Impact of sea spider parasitism on host clams: susceptibility and intensity-dependent mortality.
Impact of sea spider parasitism on host clams: susceptibility and intensity-dependent mortality.
复制标题
海蜘蛛寄生对寄主蛤的影响：易感性和强度依赖性死亡率。
DOI：
10.1017/s0025315417000200
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发表时间：
2017
影响因子：
1.2
通讯作者：
Masanori Tamaoki and Mitsuharu Toba
中科院分区：
文献类型：
--
作者：
Katsumasa Yamada;Katsumi Miyazaki;Takeshi Tomiyama;Gen Kanaya;Yoshifumi Miyama;Tomoyoshi Yoshinaga;Kunihiro Wakui;Masanori Tamaoki and Mitsuharu Toba
绦虫是一种影响双壳类动物的内寄生海蜘蛛。最近，在日本（东京湾）具有重要商业价值的马尼拉蛤（Veneridae, Ruditapes philipparum）中大规模发现了海蜘蛛。与此同时，该地区发生了大规模死亡。当地渔民认为这种大规模死亡是由寄生海蜘蛛造成的，尽管寄生虫和寄生虫强度对宿主的影响尚不清楚。为了评估马尼拉蛤对海蜘蛛的易感性及其对死亡率的影响，我们在6个月的实验室实验中建立了6种不同感染强度（新孵化的海蜘蛛幼虫密度）的处理方法。在充足的食物条件下监测死亡率和3个易感指标（清除率、挖沙速度和内收肌力量）。海蜘蛛寄生影响清除率和挖沙速度。寄生强度对马尼拉蛤寄主生存的影响模式与寄主寄生数量有关，即寄主寄生水平越低（海蜘蛛孵化幼虫总数<200只），寄主蛤蜊存活率越高，寄主寄主蛤的死亡率越高（400-4000只）。这种寄生对寄主生存的影响模式可能是野外发生马尼拉蛤大量死亡的原因之一。
Nymphonella tapetis (Pycnogonida, Ascorhynchidae) is an endoparasitic sea spider affecting bivalves. Recently, sea spiders have been found on a massive scale in the commercially important Manila clams (Veneridae, Ruditapes philippinarum) in Japan (Tokyo Bay). Simultaneously, mass mortality has occurred in this area. Local fishers assumed that this mass mortality was caused by the parasitic sea spider, despite the effect of the parasite and parasite intensity on the host being unknown. To evaluate the susceptibility of the Manila clam to sea spider infestation and the impact on mortality levels, we established six treatments at different infection intensities (density of newly hatched larvae of sea spiders) over a 6-month long laboratory experiment. We monitored mortality and three susceptibility indices (clearance rate, sand-burrowing speed and adductor muscle strength) under sufficient food conditions. Parasitization by sea spider affected clearance rate and sand-burrowing speed. The pattern of parasitic intensity effects on survival of Manila clam hosts was shown to be dependent on the levels of parasite numbers, i.e. clams with lower parasitic levels (total of <200 hatching larvae of sea spider given to a host) have a higher survival rate, and high mortality of host clams was shown in excessively higher parasitic densities (400–4000 individuals). Such pattern of parasitic effects on host survival might be one of the causes of mass mortality of Manila clams occurring in the field.