부유성 섬모충 Strombidium capitatum 시스트 형태 및 시스트 형성

Abstract

Cysts of an oligotrich ciliate were isolated from natural sediment samples collected in Onagawa Bay of Japan and in Masan Bay of Korea and incubated under laboratory culture conditions. Excysted vegetative cells were observed after protargol staining and were identified as Strombidium capitatum. Cysts of S. capitatum have a spherical shape, with a papula and cyst wall ornamented with spines. Size varied from 60-62 µm in total length and 50-55 µm in width. Seasonal changes in the vegetative population and sedimentation of newly formed cysts were investigated in situ. Planktonic vegetative cells were abundant during the cold season from December to April, when the water temperature was lower than 15 ℃. Mass encystment occurred in March, when the vegetative population flourished. Living cyst abundance in the sediments increased in January and April and empty cysts largely increased from October to March. These results indicate that S. capitatum is a well adapted species in cold-water and aestivates during the warm period in summer.