Search Results (684)

This study evaluates the ecological impacts of seawater desalination discharge on coastal marine ecosystems through a sequential analytical framework linking systematic literature synthesis, field-monitoring evidence, spatial analysis, and predictive ecological modeling. The novelty of the study lies in combining multi-regional evidence from Mediterranean coastal zones, Persian Gulf waters, and Pacific coastal environments with threshold-based ecological risk assessment, thereby linking discharge-related environmental stressors with biological responses and ecosystem-function alterations. The systematic review first retained 750 studies published between 2004 and 2024 for qualitative synthesis. On this basis, 59 high-quality references with sufficient numerical information were selected for the main quantitative meta-analysis, while field-monitoring data were used to support the interpretation of distance-based discharge gradients. Spatial interpolation and hierarchical modeling were then applied to evaluate exposure–response patterns and ecological threshold behavior. The results showed that desalination facilities generated measurable ecological impacts mainly within 50–200 m of discharge points, with a critical transition distance of approximately 127 m where hypersaline conditions, typically 1.5–2.0 times ambient seawater levels, were associated with marked changes in marine community structure. Benthic assemblages showed taxon-specific responses, with mollusks and echinoderms exhibiting greater sensitivity than polychaetes and small crustaceans. Marine vegetation declined strongly under combined salinity, thermal, and chemical stress, while phosphonate-based antiscalants accumulated in filter-feeding organisms and produced bioaccumulation factors up to 42.1 times ambient levels. Ecosystem-function indicators, including microbial community composition and sediment organic matter processing, remained altered up to 300 m from discharge points, indicating that functional impacts may extend beyond the primary hypersaline plume. The predictive modeling framework further demonstrated that ecological risk decreased nonlinearly with distance and varied according to discharge intensity, local hydrodynamics, and biological sensitivity. These findings indicate that conventional uniform buffer-based assessment may underestimate the ecological footprint of desalination discharge. Sustainable desalination management should therefore adopt site-specific monitoring, species-sensitive protection thresholds, improved brine-management technologies, and adaptive mitigation strategies based on real-time environmental feedback. Full article

Introduction: Elasmobranchs are an important component of deep-water and slope ecosystems, playing a key role in benthic and demersal food webs. Many species inhabiting offshore banks of the northeastern Atlantic are characterized by low productivity and high sensitivity to fishing pressure, which makes fishery-independent assessments particularly relevant. The Porcupine Bank supports a diverse assemblage of deep-water sharks and skates, yet quantitative information derived from standardized trawl surveys remains essential to characterize community structure and support ecosystem-based management. This study aims to provide an updated overview of the composition, relative abundance, biomass, and occurrence of elasmobranch species on the Porcupine Bank. Methodology: Data were collected during the Porcupine bottom trawl survey carried out in September–October 2023. The survey used a stratified random sampling design by depth and comprised a total of 88 valid demersal trawl hauls. Results: A total of 23 elasmobranch species belonging to four orders (Carcharhiniformes, Squaliformes, Rajiformes, and Hexanchiformes) were recorded. The assemblage was dominated by deep-water sharks, particularly squaliforms and carcharhiniforms. Galeus melastomus was the most dominant species, showing the highest stratified mean biomass and abundance and occurring in the majority of hauls. Other abundant and recurrent species included Etmopterus spinax, Scyliorhinus canicula, and Deania calceus. Skates of the genera Dipturus and Leucoraja were less abundant but showed consistent occurrences across depth strata. Several deep-water species, such as Apristurus spp. and Rajella fyllae, were recorded only sporadically, with very low abundances and limited occurrence. Conclusions: The results highlight the predominance of small- to medium-sized deep-water sharks on the Porcupine Bank and the comparatively lower contribution of rajid skates. This study provides a robust description of elasmobranch assemblage structure based on standardized sampling and constitutes a valuable baseline for future monitoring and comparative assessments in offshore Atlantic ecosystems. Full article

Introduction: Elasmobranchs are key components of marine ecosystems but are particularly vulnerable to fishing pressure due to their life-history traits, including slow growth, late maturity, and low fecundity. The Gulf of Cádiz supports a diverse assemblage of coastal and deep-water elasmobranch species, many of which are subject to incidental capture in demersal fisheries. Reliable fishery-independent information on their distribution, relative abundance, and biomass is essential to assess population status and to inform ecosystem-based fisheries management in the northeastern Atlantic. This study aims to provide an updated overview of the composition, relative abundance, biomass, and occurrence of elasmobranch species in the Gulf of Cádiz, contributing baseline information for monitoring and conservation purposes. Methodology: Data were obtained from the ARSA bottom trawl survey carried out in March 2026 using a stratified random sampling design by depth. A total of 45 valid hauls were performed. Results: A total of 29 elasmobranch species belonging to Rajiformes, Carcharhiniformes, Squaliformes, Myliobatiformes, Hexanchiformes, and Torpediniformes were identified. Small demersal sharks and skates dominated the assemblage. Scyliorhinus canicula was the most frequent and abundant species, occurring in 37 hauls and showing the highest mean abundance and biomass. Other recurrent taxa included Torpedo marmorata, Etmopterus spinax, Leucoraja naevus, and Raja clavata. Several species of conservation concern, such as Rostroraja alba, Centrophorus uyato, and Galeorhinus galeus, were recorded at low frequencies and abundances, highlighting their rarity in survey catches. The assemblage reflected a clear dominance of shelf and upper-slope species with occasional captures of deep-water taxa. Conclusions: The ARSA survey provides a valuable snapshot of the current elasmobranch community in the Gulf of Cádiz, confirming the prevalence of small-bodied, benthic species and the low occurrence of large or vulnerable taxa. These results underscore the importance of continued standardized surveys to detect temporal trends and support management strategies aimed at the conservation of elasmobranch diversity in the gulf. Full article

Shallow eutrophic lakes recover from nutrient loading on time scales ranging from less than one year to many decades, yet whether this range is set by the lake or by the biological response group has rarely been quantified within a single monitoring framework. We assembled a five-year (2020–2025) quarterly monitoring panel from three shallow Yangtze-floodplain lakes (Lake Changhu, Lake Liangzihu, and Lake Honghu; 15 stations, 21 quarters) and applied a panel mixed-effect distributed lag model (PME-DLM) to estimate the lag-response windows of phytoplankton and benthic macroinvertebrate densities against five water-quality drivers. Cross-lake consistency was tested with a station-resampled bootstrap, and the contributions of water quality, season, and lake identity to community variation were resolved by three-table variation partitioning. The PME-DLM resolved a 3-month temperature window for phytoplankton and 9–15 month chlorophyll a and temperature windows for benthic communities, while total nitrogen and total phosphorus were non-significant in either group. Cross-lake bootstrap intervals on window width overlapped substantially across the three lakes, whereas cross-group differences in window centre and shape were an order of magnitude greater. Variation partitioning further showed a mirror-image structure in which phytoplankton variation was dominated by the pure water-quality fraction (12.2%) and benthic variation by the water-quality × season joint fraction (5.8%). Within the resolution of this five-year, three-lake panel, group-level differences in lag-response time scale were more apparent than lake-level differences and provide a quantitative basis for matching restoration assessment cadence to pelagic versus benthic recovery. Full article

Mountain stream ecosystems are often considered among the least disturbed freshwater environments; however, increasing land-use pressures may affect their ecological integrity even under apparently high-water quality conditions. This study aimed to assess the relative influence of landscape, physicochemical, and hydromorphological factors on benthic macroinvertebrate communities in three sub-catchments (Ambroz, Jerte, and Tiétar) of the Sierra de Gredos (Central Spain). A total of 33 sampling sites were surveyed, and macroinvertebrate assemblages were analyzed in relation to environmental variables using partial Redundancy Analysis (pRDA) and variance partitioning. All sites were classified as having “Excellent” ecological status based on the Iberian Biological Monitoring Working Party (IBMWP) index. However, multivariate analyses revealed clear spatial patterns and responses to environmental gradients. Results indicated that catchment-scale landscape characteristics defined the pool of potential colonizers, while local physicochemical and hydromorphological conditions acted as secondary filters structuring macroinvertebrate assemblages. Landscape variables explained the largest fraction of variance in community structure (30.6%), followed by physicochemical parameters (29.0%) and hydromorphological indices (24.9%), with a significant shared component (16.5%) indicating interactions among drivers. Agricultural land use, particularly in the Jerte sub-catchment, was associated with shifts in community composition, favoring tolerant taxa such as Diptera, while sub-catchments dominated by natural vegetation supported higher richness of sensitive groups, including Ephemeroptera and Plecoptera. These findings highlight the importance of multi-scale processes in structuring mountain stream communities and reveal limitations of traditional biotic indices in detecting early ecological changes. The results support the integration of catchment-scale variables into ecological assessment frameworks and emphasize the need for preventive, basin-scale management strategies to maintain ecological integrity under increasing anthropogenic pressure. Full article

The development of digital photogrammetry techniques has revolutionized the study of marine ecosystems, enabling the generation of high-precision three-dimensional models from conventional imagery. Structure from Motion (SfM) algorithms have become effective tools for mapping and monitoring underwater habitats, offering a non-invasive and cost-effective alternative to traditional methods. This study presents a pilot methodological validation of SfM-based underwater photogrammetry for the non-invasive morphometric monitoring of vulnerable benthic species, using Pinna rudis. The research focused on refining photogrammetric methodologies for marine conservation, addressing technical challenges such as variations in light conditions, water turbidity, and image acquisition complexity. The study area, the Cabrera Archipelago Maritime-Terrestrial National Park, is a pristine marine environment in the western Mediterranean, hosting diverse benthic communities, including an abundant Pinna rudis population. Data acquisition comprises sampling by scuba diving techniques at depths ranging from 26 to 31 m, performed during the July 2022 field campaign within a permanent demographic plot established in 2013 and the methodology applied involved generating three-dimensional models using SfM, allowing for direct measurements of the seabed and extraction of morphometric parameters of sessile species. The characterization of the Pinna rudis aggregation was based on specimen density and size structure, determined using maximum shell width. The 3D model of the pilot plot covers 86.1 m², hosting 31 individuals. Morphometric measurements derived from SfM-based 3D models were validated against in situ diver measurements of maximum shell width. The results showed that the average maximum width obtained from 3D models (15.19 ± 3.23 cm) was consistent with in situ measurements (15.35 ± 3.48 cm). The mean difference between methods was −0.16 ± 0.82 cm, indicating a negligible systematic bias. The mean absolute error was 0.65 cm, corresponding to an average relative error of 4.34%, and a strong linear relationship was observed between both methods (r = 0.97). These results confirm that underwater photogrammetry is a reliable and non-invasive tool for monitoring vulnerable benthic species, providing high-resolution spatial and morphometric data to support conservation strategies in marine protected areas and allowing the collection of additional data compared to in situ surveys. Full article

The Biological Monitoring Working Party (BMWP) and Average Score Per Taxon (ASPT) indices, which rely on family-level environmental sensitivity values (FESVs), are widely used in freshwater bioassessment. However, regional differences in taxonomic composition often render existing FESV systems incomplete or incompatible, and the influence of rare families remains poorly understood. Using a historical dataset from the temperate Taizi River basin in Northeast China, we developed a regional FESV system for benthic macroinvertebrates. A total of 67 FESVs were established, including 10 families not previously scored in the UK system. These values followed a normal distribution and were ecologically validated using canonical correspondence analysis (CCA). Both BMWP and ASPT indices showed significant correlations with water quality parameters, the Water Quality Index (WQI), and the Habitat Quality Index (HQI). Notably, excluding rare families (occurrence frequency < 1%) did not reduce but slightly enhanced the responsiveness of both indices. CCA identified HQI, conductivity, and ammonia nitrogen as the primary drivers of community composition, and the inferred ecological preferences aligned well with the assigned FESVs. This study provides a robust, regionally adapted framework for family-level bioassessment in temperate East Asian rivers and supports the exclusion of rare taxa to improve cost-effectiveness and index sensitivity. Full article

Spatial and temporal variability of macrozoobenthic communities were investigated around three offshore gas structures with different architecture (a subsea well-site, a four-leg platform, and a one-leg platform) in the NW Adriatic Sea. Four post-installation surveys (two per year over two years) were conducted by sampling sediments at increasing distances from each structure (approximately 0, 30, 60, 120 and 1000 m from the structure edge). A total of 233, 271 and 260 taxa were recorded around Structures A, B and C, respectively, with polychaetes representing the dominant taxonomic group at all sites. Across all structures, community composition showed significant variability both among surveys and along the distance gradient. Near-structure stations (0–60 m) most frequently accounted for spatial dissimilarities, whereas communities at 120 and 1000 m were generally more similar. Early surveys around the well-site and the four-leg platform were characterised by low diversity and high dominance of the opportunistic polychaete Ditrupa arietina, suggesting a short-term disturbance related to installation. Post-installation trajectories differed among structures: community descriptors stabilized faster around the subsea well-site, while changes near the platforms extended for at least two years. At the one-leg and four-leg platforms, the progressive development of a bivalve mound (specimens of Mytilus galloprovincialis and/or Neopycnodonte cochlear fell from the submerged parts of the platforms) coincided with increased abundance, species richness and occurrence of hard-bottom associated taxa at 0 m stations. Overall, the results indicate that offshore gas structures can locally influence macrozoobenthic assemblages by modifying habitat heterogeneity and promoting site-specific community responses. Although based on post-installation observations only, this study provides site-specific evidence useful for future decommissioning planning in soft-bottom shelf areas. Full article

Understanding the trophic ecology of fish in mountain lakes is essential for interpreting their functional roles and managing these ecosystems. This study investigated the diet, population structure, and prey selectivity of lake charr (Salvelinus umbla) in three glacial basins of the Eastern Italian Alps: Fusine Superiore, Fusine Inferiore, and Raibl Lakes. In summer 2024, 106 fish were sampled using multi-mesh gillnets, alongside Surber sampling of littoral macrobenthos. Biometric analysis revealed populations dominated by larger size classes (>18 cm), with significant sexual dimorphism, as females were longer and heavier than males. Dietary analysis showed strong reliance on littoral Hexapoda (~90% of prey). High Schoener’s overlap index values (α > 0.90) indicated no clear ontogenetic dietary shifts in the sampled size classes, suggesting that the productive littoral zone provides a stable resource. Ivlev’s electivity index revealed lake-specific prey selection patterns, with Hexapoda positively selected in Lake Fusine Inferiore, Bivalvia and Malacostraca positively selected in Lake Raibl, and weak or absent selectivity in Lake Fusine Superiore. S. umbla appears to be a broad opportunistic feeder with site-specific prey selectivity shaped by local resource structure. Given its debated native status, these findings provide an ecological baseline for assessing its potential effects on benthic communities. Full article

Eastern Boundary Upwelling Systems (EBUSs) are among the most productive marine biomes globally, renowned for their substantial pelagic fisheries. While the role of wind-driven upwelling in stimulating primary production is well-documented, the integral contributions of the marine benthos in maintaining ecosystem productivity and fishery yields are often underrepresented. This article analyzes evidence from the Humboldt, California, Benguela, and Canary Current systems to delineate the critical functions of the seabed and its resident communities. Three primary pathways through which the benthos supports fisheries are described: (1) by facilitating the efficient regeneration of nutrients from sedimenting organic matter, thereby replenishing the inorganic nutrient pool for subsequent primary production; (2) by providing essential habitat structure that supports the life history of a myriad of species, including demersal and coastal fish species, serving as nursery and feeding grounds; and (3) by forming the foundational trophic base for benthic-feeding fishes and invertebrates of commercial importance. By comparing system-specific characteristics, such as the influence of oxygen minimum zones on benthic community structure, the integrity of the benthic subsystem as a fundamental determinant of the productivity and sustainability of EBUS fisheries is demonstrated. A holistic management approach that includes benthic habitat conservation is therefore paramount. Full article

Benthic foraminifera are widely used as indicators of marine environmental conditions due to their sensitivity to ecological changes and their excellent preservation in sediments. In this study, benthic foraminiferal assemblages from a sediment core collected in the central Yellow Sea were investigated to document faunal composition and examine temporal changes since the Late Pleistocene. A total of 54 benthic foraminiferal species belonging to 33 genera, 25 families, seven orders, three classes, and one phylum were identified. Among them, 12 species are newly recorded in Korean waters, reflecting the current incompleteness of regional faunal inventories and the importance of detailed taxonomic studies. The assemblages exhibit distinct stratigraphic variations. The lower interval (>30 ka) is characterized by low-diversity assemblages dominated by taxa commonly associated with marginal marine environments. The middle interval (ca. 20–25 ka) shows the occurrence of taxa typically reported from boreal to subarctic environments, suggesting changes in environmental conditions during the Last Glacial Maximum. In contrast, the upper interval (Holocene) is marked by increased species diversity and the dominance of taxa characteristic of normal marine shelf environments. These assemblage changes are interpreted as reflecting long-term responses of benthic communities to sea-level fluctuations, sedimentary conditions, and regional oceanographic variability in the Yellow Sea. In particular, the development of fine-grained deposits in the Central Yellow Sea Mud (CYSM) and the establishment of stable marine shelf conditions during the Holocene likely played important roles in shaping benthic habitats. This study provides new baseline data on benthic foraminiferal diversity in the Yellow Sea and demonstrates the potential of these assemblages as useful, though indirect, indicators for reconstructing past environmental changes. The results highlight the importance of integrating detailed taxonomic analyses with stratigraphic records to improve our understanding of marine biodiversity and paleoenvironmental variability in marginal seas. Full article

Gastrotrichs (Phylum Gastrotricha) are widespread and species-rich components of benthic and periphytic communities, where they are thought to contribute substantially to food-web functioning by linking the microbial loop to higher trophic levels through their feeding on detritus, bacteria, microalgae, and fungi, and serve as prey for larger animals. Despite the well-recognized role as primary consumers, their position as potential prey remains largely unresolved, with documented predators so far restricted to carnivorous protists. Here, we report the first documented case of metazoan predation on a freshwater gastrotrich, in which a cyclopoid copepod actively captures and partially consumes a chaetonotid species. The interaction was first detected under minimally disturbed conditions and subsequently replicated in controlled experimental settings. Predation was documented through in vivo video recordings and supported by species-level identification of both predator and prey. These findings expand the currently recognized trophic interactions involving freshwater gastrotrichs and provide new insight into their ecological role within aquatic food webs. Full article

To scientifically evaluate the health of river aquatic ecosystems in the Qianxinan Buyi and Miao Autonomous Prefecture, southwestern Guizhou, systematic surveys of benthic macroinvertebrate and periphytic algal communities were conducted in representative rivers during October 2024 (autumn) and April 2025 (spring), coupled with concurrent water quality monitoring. Reference sites were selected based on water quality indicators and habitat conditions. Core parameters were identified through correlation analysis, discriminatory ability analysis, and distribution range analysis to construct a Benthic Index of Biotic Integrity (B-IBI) and a Periphytic Algae Index of Biotic Integrity (P-IBI) suitable for the region. These indices were then applied to assess the ecological health of the rivers. Additionally, stepwise regression analysis was employed to investigate the key environmental drivers influencing the two biotic integrity indices. The results indicated that: (1) In terms of species composition, the benthic macroinvertebrate community structure was relatively simple, dominated by arthropods, particularly chironomid larvae. Bacillariophyta and Cyanophyta consistently dominated the periphytic algae community. (2) Assessments using both B-IBI and P-IBI showed that the overall river health in spring was slightly better than in autumn. However, more than half of the sampling sites were rated as “fair” or worse in both seasons. The reference sites (S2, S10) consistently exhibited “excellent” or “good” health, while the impaired sites showed significant spatial heterogeneity. Discrepancies between B-IBI and P-IBI ratings at some sites revealed differential responses of the two biological communities to environmental stressors. (3) Stepwise regression analysis unveiled a seasonal shift in key environmental drivers. The primary factor affecting the B-IBI in autumn was biochemical oxygen demand (BOD₅), which shifted to total phosphorus (TP) and ammonia nitrogen (NH₄⁺-N) in spring. For the P-IBI, the main factor changed from dissolved oxygen (DO) in autumn to chemical oxygen demand (COD) in spring. These findings confirm the applicability of the B-IBI and P-IBI systems in this region, and indicate that multi-assemblage integrated assessments can contribute to understanding the health status of river ecosystems in the Qianxinan Prefecture. This study could serve as a scientific reference for the protection, management, and restoration of local river ecosystems. Full article

Benthic prokaryotic communities in deep-sea sediments remain poorly studied. They are constrained by organic matter availability and oxygenation in warm deep-sea ecosystems. Here, we investigated benthic prokaryotic communities and carbon uptake in deep Red Sea sediments (218–2415 m seafloor depth), where persistently warm (~21.5 °C) waters and a strong south–north productivity gradient co-occur. Sediment particulate organic carbon (POC), prokaryotic abundance (PA), and [¹³C]-D-glucose-based carbon uptake and uptake kinetics were examined in two sediment layers (0–1 and 4–5 cm), while bacterial communities were characterized using 16S rRNA gene sequencing of the 0–1 cm layer. Sediment POC, PA, and carbon uptake declined northward, consistent with reduced organic-carbon supply to the seafloor. Bacterial community composition differed significantly across the ~500 m depth associated with the Red Sea oxygen minimum zone (OMZ). Sediments from the relatively low-oxygen upper OMZ-range (200–500 m) had higher sediment POC and PA, and were enriched in putatively anaerobe-associated taxa, whereas deeper sediments (>500 m) below the OMZ exhibited more fragmented co-occurrence networks. These results suggest that organic-carbon availability defines the basin-scale metabolic backdrop, whereas bacterial community differentiation was more clearly resolved between upper OMZ-range and below-OMZ sediments than along latitude alone. Full article

Benthic foraminifera are effective indicators of heavy metal contamination in marine ecosystems. Traditional methods for benthic foraminiferal identification and biodiversity assessment rely predominantly on stereomicroscopic analysis. However, this approach is time-consuming, labor-intensive, and cannot effectively identify small or morphologically similar species. In this study, we aimed to enhance the utility of benthic foraminifera as bioindicators. To this end, we investigated the responses of benthic foraminiferal communities to varying concentrations of Cd under controlled laboratory conditions using both morphological assessments and metabarcoding analyses. Cd exposure reduced the abundance of benthic foraminifera. High Cd concentrations led to Cd enrichment in foraminiferal tests and altered the contents of other elements. Quinqueloculina, Ammonia, and Miliammina exhibited tolerance to Cd, whereas Parasorites and Ovammina were more sensitive. This study provides an effective approach for evaluating the short-term effects of heavy metal pollution on benthic foraminiferal communities. Full article