Anthropogenic dewatering of aquatic habitats can cause stranding and mortality of burrowed larval lampreys; however, the effects of dewatering have not been quantified. We assessed: (a) changes in spatial distribution, abundance, and emergence of larvae dewatered at Leaburg Reservoir (OR); (b) emergence and mortality of larvae dewatered in a laboratory; and (c) bias, precision, and interpretation of field results by simulation and modeling of laboratory results. In the field, we examined the distribution, abundance (by N‐mixture model), and density of larvae by electrofishing at randomly selected sites before dewatering and after refill, and assessed the emergence rate by observation and excavation during dewatering. Due to dewatering in the field, about 42% of larvae emerged and spatial distribution changed toward sites dewatered less than 20 hours. Estimated average density decreased from 10.8 larvae/m² before dewatering to 2.3 larvae/m² after refilling, suggesting that abundance declined by 79%; simulation suggested this decline ranged 71–84% (interquartile range). In the laboratory, we examined the emergence and mortality rates of larvae dewatered 0–48 hrs. The emergence rate in the laboratory was similar to that in the field. Mortality rate increased with hours dewatered and was higher for emerged than burrowed larvae. Laboratory estimates of mortality rate predicted a 61% decline in abundance if only burrowed larvae survived and a 54% decline if both burrowed and emerged larvae survived. Abundance declines in the field could be from mortality (e.g., desiccation, predation) and relocation to watered habitat. Our results indicate dewatering can substantially affect spatial distribution and abundance of larval lampreys in freshwater ecosystems.

中文翻译：

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脱水对幼虫鳗鱼行为，分布和丰度的影响

水生生境的人为脱水可能导致穴居幼虫七lamp鱼搁浅和死亡；但是，脱水的影响尚未量化。我们评估：（a）在利堡水库（OR）脱水的幼虫的空间分布，丰度和出现的变化；（b）在实验室脱水的幼虫的出现和死亡；（c）通过对实验室结果进行模拟和建模来对结果，结果进行偏差，精度和解释。在野外，我们在脱水之前和补充后通过随机选择的地点，通过电钓鱼检查了幼虫的分布，丰度（通过N混合模型）和密度，并通过脱水期间的观察和挖掘评估了出苗率。由于田间脱水，大约有42％的幼虫出现，并且空间分布朝着脱水时间少于20小时的地点变化。估计的平均密度从10.8幼虫/米降低²脱水至2.3幼体/米²重新填充后，表明丰度下降了79％；模拟表明，下降幅度为71-84％（四分位间距）。在实验室中，我们检查了0-48小时脱水的幼虫的出现和死亡率。实验室的出现率与现场相似。死亡率随脱水时间的增加而增加，出苗率高于穴居幼虫。实验室估计的死亡率预测，如果仅穴居幼虫存活，则丰度下降61％；如果穴居幼虫和出苗幼虫均存活，则死亡率下降54％。农田的丰度下降可能是由于死亡（例如，干燥，捕食）和搬迁到浇水的栖息地造成的。我们的结果表明，脱水会严重影响淡水生态系统中幼虫七尾鳗的空间分布和数量。