Marine Ecology-An Evolutionary Perspective最新文献

The global whale population is shrouded in uncertainty, primarily due to the substantial costs and resource demands associated with traditional detection methods such as sighting surveys, acoustic monitoring, and high-resolution imagery analysis. This study presents a groundbreaking approach that employs transformer-based models, specifically RTDetr with customized backbone and Segformer-based encoder–decoder architecture with skip connections, for the autonomous detection, classification, and tracking of blue whales in the Indian Ocean using space-borne satellite imagery. By integrating datasets from SASPlanet, UK Polar data, and Worldview-2 imagery around Sri Lanka, and validating with Cartosat-2E Satellite data (1.16 m) from NSIL Bangalore, ISRO. The proposed research developed a robust system capable of processing high-resolution satellite images for cost-effective whale detection. This system is accessible through Telegram and WhatsApp bots, facilitating real-time detection and tracking via deployment on a Jetson Nano board. Our model achieved impressive performance metrics, including an F1 score of 90%, mean average precision (mAP) of 83%, precision of 90%, and recall of 98%. These results demonstrate the efficacy of our approach in automating whale detection, offering a scalable and efficient tool for advancing marine conservation efforts.

The crustaceans of the superfamily Paguroidea constitute one of the most diverse groups within the Decapoda, exhibiting remarkable morphological and ecological diversity. Despite the relatively high number of described species worldwide, there are still many gaps in the knowledge of this group, particularly regarding genetic information. This study aims to update the geographic distribution information currently available for the hermit crab species in the Iberian Peninsula, Azores, Canary Islands, and Madeira, and generate a molecular database supported by morphological identification. The results are summarized in an updated list of Paguroidea recorded in the study area, which comprises a total of 55 species, representing a significant increase from previous compilations. Newly generated sequences, including those from the study area and closely related species from other areas, provide the first molecular information for 35 out of the 70 species analyzed. Phylogenetic analyses provide evidence of the species delimitation capabilities of molecular tools when reliable morphology-based information is available. Molecular analyses using two mitochondrial markers largely corresponded, supporting most traditionally established species and validating the morphological characters used for delimitation. Specifically, the COI gene showed better results and clearer topologies, suggesting greater utility for exploring species delimitation when using single-gene identification as a DNA barcode. Overall, the results of this long-term study will improve the capabilities for species delimitation, in addition to updating the composition and richness of species in the area.

The relationships between meiofaunal communities and hard substrate are relatively well-documented in the scientific literature. However, a comprehensive quantitative review of global research on meiofauna colonization across different hard substrates has not yet been conducted. In this study, a scientometric analysis was performed to evaluate scientific interest in various hard substrates in studies exploring the influence of spatial heterogeneity on meiofaunal colonization. A total of 124 articles published from 1967 to 2023 were selected from online databases. Macroalgae were the most frequently studied hard substrate, and it was the one that harbors the highest abundance and richness values compared to other substrates. Studies predominantly focused on specific taxonomic groups, particularly Copepoda, Harpacticoida, and Ostracoda. Nematoda, Copepoda, Harpacticoida, and Amphipoda were the most commonly recorded meiofaunal taxa. Geographically, the United States of America was the most productive country in this field, followed by Brazil. Multivariate analyses, especially Non-Metric Multidimensional Scaling (nMDS), were the primary quantitative methods used. A decline in studies on meiofauna-substrate relationships over recent years was observed. Given the extensive research on macroalgal colonization, future studies should consider a wider variety of hard substrates to expand understanding in this field.

Wood falls—parcels of wood that sink to the deep-sea floor—represent unique and dynamic ecosystems that support a highly diverse and evolutionarily distinct assemblage of faunal communities. The fauna inhabiting wood falls exhibit a high degree of endemism, with many species using the wood not only as a substrate and habitat but also as a direct or indirect source of organic matter. Xylophagous species play a critical role in breaking down the wood, creating complex food webs and contributing to nutrient cycling in the deep-sea environment. The composition of faunal communities associated with sunken wood is influenced by several factors, including the physical properties of the wood itself, such as species, mass, and surface area, as well as environmental conditions like water depth, geographic location, and the stage of ecological succession. These factors interact to shape the biodiversity and ecological processes within wood falls, making them temporally and spatially finite habitats. Their distinct boundaries and lifespans are tightly linked to the rate of wood degradation, primarily driven by specialized wood-boring organisms. Despite their ecological significance, most knowledge about wood-fall ecosystems comes from experimental studies rather than from observations of naturally occurring wood falls. This has left significant gaps in our understanding of the natural variability and ecological roles of these systems in the deep sea. The scarcity of natural wood-fall records poses challenges for fully grasping their contribution to deep-sea biodiversity, carbon cycling, and biogeography. In this review, we synthesize the current state of knowledge on wood-fall ecosystems. We also explore the potential applications of wood-fall research in broader ecological, industrial, and environmental contexts. Wood falls offer valuable insights into deep-sea ecosystem functioning, biodiversity maintenance, and species evolution.

The severe heatwave that occurred in April–May 2016 caused widespread bleaching and mortality in the Maldivian coral reefs. In this study, the main factors that influenced coral recovery were investigated, that is, reef typology and exposure (ocean vs. lagoon) and depth (5 m vs. 10 m). Field surveys were conducted in 2019 and 2021 on 26 Maldivian reefs through photographic samplings. Changes in coral community structure and composition were analysed using the percent cover of the dominant coral families in the Maldives (Acroporidae, Pocilloporidae, and Poritidae) and of a number of benthic categories (encrusting corals, soft-bodied organisms, abiotic components). Following the climate disturbance, most of the reefs were still dominated by abiotic components (mainly coral rubble and dead corals) after 5 years, although a slight recovery in hard coral cover was registered. Ocean reefs, dominated by massive Poritidae corals, exhibited a higher recovery capacity than lagoon reefs. Lagoon reefs displayed a higher coral mortality and spatial variability in their recovery patterns and in the coral community composition. Encrusting corals and soft-bodied organisms played a major role in the reef regeneration. The predicted increase in heatwaves frequency due to climate change makes long-term monitoring mandatory to tackle coral reefs' recovery potential and to evaluate their resilience to global warming. Photographic sampling represents a cost-effective methodology to monitor coral communities regularly and objectively evaluate changes in the abundance of the main reef components.

Sea turtles exhibit temperature-dependent sex determination with warmer incubation temperatures producing more females. Evidence from some regions indicates that global warming may already be increasing the proportion of female hatchlings, but this trend may not be uniform across all areas. Therefore, it is fundamental to understand the spatiotemporal diversity of sand temperature profiles and hatchling sex ratios within each rookery when developing conservation measures. The Ogasawara Islands (27°1′–11′ N, 142°9′–14′ E), Japan, are a highly isolated oceanic archipelago and one of the most important rookeries for green turtles (Chelonia mydas) in the North Pacific. The islands show high inter-beach environmental differences, but to date no study has assessed how these differences translate into spatiotemporal diversity of sand temperatures and hatchling sex ratios. In the present study, we measured the sand temperature at different depths and estimated the hatchling sex ratios from the thermal profiles at seven important nesting beaches of the green turtle in the Ogasawara Islands during 2018–2019. Results showed a marked spatiotemporal diversity in sand temperatures, with estimated hatchling sex ratios varying from male-biased to female-biased among the seven beaches. The spatiotemporal diversity is likely associated with the environmental characteristics between beaches, such as degree of shading, ground vegetation cover, and sand color, as well as seasonal temperature shifts. Nest depth is likely irrelevant for estimating hatchling sex ratios in the Ogasawara Islands. Continuous monitoring of the nesting environments is needed for efficient conservation of green turtle resources.

The temperate coral Astrangia poculata is rapidly becoming a convenient system for studying symbiosis, microbiome, and thermal resilience. However, the ecology of this species is poorly understood. A. poculata is a temperate coral that employs facultative symbiosis to survive in cold, nutrient-rich New England waters. The two ecotypes—symbiotic mixotrophic and aposymbiotic heterotrophic colonies—exist in the same environment, but their abundance changes across depth gradients. We conducted quadrat sampling along a depth gradient to quantify the density of A. poculata at Fort Wetherill State Park, RI, and determine the correlates of ecotype distribution. Further, we quantified light availability and macroalgal cover as possible ecological drivers of abundance. Symbiotic and aposymbiotic A. poculata exhibited a bell curve distribution along the depth gradient. In shallow environments, where both light and macroalgae are abundant, macroalgal cover was inversely related to coral density, implying a negative effect on coral abundance. In deeper environments where macroalgae were not present, coral cover was higher. However, light limitation and depth may limit A. poculata abundance, with symbiotic colonies growing no deeper than 12.5 m and only aposymbiotic colonies present from 13 to 22 m. As macroalgae abundance and turbidity increase with more nutrient loading in coastal marine ecosystems, monitoring their effect on the distribution and density of A. poculata is critical to conserve this monotypic species.