A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences,Leninskij prosp., 33, 119071 Moscow,Russia.
Shirshov Institute of Oceanology, Russian Academy of Sciences,Nahimovskiy prosp., 36, 117997 Moscow,Russia.
Parasitology. 2019 Jan;146(1):105-111. doi: 10.1017/S0031182018000963. Epub 2018 Jun 14.
Removal of parasite free-living stages by predators has previously been suggested an important factor controlling parasite transmission in aquatic habitats. Experimental studies of zooplankton predation on macroparasite larvae are, however, scarce. We tested whether trematode cercariae, which are often numerous in shallow waters, are suitable prey for syntopic zooplankters. Feeding rates and survival of freshwater cyclopoids (Megacyclops viridis, Macrocyclops distinctus), calanoids (Arctodiaptomus paulseni), cladocerans (Sida crystallina) and rotifers Asplanchna spp., fed with cercariae of Diplostomum pseudospathaceum, a common fish trematode, were studied. In additional long-term experiments, we studied reproduction of cyclopoids fed with cercariae. All tested zooplankton species consumed cercariae. The highest feeding rates were observed for cyclopoids (33 ± 12 cercariae ind-1 h-1), which actively reproduced (up to one egg clutch day-1) when fed ad libitum with cercariae. Their reproductive characteristics did not change significantly with time, indicating that cercariae supported cyclopoids' dietary needs. Mortality of rotifers and cladocerans was high (25-28% individuals) when exposed to cercariae in contrast to cyclopoids and calanoids (<2%). Cercariae clogged the filtration apparatus of cladocerans and caused internal injuries in predatory rotifers, which ingested cercariae. Observed trophic links between common freshwater zooplankters and cercariae may significantly influence food webs and parasite transmission in lentic ecosystems.
捕食者去除自由生活阶段的寄生虫曾被认为是控制水生栖息地寄生虫传播的一个重要因素。然而，关于浮游动物捕食大型寄生虫幼虫的实验研究却很少。我们测试了在浅水处大量存在的吸虫尾蚴是否适合作为同域浮游动物的猎物。我们研究了淡水端足类（绿大眼水蚤、大眼盘肠溞）、哲水蚤（保罗虫桡足类）、枝角类（晶刺水蚤）和轮虫（褶皱臂尾轮虫）在摄食 Diplostomum pseudospathaceum （一种常见的鱼类吸虫）尾蚴时的摄食率和存活率，D.pseudospathaceum 尾蚴。在额外的长期实验中，我们研究了以尾蚴为食的端足类的繁殖情况。所有测试的浮游动物物种都摄食尾蚴。端足类的摄食率最高（33±12 尾蚴 ind-1 h-1），当它们自由摄食尾蚴时会积极繁殖（每天可达一个卵囊）。它们的繁殖特征随时间没有明显变化，表明尾蚴能够满足端足类的饮食需求。当暴露于尾蚴时，轮虫和枝角类的死亡率很高（25-28%的个体），与端足类和哲水蚤类（<2%）形成鲜明对比。尾蚴堵塞了枝角类的过滤器官，并对吞食尾蚴的捕食性轮虫造成内部损伤。观察到的常见淡水浮游动物和尾蚴之间的营养联系可能会显著影响湖泊生态系统中的食物网和寄生虫传播。
