Predator–prey dynamics can have landscape‐level impacts on ecosystems, and yet, spatial patterns and environmental predictors of predator–prey dynamics are often investigated at discrete locations, limiting our understanding of the broader impacts. At these broader scales, landscapes often contain multiple complex and heterogeneous habitats, requiring a spatially representative sampling design. This challenge is especially pronounced in California’s Sacramento–San Joaquin River Delta, where managers require information on the landscape‐scale impacts of non‐native fish predators on multiple imperiled native prey fish populations. We quantified relative predation risk in the southern half of the Delta (South Delta) in 2017 using floating baited tethers that record the exact time and location of predation events. We selected 20 study sites using a generalized random tessellation stratified survey design, which allowed us to infer relationships between key environmental covariates and predation across a broader spatial scale than previous studies. Covariates included distance‐to‐nearest predators, water temperature, turbidity, depth, bottom slope, bottom roughness, water velocity, and distance‐to‐nearest riverbank and nearest aquatic vegetation bed. Model selection determined the covariates that best predicted relative predation risk: water temperature, time of day, mean predator distance, and river bottom roughness. Using this model, we estimated predation risk for the South Delta landscape at a 1‐day and 1‐km resolution. This effort identified hot spots of predation risk and allowed us to generate predicted survival for migrating fish transiting the South Delta. This methodology can be applied to other systems to evaluate spatio‐temporal dynamics in predation risk, and their biotic and abiotic predictors.

中文翻译：

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鱼类在景观尺度上的捕食

捕食者－猎物动态可能会对生态系统产生景观层面的影响，然而，捕食者－猎物动态的空间格局和环境预测因素经常在离散的位置进行研究，从而限制了我们对更广泛影响的理解。在这些更广泛的尺度上，景观通常包含多个复杂且异质的栖息地，需要具有空间代表性的采样设计。在加利福尼亚州的萨克拉曼多–圣华金河三角洲，这一挑战尤为突出，那里的管理人员要求获得有关非本地鱼类捕食者对多种受困本地猎物鱼类种群的景观影响的信息。我们使用记录诱捕事件确切时间和地点的浮动诱饵系绳，在2017年对三角洲南部（南三角洲）的相对捕食风险进行了量化。我们使用广义随机细分分层调查设计选择了20个研究地点，这使我们能够在比以前的研究更广泛的空间范围内推断关键环境协变量与捕食之间的关系。协变量包括到最近的捕食者的距离，水温，浊度，深度，底坡度，底部的粗糙度，水流速度，到最近的河岸距离和最近的水生植物床。模型选择确定了最能预测相对捕食风险的协变量：水温，一天中的时间，平均捕食者距离和河底粗糙度。使用此模型，我们以1天1公里的分辨率估算了南三角洲地区景观的捕食风险。这项工作确定了掠食风险的热点，使我们能够为通过南三角洲迁移的鱼类提供预测的生存率。该方法可以应用于其他系统，以评估捕食风险的时空动态及其生物和非生物预测因子。