The effects of water eutrophication and species invasion on the food web of Xingyun Lake
Samples of lake water quality,primary producer phytoplankton(pelagic carbon source),submerged plants(benthic carbon source),terrestrial organic matter(terrestrial sources),and consumer zooplankton,benthos and fishes were systematically collected from Xingyun Lake,a shallow and eutrophic lake of Yunnan,in 2019～2020.These samples were analyzed to identify the characteristics of carbon and nitrogen stable isotope composition of primary producers and consumers,and to quantify the food sources of consumers using the MixSIAR model.We tried to find out the best model for constructing the food web structure applicable to this shallow and eutrophic lake by a comparison of the outputs from three calculation models,with the isotopic baseline of primary producer(Model A),carbon source contribution weight(Model B),and primary consumer(Model C),and thus revealed the possible effects of eutrophication and invasive alien species on the lake food web.The contributions of planktonic,benthic and terrestrial carbon source to consumers were 77.3％,12.2％and 10.5％,respectively.Moreover,no significant difference in the carbon isotope signals of fishes between littoral zone and pelagic zone indicated that planktonic carbon source was the most important food source of consumers in eutrophic lakes,and its energy flow of food webs was dominated by planktonic pathway.For fishes of different diets,omnivorous fish had wide dietary sources and carnivorous fish had a higher trophic level,separating their core ecological niches.The core ecological niche of omnivorous fish(3.79)was higher than that of carnivorous fish(2.46),indicating that omnivorous fish had higher adaptability.The trophic level results calculated by model B were more consistent with the food habits of consumers than other two models,and the model B could be selected as the best model applied to the calculation of trophic level of consumers in Xingyun Lake.The results of Model B showed that the food chain length of Xingyun Lake was 3.73,and its top predator was Silurus graham,followed by the invasive species Neosalanx taihuensis(3.37),competing with Anabarilius andersoni(3.01)in terms of food and survival space.This study concluded that the alterations of material sources and energy flows caused by the eutrophication as well as the introduction of invasive species were the main reasons for the decline of indigenous fish resources,the reduction of biodiversity in the food web structure,and the weakening of ecosystem functions in Xingyun Lake.
eutrophicationinvasive speciesstable isotope of carbon and nitrogenMixSIAR modeltrophic levelfoodwebXingyun Lake
万方数据
维普
