Effect Of Shoreline Solidification On Fish And Other Aquatic Communities In The Anqing Section Of The Yangtze River

The Anqing section of the lower reaches of the Yangtze River is about 237 km in length.The whole section is composed of floodplain,sandbar and low terrace,and the water body is rich in organic matter and nutrients.The excellent hydrological conditions and abundant feeding organisms in the Anqing River section provide excellent habitat foundation for aquatic organisms and have always been one of the most important habitats for fishery resources in the lower reaches of the Yangtze River.This paper takes the Yangtze river anqing section as the study area,the Yangtze river natural coastline,masonry shoreline and gravel coast near 3 km waters as the research scope,with fish and benthic and plankton animals as the research object,USES the continuous sampling method on different kinds of coastline waters on the characteristics of fish and other aquatic biological communities system investigation,combined with different coastline of regional water environmental indicators,The effects of shoreline solidification on aquatic communities such as fish were analyzed,and the results were as follows:1.A total of 8474 fish species（348.25kg）,belonging to 6 orders and 12 families,were collected and identified by multi-order gill nets and shrimp cage nets in the survey waters.Among them,53 species,61 species and 56 species of fish were collected from the natural shoreline waters,the masonry shoreline waters and the gravel shoreline waters,respectively.The five species are common dominant in waters of the three shoreline types are Coilia brachygnathus、Parabramis pekinensis、Megalobrama skolkovii、Culter dabryi and Hemiculter bleekeri,There is no endemic species in natural shoreline waters and the endemic dominant species in masonry shoreline waters is Acheilognathus taenianali,The endemic dominant species are Siniperca chuatsi and Saurogobio dabryi along the gravel shoreline.The number of pelagic and migratory fish species in the natural shoreline waters was higher than that in the masonry and gravel shoreline waters,while the number of carnivorous fish species and bottom fish species in the natural shoreline waters was lower than that in the masonry and gravel shoreline waters.2.The overall water quality of the investigated waters is good.According to the annual analysis,there is no significant difference in environmental factors among the three shoreline types of waters（P>0.05）;According to the seasonal analysis,different shoreline types showed different time characteristics.Among the three shoreline types,there were significant differences in the main water environmental factors in each season（P<0.05）.NO₂^-showed no significant difference in the masonry and gravel shoreline waters（P>0.05）,and Chl-a showed no significant difference in the masonry shoreline waters（P>0.05）.The eutrophication degree of water quality was calculated by the Carlson trophic state index method.The results showed that the water along each shoreline type was eutrophication state in winter,and the water in other seasons was medium trophic state.3.A total of 40 benthos were collected and identified in the survey waters,belonging to 16 families,6 classes and 3 phyla,of which 24,21 and 32 species were found in natural shoreline waters,masonry shoreline waters and gravel shoreline waters,respectively.Polypedilum sp,Nephtys sp and Stictochironomus sp were the dominant species in the three shorelines.The dominant species endemic to natural shoreline waters are Spionidae.The endemic dominant species is Teneridrilus mastix in the gravel shoreline waters.4.There were 79 species in 53 genera and 7 phyla of phytoplankton in the surveyed waters,including Cyanophyta,Dinoflagellates,Diatoms,Cryptophyta,Euglesophyta,Chlorophyta,Chrysophyta and Chrysophyta.There are 56 species of natural shoreline water,40 species of masonry shoreline water and 47 species of gravel shoreline water,respectively.There was no significant difference in the species number and average body weight of plankton community between seasons and sample areas（P>0.05）.A total of 44 genera and 63 species of zooplankton were collected and identified,of which33,31 and 36 species were collected from natural shoreland,shoreland and gravel shoreland,respectively.Twelve species of protozoa were collected from natural shoreline waters,masonry shoreline waters and gravel shoreline waters.13 species of rotifers were collected from natural shoreline waters,11 species from masonry shoreline waters and 14 species from gravel shoreline waters,respectively.Four species,three species and six species of Cladoceras were collected from natural shoreline waters,masonry shoreline waters and gravel shoreline waters,respectively.Four species of copepods were collected from natural shoreline waters,three species from masonry shoreline waters and four species from gravel shoreline waters,respectively.5.Combined with the change characteristics of fish and other aquatic communities and the status quo of water environment factors,the results show that the main reason is that shoreline solidification makes the riverbed sediment harden,changes the ecological environment factors of habitat,and further causes the change of fish and other aquatic communities.For example,the reduction of vegetation,the increase of slope,the change of substrate,etc.The reduction of vegetation changed the living conditions of fish communities.The increase of slope will lead to the abnormal increase of plankton community density.Hardened substrates reduce the density and biomass of benthic communities.