Community Characteristics Of Aquatic Insects And Bioassessement Of Water Quality In The Poyang Lake(sand Lake)

Poyang lake is one of the most preserved in our country’s fresh water lake wetland ecosystem, its rich biodiversity and ecosystem services is so powerful, and aquatic insects is an important part of the water ecological system. In 2014, dynamics of community structure, biodiversity and biological assessment of water quality of aquatic insects were studied in here. The main results are as followed:1、As a result, 19370 aquatic insect individuals were collected and identified, belonging to 16 families 5 orders. Hemiptera was dominant groups, its numbers of individuals accounted for 62.71% of all the aquatic insects; Corixidae and Culicidae were dominant in all 16 families, accounted for the total number of aquatic insects, 55.16% and 16.79%, respectively. Corixidae has been taken 45 times in a total of 48 acquisitions, but Dytiscidae and Gyrinidae just 13 times and 12 times, respectively.2、Predators has the largest number of families, 9 families, but shredders only has 1 family, in the functional feeding groups of aquatic insects in the sand lake; the number of scrapers was the most, representing the total number of aquatic insects from 65.09% to 67.02%, shredders was the least, accounted for less than 1.93%.3、The richness of aquatic insects increased in March to May, June to August decreased; the number of aquatic insects began to rise slowly from early April, the early May began to rise sharply, there was a significant period of decline and then recover in June, and the early July began to decline rapidly. The orders, the dominant families and the most common families were outbreak in early June. The water more deep, the richness of aquatic insects more small, the same as the number of aquatic insects. The number of the orders and the vast majority of families in site 3 were all listed in the 5 sites of the top two, and site 2 has consistently ranked the last two.4、The maximum values of Simpson diversity index, Shannon-Wiener diversity index and Brillouin diversity index appeared in early May, the minimum values appeared in the late May. The maximum values of Margalef richness index appeared in late April, the minimum values occurred in early March; the maximum values of Pielou evenness index appeared in late March, the minimum values occurred in late May. The average values of five diversity index were site 4>site 3>site 1>site 2>site 5 and 0-15 cm depth>15-30 cm depth>30-45 cm depth.5、According to the assessment of Shannon-Wiener diversity index, Simpson dominance index and family biotic index: the water quality in sand lake was light pollution in March and April, light pollution and moderate pollution appeared alternately in May and June. Site 1 and site 2 mainly appeared moderate pollution, site 3 and site 4 mainly appeared light pollution, site 5 always appeared moderate pollution. The water of 0-15 cm depth mainly appeared light pollution; light pollution and moderate pollution appeared alternately in 15-30 cm depth; in 30-45 cm depth light pollution and moderate pollution appeared alternately in April and June, moderate to serious pollution appeared in May.6、Aquatic higher plants, temperature, water depth, the pollution degree and predators were likely to be the key factor to affect the density of aquatic insect community and its diversity.