Rating US reservoirs relative to fish habitat condition

Fish habitats in many aging US reservoirs have become degraded and require broad-scale assessment to rate their status and facilitate rehabilitation efforts. To help prioritize habitat projects in reservoirs, we assembled a rating system for large reservoirs in the contiguous United States. Using responses to an online questionnaire about fish habitat impairment in 1299 large US reservoirs, we applied multivariate analyses to identify combinations of habitat impairment descriptors that quantified broad impairment types (i.e., a construct). Resulting constructs reflected point source pollution, nonpoint source pollution, excessive nutrients, algae blooms, siltation, limited nutrients, mudflats and shallowness, limited connectivity to adjacent habitats, limited littoral structure, nuisance species, anomalous water regimes, and large water level fluctuations. Scores were summed across constructs to create a composite number that rated overall reservoir habitat impairment. Construct and composite scores differed among geographic ecoregions of the United States. This rating system could provide a starting point for prioritizing reservoirs for habitat rehabilitation and enhancement projects.

美国诸多老化水库的鱼类栖息地已发生退化，亟需开展大范围评估以明确其现状，并为栖息地修复工作提供支撑。为助力水库栖息地修复项目的优先级排序，我们针对美国本土的大型水库构建了一套标准化评分体系。研究基于针对1299座美国本土大型水库鱼类栖息地受损情况的在线调查问卷结果，采用多变量分析方法，识别出可量化大类栖息地受损类型的受损特征组合（即构念（construct））。最终得到的构念涵盖点源污染、非点源污染、营养盐过剩、藻华、淤积、营养盐匮乏、潮滩与浅水区、与相邻栖息地连通性不足、沿岸带结构缺失、有害物种、异常水文情势以及水位大幅波动等受损类型。将各构念的得分累加，即可得到用于表征水库整体栖息地受损程度的综合得分。美国不同地理生态区的构念得分与综合得分均存在显著差异。本评分体系可为水库栖息地修复与提质增效项目的优先级确定提供初始参考框架。