College of Geography and Environment, Jiangxi Normal University, Nanchang, Jiangxi 330022, China.
College of Geography and Environment, Jiangxi Normal University, Nanchang, Jiangxi 330022, China; The Key Laboratory of Poyang Lake Wetland and Watershed Research, Ministry of Education, Jiangxi Normal University, Nanchang, Jiangxi 330022, China.
Sci Total Environ. 2022 Sep 10;838(Pt 1):155954. doi: 10.1016/j.scitotenv.2022.155954. Epub 2022 May 14.
Habitats of freshwater cetaceans are under increasing threats of deterioration globally. A complete understanding of long-term variations of habitat configurations is therefore critical. Poyang Lake in China contains a large and stable population of the Yangtze finless porpoise, a critically endangered freshwater cetacean species. However, constant water decline and intensified human activities in the lake since 2000 have led to uncertainty for porpoise conservation. We address this issue via remote sensing and hydrodynamic modeling of nine environmental variables during different seasons over the past two decades. The MaxEnt model was used to extrapolate changes in likely habitat configurations of the porpoise, and MARXAN algorithms delineated habitat protection priorities in different seasons. Results illustrate that flow velocity, water depth, Chl-a concentration, distance to grassland and boats greatly affect the porpoise distribution. Shifts in these environmental variables can lead to significant habitat decreases in all seasons. In particular, unstable hydrological regimes may force the porpoises to live in habitats with lower water depths for suitable flow velocity conditions in the dry season, and habitats are increasingly infringed by grassland and mudflats. High protection priority areas such as the northern channel and the estuaries of the tributaries urgently need long-term systematic and targeted surveys of ecosystem functionality and flexible management of anthropogenic activities. Combining remote sensing with hydrodynamic and species distribution models can also assist in understanding the situation of other aquatic species.
淡水鲸目动物的栖息地在全球范围内正受到日益恶化的威胁。因此，全面了解栖息地配置的长期变化至关重要。中国的鄱阳湖拥有大量稳定的长江江豚种群，这是一种极度濒危的淡水鲸目动物。然而，自 2000 年以来，该湖持续的水位下降和人类活动的加剧，给江豚的保护带来了不确定性。我们通过过去二十年不同季节的九种环境变量的遥感和水动力建模来解决这个问题。MaxEnt 模型用于推断江豚可能栖息地配置的变化，而 MARXAN 算法则划定了不同季节的栖息地保护优先级。结果表明，流速、水深、Chl-a 浓度、与草原和船只的距离极大地影响了江豚的分布。这些环境变量的变化可能导致所有季节的栖息地显著减少。特别是不稳定的水文状况可能迫使江豚在旱季生活在水深较浅、适合流速条件的栖息地，而栖息地越来越受到草原和泥滩的侵犯。北部航道和支流河口等高保护优先级区域急需对生态系统功能进行长期系统和有针对性的调查，并对人为活动进行灵活管理。将遥感与水动力和物种分布模型相结合，也有助于了解其他水生物种的情况。
