Aquatic communities in peatland of central Kalimantan

Abstract

In the lakes of river flood-plain ecosystems of tropical regions, the dynamics of phytoplankton species are strongly affected by fluctuations in water level throughout the year. In Central Kalimantan Lakes, phytoplankton were dominated by heterotropic-flagellated species of Euglenophycea and Bacillariphyceae. Lakes that are frequently disturbed by flood pulses from the main river tend to have high abundance and diversity of phytoplankton, which is in line with the Junk’s Intermediate Disturbance Hypothesis. Several factors governed the dynamics of zooplankton communities in the studied lakes. On a monthly basis, the temporal variation of zooplankton density was induced by the lunar cycle, whereas the seasonal density and biomass were determined by the alternations of wet and dry seasons. Dilution and washout effects were observed to cause zooplankton dispersal in interconnected lakes with the main river due to the increase of water currents during the rainy season, whereas the penetration of dissolved oxygen appeared to be the ultimate factor in causing different patterns of zooplankton vertical distribution in water columns of the studied lakes.