Thermal refuge use and parasitism: spatiotemporal variation in anchor worm and lamprey wounds on Klamath redband trout

Climate warming is increasing maximum temperatures during summer, such that they more frequently exceed the thermal tolerances of ectotherms, particularly cold-water fishes. One way that species can avoid thermal stress is by moving to thermal refuge habitats. Thermal refuges remain suitably cool during summer and are often complementary to foraging, spawning, and rearing habitats. Although the benefits associated with the thermal aspects of refuges are well studied, much less is known about potential costs associated with non-thermal aspects. For example, crowding of cold-water fishes into seasonal refuge habitats could increase parasite loads and cause declines in fitness. We assessed lamprey and anchor worm parasitism in Upper Klamath Lake where adfluvial redband trout (Oncorhynchus mykiss newberii) move to thermal refuge habitats during summer. We sampled trout in Upper Klamath Lake during spring and in adjacent thermal refuge habitats during summer. We also evaluated survival as a ..., Wound count for lamprey or anchorworm was collected by hook and line sampling. Each trout was visually assessed for a wound count from either lamprey or anchorworm., RStudio was used to analyze data.Â

气候变暖正抬升夏季最高气温，使得高温愈发频繁地超出变温动物（ectotherms）的热耐受阈值，其中冷水鱼类受此影响最为显著。物种规避热胁迫的途径之一，是迁徙至热庇护栖息地（thermal refuge habitats）。这类栖息地在夏季可维持适宜的低温环境，且通常与觅食、产卵及育幼栖息地形成功能互补。尽管学界已对热庇护栖息地的热效益开展了充分研究，但针对其非热属性相关的潜在成本，目前认知仍较为匮乏。举例而言，冷水鱼类群聚于季节性热庇护栖息地的行为，可能会提升寄生虫载量并导致个体适合度下降。我们在克拉马斯湖上游（Upper Klamath Lake）开展了七鳃鳗与锚头鳋（anchor worm）寄生情况的评估，该区域的洄游性红带鳟（Oncorhynchus mykiss newberii）会在夏季迁徙至热庇护栖息地。我们于春季在克拉马斯湖上游采样鳟鱼，夏季则在邻近的热庇护栖息地开展采样工作。此外我们还以[...]作为指标评估了存活率；通过竿钓采样法，我们记录了鳟鱼体表七鳃鳗或锚头鳋所致的伤口数量。每条鳟鱼均通过目视检查，统计其体表七鳃鳗或锚头鳋造成的伤口数。数据分析工作依托RStudio平台完成。