Riverscape scale analysis of fish/habitat relationships

为了成功地完成其生命周期，鱼类需要进入不同的栖息地，这些栖息地的特征满足与特定生命功能或生命阶段相关的要求。河流景观一词描述了河流系统中的自然栖息地的镶嵌。因此，河流景观构成了鱼类实现其生命周期的物理模板。我的长期研究计划是围绕这样一个假设构建的，即在河流景观中发现的栖息地的自然和空间结构对溪流鱼类种群的动态起着根本作用。*在我的实验室最近进行的一项研究中，使用温度传感声学标签对圣玛格丽特河(魁北克)的成年大西洋鲑鱼进行遥测跟踪，揭示了深池底热避难所在温水时段对成年鲑鱼体温调节的关键作用(Frechette等人，提交)。*尽管有这些观察，关于池底热避难所的动态仍有几个重要的问题有待阐明(它们有多常见？负责它们存在和动态的过程是什么？是否有可能根据泳池的特征来预测它们的出现？)以及它们对鲑鱼的生物学意义(这种体温调节行为有多普遍？触发河流温度调节行为的水温是恒定不变的，还是观察到局部适应了温暖的温度？池温避难所的位置对成体鲑鱼在河流中的运动模式有何影响？*以大西洋鲑鱼(Salmo Salar)为生态模型，本研究的一般科学方法主要基于经验数据的定量分析。在第一个项目中，将在不同水系的水池中进行详细的河池物理特性的现场测量，以破译导致热避难所存在的过程，并建立池底热避难所形成、持续和拆除的预测模型。在第二个项目中，将使用浮潜计数和带有温度传感标签和密集水听器阵列的成年大西洋鲑鱼的声学遥测跟踪1)监测与池底热避难所位置和河流温度有关的鱼类的大规模移动，以及2)记录避难所的精细空间和时间使用情况。*在目前观察到的气候变化背景下，理解池底热避难所的动态和作用似乎对鲑鱼种群的管理至关重要。拟议的研究将为河流生态学家和河流管理者提供有关河流生态系统动态的高度新颖的工具和信息，有助于评估、预测和减轻人为干扰和气候变化对河流生态系统的影响。

To successfully complete their life-cycle, fish need to access different habitats whose characteristics fulfill the requirements associated to specific life functions or life stages. The term riverscape describes the mosaic of physical habitats comprised within a river system. As such, the riverscape constitutes the physical template available for fish to realize their life-cycle. My long-term research program is structured around the hypothesis that the nature and spatial structure of habitats found within riverscapes play a fundamental role on the dynamics of stream fish populations. ***In a recent study conducted in my laboratory, telemetry tracking of adult Atlantic salmon in the Sainte-Marguerite river (Québec) using temperature sensing acoustic tags revealed the crucial role of deep pool-bottom thermal refuges for the thermoregulation of adult salmon during warm water episodes (Frechette et al, submitted). ***Despite these observations, several important questions remain to be elucidated concerning the dynamics of pool-bottom thermal refuges (How common are they? What are the processes responsible for their presence and dynamics? Is it possible to predict their occurrence from pool characteristics?) and their biological significance for salmon (How widespread is this thermoregulation behaviour? Is the water temperature triggering thermoregulation behavior constant across rivers or is local adaptation to warm temperatures observed? What is the role of pool thermal refuge location on the movement patterns of adult salmon in rivers?).***Taking Atlantic salmon (Salmo salar) as an ecological model, the general scientific approach of the proposed research is mainly based on the quantitative analysis of empirical field data. In the first project, detailed field measurements of river pool physical characteristics will be conducted in pools of various river systems to decipher the processes leading to thermal refuge presence and develop predictive models of pool-bottom thermal refuge formation, persistence and dismantling. In the second project, snorkeling counts and acoustic telemetry tracking of adult Atlantic salmon with temperature sensing tags and dense arrays of hydrophones will be used to 1) monitor large-scale movement of fish in relation to pool-bottom thermal refuge locations and river temperature, and 2) document the fine-scale spatial and temporal use of refuges. ***In the currently observed context of climate change, understanding the dynamics and role of pool-bottom thermal refuges appears critical to the management of salmon population. The proposed research will provide stream ecologist and stream managers with highly novel tools and information concerning the dynamics of riverine ecosystems that will help assess, predict and mitigate the impact of anthropogenic disturbances and climate change on river ecosystems.