Study On The Biodiversity Of Aquatic Organisms And Fish Productivity In Dahuofang Reservoir

In this paper, water quality, aquatic biodiversity and fish productivity in Dahuofang reservoir were studied from May 2015 to April 2016. Studies contents included water quality, the structure of aquatic biodiversity, density, biomass, diversity index and fish productivity. The main results are as follows:According to the surface water standard of environment quality, we evaluated drinking and fishing areas safety of Dahuofang reservoir. We found that DO reach the level of Ⅰ standard, TN reach the level of Ⅲ standard in national surface water, TP is higher and exceed the level of Ⅲ standard, and other index reach the level of Ⅱ standard. On the whole, the ecosystem of Dahuofang reservoir was in the state of sub-health, and the water tend to eutrophicated.To investigate the community structure of plankton in Dahuofang reservoir. A total phytoplankton of 159 species, 86 genera 7 phyla were found in the survey area. The Chlorophyta 40 genera 75 species, occupied 47.17%; and Baeillariophta 22 genera 46 species, occupied 28.93%; Cyanophyta 10 genera 17 species,occupied 10.69%; Pyrrophyta 4 genera 6 species, occupied 3.77%; Chrysophyta 4 genera 5 species, occupied 3.14%; Euglenophyta 4 genera 5 species, occupied 3.14%; Crypophyta 2 genera 5 species, occupied 3.14%. The most species is Chlorophyta, and the second is Baeillariophta. A total zooplankton of 168 species were found in the survey area. The Protozoa 37 genera 60 species, occupied 33.90%; Rotifera 37 genera 84 species, occupied 47.46%; Cladocera 11 genera 19 species, occupied 10.73%; Copepoda 12 genera 14 species, occupied 7.91%, Protozoa and Rotifera are dominant, Cladocera and Copepoda are appear few. In total of 50 species of zoobenthos were obtained, belonging to 4 phylum, Arthropoda Tokunayusurika 20 genera 40 species, occupied 80%; Annelid Oligochaeta 4 genera 7 species, occupied 14%; Nemathelminthes Nematoda 1 genera 1 species, occupied 2%; Mallusca Lamnellibranchia 1 genera 2 species, occupied 4%.The average density of phytoplankton was 5.66×106 ind/L in the whole year, and the biomass was 2.03 mg/L. The average of Shannon-Weaner was 2.35(1.63~3.02), and the Pielou was 0.53(0.26~0.75). The average density of zooplankton was 232.89 ind/L in the whole year, and the biomass was 0.349 mg/L. The average of Shannon-Weaner was 2.845(2.356~3.597), and the Pielou was 0.717(0.617~0.875). The average density of zoobenthos was 105.136 ind/m2 in the whole year, and the biomass was 0.4361 mg/m2. The average of Shannon-Weaner was 0.632(0.281~1.021), and the Pielou was 0.302(0.151~0.424). The dominant species of phytoplankton was Cyanophyta, Baeillariophta, Chlorophyta, Crypophyta. The common species are Baccillariophyta Synedra acus, Chroomonas acuta, Cryptomonas ovata,Monoraphidium contortum. The dominant species of zooplankton was Protozoa and Brachionus, the dominance submissiveness is obvious. The common species are Tintinnopsis wangi, Monostyla bulla, Ascomorpha saltans, Polyarthra trigla, Nauplius larva. The dominant species of zoobenthos were Limnodrilus uderemianus, Limnodrilus claparedianus and Limnodrilus helveticus.Using two methods to estimate fish productivity assessment in this paper, Fish productivity assessment was 0.950×106 kg in feedstuff way, and 0.753×106 kg in energy way, and the annual average fish productivity assessment was 0.852×106 kg.The research showed that plankton and zoobenthos diversity are closely related to water quality, community structure is influenced by water environment. At the same time, phytoplankton community structure intimately affect zooplankton. Water division project influenced the aquatic community structure stability and fish productivity.