Chen Jiazhang

Eco-characteristics of phytoplankton in Lake Wuli, Lake Taihu in 2007

This paper was studied the eco-characteristics of phytoplankton in Lake Wuli, Lake Taihu in 2007. The results showed that 8 classes including 123 species have been founded in Lake Wuli. Among them, dominated Chlorophyta has 57 species, accounting for 46.3% of the total phytoplankton species, and Bacillariophyta has 23 species, taken the second place, accounting for 18.7% of the total phytoplankton species. There were much more species in winter and spring than that in summer and autumn. The quantity and biomass of phytoplankton in Lake Wuli in 2007 ranged from 386.2×104 to 5581.9×104cells/L and 0.541 to 3.491mg/L, respectively. Dominated class both in quantity and biomass was Chlorophyta, then was Cyanophyta, and the third was Cryptophyta. The quantity of phytoplankton in the order from large to small was: SummerSpringAutumnWinter. Seasonal succession of phytoplankton was consistent with rule of PEG (Plankton Ecology Group) model except Chlorophyta. The analysis results of similarity showed that the eco-environment of Lake Wuli in January was similar to that on March, April and May, and the eco-environment in June was similar to that in July, August, September and November. The analysis result of the predominance index showed that there were 14 predominant species including Chlorella vulgaris, Chl.amydomonas microsphaera, Chroomonas acuta, Microcystis aeruginisa in 2007 in Lake Wuli, and the numbers of predominant species were all more than two species in every month. Furthermore, the predominant indexes were not high, ranging from 0.02 to 0.78. The analysis results of diversity and uniformity showed that the diversity index ranged from 1.5 to 2.7 and uniformity index from 0.26 to 0.59, respectively, which meant that both diversity and uniformity of phytoplankton were good status in the lake. It could be concluded that the phytoplankton community structure in Lake Wuli was complex in the ecosystem.

“空心菜-水芹”轮作对养殖池塘水质和底质环境的影响

通过测定TOC、COD、Chl、TN、NH4+-N、NO2--N、NO3--N、TP、PO43--P等水质指标和底泥中TOC、TN、TP指标，探究“空心菜-水芹”轮作模式对不同养殖品种和养殖数量情况下养殖池塘水质和底质环境的影响。结果表明，在轮作模式前期，空心菜（Ipomoea aquatica）种植能显著降低甘露青鱼（Mylopharyngodon piceus）养殖场TOC、Chl、TN、NH4+-N、NO2--N、NO3--N、PO43--P等水质指标，能显著降低苏州经济鱼亲本塘TOC、COD、Chl、NH4+-N、NO2--N、NO3--N、TP等水质指标。轮作后期水芹（Oenanthe stolonifera）种植能降低甘露青鱼养殖场TOC、NO3--N、TP等水质指标，降低苏州经济鱼亲本塘TOC、COD、NH4+-N、NO3--N、TP等水质指标。轮作前、后期均能降低底质TOC、TN和TP含量。“空心菜-水芹”轮作模式能显著降低养殖池塘水体中TOC、NH4+-N、NO3--N、TP指标和底泥中TOC、TN、TP指标。