武汉东湖沉积物中溞属种类卵鞍累积变化研究

The vertical changes of the accumulation rates and densities of the ephippia of Daphnia species in the sediment of Lake Donghu(Wuhan City)and its correlations with the nutrients

研究了武汉东湖沉积层中溞属种类卵鞍累积速率和密度的垂直变化及其与营养盐间的关系。在44~1 cm沉积层(自1914年至2015年)中,总氮、总磷的含量随沉积深度自底层至表层均逐渐增加。共鉴定到3种溞属种类的卵鞍,即中华拟同形溞、盔形溞及蚤状溞,且没有发现3个溞属种类的含休眠卵卵鞍。44~21 cm沉积层(1963年前)中的3种溞属种类总卵鞍的累积速率和密度[0~2.7×10^3 ind./(m^2·a)和0~1.0×10^3 ind./(g·dw)]均处于较低水平。在20~1 cm沉积层(1963年后)中,中华拟同形溞卵鞍的累积速率和密度均呈现明显上升的趋势,且显著高于盔形溞和蚤状溞。东湖沉积物中总氮和总磷的含量与3种溞属种类卵鞍的累积速率间均存在极显著的相关性(P<0.01)。结果暗示沉积物中溞属种类卵鞍累积速率和密度的变化能够反映东湖溞属种类群落结构的历史演替,湖泊富营养化和人为活动的干扰影响了东湖沉积物中溞属种类卵鞍的垂直变化。

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(0-2.7×10^3 ind./(m^2·a))and densities(0-1.0×10^3 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.