ZOOPLANKTON BIOINDICATORS FOR TROPICAL LAKES OF DIFFERENT TROPHIC STATUS

Abstract: Zooplankton composition and distribution patterns in lakes are closely related to environmental factors and biotic interactions with other organisms in the aquatic food web. This study was conducted to evaluate the zooplankton species composition and biodiversity in lakes with different trophic status in order to identify potential zooplankton species as bio-indicators. Bimonthly sampling was carried out in Sembrong, Putrajaya and Subang lakes from April 2015 to February 2016. Duplicate zooplankton samples were collected with a 60-µm mesh net using vertical hauls from about 30 cm from the bottom to the surface, and preserved with 10 % buffered formalin to produce 5 % final solution for identification. Zooplankton species assemblage of hypereutrophic Sembrong lake was dominated by a cladoceran, Ceriodaphnia cornuta, followed by the rotifers, Brachionus forficula, B. calyciflorus, Trichocerca similis and Pompholyx complanata. These species contributed 63.8 % of all the total zooplankton.  In the mesotrophic Putrajaya lake, the dominant species was Keratella cochlearis, Ptygura libera and Bosmina longirostris which made up 65.5 % of the total zooplankton.  Meanwhile, in the acidic mesotrophic Subang lake, P. libera and Ascomorpha ecaudis were the dominant species contributing to 82.2 % of the total species. This present study illustrated that the dominant species found in the mesotrophic and eutrophic tropical lakes were mainly small-bodied zooplankton such as rotifers and small cladocerans. More studies are needed to confirm the reliable indicators for different lake types.

Keywords: Zooplankton composition, indicator species, tropical lake, trophic status