Based on the data of phytoplankton surveys made in 1959, 1981-1982, 1985 -1986 and 1991-1992 in Dianshan lake, the main ecological changes in the phytoplankton association is discussed and the main results are as foll...Based on the data of phytoplankton surveys made in 1959, 1981-1982, 1985 -1986 and 1991-1992 in Dianshan lake, the main ecological changes in the phytoplankton association is discussed and the main results are as follows:1. The average annual increase of phytoplankton density generally decreased from the 1959’s to 1985, and exhibited a increasing trend after the 1990’s. The species composition tended to become simple, and there were some changes in the proportions of relative number of phytoplankton.2. The primary productivity of phytoplanktpn showed an increasing trend, and the diversity index of community showed a decreasing trend.3. The average caloric value and standing crop of energy of phytoplankton were 11.61 KJ.g-1 DM and 139.82 KJ.m-2, respectively: their seasonal change laws were somewhat different. The energy conversion efficiency of total radiation by phytoplankton averaged 0. 68%.展开更多
文摘Based on the data of phytoplankton surveys made in 1959, 1981-1982, 1985 -1986 and 1991-1992 in Dianshan lake, the main ecological changes in the phytoplankton association is discussed and the main results are as follows:1. The average annual increase of phytoplankton density generally decreased from the 1959’s to 1985, and exhibited a increasing trend after the 1990’s. The species composition tended to become simple, and there were some changes in the proportions of relative number of phytoplankton.2. The primary productivity of phytoplanktpn showed an increasing trend, and the diversity index of community showed a decreasing trend.3. The average caloric value and standing crop of energy of phytoplankton were 11.61 KJ.g-1 DM and 139.82 KJ.m-2, respectively: their seasonal change laws were somewhat different. The energy conversion efficiency of total radiation by phytoplankton averaged 0. 68%.
