A Research On Fish Diversity And Its Relationship With Environment In The Qingshitan Reservoir

Qingshitan reservoir is a large mountainous reservoir in Karst area,located in north of Guangxi province,belonging to a special kind of artificial lake ecosystem with its complex water ecological environment providing essential habitats for fish.In order to find out the relationship between fish community and the environmental factors in the Qingshitan reservoir,a survey on fish biodiversity and habitat was conducted.6 sampling sites in the reservoir were set where the fish samples were collected quarterly,during the period from April 2015 to January 2016,meanwhile water quality indexes such as water temperature,dissolved oxygen,pH,turbidity and conductivity of water were determined on-site and the survey of the relevant scene habitat was conducted.From some relevant public services such as Aquatic Animal Husbandry Bureau and EPA,some professional web sites such as the meteorological network,Guangxi water conservancy information network(http://www.gxwater.gov.cn),fish data,water quality data,meteorological and hydrological data were collected.Through the analysis of data both from the field and laboratory,the present situation of fish composition in reservoir was explored,the diversity of fish species and its relationship with the water environment were clarified,the main factors affecting survival of fish were identified to provide a theoretical basis for water environment management on reservoir.The main results are as following:(1)There were 32 species of fish,belonging to 5 orders,12 families and 27 genera,of which the main fish was Cypriniformes,accounting for 53.13% and 61.92% of total species and individual number(3750).The dominant species included Carassius auratus?Hemiculter lcucisculus and Cyprinus carpio.According to fish diet composition,the number of carnivorous fish species(17)was the largest,while the omnivorous fish biomass(57.06%)was the largest,the species number and biomass of herbivorous fish was least among fishes.(2)The analysis of fish diversity every season showed that fish abundance index(Dma)value is 2.5~3.52,Shannon-Wiener diversity index(He')ranged from 1.62 to 1.92,Pielou species evenness index(Je')ranged from 0.53 to 0.63.The highest diversity index was in summer,while the relatively lower in winter.In horizontal space,fish diversity showed a trend of decline from the mouth of river into reservoir,nearly the island toward the center of the reservoir.Clustering and similarity analysis(ANOSIM)showed that the differences of space-time structure of fish communities was not obvious,as the similarity between the season was high(> 60%),while there were some differences in local space.(3)Principal component analysis(PCA)and canonical correspondence analysis(CCA)analysis results showed that the water environmental factors influencing the structure fish community in the Qingshitan reservoir were inflow,water level,water temperature and turbidity orderly(n=499,P<0.05),with those can explain the relationship with total species to 77.84% extent.Most of fish were positively correlated with inflow and water temperature,while negatively correlated with water level(P<0.05),and most fish showed a cluster in a certain range of turbidity.(4)Compared with historical data,the diversity of fish species was high relatively,but fish stocks were significantly decreased,and the fish of catches became smaller.At present,the main factors affecting the change of fish community are fishing,management and treatment on water environment,destruction on bank habitat,pollution from local water and the potential biological invasion.