In this experimental series, we studied the swimming capabilities and response of grass carp (Ctenopharyngodon idella) larvae to flow turbulence in a laboratory flume. We compared three different experimental configurations, representing in‐stream obstructions commonly found in natural streams (e.g., a gravel bump, a single vertical cylinder, and patches of submerged rigid vegetation). Grass carp larvae (postgas bladder emergence) were introduced to each experimental configuration and subjected to a variety of hydrodynamic forces of different magnitudes and scales. We varied the flow velocities and water depths and found ranges of turbulent kinetic energy and Reynolds stresses that triggered a response in larval trajectories, identified by measured horizontal and vertical swimming speeds for each flow condition. Larvae apparently actively avoided areas with increased levels of turbulence by swimming away, moving faster in short bursts, and expending more energy. In addition to the magnitude of turbulent kinetic energy, the length scale and time scale of turbulent eddies also influenced the larvae response. These findings support the development of new strategies for controlling the spread of grass carp larvae in rivers, as well as the development of numerical tools incorporating active swimming capabilities to predict larval transport in streams.

中文翻译：

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利用湍流识别溪流中草鱼（Ctenopharyngodon idella）幼虫的优先区域：一项实验室研究

在这个实验系列中，我们研究了草鱼（Ctenopharyngodon idella）的游泳能力和反应幼虫在实验室水槽中产生湍流。我们比较了三种不同的实验配置，它们代表了自然流中常见的河内障碍物（例如，砾石颠簸，单个垂直圆柱体和淹没的刚性植被斑块）。将草鱼幼虫（gas气出苗）引入每种实验配置，并受到各种大小和规模的流体动力的作用。我们改变了流速和水深，发现了湍动能和雷诺应力的范围，这些湍动能和雷诺应力触发了幼虫轨迹的响应，通过测量每种流动条件下的水平和垂直游泳速度来确定。幼虫显然会游走，在短时间内移动得更快并消耗更多的能量，从而积极地避开湍流程度增加的区域。除了湍动能的大小，湍流涡流的长度尺度和时间尺度也影响幼虫的反应。这些发现支持了控制河中草鱼幼虫传播的新策略的开发，以及支持主动游泳功能以预测幼虫在河流中运输的数值工具的开发。