关键词: 阻隔湖泊, 浮游甲壳动物, 群落结构, 时空分布, 水产养殖

Abstract: A survey was carried out of Lake Junshan, a dammed lake of Lake Poyang for variation of community structure and spatio-termporal distribution of planktonic crustaceans, during the wet, normal and dry seasons of 2012—2013. Results show that the planktonic crustaceans in the lake varied between 29.4 (normal season）and 154.7 L^-1(dry season) in abundance, and between 0.64 (wet season）and 7.44 mg·L^-1(dry season) in total biomass. The cladoceran in the lake was dominated by Daphnia cucullata in abundance and biomass during the dry and normal season, and by Bosmina spp. , Ceriodaphnia spp. and Diaphanosoma spp. during the wet season, while the Copepods was by nauplius and copepodids all the year round. The annual mean abundance of planktonic crustaceans was much higher at Sites J6, J7, J8 and J9, in the middle of the lake, than at any other sites, and lower at Sites J4 and J5 in the estuary and J1 at the outlet of the lake. It is held that aquicultural activities are the key factor affecting seasonal spatial distribution and community structure of planktonic crustaceans in Lake Junshan. Uneven spatial distribution of flow velocity was also a factor affecting the variation. Lake Junshan was obviously higher than Lake Poyang in abundance of planktonic crustaceans and different from the latter in community structure of planktonic crustaceans, which may be attributed to the slower flow velocity, longer cycle of water replacement and higher nutritional level of the water in the lake as a result of the barricade between the two lakes. Such hydraulic environment is more favorable to growth and propagation of planktonic crustaceans. Aquicultural activities in the lake are probably the main cause to the difference between the two lakes in community structure of planktonic crustacean.

Key words: barrier lake, planktonic crustacean, community structure, spatio-temporal distribution, aquaculture