Water level and temperature and zooplankton population abundances in Lake Surinumu, Papua New Guinea

Abstract

Lake Surinumu, an oligotrophic hydroelectric impoundment on the Laloki River in Central Province, Papua New Guinea, was sampled throughout 1982 for its zooplankton community composition, water level and surface temperature. The zooplankton community was observed to be normally dominated byEodiaptomus lumholtzi, Ceriodaphnia cornuta and theDiaphanosoma speciesD. sarsi andD. excisum, though the rotiferT. equatorialis became dominant toward the end of the sampling period. Nutrient levels, especially with regard to ionic nitrogen, were observed to decrease following the monsoonal influx. Close correlations were found between water level and surface temperature, and between water level and the relative abundances ofE. lumholtzi, diaphanosomids andT. equatorialis. The zooplankton community was observed to undergo the most significant changes during periods of monsoonal influx and lowest water level/highest water temperature. In the absence of significant interspecific abundance correlations, it is suggested that climatic factors are primarily responsible for the dynamics of the zooplankton community composition.