The Niagara River, which connects two Great Lakes (Erie and Ontario) and forms a border between Canada and the United States, has experienced decades of abiotic and biotic disturbance as well as long-term restoration efforts. Given the iconic riverscape and importance as a binational fisheries resource, a biodiversity assessment of the mainstem Niagara River fish assemblage is overdue. Here, fish assemblage and habitat data from a standardized boat electrofishing program of the Niagara River were combined with species trait data related to substrate associations, diet preferences, reproductive strategies, and body size to quantify biodiversity patterns among river sections (sites above and below Niagara Falls), seasons (spring, summer, fall), and years (2015–2017). Sixty-five species were captured representing a variety of trait combinations. Significant differences in functional dispersion and divergence (i.e., functional diversity) were observed between river sections, seasons, and (or) years. The fish community captured in the lower river in spring 2015 had both the highest average functional dispersion (2.08 ± 0.32 SD) and divergence (0.88 ± 0.04 SD) compared to the other seasonal sampling efforts, but relatively few fishes were captured (n = 686). Although non-native fishes represented a small portion of the catch over the 3 years (8.6% of catch), the seasonal presence (spring and fall) of mostly introduced large-bodied salmonids expanded functional trait space in the lower river during these periods. The importance of rare species on functional diversity metrics suggests further insight on local species detection probabilities is needed to understand if differences in functional diversity reflect ecological patterns or are driven by sampling design.

中文翻译：

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尼亚加拉瀑布上下的淡水鱼功能和分类多样性

尼亚加拉河连接两个五大湖（伊利湖和安大略湖）并形成加拿大和美国之间的边界，经历了数十年的非生物和生物干扰以及长期的恢复工作。鉴于标志性的河流景观和作为两国渔业资源的重要性，对主要的尼亚加拉河鱼类组合进行生物多样性评估已经过期。在这里，来自尼亚加拉河标准化船电捕鱼计划的鱼类组合和栖息地数据与与基质关联、饮食偏好、繁殖策略和体型相关的物种特征数据相结合，以量化河段（尼亚加拉上方和下方的地点）之间的生物多样性模式。秋季）、季节（春季、夏季、秋季）和年份（2015-2017）。捕获了代表各种性状组合的 65 个物种。在河段、季节和（或）年份之间观察到功能分散和发散（即功能多样性）的显着差异。与其他季节性采样工作相比，2015 年春季在下游河流捕获的鱼类群落具有最高的平均功能分散 (2.08 ± 0.32 SD) 和差异 (0.88 ± 0.04 SD)，但捕获的鱼类相对较少（n = 686 ）。尽管非本地鱼类占 3 年捕获量的一小部分（占捕获量的 8.6%），但大部分引入的大体鲑鱼的季节性存在（春季和秋季）在这些时期扩大了下游河流的功能性状空间。