Research Of Fish Resources In Yuanxiejing,a Tributary Of The Upper Huangpu River

The Huangpu River is the last tributary of the lower reaches of the Yangtze River before it enters the East China Sea.The water quality of the upper reaches obviously restricts the water environment of the main stream of the Huangpu River.The upper reaches of the Huangpu River are mainly divided into three branches:the northern branch is the slope pond from the Taihu Lake Basin,the middle branch is the Yuanxiejing from the Hongqi Tang in Zhejiang Province,and the southern branch is the Dasi Port from the Shanghai Tang in Zhejiang Province.Domestic research on the quality of upstream incoming water is focused on the sloping ponds of Jiangsu,while Yuanxiejing occupies a dominant position in the discharge volume before the opening of Taipu River,so it is of great significance to study Yuanxiejing.With the increase of population and the rapid development of economy,rivers and lakes in China are generally polluted.The slight deterioration of the aquatic ecological environment leads to the decline of fishery production such as fish and shrimp in the water body,and the serious one leads to the death of fish and shrimp and endangerment of species.Therefore,in order to understand the water quality and fish resources in the economically developed areas,Yuanxiejing waters in the upper reaches of the Huangpu River were selected for the research.1.In order to understand the present situation of water environment in Yuanxiejing,15 indicators such as TN,TP,NH₄⁺-N,DO and pH were selected monthly from 2016 to 2018.Single factor analysis of variance?ANVOA?was carried out in terms of annual trend and seasonal variation.Indicators DO,TN,TP and NH₄⁺-N were evaluated by single factor index and comprehensive pollution index.?1?Seasonal variation of water temperature and dissolved oxygen is obvious in terms of season.Water temperature in winter is significantly lower than that in other three seasons?p<0.05?,and dissolved oxygen content in winter is significantly higher than that in other three seasons?p<0.05?.The seasonal variation of other indicators is not obvious.?2?The indicators in 2016 were higher than those in 2017 and 2018 in terms of years especially,in spring and summer of 2016.Transparency,pH value,nitrogen and phosphorus concentration were significantly higher than those in 2017 and 2018?p<0.05?.?3?By single factor evaluation method,the DO content index of this water area is in the surface I-IV level,the NH₄⁺-N concentration can basically reach the level III-IV water standard,the TP concentration is between the level III-IV,the TN concentration can not reach the V level water standard,and it is in the inferior V level water for a long time.?4?The water quality comprehensive pollution index evaluation method shows that the pollution status in this area is far beyond the limit of heavy pollution P?P>2?,and the single pollution index?P_i?NH₄⁺-N and TN are seriously beyond the standard.2.In order to understand the structural characteristics of fish resources in Yuanxiejing waters,a tributary of the upper Huangpu River,fish samples were collected from 2016 to 2017 using ground cage nets.Relative abundance?RD?,Shannon-Weiner diversity index?H??,Simpson dominance index?D?,Margalef richness index?d?and relative rare species index?R?were used to study the composition of fish structure in the waters.Seasonal variation of fish diversity was analyzed by standard analysis.In order to understand the difference of sexual morphological characteristics among three dominant species of Megalobramidae?Mackerel,Mackerel and Mackerel?,the main characteristics of body length,body weight,body height,head length,tail stalk length and tail stalk height were selected and analyzed by Duncan multiple comparison.?1?From 2016 to 2017,40 species of fish belonging to 13 families and 6 orders were captured in the waters,mainly Cyprinidae,accounting for more than 60%of the total species.The dominant species were small fish such as Carassius auratus,Pseudorasbora parva,Abbottina rivularis,hemiculter leucisculus and Rhodeus light.?2?There were significant seasonal differences Shannon-Weiner diversity index?H??and Margalef richness index?d?between 2016 and 2017?p<0.05?,and the indexs of summer was significantly higher than the other three seasons?p<0.05?.There was no significant difference in relative rare species?R?between seasons?p>0.05?.?3?The body length and body weight of Rhodeus light,Rhodeus ocellatus and Rhodeus sinensis were significantly higher in males than in females?p<0.05?in this water.?4?There were significant differences between male and female adults in body length/body height,body length/head length,and body length/tail stalk length and body length/tail stalk height ratio?p<0.05?.