Seasonal dynamics of zooplankton communities in interconnected tropical swamp lake ecosystems

摘要

As has been reviewed by Lehmusluoto et al. (1999), information on Indonesian freshwater zooplankton is currently inadequate. In 1998 we initiated ecological studies of zooplankton communities in back-water ecosystems of Central Kalimantan, confirming that lake ecosystems in this region mostly consist of back-water, oxbow lakes with highly fluctuating water levels, where differences between low and high water can be up to 6 m (Gumirj et al. 2000). Zooplankton communities are usually dominated by rotifers with their vertical distribution strongly controlled by the stratification of dissolved oxygen concentration (Gumiri Iwakuma 2002). In a previous study of two separate oxbow lakes, the seasonal dynamics of zooplankton densities were identical, showing low density between November and June, increasing in July, and remaining dense until September (Gumiri 2002). We here report the seasonal dynamics of zooplankton communities in four interconnected tropical swamp lake ecosystems along the Kahayan River. In particular, we studied the seasonal species richness of rotiferan zooplankton and assessed the degree of association among the four lakes by examining similarity indices and species dispersal between lake pairs.