SPATIO-TEMPORAL RESPONSE OF SEDIMENTARY DIATOMS TO WATER LEVEL IN A SHALLOW LAKE

Abstract

In recent years, human activities have resulted in variations of hydraulic conditions in shallow lakes, thereby affecting interactions between environmental variables and aquatic plants. This feedback of plants on environmental changes is largely recorded in lake sediments. In this study we collected surface sediments in different seasons and a sediment core from a shallow lake Baiyangdian. We investigated the seasonal effects of water level and six physicochemical variables in surface sediments, as well as their impacts on the distribution of diatom assemblages. Therein the response of diatom assemblages to water level and the spatio-temporal effects of water level are highly emphasized. Results indicate that water level significantly changes between seasons, however there is no significant seasonal effects for the com- position of grain size. The lake productivity increases with the vigorous growth of aquatic plants. Water level largely determines the distribution of diatom assemblages in surface sediments and the sediment core. Spatial isolation causes the difference between the habitats and alters the relation between water level and diatom taxa. Human activities also affect the relevance of water level with diatom assemblage. The results can provide the helpful information for the local water resource management.