Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

Odonata is a cosmopolitan, indicator group of insects residing on all continents except Antarctica, with notable species richness in Africa's tropical montane forests. In East Africa, this group is threatened by habitat loss and degradation driven by rapid population growth. This study investigated odonate assemblages and their conservation concern in Bwindi Impenetrable National Park (BINP, Afromontane) and Bugoma Central Forest Reserve (BCFR, mid-altitude) in the Albertine Rift in Uganda. From December 2022 to July 2023, 61 sites were cross-sectionally surveyed (26 in BCFR, 35 in BINP) to analyse community composition, habitat preferences, and conservation threats. Odonate key habitats in these forests were mapped. Nonmetric multidimensional scaling revealed distinct odonate communities in BCFR and BINP with limited overlap. Odonate diversity was computed using both Shannon diversity indices and species richness. BCFR registered a significantly higher overall species richness (median = 3.0) than BINP (median H = 2.0, p < 0.01). However, BINP hosted more range-restricted and globally threatened species, with a higher threat-based score (median TBS = 2.00) compared to BCFR (median TBS = 0.00, p < 0.01). Threatened species such as Neodythemis munyaga (Endangered) and Albertine Rift endemics such as Stenocypha molindica and Stenocypha jacksoni were strongly associated with BINP's high-altitude, pristine streams characterized by clear water with low salinity, total dissolved solids and electrical conductivity. Substantial anthropogenic pressures were recorded in BCFR, threatening critical odonate habitats. We emphasise the urgent need for targeted conservation efforts to preserve the forest ecosystem services and their unique odonate diversity.

The jaguar cichlid (Parachromis managuensis), an invasive species native to Central America, was first recorded in Feitsui Reservoir, Taiwan, in 2014. From 2014 to 2024, 846 individuals were captured, with abundance increasing notably from 2018. Stomach content analysis revealed predation on native crustaceans (Caridina, Macrobrachium) and native fish (Sinibrama macrops), suggesting potential ecological impacts. Growth analysis indicated negative allometric growth and signs of growth retardation in larger individuals. The decline of S. macrops may be linked to increasing predation. This study marks the northernmost record of this species in East Asia and raises concerns about its ecological impact.

The inclusion of all Anguilla eel species in CITES Appendix II, now being discussed, is an insufficient measure. Four severely threatened species should be in Appendix I, whereas the other 13 species qualify for Appendix II. More ambitious CITES amendments are needed to achieve effective protection of Anguilla eels.

Stakeholders' engagement in conservation planning is key to the success of any in situ conservation programme. Therefore, an understanding of stakeholders' knowledge, attitudes and perceptions is important. In this study, we investigated the accidental and intentional illegal catch of the endangered Ganges River dolphin (Platanista gangetica) in the lower Gangetic plains region, Bangladesh, and assessed the knowledge, attitude and perceptions of dolphin-stakeholder groups in the value chain (88 general fishermen, 16 catfish fishermen, eight dolphin hunters, six dolphin oil producers and 31 fishing store keepers). General fishermen and dolphin hunters captured 139 P. gangetica since 2000, of which 93% were sold for making dolphin oil. The fate of accidentally caught dolphins was affected by the level of education of fishermen. Only 3.4% of general fishermen and 9.7% of fishing store keepers were aware of the threatened status of the species. Respondent stakeholders had no training on dolphins and their conservation, and were unaware of dolphin conservation laws. Poor knowledge of fish oil, an alternative to dolphin oil for catfish fishing, was also recorded. Stakeholders' responses to various dolphin conservation issues revealed a conflict of interests among stakeholder groups and negligence regarding several conservation issues. We recommend the inclusion of all stakeholder groups in dolphin conservation management, ensuring proper education through training and frequent policing for illegal catch. In addition, rewarding general fishermen for each successful release of accidentally caught dolphins and exploration of alternate livelihood opportunities for dolphin hunters are also suggested.

The Chinese tapertail anchovy (Coilia nasus) stands as the last self-sustaining anadromous species maintaining large upstream migratory populations in the Yangtze River basin. The migratory ecology of C. nasus remains poorly understood owing to challenges in tracing natal origins and freshwater habitat use. To address this, we developed a Sr isotope baseline (⁸⁷Sr/⁸⁶Sr) using water samples and juvenile otoliths (younger than 2 months). Distinctive ⁸⁷Sr/⁸⁶Sr ratios in Poyang Lake served as reliable natural markers, enabling 100% accurate identification of Poyang Lake origin freshwater-resident Coilia brachygnathus individuals, making it possible to trace the natal origins and freshwater habitat use in Poyang Lake. However, the classification success rates of the low and middle reaches of the Yangtze River main channel, Dongting Lake and Shijiu Lake are relatively low. Otolith ⁸⁷Sr/⁸⁶Sr ratio analysis of adults revealed strong natal homing, with 97.7% (127/130) of specimens captured in Poyang Lake originating from Poyang Lake. The ⁸⁷Sr/⁸⁶Sr profiles demonstrated the diversity in the timing of their migration out of Poyang Lake, illustrating variations in life history. Three distinct life-history categories emerged from ⁸⁷Sr/⁸⁶Sr profiles: long-term residents (> 60% juveniles) exhibiting prolonged lacustrine residency, medium-term residents transitioning to the Yangtze mainstem prior to marine migration and short-term residents (body length, < 28 mm) demonstrating rapid freshwater outmigration. Notably, almost all juveniles completed marine transition before the first annulus formation (one exception). These findings establish critical ecological benchmarks for assessing the impacts of the construction, management and operation of the Poyang Lake Hydraulic Project on C. nasus life-history diversity and population connectivity.

The application of artificial intelligence is gaining traction in the study of cultural ecosystem services (CESs). In response to this trend, we have developed an approach based on photo categorisation and semantic segmentation to assess CESs, including aesthetic values in riverscapes and river elements (large wood, erosion banks and river bars). Semantic segmentation allows the precise identification of photos, including quantification of features coverage. To validate our approach, we chose the riverscape of the Odra River in the Czech Republic, a smaller but significant site protected under the Ramsar Convention and Natura 2000. Our goal was to understand the content of the photographs and to delineate the categories of CESs present in this region. We demonstrated the efficacy of our approach and found that our manual categorisation of publicly available photos from Google Maps and Flickr revealed a consistent trend: visitors predominantly took photos from the river and pond and urban categories. CESs presented in the area include outdoor recreation, bird watching, education and hiking. Semantic segmentation analysis revealed that the photographs primarily depicted water, vegetation types and sky, while the river elements in the photographs were of minimal size. Our results highlight the need for improved visitor education about riverscapes, including river elements defined as important hydromorphological parts of the river. Our method does not require extensive programming knowledge, making it suitable for river managers. This approach allows for better monitoring of important riverscape features, which may contribute to more effective river protection.