Seasonal Abundance and Vertical Distribution of Zooplankton in Lake Ikeda, Southern Japan

Abstract

Species composition, seasonal variation and vertical distribution of zooplankton in Lake Ikeda, located in the south of Kyushu Island, Japan, were investigated from July 1993 to December 1994. Twenty-six species were identified, of which fourteen were newly recorded for the lake, these being five rotifers, six cladocerans and three copepods. The zooplankton community was dominated by copepods, cladocerans and rotifers. As the mean of 3 stations, they represented 49.6%, 28.5% and 21.9%, respectively. Rotifera was the most diverse group (13 species); other groups were Cladocera (9 species) and Copepoda (4 species). The zooplankton population was predominantly rotifers in the summer of 1993, of which Polyarthra euryptera and Conochilus unicornis were abundant. The calanoid copepod Eodiaptomus japonicus appeared in May 1994 and became dominant from August onwards. Vertical distribution showed that the majority of the zooplankton population appeared in the upper water layer (0-15 m) of the lake. © 1998, Japanese Society of Microbial Ecology & The Japanese Society of Soil Microbiology. All rights reserved.