Flow‐related changes of physical habitat represent a potentially significant environmental filter determining the presence and composition of fish assemblages in rivers. The mesoscale (10⁰–10³ m) of river habitat has been identified as an appropriate resolution to model linkages between fish and their abiotic environment that are relevant yet logistically feasible for management of large rivers with complex habitats and diverse fish assemblages. This study identified well‐defined mesohabitat types (i.e. hydro‐morphological units) that influence the fish community of the lower Saint John River, New Brunswick, downstream of a large hydropower generating station (the Mactaquac Generating Station). Four hydro‐morphological units or habitats (i.e. pool, riffle, run and slack water) were identified and linked to three distinct fish assemblages. Eurytopic species represent habitat generalists that were common among all habitats throughout the study area. Rheophilic species preferred fast‐flowing run habitat, whereas limnophilic species were mainly associated with slack water habitat. Riffle habitats that frequently run dry during low flows were mostly vacant of fish species, suggesting that fish assemblages that would naturally occur in these environments could be affected by fluctuations in flow (i.e. hydropeaking) due to dam operation. Our improved understanding of the relationship between fish assemblages and hydro‐morphological units is a fundamental first step to develop meaningful habitat models that can facilitate the effective evaluation of flow management options regarding hydropower and other flow manipulation activities in large rivers with diverse fish fauna.

中文翻译：

---

将大型鱼类河流中的鱼群与水文形态单位联系起来

与流量有关的物理栖息地变化代表了潜在的重要环境过滤器，决定了河流中鱼类种群的存在和组成。中尺度（10 ⁰ –10 ³m）河流生境已被确定为模拟鱼类与其非生物环境之间联系的适当解决方案，这些联系对于在栖息地复杂且鱼类种类繁多的大型河流的管理而言是相关但在逻辑上可行的。这项研究确定了影响大型水力发电站（麦塔夸克发电站）下游新不伦瑞克省圣约翰河下游鱼类群落的明确的中栖息地类型（即水文形态单位）。确定了四个水文形态单位或栖息地（即水池，浅滩，流水和松弛水）并将其与三个不同的鱼类组合相关联。优生物种代表了栖息地通才，在整个研究区域的所有栖息地中都很常见。亲液物种更喜欢快速流动的栖息地，嗜嗜性物种主要与松弛的水生境有关。在低流量时经常干dry的Riffle生境大多是空缺的鱼类，这表明在这些环境中自然发生的鱼类聚集可能会受到大坝运行引起的流量波动（即水峰）的影响。我们对鱼群和水文形态单位之间关系的进一步了解是开发有意义的栖息地模型的基本第一步，该模型可以促进对鱼类种类繁多的大河流中水力发电和其他流量操纵活动的流量管理选择进行有效评估。这表明在这些环境中自然发生的鱼类聚集可能会受到由于大坝运行而引起的流量波动（即水峰）的影响。我们对鱼群和水文形态单位之间关系的进一步了解是开发有意义的栖息地模型的基本第一步，该模型可以促进对鱼类种类繁多的大河流中水力发电和其他流量操纵活动的流量管理选择进行有效评估。这表明在这些环境中自然发生的鱼类聚集可能会受到由于大坝运行而引起的流量波动（即水峰）的影响。我们对鱼群和水文形态单位之间关系的进一步了解是开发有意义的栖息地模型的基本第一步，该模型可以促进对鱼类种类繁多的大河流中水力发电和其他流量操纵活动的流量管理选择进行有效评估。