Investigation On Present Situation Of Fishery Resources In Tongwan Reservoir,Hunan Province

This paper took tongwan reservoir in hunan province as its research object,an investigation on physiochemical of water quality and bait biological changes were conducted in tongwan reservoir from 2015 to 2016.on the basis of these investigations the trophic type and present situation of fishery resources were evaluated in order to provide theoretical base for the reasonable utilization of fishery resource and Ecological management of environment,the main results obtained were as follows:1.In the whole year,the range of water temperature,pH and DO in the tongwan reservoir were 5.8-27.2-C,7.22-7.54 and 7.11?11.34 mg/L,respectively.The value of NH4+-N,NO2--N were 0.01?0.21mg/L,0-0.0057mg/L,Lrespectively.The TP values was 0.03?0.05mg/L,respectively.The content of COD was 2.01?4.23mg/L?2.There were 34 phytoplankton species in the tongwan reservoir,which belongs to 5 phyla and 16 genuses.The range of phytoplankton biomass was 0.08?0.35 mg/L.Redundancy analysis was used to analysis the relationship between dominant species and the environment factors,the result showed that P043--P,TP and DO had mostly affected on phytoplankton community.zooplankton species was identified and most of them were protozoan and rotifera.The biomass of zooplankton was 1.02?6.25mg/L.N03--N,TN and TP were the dominant environment factors affected on the community structure of zooplankton.There were 3 species macrozoobenthos included oflimnodrilushoffmeisteri,chironomid larvae,coarse ventral chironomid larvae were indentifiedin the tongwan reservoir,midges larvae were the dominant species,the density and biomass were 75-488 ind/m2 and 0.21?0.84g/m2 respectively in the tongwan reservoir.Meanwhile,NH4+-N and TP were the dominant environment factors to macrozoobenthos community.3.Tongwan reservoir has higher nitrogen content in contrast with the former researches,and phosphorus is closely correlated to food organism of fish.So measures should be done to control the input of nitrogen and phosphorus elements in case of eutrophication.On the other hand,management should control the stocking of bighead carp and adjust the ratio of bighead carp with silver carp,meanwhile,raise the amount of predatory fishes appropriately,to highlight the stability of the tongwan reservoir.