Effects Of Climate Warming And Water Eutrophication On Zooplankton Community Structure In Shallow Lakes

Global warming can cause the temperature increase,and the rise of average temperature of the water ecosystem,which leads to the rapid growth of algae,further may lead to eutrophication of the water body.With the development of human activities,most of the lakes in the middle and lower reaches of the Yangtze River are facing the threat of eutrophication.In present time,the climate warming and water eutrophication will be a major problem that humanity are to face today.In this thesis,the outdoor mesocosm experiment was conducted to investigate the effect of climate warming,eutrophication and their synergistic effect on crustacean zooplankton community within a period of one year by increasing the water temperature and adding phosphate.The main results are as follows:1?The community structure of planktonic crustaceans can be changed by 4.5 ?above the ambient temperature.However,the influences of water temperature increasement on the dominant species,density and the change trend are different.The increase of temperature can lead to advance in the recovery time of some cladoceran species,and increase the density of some heat resistant species of cladocerans,which can significantly improve the total density of the cladocerans in the water.However,the effect of the recovery time and density of the copepods are not very obvious.2?The effect of nutrient addition on the recovery time was not significant,but it could significantly increase(p=0.032)the density of the cladocerans and copepods.While adding phosphorus salt can change the dominant species structure of cladoceran,causing a significant increase in pollution indicator species density such as Bosmina longirostris,and reduced the density of Chydorus sphaericus which live in clean water.3?The synergistic effect of elevated water temperature and phosphorus addition are different for different species of cladoceran and copepod.Heating and phosphorus addition could significantly increase(p<0.01)the cladoceran density and change the distribution of dominant species of cladoceran.It also increase the average density ofAlona and Bosmina longirostris,but had no significant effect(p=0.753)on the average density of Chydorus sphaericus.Although the increase of temperature and phosphorus do have no significant effect(p=0.921)on the total density of copepods.It does significantly inhibit(p <0.01)the density of Nauplii,and increase the Cyclops larve density.At the same time,the increase of temperature and phosphorus can advance the recovery time of Alona and Bosmina longirostris,and delay the recovery time of Nauplii,while it has little effect on the recovery time of other zooplankton.