The effect of environmental factors on population dynamics of Drepanopus bispinosus (Calanoida: Copepoda) in Burton Lake, Antarctica

The population dynamics of Drepanopus bispinosus (Calanoida: Copepoda) was studied throughout the year from December 1983-January 1985 in Burton Lake, a littoral saline lake in the Vestfold Hills, Antarctica. Also the environmental factors of the lake were observed simultaneously. D. bispinosus is univoltme The population life cycle could be in 20-21 months. Their reproductive activities spread from winter to early summer. The adults (male and female) and naupln mainly constitute the winter population. Adult females and copepodites are absolutely components of the summer population. From late summer through autumn, the population consists mainly of copepodites in stages II-V. The densities of population components have presented considerable variations throughout their life time Most of naupln occurring in winter might not develop and transform into further stages because of restrictive conditions such as low oxygen content and food scarcity. Earlier stage copepodites of new generation appear largely in summer, when the lake is rich m oxygen and phytoplankton. The adult females decrease markedly after their reproductive activities when the strong salinity was diluted in early summer. Such variations of densities of population compositions are closely related to changing of environmental factors m the lake The material obtained from another saline lake m the same hills supported the above