PDF(Pubmed)
Abstract：
Nepal initiated numerous hydropower and irrigation-related infrastructure projects to enhance and promote green energy, water security, and agricultural productivity. However, these projects may pose risks to natural habitats and the well-being of aquatic fauna, leading to significant effects on delicate ecosystems. To understand these potential impacts, it is crucial to gather reliable baseline data on the population status and habitat characteristics of species. This study specifically focuses on Gharials (Gavialis gangeticus), a critically endangered species. We recorded data on pre-determined habitat variables at stations spaced 500 m apart along the two major river streams of Bardia National Park, as well as at locations where Gharials were sighted between February and March 2023. We used binary logistic regression with a logit link function to investigate the habitat characteristics related to the occurrence of Gharials. The presence/absence of Gharials at sampling points served as the dependent variable, while 10 other predetermined variables (ecological variables and disturbance variables) served as independent variables. Our study recorded 23 Gharials, comprising 14 adults, six sub-adults, and three juveniles, with a sex ratio of 55.56 males per 100 females. Most individuals (83%) were found basking. Among the 10 habitat predictors, three variables (mid-river depth, river width, and water temperature) were significantly correlated (p < .05) with the probability of Gharial occurrence. The model shows that Gharial detection probability increases with greater mid-river depth and width and lower water temperature. This study establishes a population baseline for Gharials within the river system before the construction of large infrastructure projects, such as dams and irrigation canals. It also recommends continuous monitoring of Gharial populations after water release and/or diversion to evaluate the impact of large infrastructure projects on the population and their associated habitat characteristics. This will help enable more informed and targeted conservation efforts.
摘要：
尼泊尔启动了许多水电和灌溉相关的基础设施项目，以加强和推广绿色能源，水安全,和农业生产力。然而,这些项目可能对自然栖息地和水生动物的福祉构成风险，对脆弱的生态系统产生重大影响。为了了解这些潜在的影响，收集有关物种种群状况和栖息地特征的可靠基线数据至关重要。本研究特别关注Gharials（Gavialisgangeticus），极度濒危的物种。我们记录了沿Bardia国家公园两条主要河流相距500m的站点的预定栖息地变量的数据，以及2023年2月至3月期间发现Gharials的地点。我们使用具有logit链接函数的二元逻辑回归来研究与Gharials发生相关的栖息地特征。采样点存在/不存在Gharials作为因变量，而其他10个预定变量(生态变量和干扰变量)作为自变量。我们的研究记录了23个Gharials,包括14名成年人，六个亚成年人，还有三个少年,性别比例为每100名女性55.56名男性。大多数人（83％）被发现晒太阳。在10个栖息地预测因子中，三个变量(中河深度，河流宽度,和水温）与Gharial发生的概率显着相关（p<.05）。该模型表明，随着中河深度和宽度的增加以及水温的降低，Gharial检测概率增加。这项研究在大型基础设施项目建设之前为河流系统内的Gharials建立了人口基线，如水坝和灌溉渠。它还建议对放水和/或改道后的Gharial种群进行连续监测，以评估大型基础设施项目对种群及其相关生境特征的影响。这将有助于实现更知情和有针对性的保护工作。
