Search Results (279)

Elasmobranchs play a major role in shaping the structure and functioning of marine ecosystems through their position in food webs. The Lusitanian cownose ray Rhinoptera marginata, a benthopelagic species classified as Critically Endangered on the IUCN Red List, is frequently landed in fisheries off the Mauritanian coast, yet its trophic ecology remains poorly documented. We investigated the diet of R. marginata along the coast of Nouadhibou through stomach content analysis of 308 individuals sampled between March 2022 and August 2023; 135 stomachs (66 females and 69 males) contained identifiable prey and formed the basis of the analyses (disc width range 33–87 cm). Common dietary indices (frequency of occurrence, numerical and gravimetric percentages, Pinkas’ IRI, Hureau’s Q) were combined with multivariate approaches (PERMANOVA on Bray–Curtis dissimilarities, SIMPER, non-metric multidimensional scaling), measures of trophic niche breadth and specialization (Levins’ standardized index Bi, Shannon H′, Pielou’s J′, modified Costello plot), niche overlap (Pianka and Schoener indices), and ontogenetic modelling (generalized additive models). A total of 33 prey taxa were identified, dominated by Bivalvia (86.1% IRI), followed by Gastropoda (6.9%) and Crustacea (6.7%). The species exhibited a strongly specialized feeding strategy (Levins Bi = 0.06; Shannon H′ = 1.42) with high niche overlap between sexes (Pianka = 0.89). PERMANOVA detected significant compositional differences across seasons (pseudo-F = 6.98, p < 0.001) and size classes (pseudo-F = 4.98, p < 0.001) but not between sexes (pseudo-F = 1.87, p = 0.077). The proportion of bivalves significantly decreased with body size (R² = 0.176, p < 0.001), revealing a clear ontogenetic shift towards more diversified prey in larger individuals. The estimated trophic level (3.13) confirms a mesocarnivore benthic position. These results provide the first comprehensive description of the diet of R. marginata in West Africa and highlight its role as a specialized durophagous predator of bivalve molluscs, omnipresent along the northern Mauritanian coastal ecosystems. By identifying the principal prey, our findings provide a basis for identifying potentially important foraging habitats for this Critically Endangered species and informing future conservation and management strategies. Full article

With climate change, marine heatwaves become more frequent and may favour the emergence of cyanobacterial blooms. Because cyanobacteria lack long-chain polyunsaturated fatty acids, they provide poor dietary quality for consumers, potentially altering the fatty acid composition of primary consumers and propagating nutritional stress through food webs. We examined how a simulated heatwave (12 °C to 18 °C) and an associated cyanobacterial bloom-like dominance may affect trophic transfer from phytoplankton to the herbivorous rotifer Brachionus plicatilis and further to its predator, the mysid Neomysis integer. Rotifers were fed either high-quality algae or a low-quality cyanobacteria-dominated diet mixture. Rotifers were then rinsed to remove external residual phytoplankton and subsequently offered as prey to mysids. We analyzed the fatty acid profiles of both rotifers and mysids and monitored mysid survival. High temperature and the presence of cyanobacteria at the base of the food web reduced mysid survival. Both factors also influenced the fatty acid composition of rotifers and mysids. For mysids at the third trophic level, warming modulated how strongly diet quality affected their fatty acid profile. These results suggest that concurrent heatwaves and cyanobacterial blooms may intensify cyanobacteria’s negative impacts on food webs by altering the transfer of key fatty acids across trophic levels. Full article

Pufferfishes (Tetraodontidae) accumulate tetrodotoxin, a potent neurotoxin, primarily through microbial and trophic pathways rather than endogenous biosynthesis, linking their toxicity directly to marine microbial ecology and food-web structure. Anthropogenic climate change, ocean warming, deoxygenation, and acidification are reshaping the environmental conditions that govern TTX production, transfer, and accumulation. This review synthesizes evidence from 62 studies (28 with quantitative data) identified through a PRISMA-ScR-compliant search. We organize findings around three mechanistic pathways: (1) warming-associated proliferation of TTX-producing bacteria and consequent shifts in environmental TTX availability, (2) climate-driven range shifts and hybridization that generate novel and unpredictable toxicity phenotypes, and (3) physiological responses of pufferfishes to warming, hypoxia, and acidification that may alter toxin allocation. We identify priority research needs, long-term monitoring, multi-stressor experiments, and standardized LC-MS/MS-based surveillance and outline an integrated framework for anticipating climate-driven shifts in pufferfish toxicity. Full article

Accidental releases of radionuclides from nuclear-powered vessels or ships carrying nuclear weapons may expose marine organisms to radioactive contaminants. The consequences of such events can differ markedly between resident fish populations and migratory species that move through affected areas. While these contrasting responses have been evaluated by the authors for coastal nuclear accidents, comparable assessments for open-sea scenarios remain limited. We simulated radionuclide releases from vessels in the North Atlantic to evaluate exposure pathways and potential ecological effects on both resident and migratory fish, since several naval bases operating nuclear-powered vessels are located along the eastern North American coastline. Physical transport of radionuclides was modeled using a Lagrangian framework that incorporates advection by ocean currents, three-dimensional turbulent diffusion, radioactive decay, and dynamic sediment–water exchanges. This transport model was coupled to a four-compartment food-web bioaccumulation model representing phytoplankton, zooplankton, non-piscivorous fish, and piscivorous fish. The approach allows evaluation of contaminant uptake in resident fish populations and along the migration routes of highly mobile species. Bluefin tuna (Thunnus thynnus), a key ecological and commercially valuable species, was selected as the migratory case study. Migration paths reconstructed from electronic tagging data were integrated to estimate radionuclide exposure along individual trajectories. This combined modeling framework provides new insight into how open-sea nuclear releases may differentially affect resident fish communities and wide-ranging migratory species in the North Atlantic, with relevance for fish ecology, population risk assessment, and fisheries management. Full article

Microplastic pollution has emerged as a pervasive stressor in aquatic ecosystems, with aquatic invertebrates playing central roles in particle uptake, retention, and transfer within food webs. This review synthesises evidence on microplastic ingestion, bioaccumulation, trophic transfer, and biomagnification across major aquatic invertebrate groups, including arthropods, molluscs, sediment-associated worms, suspension feeders, and echinoderms. A structured literature search identified 66 studies spanning freshwater, estuarine, and marine environments. Evidence indicates that microplastic uptake occurs through multiple pathways, including filter feeding, deposit feeding, grazing, and predator–prey interactions. Across the reviewed studies, feeding strategy, habitat-specific exposure, and particle characteristics were recurrently associated with variation in microplastic ingestion, retention, and trophic transfer. While ingestion and bioaccumulation were widely documented, quantitative understanding of trophic transfer within aquatic invertebrate food webs remained limited, and no conclusive evidence of biomagnification was identified. To interpret recurring patterns, this review proposes the Trait–Habitat–Particle (THP) framework as a conceptual tool linking biological and functional traits, habitat-mediated exposure, and particle properties. Methodological inconsistencies, limited representation of certain taxa and habitats, and insufficient quantification of trophic transfer remain important knowledge gaps. Future research should prioritise methodological standardisation and ecologically realistic long-term studies. Full article

Small pelagic fishes play a crucial role in structuring marine food webs, yet their trophic flexibility and feeding interactions remain poorly understood in highly dynamic, nutrient-rich systems such as upwelling regions. This study combines bulk stable isotope analysis (δ¹³C and δ¹⁵N), compound-specific nitrogen isotope analysis of amino acids (CSIA-AA), and fatty acid (FA) profiles to assess feeding patterns and trophic overlap among four planktivorous species in the North Iberian shelf (Galicia and the Cantabrian Sea). The combined trophic indicators reveal clear niche partitioning between clupeids (sardine and anchovy) and scombrids (mackerel and chub mackerel), with the latter exhibiting higher CSIA-AA-derived trophic positions and distinct FA composition. Our analysis further shows that fatty acid biomarkers are essential for resolving finer-scale differences within each group, driven by variable contributions of phytoplankton and zooplankton to species diets. Although all species shared resources within the same food web, isotopic baselines indicate a decoupling between carbon and nitrogen pathways. For sardine, we compared neutral and polar lipid fractions with the total lipid extract in terms of FA composition and key dietary markers. Our results suggest that separating lipid fractions can improve dietary resolution, especially when lipid content is low. Overall, our findings highlight the value of integrating classical and emerging biochemical tracers to better resolve trophic dynamics in coexisting planktivorous fishes. Full article

Emerging contaminants (ECs), including pharmaceuticals, endocrine disruptors, pesticides, PFAS, and microplastics, are increasingly detected in aquatic environments due to their persistence, bioactivity, and limited removal by conventional treatment processes. These challenges are intensified in hyper-arid regions where desalination and wastewater reuse dominate water supply, concentrating contaminants and creating unique exposure pathways. The Arabian Gulf is one of the most environmentally stressed marine systems, characterized by hypersalinity, extreme temperatures, dense coastal development, and strong petrochemical influence. Despite its major role in global petrochemical and plastic production, the region lacks coordinated monitoring and regulatory frameworks, creating significant gaps in understanding EC occurrence, fate, and risks. Treatment systems designed for temperate climates often underperform under Gulf conditions, enabling contaminants to persist, accumulate in sediments, and enter marine food webs. This review examines the occurrence, behaviour, and removal challenges of ECs in the Gulf, where concentrations frequently exceed international benchmarks due to wastewater reuse, desalination brine discharge, maritime activities, and oil-related pollution. Regional factors such as hypersalinity, high temperatures, and petrochemical interactions further influence contaminant persistence and toxicity. Conventional treatments show reduced efficiency, while alternatives such as halophyte-based wetlands and brine valorisation show promise. However, key gaps remain in nanoplastics, PFAS speciation, and cumulative exposure, requiring coordinated monitoring and unified GCC regulations. Full article

Phytoplankton are the major primary producers in the Southern Ocean, are important to global nutrient cycles, and are at the base of marine food webs. Polar ecosystems are unique in their extended periods of darkness in the winter, and prolonged darkness has the potential to exert selection that affects diatom population composition if there is differential survival in the dark, the variation in population growth rates in subsequent light periods, or both. We tested whether prolonged darkness has the potential to exert within-species selection on a model polar diatom species by exposing five strains of the polar diatom Porosira glacialis to prolonged darkness at two different temperatures in the laboratory. We measured population survival in the dark, growth rate upon re-illumination, and between-strain variability in these traits. We found a pronounced decline in survival and growth rate with time spent in the dark, as well as important intraspecific variation in the tested strains. Declines in survival and growth were exacerbated at a higher temperature. Our results show that the darkness of polar night can exert intraspecific selection in a common Southern Ocean diatom. Full article

Introduction: As apex and mesopredators, elasmobranchs help maintain marine ecosystem balance by shaping food-web structure and habitat connectivity, yet more than one-third of species are threatened with extinction. Identifying where and when they aggregate within atoll systems is therefore a prerequisite for spatially explicit conservation planning. Lhaviyani Atoll, in the central Maldives, lies within a recognised Indian Ocean elasmobranch hotspot and hosts two Important Shark and Ray Areas (ISRAs), yet fine-scale information on aggregation sites, habitat partitioning and seasonal use remains limited. Objective: To map persistent activity hotspots, characterise habitat partitioning between sharks and batoids, quantify seasonal and inter-annual dynamics, and provide an ecological basis for habitat-focused conservation in Lhaviyani Atoll. Methodology: Using a seven-year (2017–2024) opportunistic dive-log dataset of 12,732 SCUBA surveys and 142,994 elasmobranch records across 94 dive sites, spatial kernel-density estimation was applied separately to sharks and batoids to identify activity hotspots and visualise spatial overlap. Habitat associations were examined across substrate types and reef geomorphic zones. Seasonal and inter-annual dynamics in relative abundance and diversity (Shannon, Pielou’s evenness) were quantified across monsoon phases and the 2017–2024 period. Results: Twenty-eight species (14 sharks, 14 batoids) were recorded, including 23 listed as threatened on the IUCN Red List (4 Critically Endangered, 12 Endangered, 7 Vulnerable). Four persistent activity hotspots were identified along the northern atoll rim, two overlapping with the Fushifaru Kandu and Kuredhu–Huravalhi–Komandoo ISRAs. Sharks were concentrated along more complex exposed and semi-sheltered slopes and high-flow channels, with significantly higher occurrence on reef and sheltered reef slopes and lower occurrence on rubble and sand substrates; batoids were distributed broadly within lagoonal habitats with no strong substrate or geomorphic preferences. Relative abundance and diversity peaked during the late southwest monsoon (August–September) and declined into the northeast monsoon (December–March); after 2021, diversity and evenness increased while overall abundance declined. Conclusions: Persistent hotspots, contrasting habitat use by sharks and batoids, and consistent monsoonal seasonality support the ecological relevance of existing ISRAs in Lhaviyani Atoll, while providing finer-scale information on habitat partitioning and additional priority areas for threatened elasmobranchs, including four Critically Endangered species. Full article

Introduction: Elasmobranchs play a vital role in marine food webs through top-down control and the structuring of ecosystem stability, yet more than one-third of species face extinction. The Maldives, a recognised Indian Ocean hotspot for shark and batoid diversity, designated its EEZ as a shark sanctuary in 2010, but multispecies elasmobranch occurrence patterns and environmental drivers remain poorly characterised in Lhaviyani Atoll in the central Maldives, which hosts two Important Shark and Ray Areas (ISRAs). Recreational SCUBA networks can turn routine dive activity into long-term conservation evidence, already informing nearly 10% of the western Indian Ocean ISRAs. Objective: To characterise spatiotemporal patterns of elasmobranch assemblages in Lhaviyani Atoll (2017–2024), quantify how environmental and geomorphic drivers shape relative abundance, diversity, and hotspots, and provide evidence for targeted elasmobranch conservation. Methodology: A seven-year opportunistic dive-log dataset of 12,732 SCUBA surveys and 142,994 elasmobranch records across 94 dive sites was analysed. Effort-standardised relative abundance and community metrics (Shannon diversity, Pielou’s evenness) were modelled against sea surface temperature (SST), salinity, dissolved oxygen, chlorophyll-a, zonal current velocity, substrate type, and reef geomorphology using generalised additive models (GAMs). Spatial analyses identified persistent northern-rim aggregation areas aligned with ISRAs. Results: Twenty-eight species (14 sharks, 14 batoids) were recorded, including 23 threatened on the IUCN Red List (4 Critically Endangered, 12 Endangered, 7 Vulnerable). Relative abundance and diversity peaked during the late southwest monsoon (August–September) and declined during the northeast monsoon (December–March). After 2021, diversity and evenness increased while overall abundance declined. Relative abundance was primarily driven by SST, salinity, and current velocity; for sharks, dissolved oxygen and chlorophyll-a were additionally significant, whereas batoid abundance was driven mainly by temperature, oxygen, and current velocity. Four persistent hotspots along the northern atoll rim were identified, with sharks concentrated along exposed slopes and channels, and batoids distributed broadly within lagoonal habitats. Conclusions: Long-term citizen science dive-log monitoring is cost-effective for elasmobranch conservation in remote tropical seascapes. These results show how dive-industry partnerships can inform conservation governance over a decade after sanctuary designation, supporting targeted, habitat-focused management as shark and batoid conservation frameworks continue to evolve. Full article

Environmental contamination by rare earth elements (REEs) is increasing globally due to their extensive use in modern technologies, medicine, agriculture, and aquaculture. Their release into aquatic systems via wastewater discharge, industrial emissions, surface runoff, and atmospheric deposition has raised concerns regarding their environmental fate and potential ecotoxicological effects. Despite this, information on REE accumulation in marine predators remains limited. This study provides a multi-species assessment of REE bioaccumulation in elasmobranchs. Concentrations of 14 REEs (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Tm, and Yb) were quantified in liver and muscle tissues of six elasmobranch species collected from demersal and deep-sea habitats along the Portuguese continental shelf. Generalized linear models (GLMs) were used to evaluate differences in REE concentrations among species and tissues, and to explore potential patterns associated with ecological traits. Results indicated that REE concentrations varied significantly across tissues and species, with muscle generally exhibiting higher accumulation than liver. Overall, this study provides the first comprehensive baseline of REE bioaccumulation in elasmobranchs from the Portuguese coast, contributing to a better understanding of emerging contaminants in marine food webs. These findings have important implications for environmental biomonitoring and highlight potential risks associated with seafood consumption. Full article

Introduction: The physical characteristics of microplastics (MPs), particularly their size and color, closely resemble natural food prey for several marine organisms, leading to active or accidental ingestion by marine species, including fish larvae. Despite growing concern, the occurrence of MPs in wild fish during early developmental stages remains insufficiently documented, and laboratory studies report inconsistent results. Given their key ecological role in marine food webs and their economic relevance, the health and survival of fish larvae are critical for maintaining fish populations. Objective: This study aimed to investigate MPs’ presence throughout the larval developmental stages and assess whether MP contamination profiles (concentration, color, type, and size) differ between species. Methodology: MPs were analyzed in the larval stages of two fish species with distinct ecological niches: the European sardine (Sardina pilchardus), a marine migratory species, and the common goby (Pomatoschistus microps), an estuarine resident species. Samples were collected from the Douro Estuary (NW Portugal) over one year, covering different developmental stages. Results: MPs were detected in both species at all developmental stages observed, including the yolk-sac stage (where the feeding of larvae is endogenous), indicating contamination at a stage when the mouth is not yet functional. Sardina pilchardus showed a higher abundance of transparent nylon fibers of 0.5 mm, and Pomatoschistus microps transparent polypropylene fibers of size 0.4 mm. Moreover, MP contamination did not vary between species or throughout the developmental stages, showing similar levels and profiles of MPs contamination. Conclusions: These findings provide new evidence that MP contamination begins at the earliest developmental stages of the fish, from hatching onwards. The results further suggest that MP uptake in fish larvae is primarily driven by environmental availability rather than fish larvae’s preferences or ecological guild, physical characteristics, or even the ontogenetic developmental stage. Full article

Microplastics (MPs) are increasingly detected environmental contaminants in both marine and freshwater ecosystems, with reported concentrations ranging from a few to thousands of particles per cubic meter depending on location and methodology. Although growing evidence suggests potential risks to aquatic organisms, the extent of their ecological and biological impacts is still under active investigation. Their size, persistence and capacity to transport chemical additives and co-contaminants allow them to enter biological systems by ingestion and respiration. When ingested, MPs cause oxidative stress, inflammation, and metabolic disorders, resulting in the destruction of vital tissues in major body organs including liver, gills, intestines, and brain. They also change gene expression, cause endocrine and immune pathway perturbation, induce apoptosis, and cause gut microbiome dysbiosis, all of which worsen the health and survival of the organism. MPs also serve as vectors of heavy metals, antibiotics, pesticides, and pathogens and enhance toxicity due to the Trojan horse effect and enable bioaccumulation in food webs. Due to their widespread presence in water, soil, air, and food, MP pollution has direct effects on human, animal, and ecosystem health. This review synthesizes current knowledge on the sources of MPs, the mode of exposure, and the mechanism of toxicity and new ecological implications. It also presents mitigation measures, and stresses a One Health paradigm as the key to taking concerted action on the international level to minimize MP pollution and protect both the environment and human health. Full article

Benthic foraminifera, single-cell marine organisms found worldwide, represent an important component of seabed ecosystems. Due to their sensitivity to environmental pollution, they are often used as bioindicators, providing an efficient tool in toxicity studies. Among the pollutants affecting marine coastal and estuarine environments, persistent flame retardants, such as polybrominated diphenyl ethers (PBDEs), are frequently found. Low-level exposure to BDE-47, a PBDE congener, is known to affect organismal development. In this framework, this study aims to assess the effects of BDE-47 exposure on benthic foraminifera from coastal marine environments. Foraminifera specimens belonging to the symbiont-bearing Peneroplidae family were sampled and exposed to two different BDE-47 concentrations for up to 48 h. Vitality indicators such as changes in pseudopodial activity, movement, reproduction, loss of symbiont algae, and occasional mortality events were monitored during the experiment. Exposure to BDE-47 induced alterations in pseudopodial activity, movement, reproduction, and symbiont retention, with the progressive loss of vitality and limited mortality at increasing exposure levels, highlighting the sensitivity of this species to BDE-47. These findings suggest the harmful repercussions of PBDE pollution on marine coastal ecosystems, affecting benthic organisms and potentially contributing to biomagnification processes within the food web, with possible implications for human health. Full article

This systematic review was conducted and reported according to the PRISMA 2020 statement to synthesize evidence published between January 2020 and January 2025 on food-derived antihypertensive peptides, with emphasis on mechanisms of action, molecular stability, bioavailability, and functional food applications. PubMed, Scopus, and Web of Science were searched using combined terms related to bioactive or ACE-inhibitory peptides, stability or bioavailability, and alternative protein sources. Original peer-reviewed studies in English evaluating antihypertensive or ACE-inhibitory peptides from plant, marine, insect, fungal, dairy, or terrestrial animal matrices were considered eligible when they reported experimental evidence on activity, stability, transport, or in vivo efficacy. Three reviewers independently screened records and extracted data. A total of 177 studies were included. Plant and marine matrices accounted for approximately 72% of the evidence base, with a strong focus on low-molecular-weight peptides (<3 kDa) and multistage validation pipelines integrating in silico screening, in vitro enzymatic assays, Caco-2 transport models, ex vivo assays, and spontaneously hypertensive rat studies. Overall, the evidence supports the antihypertensive potential of selected food-derived peptides, particularly through ACE inhibition and related vascular mechanisms. Encapsulation and advanced delivery approaches improved peptide stability and bioavailability in several studies. Food-derived antihypertensive peptides represent promising candidates for functional foods and nutraceuticals; however, greater methodological standardization, formal risk-of-bias assessment in primary studies, and well-designed human trials remain necessary to strengthen translation into practice. Full article