Search Results (1,984)

The aim of this study is to determine the age and depositional environment of the Harami Formation through an integrated interpretation of XRF, ICP-MS, SEM-EDS, stable isotope, and radioactive isotope analysis results and findings of larger benthic foraminifera. Findings from the authors’ previous studies regarding the characteristics of larger benthic foraminifera were utilized; geochemical analysis results were obtained for the first time in this study. The mean ⁸⁷Sr/⁸⁶Sr values are generally consistent with the ages determined from the larger benthic foraminifera. The analysis results and Y/Ho values indicate that CaO is the dominant component, while negative Ce and positive Eu anomalies are indicative of a low-grade diagenetic effect. The absence of hydrothermal activity in the depositional environment and the proximity of the values to those of seawater are supported by the Y/Ho and Eu/Sm ratios. Similarly, to the larger benthic foraminifera content that indicates the Harami Formation was deposited in a shallow, oxic environment, the trace element ratios (V/Cr and V/V+Ni) and slightly negative Ce anomalies also support deposition in an oxic environment, while the Sr/Ba and Sr/Rb analysis results indicate a shallow marine environment. The analysis results further indicate that the depositional environment ranged from warm-temperate to arid conditions. A decrease in mean temperature is observed from the late Campanian to the early Maastrichtian, with an increase from the early Maastrichtian to the late Maastrichtian. Full article

Mesophotic kelp habitats may contribute to marine carbon cycling, yet their productivity and long-term carbon retention remain poorly constrained. We assessed a depth-constrained analytical support domain for the endemic and endangered Brazilian kelp Laminaria abyssalis across 45–70 m on the southwestern Atlantic shelf using a published species distribution model, high-resolution bathymetry, biomass observations, and literature-based productivity scenarios. Accounting for within-cell bathymetric variation yielded 12,514.60 km² of depth-constrained analytical support within non-NA SDM coverage. The biomass dataset contained 23 observations aggregated into 19 raster cells. Leave-one-out validation showed that inverse distance weighting did not outperform a non-spatial mean (RMSE = 75.25 vs. 74.02 kg km⁻²; r = −0.389, p = 0.100); therefore, no regional biomass or biomass-derived productivity surface was produced. Using the only depth-overlapping Laminaria productivity analog (22.32 g C m⁻² yr⁻¹), the full-occupancy area-integrated NPP scenario was 279,326 t C yr⁻¹, with an empirical transferability envelope of 4242–1,074,367 t C yr⁻¹. At a long-term retention fraction of 0.11, the retained-carbon equivalent ranged from 467 to 118,180 t C yr⁻¹. These values are assumption-dependent screening estimates, not measurements of export, burial, sequestration, or carbon-credit potential. Field measurements of occupancy, local productivity, transport, burial, and permanence are required before carbon-accounting claims can be supported. Full article

Sandy littorals are highly dynamic coastal ecosystems but remain poorly studied as wintering habitats for waterbirds in Mediterranean regions. We analysed mid-winter International Waterbird Census data collected along the 100 km sandy littoral of the province of Venice, northern Adriatic Sea (Italy), between 1994 and 2022. The dataset included 28 winter censuses, 70 species, and 150,083 individuals. The assemblage was rich but highly uneven: the Yellow-legged Gull Larus michahellis, Dunlin Calidris alpina, Black-headed Gull Chroicocephalus ridibundus, and Great Cormorant Phalacrocorax carbo accounted for most individuals. Total abundance was stable, despite strong interannual variability, whereas species richness increased significantly. Eco-functional guilds showed contrasting trends: benthic feeders and diving piscivores increased moderately, omnivores declined moderately, whereas the trends of the remaining four guilds were classified as uncertain. The Community Temperature Index did not show a significant directional trend, either for the whole assemblage or after excluding dominant species, suggesting that the observed changes cannot be interpreted as progressive thermophilisation. Overall, the Venetian sandy littoral supports a diverse and functionally heterogeneous wintering bird assemblage, whose long-term changes reflect shifts in community structure and the changing use of open-coast, nearshore, and artificial roosting habitats. The results provide a long-term evidence base for identifying conservation-relevant shoreline sectors, protecting feeding and high-tide roosting habitats, regulating disturbance and beach-management practices, and maintaining continued IWC monitoring of open-coast waterbird assemblages. Full article

We reexamined the critical importance of water motion in measuring algal growth and photosynthetic rates, addressing a significant limitation in traditional static incubation approaches. It presents a comprehensive framework for dynamic measurement methods that better simulate natural hydrodynamic conditions experienced by both macroalgae and other benthic autotrophs. We considered the barrier effects of the diffusion boundary layer surrounding the algae on the fluxes of gases and nutrients across the cellular membrane, and integrates findings demonstrating that flow-enhanced mass transfer of nutrients, inorganic carbon and O₂ across diffusion boundary layers can increase photosynthetic performance in macroalgae including the tested Sargassum, Porphyra and Macrocystis species. We provide quantitative comparisons demonstrating that increased velocities of water current can enhance photosynthetic and/or nutrient uptake rates compared to stagnant conditions. The comparative analysis highlights the advantages of flowing water systems in reducing diffusion limitations and better simulating natural environments against the technical simplicity of static methods. We detailed practical methodologies including flow-through system setup and sealed chamber with magnetic stirring techniques for macroalgae, and brush substrate for benthic diatoms. These approaches enable diurnal physiological tracking and reveal saturation responses to increasing water velocities. The methodological framework provides researchers with robust protocols for more accurate assessment of algal photosynthesis and primary productivity in both experimental and applied contexts such as aquaculture, carbon sequestration, and ecological monitoring. Full article

Hypersaline semi-enclosed seas impose physiological constraints on marine bivalves by increasing osmotic regulation costs and limiting somatic growth. This study examined life-history variation in natural populations of the pearl oyster Pinctada radiata across contrasting salinity regimes along the eastern and western coasts of Bahrain in the Arabian Gulf. Environmental conditions, shell morphometrics, growth modeling, oocyte abundance, physiological condition indicators, and the production-to-biomass ratio (P:B) were assessed to determine whether high salinity constrains somatic growth while reproductive persistence is maintained. Monthly surveys were conducted from June 2021 to May 2022 at one pearl oyster bed on each coast, comprising 12 surveys per coast. The two coasts formed a salinity gradient, averaging approximately 42‰ in the east and 55‰ in the west. Oysters from the western coast were smaller, with a mean shell height decreasing from 63.12 ± 6.47 mm in the east to 45.88 ± 3.41 mm in the west. The Gompertz model indicated a lower asymptotic shell height in the more saline population. The population-level P:B ratio was 0.23 yr⁻¹ on the eastern coast and 7.46 yr⁻¹ on the western coast. Despite reduced shell size, western oysters maintained strong seasonal oocyte abundance. The higher biomass turnover in the west partly reflected greater oyster density. This pattern is consistent with osmoregulatory costs and constrained shell biomineralization under chronic hypersalinity. Reproductive activity followed a bimodal pattern on both coasts. These findings are consistent with a life-history trade-off in which pearl oysters exposed to chronic salinity stress maintain reproductive activity despite constrained growth. Overall, this study links environmental forcing, growth limitation, population-level biomass turnover, and reproductive activity, providing field-based evidence that chronic hypersalinity constrains somatic growth while reproductive persistence is maintained in a benthic bivalve inhabiting hypersaline coastal systems under climate-related stress. Full article

Springs are biodiversity hotspots and climate refugia, yet they remain among the most overlooked and threatened freshwater ecosystems, largely absent from regional monitoring programs. In the Emilia-Romagna Region (Northern Apennines, Italy), where more than 8400 springs are documented but most persist as unmonitored “ghost springs”, we developed and tested an ecohydrogeological framework to support their long-term monitoring and conservation. Twenty-five springs were selected as representatives of five strategic zones, which we identify, defined by aquifer type (Ophiolites, Turbiditic Sandstones, Shallow Marine Sandstones, Triassic Gypsum, and lowland Fontanili) and characterized through integrated hydrogeological, hydrochemical, and biological sampling. Benthic diatoms (393 species in 69 genera) growing on three different substrates (epibryon, epilithon and epipelon) per spring, vegetation, and physical and chemical parameters were analyzed. Diatom assemblage composition differed significantly among zones (PERMANOVA, p < 0.001), structured primarily by electrical conductivity between sites (community level) and by discharge regime between substrates (microhabitat level); the proportion of aerial diatoms (88 species) proved a useful indicator of discharge fluctuations, inferable from a single biological sample. Threatened taxa (41% of evaluated species) concentrated in the ridge zones. Although calibrated in the Northern Apennines, the five-zone framework offers a biologically validated and transferable tool to other regions for spring conservation as sentinel ecosystems under climate change and anthropogenic exploitation. Full article

Wetlands constitute critical habitats sustaining cyanobacterial diversity. Nevertheless, taxonomic research on wetland benthic filamentous cyanobacteria is far from complete, largely limited by phenotypic plasticity and challenges in strain isolation and cultivation. To unravel the species diversity and taxonomic affiliations of epiphytic cyanobacteria in an urban wetland, cyanobacterial strains were isolated from riparian rocks of the Sanyang Wetland (Zhejiang Province) and characterized via morphological observation, 16S rRNA phylogenetic analysis and 16S–23S ITS structural comparison. Strain WZU 2025, sheathless with occasionally conical apical cells, fell into the genus Kamptonema. It shared less than 97.5% sequence similarity with K. animale and possessed distinctive ITS signatures, hereby proposed as Kamptonema schistus sp. nov. Strain WZU 2023, featuring colorless rigid sheaths and conical apical cells, formed a stable clade with Microcoleus but exhibited distinct ITS structures, and is designated Microcoleus wenzhouensis sp. nov. Strain WZU 2030 bears colourless rigid sheaths and trichomes mostly filled with chromatophores; it clustered reliably with known Wilmottia species yet differed in ITS traits, and is described as Wilmottia sanyangensis sp. nov. Conflicts between morphological taxonomy and molecular phylogeny reveal ambiguous intergeneric relationships within Coleofasciculaceae and Microcoleaceae. The present study expands the known diversity of Microcoleaceae and provides evidence for future taxonomic revisions of cyanobacteria. Combined with the new genus Paludothrix reported from this wetland in 2024, our data demonstrate that cyanobacterial diversity in Sanyang Wetland has been severely underappreciated. Full article

New health-promoting food ingredients should combine nutritional functionality, traceable production and sustainable sourcing. Freshwater and brackish gammarid amphipods are usually considered ecological indicators, fish prey or invasive crustaceans, but their biochemical and ecological traits suggest a candidate role as low-trophic aquatic biomass. This narrative review evaluates gammarids primarily as EPA-oriented crustacean biomass and as a potential source of protein, minerals, chitinous material and processing fractions for feed, supplement and functional-food research. Available data indicate meaningful long-chain omega-3 content, especially EPA, but direct evidence for human health effects, bioavailability, clinical efficacy and industrial cultivation remains limited. Wild harvest is unlikely to provide a safe or standardized raw material. The central proposition is, therefore, that gammarid-derived ingredients should be developed through controlled benthic production systems, followed by hygienization, fractionation and safety validation. The most realistic near-term pathway is not direct consumption of whole animals, but standardized feed ingredients, EPA-oriented lipid blends, protein–lipid fractions and supplement-grade materials after regulatory assessment. The review distinguishes established evidence from technological hypotheses and identifies the research required before gammarids can be considered reliable industrial ingredients. Full article

Detecting changes in coral and seagrass habitat composition from satellite imagery places exceptionally high demands on sensor design due to low underwater reflectance signals and variable water column conditions. Recent multispectral satellite-based attempts to assess such changes across large spatial extents illustrate this challenge through an inability to reliably distinguish live coral from algae, often resulting in broad confidence intervals. This study quantifies the radiometric sensitivity requirements for detecting 10% absolute changes in live coral and seagrass fractional cover from spaceborne imaging spectroscopy using representative parameters for an aquatic imaging spectrometer. The analysis combined representative benthic spectra with realistic, management-relevant co-occurrence scenarios informed by extensive regional knowledge and field measurements from Fiji, Australia, and the Solomon Islands to evaluate detection performance across depths from 0 to 30 m. We show that live coral is the most demanding of the benthic targets evaluated because of its low reflectance and spectral similarity to algal cover types, requiring SNRs of approximately 300–700 to detect 10% absolute changes in cover at depths up to 10 m. In contrast, the greater spectral separation between seagrass and adjacent sandy substrates allows detection of 10% absolute changes in cover to depths exceeding 20 m in clear water. These results highlight the importance of high radiometric sensitivity and contiguous spectral sampling for future aquatic imaging spectrometers intended to monitor benthic change. Approaches that increase effective SNR, such as ground motion compensation (GMC), can extend the depth and confidence with which changes in benthic composition are detected, supporting a transition from broad-area habitat mapping toward quantitative monitoring of benthic change from space. Full article

Deep-sea mining generates plumes containing heavy metals harmful to marine ecosystems. Assessing their impact on benthic organisms is essential. Traditional monitoring methods commonly employ acoustic, optical, and electrical approaches to investigate collective behaviors of organisms, while direct acquisition and in situ preservation of biological specimens during deployment remain challenging. To address this limitation, a novel sequential near-bottom mobile organisms sampling equipment equipped with multiple chambers was developed. Sequential sampling of near-bottom mobile organisms was conducted to obtain samples at different time points for individual-level biological assessment. This study investigates the alcohol diffusion dynamics at various injection volumes. The results show that during injection, alcohol is concentrated in the upper section of the chamber. When 5.0 L of alcohol is introduced, the alcohol mass fraction within the sampling container rapidly reaches and stabilizes at 87%. The sampling equipment’s performance was evaluated through dock experiments and deep-sea trials at a depth of 1571 m in the South China Sea. Field tests successfully captured five jellyfish, with alcohol mass fractions of 85%, 87%, and 87% achieved in the respective chambers. These results demonstrate the feasibility of the equipment for sequential biological sampling and in situ preservation in deep-sea environments. Full article

Giant kelp forests, Macrocystis pyrifera, dominate the coasts of southern Patagonia and are particularly abundant in the coastal ecosystems of Cape Froward, where they play a key role in biodiversity conservation and the provision of multiple ecosystem services, establishing themselves as one of the most resilient kelp forest ecosystems on the planet. This study constitutes one of the first spatiotemporal assessments of the diverse components inhabiting kelp forests in the Strait of Magellan (Cape Froward). In total, 238 taxa belonging to zooplankton, benthic invertebrates, fish, and understory of macroalgae inhabiting the understory were identified in these ecosystems, including species that are key to the coastal communities of the Magellan region. In general terms, the results show that the coastal ecosystems of Cape Froward support highly diverse, dynamic, and complex communities, with characteristics representative of ecological systems of regional and global significance. In this regard, the present study provides a solid scientific basis for promoting conservation measures for these ecosystems at the southern tip of Patagonia. Full article

Alpine karst lakes in Jiuzhaigou exhibit spatial variations in optical properties associated with differences in water depth, underwater substrates, and travertine distribution. Conventional satellite observations may not provide sufficient spatial resolution to resolve the small-scale optical variations present in these shallow and heterogeneous lakes. In this study, UAV-based hyperspectral imagery was used to quantify spatial optical variations among three representative cascade lakes located in the “Y-shaped” valley network of Jiuzhaigou, China. Hyperspectral reflectance data were transformed into the CIE L*a*b* color space to quantify perceptual color variability, while the Euclidean color difference metric (ΔE) was used to assess relative spatial heterogeneity. In addition, seven empirical optical proxies were developed to describe spatial variations in apparent optical properties without attempting absolute retrieval of water constituents. A tiered unsupervised K-means clustering approach was applied to resolve optical heterogeneity across multiple spatial scales. Global-scale clustering separated the major optical differences among lakes, whereas lake-specific clustering revealed distinct intra-lake optical zones, including areas with stronger benthic influence, transitional optical conditions, and zones dominated by water-column signals. Non-parametric Kruskal–Wallis H tests showed significant differences among optical zones, indicating that the selected proxies can distinguish spatial optical variability. The results show that UAV hyperspectral observations combined with color metrics and empirical optical proxies can effectively describe fine-scale spatial optical variations in alpine karst lakes. Rather than retrieving absolute biogeochemical or bathymetric parameters, this approach provides a reference description of relative optical variability that may assist future repeated observations and spatial monitoring of protected aquatic ecosystems. Full article

Sandy beaches in the Central Region of Veracruz (CRV) face constant anthropogenic pressure from port and urban activities. This study aimed to evaluate total hydrocarbon (TH) concentrations in the intertidal interstitial water of five beaches in the CRV, analyzing their variability by depth (15 and 30 cm) and seasonality (northerly winds, dry, and rainy seasons). TH determination was performed using gas chromatography (GC-FID), following the NMX-AA-117-SCFI-2001 and NOM-138-SEMARNAT/SSA1-2012 standards. Results showed concentrations ranging from 0.86 to 6.53 µg L⁻¹. Significant spatial differences were identified (p < 0.05); Antepuerto beach presented the highest levels due to its proximity to the port, while Farallón showed the lowest concentrations, confirming its role as a reference site. No significant variations were detected by depth or season (p > 0.05), indicating temporal stability associated with continuous anthropogenic inputs. Although levels comply with Mexican regulations, the continuous presence of TH represents a potential risk to benthic biota and the integrity of the Veracruz Reef System (SAV). This study provides a critical baseline for strengthening coastal ecosystem management strategies in the Gulf of Mexico. Full article

Shiga toxin-producing Escherichia coli (STEC) contamination and proliferation in aquaculture and aquatic systems is worrisome for global food safety, as well as veterinary and public health. Traditionally linked with terrestrial ruminant reservoirs, aquaculture matrices, including farmed finfish, shellfish, culture water, and benthic organisms, are increasingly acknowledged as potential conduits for the dissemination of STEC. Herein, the review documented data concerning the prevalence, genomic composition, and ecological dynamics of STEC across various aquaculture environments across different regions of the globe. As a result, the persistence of virulence-associated genes (VAGs) and antibiotic-resistant genes (ARGs) in STEC within the aquaculture supply chain presents a considerable risk to global food security and public health, highlighting the urgent necessity for comprehensive “One Health” surveillance frameworks aimed at alleviating aquatic biosecurity challenges. Full article