Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

Habitat selection is a fundamental aspect of animal movement and behaviour, involving strategies that influence population regulation, species interactions, community structure and the generation and preservation of biodiversity. The Greater Caribbean Manatee is a megaherbivorous aquatic mammal with high environmental plasticity, found in a variety of coastal-marine ecosystems from the United States to Brazil. The subspecies is locally threatened because of intense poaching in recent centuries, which has led to the disruption of small populations. In this study, we aimed to understand habitat selection patterns and their variation across study sites, sex, age classes and between captive-released and wild manatees in northeastern Brazil to inform conservation policy. We used high-resolution GPS telemetry data from 20 tagged manatees and applied autocorrelation-informed resource selection functions (RSF) using (i) seagrass meadows, (ii) coral reefs, (iii) estuaries and (iv) freshwater springs as environmental predictors. As a proxy for anthropogenic impact, we also used a predictor combining multiple human activities at sea, which imposes substantial pressures with a subsequent degradation of manatee habitat. All environmental predictors had statistically significant results at the population level. Positive estimates were found for estuaries (1.52), springs (0.85) and seagrass meadows (0.77), indicating that manatees hierarchically select these habitats. The human impact was also positive (1.12), suggesting that the habitats selected by manatees overlap with human-impacted areas. Coral reefs (−0.92) were found to have a negative estimate, indicating that the animals avoid using this habitat. Our results confirm the vital role of seagrass meadows and freshwater in manatee movement behaviour. The selected habitats overlap with human-impacted areas, particularly in areas close to urban centers and ports. This creates obstacles to manatee free movement and the reconnection of subpopulations, highlighting the importance of conserving and restoring these marine coastal habitats.

Understanding the impact of human activities on fish communities is critical for the effective conservation of Amazonian ecosystems. In this study, we sampled environmental DNA (eDNA) from 17 sites (lakes and rivers) in two Peruvian national reserves, Pacaya-Samiria and Allpahuayo-Mishana, using a metabarcoding approach with four genetic markers (2 COI and 2 12S). We hypothesized that fish community composition and functional diversity in Amazonian freshwater systems could be impacted by anthropogenic factors, such as deforestation or a set of variables included in the Human Modification Index (SEDAC). Our analyses identified 319 species in Pacaya-Samiria and 207 species in Allpahuayo-Mishana, demonstrating the efficacy of eDNA for generating robust biodiversity inventories. While human disturbances did not significantly reduce species richness, they altered species composition and impacted functional diversity. Specifically, deforestation reduced functional richness, indicating the loss of ecological functions, while increasing functional dispersion, reflecting shifts towards more generalist species. These findings underline the vulnerability of functional diversity to anthropogenic pressures, even in high-biodiversity systems, and emphasize the need for conservation strategies that incorporate functional diversity alongside taxonomic diversity. In practical terms, management actions should prioritize the maintenance of structurally complex and forested riparian habitats, which support functionally diverse fish assemblages, and monitor functional traits as early indicators of ecosystem degradation. Approaches such as functional vulnerability analysis can help identify key ecological functions at risk, while targeted habitat restoration in deforested buffer zones may mitigate human impacts. Strengthening community-based management and integrating eDNA monitoring into long-term conservation plans offer a proactive, adaptable framework for safeguarding Amazonian freshwater ecosystems.

The neotropical otter Lontra longicaudis (Olfers, 1818) is a semi-aquatic carnivore from the Mustelidae family with a piscivorous habit that interacts with riverine populations because of fishing resources, and this relationship is often negative, especially in the Amazon where fishing represents an important activity for several communities. Therefore, this study aims to confirm the occurrence of L. longicaudis in the Guamá River (Northern Brazil) and analyse its interactions with the local fishing community. A total of 29 interviews were carried out with artisanal fishermen from the village of Igarapé-Açú (Northern Brazil). The Snowball methodology and monitoring of the banks of the Guamá River were used and it was possible to confirm the presence of otters in the Guamá River by the presence of nests and fishermen's perception. River dwellers, through their perceptions, have information about otter ecology, becoming an alternative source of new data. The interaction between fishermen and otters occurs because of the latter's piscivorous habit. Overall, in the study area the otter interferes with fishing by damaging equipment when removing fish, generating conflicts. There are also reports of otters being raised as domestic animals. Therefore, the interaction between otters and fishermen in this region is negative. Conservation measures are necessary to minimize these conflicts, such as an environmental education program.

The Comal Springs dryopid beetle (Stygoparnus comalensis) (Coleoptera: Dryopidae) is an endangered, subterranean-obligate, long-toed water beetle known only from three spring complexes in the Edwards Aquifer region of Texas. Due to their small size and reliance on groundwater karst habitats, little is known of the biology of these beetles. The aim of this study was to investigate evolutionary, ecological and morphological divergence among known S. comalensis localities in order to inform conservation management plans for this species. We used genotyping-by-sequencing, stable isotope ($��{�\delta �}^{�15�}�$N and $��{�\delta �}^{�13�}�$C) analysis and morphometric analysis, to describe variation among the three known localities and to ask whether ecological or morphological differentiation is associated with population genomic divergence. S. comalensis populations are highly structured with no evidence of gene flow. Stable isotope ratios and morphology did not significantly differ among populations, suggesting that isolation is the driver of genetic diversification in S. comalensis. These results indicate that isolated populations show great levels of overall genomic divergence, while stasis or stabilizing selection has constrained ecological or morphological divergence. The three localities where S. comalensis has been found should be considered as evolutionarily distinct units based on levels of genomic differentiation and conservation efforts should prioritize maintenance of the known localities and continued surveys to discover other localities for this endangered beetle.

Elasmobranchs are globally threatened and experiencing ongoing declines. Understanding threatened elasmobranch distribution is critical for developing effective marine conservation strategies. However, our knowledge of fine-scale elasmobranch habitat association and distribution in temperate nearshore systems is limited. Here, we examined the presence, relative abundance and habitat association of sharks, skates and rays using benthic baited remote underwater stereo-video systems (SBRUVS). From 772 deployments (682 total hours and 53-min average soak time) across 3 years (2021–2023) and two Scottish sea lochs and adjacent bays, elasmobranchs were detected on 31.2% of deployments (n = 241). Our surveys detected six species of elasmobranchs: flapper skate (Dipturus intermedius), thornback ray (Raja clavata), spotted ray (Raja montagui), lesser-spotted dogfish (Scyliorhinus canicula), spiny dogfish (Squalus acanthias) and porbeagle (Lamna nasus), representing 17.6% of the resident elasmobranch diversity reported to date in UK nearshore waters < 200 m depth. The species detected include two species listed as globally Vulnerable on the IUCN Red List, spiny dogfish and porbeagle and one Critically Endangered species, flapper skate. Critically Endangered flapper skate were detected in 5.2% of deployments (n = 40) and were the only species recorded that did not show a relationship between the probability of presence and substratum type. Our findings provide critical data on the fine-scale spatial distribution and habitat association of elasmobranchs, which could be used to inform evidence-based conservation measures and support more consistent and targeted policy action for these species in Scotland.