Taxonomy and ecology of parasites on zooplankton, in particular, copepods

研究了濑户内海中上层桡足类寄生的吸血虫（Vampyrophyra pelagica）的寄主特异性、超微结构和生活史。它的生命周期的完成通常需要无脊椎捕食者的喂养，比如桡足类动物身上的毛齿动物。相比之下，鱼类幼虫的捕食不参与其中。纤毛的纤毛在体毛内形成，保证快速脱落。细胞质中大量厚膜被认为是滋养体食物液泡膜的前体，在完全生长的细胞中完全消失。用扫描电镜和透射电镜观察了胞壁的形态。在实验室研究了水温与纤毛虫各阶段持续时间的关系。在最低温度（10℃）下，羽衣虫从羽衣虫孵化到羽衣虫出现的最长时间是最高温度（25℃）下最短时间的近20倍，这可能是由于包囊延长所致。在海洋岛屿、深海超底栖层和咸淡水中收集的桡足类动物中广泛发现了Apostome phorts。这有力地表明了它们在海洋食物网中的至高无上的重要性。在濑户内海的有袋动物中新发现了一种烟状桡足类和一种外缘等足类。这些寄生虫的最高发病率分别高达11%和19%。这些寄生虫可能与相同的栖息地和食物激烈竞争。发现了sibogae虾和日本芽虾（Siriella japonica izuensis）的双性个体，后者的双性个体可能是由球蛾类感染引起的。此外，还首次报道了在朝鲜远洋毛纲动物上发现鞭毛类的Oodinium inlandicum，在片足类动物上发现有袋类的Thalassomyces vosseleri。

The host-specificity, ultra-structure and life-cycle of the apostome ciliate Vampyrophyra pelagica parasitic on pelagic copepods were studied in the Seto Inland Sea. Completion of its life cycle usually needs feeding by invertebrate predators such as chaetognaths on copepods with phoronts of the ciliates. In contrast predation by fish larvae was not involved in it. Cilia of the ciliates are formed within the phoront, which guarantees quick excystation. Numerous thick membranes detected in the cytoplasm are considered to be precursors of food vacuole membranes of the trophont, and totally disappeared in the fully-grown cell. The morphology of the cytostome was newly revealed with SEM and TEM. Relationships between water temperature and duration of each stage of the ciliate were investigated in the laboratory. The maximum time from phoront hatching to tomite appearance at the lowest temperature (10℃) was nearly 20 times as long as the minimum time at the highest temperature (25℃), which seems to be caused by prolongation of the tomont. Apostome phoronts were broadly found from copepods collected from oceanic islands, deep-sea hyperbenthic layers, and brackish waters. This strongly suggests their paramount importance in marine food webs.A nicothoid copepod and an epicaridean isopod were newly described from the marsupium of the mysid Siriella okadai in the Seto Inland Sea. The maximum incidences of these parasites were up to 11 and 19 %, respectively. These parasites may compete severely with the same habitat and food.Intersex individuals of the shrimp Acetes sibogae and the mysid Siriella japonica izuensis were discovered, in the latter of which it seems to have been caused by infection of ellobiopsids. The occurrence of the dinoflagellate Oodinium inlandicum on pelagic chaetognaths in Korean and of the ellobiopsid Thalassomyces marsupii on the amphipod Scina vosseleri were also reported for the first time.