Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

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.

Ecosystem restoration is gaining momentum as communities and policymakers increasingly appreciate the need to recover lost ecosystem services. However, more knowledge about the potential ecological outcomes of restoration for ecosystem services is needed to promote engagement of stakeholders with restoration targets. In Tasmania, the giant kelp, Macrocystis pyrifera, is a productive canopy species that has declined by 95%. We aimed to predict the effects of M. pyrifera restoration on food webs and fisheries production. The primary productivity ratio of M. pyrifera compared to the dominant understory species Ecklonia radiata was quantified and then incorporated into an Ecopath with Ecosim (EwE) model of Tasmanian waters. Predator/prey interactions were estimated using the EwE model framework, which fits the model to historical fisheries data. Several scenarios were then simulated, representing uncertainty in predator/prey interactions and different areas of M. pyrifera restoration. Restoration of degraded reefs with M. pyrifera was predicted to increase primary productivity by about 40 times per unit area compared to the existing habitat. We predicted that restoring 30% of the degraded M. pyrifera area would increase abalone and coastal demersal fish catches by ~2.7%. Rock lobster and reef-associated fisheries catches were predicted to increase by 0.4% and 1.4%, respectively. Future improvements could include downscaling the model to capture local increases in biomass and catch and refining predator/prey interactions through experimental studies. By modelling outcomes of ecological restoration, achievable targets can be set that are locally relevant and therefore more likely to attract support.

Despite the global growth of marine wildlife tourism, potential physiological effects on teleosts remain poorly understood. Physiological responses are important indicators of individual health that may precede population-level impacts; thus, their evaluation is essential for sustainability. We assessed immunological and general health indices in two marine reef fish species—the rockfish Sebastes oculatus and the Patagonian grouper Acanthistius patachonicus—exposed to long-term scuba-diving tourism. We compared fish from moderately—and heavily visited reefs to those from control (unvisited) reefs. The idiosyncratic patterns observed provided no evidence consistent with impaired immune function or general health in response to diver presence. These outcomes could indicate that fishes have become habituated to diver presence, that more sensitive individuals have been selectively displaced to undisturbed areas and/or the intensity and nature of scuba-diving practices in our study system are below thresholds that would trigger physiological changes. Beyond the ecological significance, our findings provide valuable insights for the sustainable management of marine wildlife tourism. The absence of a clear physiological response in Patagonian grouper and rockfish suggests that properly managed scuba-diving tourism can be compatible with marine conservation goals. Nonetheless, ongoing monitoring is essential to ensure the long-term health of fish populations and the sustainability of tourism in these ecosystems.

Microplastics pollution is a growing environmental concern, particularly in aquatic ecosystems, where it poses significant threats to organisms and ecosystems. Originating from the widespread use of consumer products and inadequate waste management, microplastics are commonly found in aquatic environments, presenting various physical and chemical hazards to aquatic life. These risks include ingestion, which can lead to blockages in the digestive system, reduced nutrient intake and death. Additionally, microplastics absorb and transport toxic chemicals, contributing to bioaccumulation and biomagnification in the food chain. The impacts of microplastic exposure include oxidative stress, inflammation and potential reproductive issues in aquatic organisms. Southeast Asia, known for its abundant aquatic resources, confronts particular challenges in managing pollution, and effective management strategies are needed. We can safeguard the health and sustainability of Southeast Asia's aquatic ecosystems by addressing these issues comprehensively. This review provides detailed insights into the dual physical and chemical effects of microplastics on aquatic organisms in Southeast Asia, underscoring the need for continued research and innovative solutions.

The coral reefs of Mauritius have faced significant decline due to tourist activity, overfishing and ongoing environmental stress. Artificial reef structures are a promising approach to restoring damaged reefs and enabling recovery of associated marine biodiversity. The current research investigated the Stegastes species assemblage at two Mauritian coastal locations: Flic en Flac (FEF) on the west coast and Pointe aux Feuilles (PAF) on the east coast. The study compared the impact of two types of artificial reef interventions, specifically metal frames (galvanized and non-galvanized), and concrete blocks, on fish presence as well as coral community health at the locations. The fish assemblage on these artificial structures was first analysed after 1 week of deployment. The abundance was calculated for the first visit only, and in the following visit, the Stegastes spp. prevalence and coral status were analysed. There were five Stegastes spp. observed in this study, with Stegastes fasciolatus, Stegastes limbatus, Stegastes lividus and Stegastes nigricans found at both sites and only Stegastes pelicieri seen at PAF. The prevalence of species was more within the galvanized structures in contrast to the non-galvanized structures. Coral status was also noted over the study period with most of the coral present within the frames being in a healthy state, with up to 93% of corals remaining unbleached on galvanized structures during winter, compared to 73%–87% on non-galvanized frames. Coral recovery was higher during summer, reaching 53%, and new coral recruits were observed in winter 2022 (up to 13% at FEF and 40% at PAF). Concrete blocks enhanced shelter availability and supported fish colonization when corals were absent, contributing to overall species persistence. This study highlights the positive impact of artificial structures in restoring degraded reef areas, promoting recolonization by key species and new coral growth based on findings from 2021 to 2023.