Study On Fishery Community And Food Web Of Changyang Lake

In order to study the basic water ecological environment of Changyang Lake in Wujiang City,Jiangsu Province,fish community and food web structure were conducted in four seasons from 2016 to 2017 and in summer and autumn of 2017 and spring of 2018,respectively.The contents of this paper are:the fish resources in Changyang Lake,and the composition of aquatic food web and trophic level in Changyang Lake.Exploring the temporal and spatial distribution characteristics of fish resources and analyzing the structure and trophic level of Changyang Lake food web is a practice to fully understand the aquatic ecological environment of freshwater basins.It can help provide certain basic data for the follow-up environmental science research of Changyang Lake.The demonstration of the intuitional data of the ecological environment of Changyang Lake will help the society to pay extensive attention to the protection of the fishery ecology.It can also rationally protect and utilize the aquatic resources of the Changyang Lake and promote the ecological environment of the waters.Relevant policies making for the lake development can also refer to the materials and evidence provided in the study.The main results are as follows:1.There are 38 species of fish caught in Lake Changyang,belonging to 6 orders,10 families and 22 genera,respectively.Among them,there are up to 26 species of scorpion,5 species of scorpion,5 species of scorpion,and 2 species of squid.There are only one species of scorpionidae and scorpionidae;three species of crustaceans belong to 1 order,2 families and 3 genera;the results of Index of Relative Importance(IRI)show that there are 6 species belonging to dominant species.They are Aristichthys nobilis(Richardson)?Macrobrachium nipponense(de Haan)?Hypophthalmichthys molitrix(Cuvieret Valenciennes)?Coilia nasus(Temminck et Schlegel)?Culter dabryi,Carassius auratus(Linnaeus);the order of dominant species in each season is:spring>summer>autumn>winter;4 species of dominant species in the core area of Changchun Lake,6 species in the southern experimental area and the northern experimental area;The value of Shannon-Wiener changes with temperature.The spring and summer festival values are higher than autumn and winter.The spring core area is higher than the other two regions.The summer and winter are the highest in the southern experimental area,and the autumn is the highest in the northern experimental area.Season(except spring north of the experimental area)evenness index(Pielou)were higher than 0.3,the core area of spring and winter evenness index higher than the other two districts,the uniformity of the northern summer and autumn experimental zone index is higher than the other two zones.2.Through investigation and analysis,the ?13C value of the main organisms in Chanyang Lake in spring was significantly different from that in summer and autumn(p<0.01),and there was no significant difference in summer and autumn.And there were no significant difference about the ? 15N values between seasons.The ? 13C and ? 15N values of Culter Mongolicus which was the main protected species were significantly different from those of the Xiaojiang waters in the Three Gorges reservoir.The ? 13C value is lower and the ? 15N value is higher than that area.In summer,the trophic level of Culter Mongolicus in Changyang Lake was lower than Xiaojiang waters of the Three Gorges Reservoir,but higher in spring.The reason may be the difference of sampling time and sampling sites,or the difference in the composition of the bait,or the difference between the selection of the baseline and the fractionation value,or all of them.The ?15N value and trophic level of Hemibarbus maculatus which was also the main protected species were higher in spring than summer,which may be due to inconsistent sample specifications and dietary changes.What's more,There is no correlation between the ? 13C and ? 15N values of the main aquatic organisms in Changyang Lake(p>0.05),indicating that the carbon source is complex,and the C/N ratio of particulate organic matter is higher than 30,indicating that the main source of organic matter is terrigenous organic matter,further research is needed to be done.Furthermore,The long-term trophic level of Changyang Lake is larger,which may be related to the rich biological resources of bait in spring.All of these results provided basic data accumulation and theoretical references for the water resources utilization and protection in Changyang Lake.