Quality evaluation and characteristics of the ecological environment of the fisheries in Songhua River

The paper is mainly concerned with the quality evaluation and characteristics of the ecological environment of the fisheries in Songhua River,which is the number-one major tributary of Heilongjiang River. Through 23 monitoring sections in the trunk stream of Songhua River,it would be possible for us to get access to the data of physical and chemical factors,according to the plankton investigation and analysis,and the three types of surface water and fishery water quality standards stipulated by the state environmental departments,our evaluation of the fishery ecological environment characteristics and Songhua River water quality has been done by using the comprehensive evaluation index(P),the organic pollution comprehensive evaluation index(A) and the biodiversity index(H) in an integrated way. The results of our investigation and evaluation show that the frozen season is an ecologically fragile period for fishing in the river area,and the water quality has been significantly improved as a result of the decades' management and sewage treatment and separation. The water permanganate index in the branch streams of the river is below 5. 0mg / L on the average,with the biochemical oxygen demand being below 4. 0 mg / L and the average dissolved oxygen mass concentration being over 8. 0 mg / L on the whole. Statistical analysis shows that there are 102 species of phytoplanktons with almost47% being the bacillariophyta. The zooplankton includes rotifers,cladoceras,copepods and protozoa,with the rotifers occupying almost 57. 6% of the total. More specifically speaking,P value of the water is 1. 05,whereas A value is 1. 25,with the value of phytoplankton biodiversity index H being 2. 48,that of the zooplankton biodiversity index H being 1. 58,which can be on the whole considered to be contaminated from the moderate pollution grade to that of the light pollution. Thus,it can be thought that ecological environment of the fishery and the fish resources are under the stage being gradually recovered,meanwhile the biological diversity in under-noticeable increase. Hence,the improvement of the water quality in the river reach should help to provide important conditions for the growth and reproduction of the fish.