Changes in animal movement and behaviour at fine scales (tens of metres) in immediate proximity to tidal stream turbine structures are largely unknown and have implications for risks of animal collision with turbine blades. This study used upward-facing multibeam echosounder data to detect and track animal movement comprising fish, diving seabirds, and marine mammals. Measurements over spring-neap tidal cycles at a turbine structure (no blades present) are compared to a neighbouring reference area with no structure and comparable conditions, with measurements consecutive in time to maximize comparability. The majority of tracked animals (93.4% around turbine structure and 99.1% without turbine structure) were observed swimming against the flow, with 87.5% and 97.8%, respectively, making ground and showing capability of manoeuvring in tidal stream flow speeds. Track tortuosity increased around the turbine structure compared to the reference site, particularly in the wake and at low flow speeds, indicating animal station-holding or milling behaviour. These data also evidence the benefits of multibeam echosounders to measure animal movement through larger measurement volumes rather than relying on single-beam echosounders to measure animal presence alone, including to avoid large biases overestimating the size of schools swimming against the flow measured by time-in-beam.

中文翻译：

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应用多波束测深仪记录潮汐涡轮机结构周围动物运动和行为的变化

紧邻潮汐流涡轮结构的动物运动和行为在精细尺度（数十米）上的变化在很大程度上是未知的，并且对动物与涡轮叶片碰撞的风险有影响。这项研究使用向上的多波束回声测深仪数据来检测和跟踪包括鱼类、潜水海鸟和海洋哺乳动物在内的动物运动。将涡轮机结构（不存在叶片）处的春季-小潮汐周期的测量结果与没有结构和可比条件的相邻参考区域进行比较，并在时间上连续进行测量，以最大限度地提高可比性。大多数被跟踪的动物（93.4% 围绕涡轮结构，99.1% 没有涡轮结构）被观察到逆流游泳，分别为 87.5% 和 97.8%，制造地面并显示在潮汐流速度下机动的能力。与参考站点相比，涡轮结构周围的轨道曲折度增加，特别是在尾流和低流速下，表明动物站保持或碾磨行为。这些数据还证明了多波束回声测深仪通过更大的测量体积来测量动物运动的好处，而不是依靠单波束回声测深仪来单独测量动物的存在，包括避免高估学校规模的大偏差-光束。