| By investigating fish,phytoplankton,zooplankton and zoobenthos in 4 Section 7 monitoring points in the Yangtze River in Jiangsu Province during 2004 to 2005,to research of the hydrobiology in this section,the specific results are summarized as follows:1 Fish Composition and Dominant Species in the Yangtze River in Jiangsu ProvinceThe survey showed that 109 fish species representing 15 orders(32 families)in the Yangtze River in Jiangsu Province,and two new species and two new-province-record species were found.The Cyprinidae consisting of 48 species is the largest family in the number of species,accounting for 44.04%;the Cobitidae and the Bagridae consists of 7 species respectively,accounting for 6.42%;the Gobiidae consists of 6 species,accounts for 5.50%;the Serranidae consisting of 5 species,accouts for 4.25%;the Salangidae and the Eleotridae consist of 3 species respectively,accounting for 2.75%;the Engraulinae,the Siluridae,the Mugilidae,the Periophthalmidae and the Taenioididae consist of 2 species respectively,accounting for 1.83%;for the remains,20 families were represented by one species respectively.The dominant species in the Yangtze River in Jiangsu Province are Hemiculter leucisculus(Basilewsky),Carassius auratus auratus(Linnaeus),Parabramis pekinensis(Basilewsky),Cyprinus capio Linnaeus,Coilia nasus Schlegel,Hemiculter bleekeri Warpachowsky,Pseudobrama simony(Bleeker),Callionymus olidus Gunther, Hypophthalmichthys molitrix(Valenciennes),Ctenopharyngodon idellus(Valenciennes), and the mean weight of the dominant species is 0.974～292.431g.And the fish resources tend to be young in age and miniaturized in size.Combining monitoring data with historical data of fish in the Yangtze River in Jiangsu Province in the period of 2001～2005,it is concluded that there are 162 species of fish(19 orders)in the Yangtze River in Jiangsu Province.2 The Community Character of Phytoplankton in the Yangtze River in Jiangsu ProvinceDuring the flood period,usual dischange period,drought period of the Yangtze River in Jiangsu Province from September in 2004 to March in 2005,168 species(including undetermined species),96genus,10phylum phytoplankton were checked out.The phylum Chlorophyta contained 64 species,accounting for 38.10%;Bacillariophyta contained 58 species,accounting for 34.52%;Cyanophyta contained 25 species,accounting for 14.88%;Euglenophyta contained 8 species,accounting for 4.76%;Xanthophyta contained 5 species,accounting for 2.98%;Chrysophyta contained 3 species,accounting for 1.79%;Pyrrophyta contained 2 species,accounting for 1.19%;Rhodophyta, Cryptophyta and Charophyta contained 1 species,respectively,accounting for 0.60%.The dominant genus were Melosira,Oscilatoria,Fragilaria and Ankistrodesmus in the flood period;Melosira,Oscilatoria,Fragilaria,Microspora and Coscinodiscus in the usual dischange period;Asterionella,Closterium,Melosira and Fragilaria in the drought period.The density of phytoplankton was maximal in the drought period in each segment, and minimal in the flood period.3 The Community Character of Zooplankton in the Yangtze River in Jiangsu Province.By investigating the community structure of the zooplankton in the Yangtze River in Jiangsu Province during September of in 2004 to March of 2005,the result enunciates that are 108 species of zooplankton in the segment,the rotifera is the maximal group,having 45 spcies,accounting 41.66%.Protozoa are 12 species,accounting for 11.11%;cladocera are 25 species,accounting for 23.14%;copepoda are 26 species.The average density of zooplankton is 47.96 ind/L,mainly be composed by rotifera.The dominant genus are: Brachionusa,Filinia,Keratella,Asplanchna;Bosmina,Diaphanosoma;Eucyclops,thermocyclops,Schmackeria and so on.4 The Status of Zoobenthos Community Structure and Preliminary Evaluation of Water Quality in the Yangtze River in Jiangsu ProvinceBy investigate the zoobenthos in the Yangtze River in Jiangsu Province during September of in 2004 to March 2005,58 species of zoobenthos were found out,including 12 species of Annelida,16 species of Mollusca and 30 species of Arthropoda;The average density of the zoobenthos in the Yangtze River in Jiangsu Province was 95.03 ind/m~2.The density was 115.74 ind/m~2 in flood period,127.07 ind/m~2 in usual dischange period,and 42.27ind/m~2 in drought period,respectively.The dominant species were Tubifex sinicus, Oncomelania sp.,Nereis japonica,Corbicula flurninea and Branchiura sowerbyi.The Shannon-Wiener species diversity index of the Jiangsu section was 3.281.It could be overall evaluated that the average water quality in the Jiangsu section was slightly polluted. |
