Enzymatic basis underlying the biosynthesis of Δ7-desaturated C22 polymethylene-interrupted fatty acids across marine invertebrates.

No refuge from pollution: ingestion of synthetic debris by the endangered Iberian desman (Galemys pyrenaicus) in freshwater ecosystems of Spain.

Morphological and molecular identification of Marine Fungi associated with Sea Cucumbers (Holothuroidea) on Rocky-Tidal Coasts of Bushehr Province (first report)

Analysis of the mechanism of MKK4 participating in heat stress response in Mytilus coruscus.

Top predators drive changes in ecosystem structure. For the last ~370 million years, large-sized vertebrates have dominated the apex of the marine food chain, while invertebrates have served as smaller prey. Here we describe invertebrate top predators from this "age of vertebrates," the earliest finned octopuses (Cirrata) from Late Cretaceous sediments (~100 to 72 million years ago), as identified based on huge, exceptionally well-preserved fossil jaws and their wear. This extensive wear suggests dynamic crushing of hard skeletons. Asymmetric wear patterns further indicate lateralized behavior, suggesting advanced intelligence. With a calculated total length of ~7 to 19 meters, these octopuses may represent the largest invertebrates thus described, rivaling contemporaneous giant marine reptiles. Our findings show that powerful jaws, and the loss of superficial skeletons, convergently transformed cephalopods and marine vertebrates into huge, intelligent predators.

Rivers and other surface waters worldwide receive thousands of chemicals from diverse sources, including road runoff. We identified more than 170 chemicals that have been associated with road runoff across published literature that derive from tyre wear, exhaust emissions, and brake pad abrasion, amongst other sources. The impact of these chemicals on aquatic organisms however is poorly understood. Addressing this knowledge gap for U.K. surface drains, we first analysed the available literature studies on road run-off (23) to determine the concentrations of 70 chemicals in road run off monitored in surface drains by the U.K. Environment Agency over 25 years (between the years 2000 and 2024). We show 43 of the 70 monitored chemicals in U.K. surface drains exceed reported minimum concentrations and 19 the highest measured concentrations across existing literature. Twenty of the monitored chemicals exceeded the lowest effect concentration for 50% lethality (LC50) in fish and/or aquatic invertebrates. These findings suggest that road-runoff chemicals in U.K. surface drains pose a potential risk to aquatic life, but their impacts will depend upon other factors including their dilution levels in rivers.

Abstract Monitoring biodiversity patterns and their changes in Arctic coastal ecosystems is critical under ongoing climate change. However, common current approaches require high effort and expertise and this in turn limits the spatial and temporal scale of these monitoring efforts. Here, we investigated both the fish and the marine invertebrate communities across Svalbard using a multi-marker environmental DNA metabarcoding approach. We collected and analysed marine water, sediment and zooplankton filtered from marine water from sites influenced by the warm West Spitsbergen Current and the cold East Spitsbergen Current. Following metabarcoding amplification using mitochondrial COI, 12S, 16S and nuclear 18S markers and high-throughput sequencing, we retrieved an extensive overview of Svalbard marine biodiversity. Water, sediment and especially zooplankton samples collected across Svalbard revealed spatial differences in community composition, with significantly distinct assemblages in the northwest and southeast of Svalbard. We identified potential bioindicator species for use in rapid assessment of impacts of marine temperature increase and confirmed observed patterns of ongoing shifts in community structure as a response to changes in dominant water masses. Overall, our findings show that species composition depending on fine-scale climate variation of Arctic waters can be effectively studied and monitored using environmental DNA. These insights can help us understand current and evolving climate-driven changes.

Abstract Biotic interactions are a cornerstone of modern marine ecosystems, shaping community diversity and persistence through time. For most of the fossil record, however, such interactions are difficult to detect due to limited in situ preservation. At Nilpena Ediacara National Park (NENP), South Australia, the exceptional preservation of tens of thousands of fossils from the Ediacara Member of the Rawnsley Quartzite provides a unique opportunity to test whether biotic interactions were already common in some of Earth’s earliest ecosystems. Here we analyze three populations of the widespread form-genus Aspidella, interpreted as the holdfast of the frond Arborea, to investigate whether the recurring pattern of “kissing”, where the margins of adjacent Aspidella make contact, reflects a reproductive process (e.g., budding or fission) or a competitive process (overgrowth). Our results show that 75% of kissing Aspidella exhibit boundaries deformed by their neighbors, that body size and density are strongly negatively correlated, and larger individuals tend to be more spatially isolated. These results indicate that kissing Aspidella at NENP is best explained by competitive interactions rather than reproductive processes. Because overgrowth is widespread among modern marine invertebrates, and kissing Aspidella occur globally, multiple frond taxa may have employed this strategy, suggesting that competition for seafloor space was already a pervasive feature of Ediacaran ecosystems.

Despite growing insights into the composition of marine invertebrate microbiomes, our understanding of their ecological and evolutionary patterns remains poor, owing to limited sampling depth and low-resolution datasets. Previous studies have provided conflicting results that both confirm and deny the existence of phylosymbiosis between marine invertebrates and marine bacteria. Here, we investigated potential animal-microbe symbioses in Pseudoalteromonas, a bacterial genus consistently identified as a core microbiome taxon in diverse invertebrates. Using a pangenomic analysis of 236 free-living and invertebrate-associated bacterial strains (including two new nematode-associated isolates generated in this study), we confirm that Pseudoalteromonas is a symbiont with substantial evidence of phylosymbiosis across at least three marine invertebrate phyla (e.g., Nematoda, Mollusca, and Cnidaria). Patterns of symbiosis were consistent irrespective of geography (including in Antarctica), with FISH images from nematodes indicating that bacterial symbionts form biofilms in the mouth and esophagus and are sometimes present in female nematode ovaries exhibiting stunted development. The evolutionary history of Pseudoalteromonas is marked by substantial host-switching and lifestyle transitions, and host-associated genomes suggest that these bacteria are facultative symbionts involved in nutritional symbioses. In marine environments, we hypothesize that horizontally acquired symbionts may have co-evolved with invertebrates, using host mucus as a physical niche and food source, while providing their animal hosts with Vitamin B, amino acids, and bioavailable carbon compounds in return.

Environmental epigenetic regulation in marine invertebrates: mechanisms and evolutionary consequences

Seabirds play a key role in connecting different parts of Antarctic ecosystems, yet the biogeochemical consequences of their interactions with marine invertebrates are not well understood. This study examines Nacella concinna shells recovered from kelp gull (Larus dominicanus) pellets across ten Antarctic islands, investigating how interactions between seabirds and limpets record elemental signatures shaped by organismal traits and environmental conditions. By analysing the levels of various elements (calcium, magnesium, sodium, phosphorus, manganese, iron, zinc, copper, cobalt, aluminium, nickel, tin and beryllium), we demonstrate that gull pellets provide a unique and underutilised record of marine-terrestrial nutrient transfer. This approach reveals how seabirds redistribute elements from coastal benthic habitats to terrestrial deposition sites, offering new insights into nutrient cycling and ecological connectivity in extreme polar environments. The elemental patterns in the shells reflect a combination of intrinsic and extrinsic factors. Shell size, used as a proxy for age, strongly influenced the concentrations of Mg, P, Mn, Be and Zn, indicating that there are age-related physiological controls on biomineralisation. Geographic location also modulated elemental composition, with elements such as copper and tin (Sn) showing pronounced spatial variability. This suggests that local environmental conditions shape elemental uptake prior to ingestion by gulls. The combined sensitivity of Mg, P, Sn and Ni to both size and geography highlights their potential as reliable indicators of ecological variability and environmental change across Antarctic islands. This study provides a novel framework for understanding how biological processes mediate nutrient redistribution in polar ecosystems by capturing the biogeochemical imprint of seabird-limpet interactions. Gull pellets are revealed to be not only biological remnants, but also focal points of elemental deposition and integrative records of marine-terrestrial linkages. These findings enhance our comprehension of ecosystem resilience in the swiftly evolving Antarctic region, emphasising the significance of seabird-mediated pathways in shaping nutrient dynamics and habitat functionality.

ABSTRACT In agricultural areas, aquatic invertebrates can be exposed to mixtures of pesticides and metal(loid)s. In the fruit-production region of north Argentine Patagonia, the insecticides azinphos-methyl (AM) and carbaryl (Cb) have been widely applied. Besides, in this region, arsenic (As) occurs naturally in streams near volcanic areas. This study aimed to evaluate survival and biochemical markers in Hyalella curvispina amphipods acutely co-exposed to As and insecticides, comparing populations from a reference and an agricultural site. Co-exposure to As and AM increased mortality in both populations, indicating potentiation of acute toxicity, while co-exposure to As and Cb also increased mortality in the more susceptible population. Joint exposure inhibited acetylcholinesterase (AChE) activity, confirming it as a reliable biomarker of acute exposure and co-exposure. Population-specific differences in glutathione S-transferase (GST) and reduced glutathione (GSH) responses to the toxicants were observed, likely linked to different tolerance to anticholinesterase insecticides. According to the Relative Interaction Index, the combined effects of As and insecticides were mainly antagonistic (15 cases), followed by synergistic (5) and additive (4). The results obtained demonstrate that co-exposure can alter responses to single toxicants and enhance acute toxicity, emphasising the need to assess joint exposures to better reflect realistic environmental scenarios.

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.

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.

Abstract The Mesoamerican biodiversity hotspot is extraordinarily rich, yet most invertebrate genetic diversity remains invisible, hampering effective conservation planning amid accelerating biodiversity loss. How can this hidden diversity be revealed while simultaneously building local scientific capacity? Panama BioResearch, a hands-on molecular course, addressed this issue by embedding DNA barcoding within training and conservation contexts. Participants collected terrestrial and marine invertebrates across three protected areas and generated 158 DNA barcode sequences, two-thirds of which represented first genetic records for their species. Comparisons with public databases revealed striking under-representation of Mesoamerican taxa, especially non-iconic groups with key ecosystem roles. Barcoding also enabled the rapid detection of two invasive species, prompting immediate management responses. Beyond documenting biodiversity, this experience demonstrates that small, low-cost educational initiatives can produce actionable data, foster local expertise, and inform conservation priorities. Embedding molecular tools in education provides a scalable model for linking research, training, and management in species-rich but data-deficient regions.

The common octopus, Octopus vulgaris, is renowned for its advanced nervous system and complex behavior, yet its immune system remains poorly understood despite its relevance for health and pathogen resistance. Understanding octopus immunity is key to sustainable aquaculture and animal welfare. Single-cell RNA sequencing (scRNA-seq) provides high-resolution insights into immune cell diversity but requires viable single-cell suspensions, which are challenging in octopus hemocytes due to aggregation, high salinity, and chemical constraints. This study presents an optimized protocol for isolating circulating hemocytes and white body-resident hemocytes (WBH) from O. vulgaris. Hemocytes resuspended in Marine Antiaggregant Solution (MAS) maintained > 90% viability and structural integrity for at least 2h post‑extraction, while WBH were dissociated using combined mechanical and enzymatic methods. Cell counting comparisons revealed poor correlation between LUNA-FL and flow cytometry, whereas Neubauer chamber counts aligned closely with cytometry data. Furthermore, a reduced-EDTA MAS medium (MAS low) proved compatible with 10 × Genomics chemistry, enabling successful GEM generation, reverse transcription, and cDNA library construction. Shallow sequencing confirmed recovery of high-quality transcriptomes and distinct hemocyte populations, demonstrating the feasibility of scRNA-seq in this non-model marine species. These findings provide the first methodological framework for applying scRNA-seq to octopus immune cells, enabling detailed analysis of hemocyte diversity and function. This pipeline establishes the foundation for investigating immune responses and adaptation and offers a valuable tool for extending single-cell applications to other marine invertebrates, enhancing immunity understanding of cephalopod immunity, and supporting animal welfare and sustainable aquaculture practices.

From 2020 to 2024, The Institut Mauritanien de Recherches Océanographiques et des Pêche (IMROP) and the Senckenberg Research Institute conducted five joint expeditions, exploring the marine biodiversity of the North-Mauritanian coastal habitats, primarily focusing on the Baie de l'Étoile north of Nouadhibou and to the Banc d'Arguin National Park. In order to establish a Mauritanian scientific reference collection of the marine fauna and to build up a DNA barcode library, macrozoobenthic invertebrates from all major groups were collected using various methods and gear. A total of 103 living marine macrozoobenthic invertebrate species were found and their key morphological features were described herein. This checklist gives an overview on the most common species of the Mauritanian coastal macroinvertebrates and provides a baseline for future biodiversity assessments along the Mauritanian coast.

Umifenovir protects Procambarus clarkii against white spot syndrome virus by suppressing viral replication and modulating innate immunity.

Involvement of gut microbiota in sub-chronic chlorantraniliprole-induced metabolic alteration in chironomid larvae (Propsilocerus akamusi): Evidence from multi-omics, histopathological and biochemical analysis.

Host species as key drivers of Symbiodiniaceae assemblages: Coral and free-living diversity in a Southwestern Atlantic oceanic island.