摘要 : As a result of comparative analysis of phytoplankton population structures between the ancient lakes Biwa and Baikal, we found floristic similarities and differences; but the former were minor. Both lakes had highly original algal... 展开 As a result of comparative analysis of phytoplankton population structures between the ancient lakes Biwa and Baikal, we found floristic similarities and differences; but the former were minor. Both lakes had highly original algal florae due to presence of endemic, relict and rare forms. The richest in species number in the lakes were green algae and diatoms; Scenedesmus, the most diverse genus in Chlorococcales and Cyclotella, Stephanodiscus, Aulacoseira and Synedra in diatoms. The chief distinction between the lakes was that desmids appeared abundantly in the pelagic zone of Lake Biwa, whereas they were observed only in shallows and bays in Lake Baikal. The Sorensen's coefficient calculated for the planktonic florae was very low. This suggests that the algal florae of these lakes are significantly diverse. 收起