Abstract:

The ecology of D bispinosus (Copepoda: Calanoida) was studied through the year of December 1983-January 1985. The animal had one generation for one year. Their individual life cycle of male could be in 10-12 months, and female could be in 12-18 months. The population density had marked seasonal variations. The higher density of adult appeared in June- September, and higher density of larva (mainly are nauplii) appeared in November and higher copepodites in January. Reproductive activities of animal went through from June to next January. There were two reproductive peaks in this period. The first peak arised in July to August. Although, a few of stage I copepodite would be found in the lake, mostly the nauplii presented in this peak time would not be able to grow into copepodites by restraining factors, such as food lack and low dissolved oxygen. The second peak arised about in October-December. Many of nauplii presented in these months could develop to copepodites and further to adults. The ecological characteristics of population as above, are related with seasonal changes of the environmental condition of the meromictic lake. The copepods were in progress of life activities following seasonal conditions of the lake, for obtaining best existence. They mated and laid eggs in winter to spring, in which it was more stability in temperature and salinity in the lake. And numbers of larva presented and grew in summer to autumn, being in conditions of abundant food and rich dissolved oxygen.