Abstract: In this paper, the vertical changes of the accumulation rates and densities of Daphnia ephippia in the sediments (44 cm) of Lake Donghu and its correlations with the nutrient contents were studied. In the sediments 44-1 cm (from 1914 to 2015), the contents of total nitrogen and total phosphorus displayed an obviously increasing trend from the bottom to the surface. The ephippia of three Daphnia species were identified, namely, D. similoides sinensis, D. pulex and D. galeata. However, the ephippia containing resting eggs of three Daphnia species were all not found. In the 20-1 cm sedimentary layers (1963 year ago), the accumulation rates (0-2.7×103 ind./(m2·a)) and densities (0-1.0×103 ind./(g·dw)) of total ephippia of three Daphnia species were all at low levels, whereas the accumulation rates and densities of D. similoides sinensis showed an obviously increasing trend in the 44-21 cm sedimentary layers ( after 1963) and were significantly higher than those of D. pulex and D. galeata. There were all significant relationships (P<0.01) between total nitrogen and total phosphorus contents and the ephippial accumulation rates of three Daphnia species. Our results suggested that the changes of the accumulation rates and densities of Daphnia ephippia in the sediments could reflect the historical succession of Daphnia community in Lake Donghu, and lake eutrophication and the interference of human activities affected the vertical changes of Daphnia ephippia in the sediments of Lake Donghu.

Key words: Lake Donghu in Wuhan City, sediment, Daphnia, total nitrogen and total phosphorus, accumulation rate and density