Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12589, Berlin, Germany.
Faculty of Life Sciences, Humboldt University, Invalidenstrasse 42, 10115, Berlin, Germany.
Parasitol Res. 2019 Sep;118(9):2531-2541. doi: 10.1007/s00436-019-06389-5. Epub 2019 Jul 8.
Visual performance and environmental conditions can influence both behavioral patterns and predator-prey interactions of fish. Eye parasites can impair their host's sensory performance with important consequences for the detection of prey, predators, and conspecifics. We used European perch (Perca fluviatilis) experimentally infected with the eye fluke Tylodelphys clavata and evaluated their feeding behavior and competitive ability under competition with non-infected conspecifics, in groups of four individuals, for two different prey species (Asellus aquaticus and Daphnia magna). To test whether the effect of T. clavata infection differs at different light conditions, we performed the experiments at two light intensities (600 and 6 lx). Foraging efficiency of perch was significantly affected by infection but not by light intensity. The distance at which infected fish attacked both prey species was significantly shorter in comparison to non-infected conspecifics. Additionally, infected fish more often unsuccessfully attacked A. aquaticus. Although the outcome of competition depended on prey species, there was a general tendency that non-infected fish consumed more of the available prey under both light intensities. Even though individual prey preferences for either A. aquaticus or D. magna were observed, we could not detect that infected fish change their prey preference to compensate for a reduced competitive foraging ability. As infection of T. clavata impairs foraging efficiency and competitive ability, infected fish would need to spend more time foraging to attain similar food intake as non-infected conspecifics; this presumably increases predation risk and potentially enhances transmission success to the final host.
视觉表现和环境条件会影响鱼类的行为模式和捕食者-猎物相互作用。眼寄生虫会损害宿主的感官表现，对猎物、捕食者和同种个体的检测产生重要影响。我们用欧洲鲈鱼（Perca fluviatilis）进行了实验感染，感染了眼吸虫 Tylodelphys clavata，并在 4 个个体的群体中，在两种不同的猎物物种（水生拟步甲和大型水蚤）中，评估了它们在与未感染的同种个体竞争时的摄食行为和竞争能力。为了测试 T. clavata 感染在不同光照条件下的效果是否不同，我们在两种光照强度（600 和 6 lx）下进行了实验。鲈鱼的觅食效率受到感染的显著影响，但不受光照强度的影响。与未感染的同种个体相比，感染鱼攻击两种猎物的距离明显缩短。此外，感染鱼更频繁地不成功地攻击水生拟步甲。尽管竞争的结果取决于猎物物种，但一般来说，在两种光照强度下，未感染的鱼消耗更多的可用猎物。尽管观察到个体对水生拟步甲或大型水蚤的猎物偏好，但我们无法检测到感染鱼会改变其猎物偏好以补偿竞争觅食能力的降低。由于 T. clavata 的感染会损害觅食效率和竞争能力，感染的鱼需要花费更多的时间觅食，以获得与未感染的同种个体相似的食物摄入量；这可能会增加被捕食的风险，并可能增强最终宿主的传播成功。
