Effects of Aulacoseira granulate bloom process on population dynamics of Apocyclops borneoensis (copepod)

A lot of studies were conducted to reveal the mechanisms of algal blooms occurrence and its ecological effects in lakes and reservoirs. However, the effects of algal bloom process on zooplankton community structure were rarely investigated. In this study, the influences of Aulacoseira granulate bloom on dynamics of Apocyclops borneoensis (copepod) population and the effects (top-down control) of the latter's grazing on developments of the algal bloom were evaluated with mesoscale water column in two concrete ponds. It was found that the bloom of A. granulate formed and disappeared quickly: the chlorophyll a concentration increased from (21.24 �� 0.75) ��g �� L-1 to (240.34 �� 11.00) ��g �� L-1 within 5 days, and decreased rapidly and reached (53.63 �� 0.47) ��g �� L-1 in 3 days. On the other hand, the existence of A. borneoensis suppressed the appearance of A. granulate blooms: the chlorophyll a concentration of cultures with zooplankton was about 20 ��g �� L-1 lower than the zooplankton free ones, with the biggest difference of 26.08 ��g �� L-1 between them. Furthermore, the abundance of A. borneoensis increased from (56.50 �� 4.32) ind �� L-1 to (142.11 �� 6.35) ind �� L-1 during the process of A. granulate bloom. These results indicated that the process of A. granulate bloom had no negative impacts on growth and reproduction of A. borneoensis individuals. The amplification of A. borneoensis population can be ascribed to the adequate food supply during A. granulate bloom formation.