Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

Species occupying dryland river ecosystems often experience “boom-and-bust” demographic cycles that coincide with shifts in habitat availability. Knowing whether declines are within natural thresholds versus those caused by acute human disturbance is critical for managing protected species. We investigated temporal shifts in abundance and habitat use of an endangered population of the threespine stickleback Gasterosteus aculeatus in southern California, where a Mediterranean climate leads to ephemeral habitat in one of the regions' least hydrologically modified rivers, the Santa Clara River. We conducted population surveys over a period of below-average rainfall in the upper watershed in Soledad Canyon, with predefined reaches surveyed multiple times per year to capture different hydrologic conditions. Abundances were stable across years but varied significantly depending on location, with some reaches remaining dry and others drying seasonally to varying degrees. Occupancy models showed that the presence of stable perennial reaches, drying regime, and other site-specific factors were important predictors of habitat use, and that certain reaches may be key to ensuring source-sink dynamics as flow dissipates over the dry season. Low occupancy in two sections was driven by different predominant mechanisms, one by diel cycles of evapotranspiration and the other by cattails (Typha spp.), with both having greater effects during the hotter, drier parts of the year. As dryland river ecosystems are vulnerable to the effects of anthropogenic-induced climate change, this study demonstrates how temporal monitoring can delimit dry-state benchmarks for improving management interventions (i.e., translocation and habitat restoration) for protected species under conditions that are predicted to worsen in the coming years.

Benefits to wildlife communities stemming from the protection of a single species have been documented in terrestrial and marine systems but remain understudied within the context of freshwater-protected areas (FPAs). We used five long-standing (>80 years) FPAs in three lakes in eastern Ontario, Canada, which were initially established to protect native black bass (Micropterus spp.) from angling exploitation, to assess whether this protection affected wildlife communities found in the riparian areas of these FPAs. From May to July 2021, we used baited remote camera traps and visual surveys to assess species diversity within and outside of FPAs. We recorded 61 species spanning mammalian, avian and herpetofauna taxa, with the two assessment methods identifying unique sets of species (23% overlap). Camera traps showed that animals were more active in riparian areas during the day (62% of detections) than at night. FPAs had a variable but overall positive influence on riparian wildlife biodiversity, hosting more bird, mammal, amphibian and reptile species than non-protected areas and having higher species richness. FPAs differed from other sites in the lakes by having higher habitat complexity, less human infrastructure and less human use, which potentially contributed to these differences. This study raises awareness that even small FPAs can have legacy, umbrella-type benefits that extend beyond fishes to the wildlife that use the adjacent riparian areas.

Rivers offer cultural ecosystem services (CES) that improve people's quality of life. Advancements in computing and data storage have primarily focused on terrestrial CES, neglecting riverine areas. This study aims to develop a methodology to assess CES in riverine landscapes from social media and citizen science images related to environmental information. We collected georeferenced pictures from Flickr and iNaturalist for three main test rivers in northwest Portugal (Minho, Lima and Cávado) and classified them based on content such as ‘biodiversity’, ‘recreation/river beaches’, ‘historical heritage’ and ‘landscape’, as well as environmental spatial variables. A multimodel inference approach was applied to predict the spatial distribution of the pictures and environmental variables to support CES mapping. The methodology was applied during two time periods, before and during the most restrictive period of the COVID-19 pandemic. Results showed that estuaries were identified as ‘hotspots’ for CES related to rivers provision. There was distinct prevalence of pictures depending on the targeted river: pictures exhibiting ‘recreation/river beaches’ prevailed in Cávado (62%), ‘biodiversity’ in Lima (70%) and ‘historical heritage’ in Minho (39%). Only the values and patterns from the category ‘biodiversity’ were maintained on the two analysed periods, with the other categories not having posts in social media during COVID-19 most restrictive period. The methodology for CES assessment in rivers can be replicated using different time periods and regions due to its simple stepwise framework. The study provides valuable insights for sociocultural approaches, aiding in decision-making on freshwater environment management, despite potential limitations in image distribution.

Island species are particularly vulnerable to various anthropogenic impacts. Because several island endemics are rare and not accessible, obtaining genetic information and reconstructing their biogeographical and evolutionary history becomes increasingly difficult. In the present study, we investigated the endangered freshwater gastropod Paludomus ajanensis (family Paludomidae) endemic to the Seychelles (Mahé and Silhouette) in the western Indian Ocean. By analysing historical DNA of this species, we were able to place this species in the family Paludomidae and to uncover its Asian affinity. The patchy distribution plus the documented recent population decline suggests this species should be considered ‘Critically Endangered’.