Study On The Relationship Between Fish Species Diversity And Water Environmental Factors In Qixing River Protected Area

In this study,fish community structure in relation to water environmental factors was studied in Qixing River Protected.Area.The Qixing River Protected Area is composed of two nature reserves,namely Sanhuanpao Nature Reserve and Qixinghe Nature Reserve.The study was conducted in May,June and September 2017 for three sampling.Eight sampling points were set in Sanhuanpao Nature Reserve and Qixinghe Nature Reserve and fish samples collected.A total of 10446 fish samples were collected belonging to 4 orders,6 families,11 genera and 14 species.The fish community was mainly composed of low-temperature and low-oxygen-resistant small bottom fish.The most dominant fish species were Perccottus glehn,Carassius auratus gibelio,Phaxinus percnuru,Cobitis lutheri and Alisgurnus mohoity.The fish species were found to be relatively stable,however,the overall fish diversity was low in this region.The redundance analysis(RDA)results showed that pH.TP,TN,and conductivity were the main environmental factors that influenced fish community.Rhodeus sericeus,Phaxinus czekanowskii,Barbatula barbatula nuda,Cobitis granoei,Misgurnus bipartit and Channa argus were positively correlated with TP.With exception of several fishes with strong environmental tolerance(such as Perccottus glehni,Barbatula barbatula nuda,Cobitis granoci,and Misgurnus bipartitus),the other species showed a negative correlation with CODcy,BOD5,TN,pH and conductivity.All of the fish species showed negatively correlation with water temperature.There was no correlation between the environmental factors and Perccottus glehni.By constructing a BP artificial neural network,the fish Shannon-Wiener index response in 5 hypothetical scenarios with different TP and TN concentrations was predicted.The prediction results showed that the fish Shannon-Wiener index was highest when TN was 1.00 mg/L～2.00 mg/L and TP was 0.20 mg/L～0.40 mg/L in the Qixing River Protected Area.It was suggested that the water body in Qixing River Protected Area should be maintained at a TN of 1.00 mg/L and a TP of 0.20 mg/L,which can promote the growth of fish species diversity and minimize the risk of water eutrophication.