Temporal And Spatial Variations Of Fish Diversity In Sub-lakes Littoral Zone Of Jiangxi Poyang Lake National Reserve

As a subtropical floodplain ecosystem,the Yangtze River floodplain is one of the most important ecosystem in China,as well as in the world.At present,Poyang Lake is one of the three existing lakes that connected to the main stem of Yangtze River.However,fishes in Poyang Lake is facing multiple threats,such as overfishing,sand overmining,water pollution,and unusually low water levels in dry seasons because of flow regulations by upstream reservoirs and climate changes.A full recognition of the value of these lakes for sustaining biodiversity is critical for the implement of management strategies for the strongly human-disturbed Yangtze River ecosystem.In order to reveal the temporal and spatial patterns of fish diversity and the main environmental factors affecting the spatial and temporal pattern of sub-lakes,this study was carried out in the sub-lakes in Poyang Lake National Nature Reserve,Jiangxi Province,the diversity of fish in the littoral zone of the sub-lakes was investigated and analyzed.The main findings are as follows:(1)An investigation was carried out in three sub-lakes(Banghu,Dahuchi,Shahu),in July 2015,October,December and April 2016,totally 37 fish species were collected,belonging to 7 orders,11 families,and 31 genera,the largest group was from Cypriniformes(62.16%),the dominant species(IRI>100)were Hemiculter leucisculus,Carassius auratus,Rhodeus lighti,Xenocypris macrolepis,Pseudobrama simony,.Pseudorasbora parva,Botia superciliaris and Rhinogobius giurinus.Significant differences in fish species diversity between seasons and sub-lakes.The main environmental factors influencing the seasonal distribution of fish community structure are vegetation cover area,conductivity,dissolved oxygen and water level.(2)An investigation was carried out in nine sub-lakes,in July,October 2014 and July,October 2015,totally 43 fish species were collected,belonging to 5 orders,13 families,and 36 genera,the largest group was form Cypriniformes(60.47%),the dominant species(IRI>300)were Mylopharyngodon piceus,Ctenopharyngodon idella,Hemiculter leucisculus,Carassius auratus,and Rhinogobius giurinus.Significant difference in the diversity of fish between the interannual and the sub-lake.The main environmental factors that affect the interannual distribution of fish community structure are: sub-lake area,water level,water temperature,sampling point water depth.