cys2–Cys4, and Cys3–Cys5 disulfide connectivity, which is also found in alpha-defensins. The results from this study show that Arctic marine ascidians are a rich source of novel bioactive peptides. Full article

Natural and artificial marine surfaces are rapidly colonized by microscopic communities, including propagules of some macrofoulers, in a process called biofouling. These microbiomes play an important role in modulating the evolving microbial community, as well as the attachment and settlement of other invertebrate larvae. Microbiomes act as biochemical and biophysical interfaces in marine communities. This review explores the gene-level processes that underlie microbial functions relevant to biofouling and larval settlement, such as quorum sensing, extracellular polymeric substance (EPS), and innate immune system components, as well as biosynthetic and degradative processes that generate signaling molecules. We critically evaluate current knowledge on how microbial metabolites promote or inhibit larval recruitment in corals, barnacles, polychaetes, and bivalves, and how omics-based approaches are uncovering the functional potential of biofilm communities. We evaluate how these interactions influence ecosystem services, such as habitat structuring, reef resilience, and coastal infrastructure maintenance. Full article

Glyphosate is one of the most widely used herbicides worldwide and has been increasingly reported in aquatic environments, including riverine, estuarine, and coastal systems. However, information on its intestinal effects in benthic marine invertebrates remains limited. In this study, we investigated dose-dependent intestinal responses of the sea cucumber Apostichopus japonicus following acute waterborne glyphosate exposure using integrated transcriptomic and metabolomic analyses. Sea cucumbers were exposed for 24 h to four nominal glyphosate concentrations: 0, 9.23, 46.15, and 230.77 mg/L. Mortality occurred only in the highest-concentration group, allowing phenotypic stratification of this group into high-dose survivors (HL) and high-dose dead individuals (HD) for downstream multi-omics comparisons. Principal component analysis and orthogonal partial least-squares discriminant analysis indicated clear exposure- and phenotype-associated shifts in intestinal molecular profiles. Differential expression analysis and pathway enrichment showed that low-dose exposure was mainly associated with metabolic and digestion-related adjustments, whereas higher exposure levels were characterized by broader perturbation of immune regulation, stress-response signaling, proteostasis-related processes, and cell fate-associated pathways. Metabolomic profiling further revealed progressive remodeling of lipid, amino acid, energy, redox, and transport-related pathways, with the most extensive alterations observed in HD. Integrated transcriptome–metabolome analysis supported increasingly structured cross-omics covariation with rising exposure severity, highlighting coordinated intestinal system disruption under high-dose glyphosate stress. Overall, these findings demonstrate that acute waterborne glyphosate exposure induces dose-dependent intestinal molecular reprogramming in A. japonicus, with marked divergence between surviving and dead individuals at the highest exposure level. This study provides mechanistic evidence for early intestinal responses to glyphosate in a representative marine deposit-feeding invertebrate and offers a basis for future studies linking controlled exposure experiments with environmentally relevant marine risk scenarios. Full article

Innovation in the field of bioinspired therapeutic anticoagulants, as an alternative to heparin and its derivatives, is increasingly focused toward the discovery of new molecules from natural sources. Inspired by the compelling observation that marine organisms possess a wide array of acidic polysaccharides (APs) within their extracellular matrix (ECM) with promising anticoagulant potential, this study investigates AP topographic distribution, content, and bioactivity in the body of seven phylogenetically distant Mediterranean sponge species. Tissue architecture was evidenced by Alcian Blue histological staining whereas biochemical analyses were carried out on APs purified from papain-digested tissue extracts using anion-exchange chromatography. Four polysaccharide fractions were obtained and assessed for hexuronic acid content. The two most abundant ones, up to 98% of the total, were characterized by electrophoretic analyses, and assessed in vitro for inhibitory activity on blood coagulation. Histology evidenced a heterogeneous distribution of APs within the sponge’s ECM, along with marked interspecific variability in both concentration and electrophoretic profiles. Neither Tethya aurantium nor Crambe crambe showed any significant in vitro effects on coagulation, whereas the other species exhibited a strong inhibitory effect on both activated partial thromboplastin time (aPTT) and thrombin time (TT), comparable to standard heparin (Hep). Concerning aPTT, both I. retidermata and H. communis reached the endpoint of 300 s at 5 µgUA/mL, whereas S. spinosulus, O. lobularis, A. aerophoba reached it at 10 µgUA/mL. With reference to TT, A. aerophoba, I. retidermata, S. spinosulus and H. communis had comparable effects on coagulation time with respect to Hep (endpoint at 5 µgUA/mL), whereas O. lobularis was less effective (endpoint at 100 µgUA/mL). These findings show that Porifera, one of the most basal Metazoa, have an ECM rich in APs with anticoagulant properties towards both intrinsic and common pathways of coagulation, consistent with known inhibitory mechanisms reported for certain marine sulfated polysaccharides derived from other invertebrate taxa. These molecules, obtainable through sustainable blue technology, represent compelling candidates for bioinspired next-generation anticoagulant therapeutics, with broader applications in regenerative medicine and tissue engineering. Full article

Sea urchins are invertebrates that play a crucial role in marine ecosystems by controlling benthic algal communities and whose natural populations are being affected by different biotic and abiotic factors. Triggering physiological processes promotes the activation of certain metabolic pathways, so oxidative status markers could be a suitable tool to asses maturation stage in which natural populations are. Antioxidant status of three species of Mediterranean Sea urchins, A. lixula, P. lividus and S. granularis, was evaluated in gonadal and digestive tissue. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione s-transferase (GST), glucose 6-phosphate dehydrogenase (G6PDH), NAD(P)H: quinone oxidoreductase (NQO1) and lipid peroxidation were assayed. Significant differences were found among species, displaying in general higher antioxidant activity in A. lixula and S. granularis compared to P. lividus. A significant effect of sex was observed with females exhibiting a higher gonadosomatic index and higher levels of lipid peroxidation mainly in A. lixula. These results seem to be related to metabolic fluctuations associated with the gonadal maturation stage. Changes in digestive tissue were less evident, but some differences among species could be related to triggered digestive processes for replenishment of energy reserves in gonads. Oxidative status can be a useful complementary tool to evaluate gonadal condition in species of sea urchin from the same habitat. Integrative physiological and biochemical studies will contribute to the knowledge of invertebrate physiology. Full article

Nitrogen metabolism is fundamental to all organisms, with ammonium transporters (Amt) playing a pivotal role in transmembrane ammonium transport. Brachiopods, as “living fossils”, offer unique insights into the evolutionary adaptation of marine invertebrates. This study systematically identified and characterized the Amt gene family in the brachiopod Lingula anatina. Five canonical Amt genes were identified, with nonrandom chromosomal distribution and evidence of lineage-specific duplication events. Phylogenetic analysis revealed that these Amt proteins cluster into three well-supported clades, showing closer affinity to Caenorhabditis elegans, reflecting conserved ancestral features predating protostome radiation. Structural predictions showed that LanAmtA and LanAmtB retain the canonical 11-transmembrane helix (TMH) topology with an extracellular N-terminus, while LanAmtC features a unique 12-TMH architecture with an intracellular N-terminus, resembling certain vertebrate Amt-related proteins. Critical functional residues involved in ammonium selectivity and transport were preserved across all paralogs. Expression profiling revealed non-redundant spatiotemporal patterns: LanAmtA1 and LanAmtB2 dominate early embryogenesis, with LanAmtB2 becoming the major isoform in late developmental stages; LanAmtC exhibits constitutive high expression across adult tissues. Collectively, our findings demonstrate that the L. anatina Amt family expanded via local duplications, evolving structural stability, regulatory diversity, and functional specificity. This study provides a comprehensive molecular framework for understanding the evolutionary adaptation of nitrogen-handling mechanisms in basal lophotrochozoans and sheds light on how intertidal organisms cope with dynamic environmental conditions. Full article

Fossils provide invaluable data for evolutionary studies in oceanic islands. The paleontological record of the Macaronesian archipelagos has been the target of many researchers for a long time, with a recent surge in interest in scientific research related to their paleontological heritage. In the Macaronesian Azores archipelago, the marine invertebrate fossil record from the warmest period of the Last Interglacial stage (also known as Marine Isotopic Stage 5e—MIS 5e) represents approximately 95.6% of the total species. In contrast, the MIS 5e marine vertebrate fossil record comprises only four reported species (2.2%), with marine algae accounting for the remaining 2.2% (four species). This study reports on—and adds to the paleobiodiversity of the MIS 5e deposits at Santa Maria Island (Azores Archipelago)—two marine mesopelagic lanternfishes, identified from their otoliths: Diaphus cf. holti Tåning, 1918, and Symbolophorus veranyi (Moreau, 1888). Finally, we offer a plausible explanation for the presence of mesopelagic fishes in the MIS 5e fossiliferous deposits of Santa Maria Island. Full article

Analyzing microplastics in marine organisms is essential for understanding the ecological and toxicological impacts of marine microplastic pollution in coastal food webs. This study investigated microplastic ingestion in three edible invertebrate species commonly found on Vietnamese sandy beaches, wedge clam Donax sp., hermit crabs Pagurus sp., and horn-eyed ghost crabs Ocypode ceratophthalmus, which differ in feeding modes and mobility, using micro-Fourier Transform Infrared spectroscopy (µ-FTIR) with a detection limit of 20 µm. Results showed that all three species ingested microplastics, with ingestion patterns varying according to species-specific traits and habitat-related feeding behaviors. The highly mobile crabs Ocypode ceratophthalmus (omnivore) and Pagurus sp. (scavenger) were found to partially reflect the polymer pollution in their ambient environment. The higher ingestion rate and diversity of polymer types observed in sedentary Donax sp. suggest that this species could serve as a potential bioindicator for microplastic pollution, given its mixed suspension and deposit feeding habits that integrate pollution from both the water column and beach sediments. Overall, these results reveal widespread microplastic ingestion among edible beach fauna, highlighting potential ecological and human health concerns, and emphasizing the need for targeted pollution management and increased public awareness. Advancing our understanding will require larger datasets and controlled experiments to more robustly assess species-specific responses and the likelihood of trophic transfer. Full article

The Black Sea is highly vulnerable to environmental degradation, making the evaluation of contaminant transfer within its food webs essential for ecosystem protection, sustainable resource management, and human health risk assessment. Marine organisms accumulate contaminants through three main processes: bioconcentration (direct uptake from the abiotic environment), biomagnification (trophic transfer through consumption of contaminated prey), and bioaccumulation, which integrates contaminants from all exposure pathways. Despite numerous studies reporting contaminant concentrations in Black Sea waters, sediments, and biota, integrated analyses of trophic transfer within both pelagic and benthic food webs in the Romanian coastal sector remain limited. This study assessed the bioamplification of heavy metals—HMs, persistent organic pollutants—POPs (OCPs, PCBs) and polycyclic aromatic hydrocarbons—PAHs along the main pelagic and benthic food webs in the Romanian coastal sector, based on concentrations measured in representative invertebrate and fish species. The results revealed a compartment-driven contamination pattern, with the benthic food web functioning as an important reservoir and transfer pathway. Heavy metals showed variable and context-dependent trophic transfer, with selective amplification for Cu and Ni in some benthic links, trophic dilution or neutral transfer for Cd and Pb, and more consistent retention for Cr. In contrast, several PCB congeners showed clear biomagnification, particularly in benthic predator–prey relationships. PAHs displayed compound-dependent trophic transfer, with more pronounced amplification in benthic pathways. Overall, biomagnification was stronger for organic pollutants, particularly PCBs, than for heavy metals. The study contributes to two United Nations Sustainable Development Goals (SDGs): SDG 14 (Life Below Water) and SDG 12 (Responsible Consumption and Production). Full article

Marine invertebrates produce a remarkable diversity of polyhydroxylated steroids and secosteroids whose structural features—particularly vicinal (1,2-)diols, 1,3-diols, and clustered hydroxyl arrays—make them well suited for coordination with boron species. In the marine environment, where boron is abundant, chemically stable, and predominantly present as borate under mildly alkaline conditions, such interactions are not only plausible but may be widespread. This review examines the chemistry of boron–steroid complexation in marine systems, emphasizing how rigid steroidal frameworks preorganize diol motifs to form reversible yet stable borate esters under environmentally relevant conditions. We discuss how polyhydroxy steroids may exist in dynamic equilibria between free and boron-bound forms, with speciation governed by pH, boron concentration, and local microenvironmental factors rather than enzymatic control. Boron complexation can modulate key physicochemical properties, including solubility, conformation, and membrane affinity, thereby influencing the biological activity of marine steroids without covalent modification of the carbon framework. By integrating examples from sponges, echinoderms, and corals together with well-characterized model polyols, this review highlights boron complexation as an underrecognized but potentially important factor influencing the structure, function, and bioactivity of marine steroid metabolites. Full article

The Mediterranean Sea is a biodiversity and climate change hotspot. The increase in seawater temperature affects marine ecosystems causing marine species to change their distribution and abundance. Such changes lead to alterations in community composition, often characterized by an increase in warm-affinity species over time, known as tropicalization of temperate seas. Monitoring programmes are useful for understanding the consequences of the ongoing transformations driven by ocean warming. In this study, underwater visual censuses (UVC) were conducted for fish and benthic communities at 24 stations of the Balearic Archipelago in 2022 and 2025. The comparison between both periods revealed an increase in the frequency of warm-affinity species, including the fishes Sparisoma cretense (Teleostea, Scaridae) and Caranx crysos (Teleostea, Carangidae); the invertebrates Telmatactis cricoides (Cnidaria, Actiniaria) and Hermodice carunculata (Annelida, Polychaeta, Amphinomidae) and the algae Penicillus capitatus (Chlorophyta, Ulvophyceae). Our findings highlight the importance of monitoring programmes to identify evidence of processes such as tropicalization and to provide timely information to respond to shifting marine ecosystems. Full article