Aquatic habitat has been extensively altered throughout the Laurentian Great Lakes to increase navigation connectivity. In particular, the St. Marys River, a Great Lakes connecting channel, lost >50% of its historic rapids habitat over the past century. In 2016, the natural flow was restored to the Little Rapids area of the St. Marys River. The goal of our study was to evaluate physical and ecological responses to the restoration of the Little Rapids area. Extensive habitat and biological data were collected prior to restoration (2013 and 2014), and after restoration (2017 and 2018). Measured parameters included total suspended solids, current velocity, benthic macroinvertebrates, and larval, juvenile, and adult fishes. Total suspended solids stayed low (<4 mg/L) following restoration, with the exception of a single construction‐related event. Pre‐restoration data indicated that all measured velocities were below the target flow rate of 0.24 m/s, whereas 70% of the measured habitat was above the target flow post‐restoration. Abundance and richness of benthic macroinvertebrates were reduced following restoration (>90% reduction). We observed a 45% increase in richness of larval fish 2 years after restoration and a 131% increase in catch per unit effort. For adult fishes, the proportion of individuals with a preference for fast‐moving waters increased from 1.5 to 45% in the restored area, and from 7 to 15% upstream of the restored area; a similar response was observed for lithophilic spawners. The physical and biological conditions of the Little Rapids improved and resembled conditions typical of rapids habitat extent in other areas of the river and other systems.

中文翻译：

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在密歇根州圣玛丽斯河的大湖连接通道中恢复急流栖息地

整个劳伦式五大湖的水生生境已发生了很大变化，以增加通航能力。特别是大湖区的连接河道圣玛丽河，在过去的一个世纪中失去了超过50％的历史急流栖息地。2016年，自然流量恢复到圣玛丽斯河的小急流地区。我们研究的目的是评估对小瀑布城地区恢复的物理和生态响应。恢复之前（2013年和2014年）以及恢复之后（2017年和2018年）收集了大量的栖息地和生物学数据。测得的参数包括总悬浮固体，流速，底栖大型无脊椎动物以及幼体，幼鱼和成鱼。恢复后，总悬浮固体含量保持较低（<4 mg / L），除了与施工相关的单个事件。恢复前的数据表明，所有测得的速度均低于0.24 m / s的目标流速，而70％的测量栖息地均高于恢复后的目标流速。恢复后底栖大型无脊椎动物的丰富度和丰富度降低（减少幅度超过90％）。我们观察到，恢复2年后，幼鱼的丰富度增加了45％，每单位工作量的捕捞量增加了131％。对于成年鱼类，在恢复区域中，喜欢快速流动水域的个体比例从1.5％上升到45％，在恢复区域上游从7％上升到15％。亲石性产卵者观察到类似的反应。