Factors influencing the seasonal occurrence and abundance of the zooplankton in two waste stabilization ponds

Abstract

Zooplankton community structure was studied in two maturation ponds at Gumeracha, South Australia. Abundance of the major zooplankters was related to physicochemical parameters and interspecific interactions. Daphnia carinata and Mesocyclops leuckarti were the numerically dominant zooplankters. Temperature was the most important factor affecting the seasonal occurrence of D. carinata, the dominant species in autumn and late winter, and M. leuckarti, the dominant species during mid-summer. Physicochemical parameters appeared to be unimportant in accounting for the occurrence and abundance of Simocephalus exspinosus, Macrothrix hirsuticornis, and Boeckella triarticulata. Although population densities of D. carinata and S. exspinosus were negatively correlated, population parameters did not indicate a marked competitive interaction. Mesocyclops leuckarti may have preyed upon the immature stages of D. carinata, although this was generally not reflected in mortality rates.