Study On The Food Sources Of Dominant Consumers In The Sub-Lakes Of Poyang Lake

Poyang Lake is the largest freshwater lake in China, is important flood storage area and water supply area in the downstream of the Yangtze River.Poyang Lake not only provide spawning place for a variety of migratory fish and is important migratory bird route. The study of energy and material transfer pathways and mechanisms in Poyang Lake food web is of great significance for understanding the flow of nutrients, the structure of species community and ecological processes. In this study, we mainly studied the differences of basic food sources in the Poyang Lake and the consumer's use of food. We set study sites in the shore area of the three Sub-lakes in Poyang Lake, combined with stable isotopes and fatty acid analysis method, studying the seasonal dynamics of food sources and food sources to benthic animals(B.aeruginosa and C.cahayensis) and two kinds of fish(H.leucisculus and C.auratus). The main results are as follows:1. Values of ?13C of seston in different locations shown significant difference(P = 0.038), and other food resources in different location don't have significant difference. But other results show that value of ?13C of SOM, benthic animals, seston and epiphytic algae are highest in Shahu Lake and lowest in Dahuchi Lake. Values of ?13C of six kinds of food sources showed different degree of changes between months; according to the experimental results, it is speculated that, changes of the isotope values of food sources are mainly affected by allochthonous organic matter.2. Using the binary mixture model calculation, the seston in three lakes consisting mainly autochthonous organic mattter, The average contribution rate of Banghu Lake,Dahuchi Lake and Shahu Lake was 81.22%, 82.44% and 63.24% respectively. The contribution rate of allochthonous organic matter to food web is affected by the fluctuation of water level. The contribution rate of allochthonous organic matter in Dahuchi Lake and Shahu Lake reached peak in July and August respectively.3. The food sources to consumers exist differences in time and space; two snails food sources is mainly sediment, C. chinensis food source during the study period with changes, and food sources to the fishes are mainly seston; values of ??3/??6 to snails are lower than fishes, and the dependence of allochthonous organic matter to snail is higher than fish.