Research On Macrobenthic Community Structure In 11 Reservoirs In Zaoyang County

Macrobenthos are important ecological taxa in water ecosystems,which play a very important role in the material circulation and energy flow in water ecosystems,and also play an important role in water quality monitoring and evaluation.In this study,the macrobenthos community structure in 11 reservoirs including Huayanghe Reservoir,Xihe Reservoir,Dahuanghe Reservoir,Jihe Reservoir,Zhouqiao Reservoir,Luoqiao reservoir,Liuqiao reservoir,Gaoan reservoir,Zishan reservoir,Qingtan reservoir and Renhezhai Reservoir in Zayang County were investigated and analyzed in July 2022,December2022 and March 2023,respectively.Combined with physicochemical parameters and macrobenthos data,the water quality was evaluated comprehensively,and the internal relationship between them was explored.At the same time,the potential fish productivity of these reservoirs was estimated according to the standing stock of macrobenthos,which aimed to providing theoretical guidance for optimizing the stocking structure of the 11reservoirs,rational and effective utilization of fishery resources,and scientific basis for the development of ecological fishery in reservoirs in Zaoyang County.The results are as follows:1.During the survey period,a total of 4572 macrobenthos individuals were collected in the three hydrological periods,including 30 species,belonging to three phyla,four classes,six orders and 12 families.Aquatic insects accounted for 50.00%of the total species,respectively.The number of species and individual of macrobenthos presented no significant difference in different water periods,but exihibted significant differences among different reservoirs.2.The dominant taxa composition was different in different water periods,and the dominant taxa in wet periods were Lumbriculus,Limnodrilus,Microchironomus and Tanypus.The dominant taxa in dry season were Lumbriculus,Microchironomids,Tanypus,and Propsilocerus.The dominant taxa in normal water period were Lumbriculus,Tanypus,Tubifex and Cryptotendipes.In addition,annelid species also had high dominance in each reservoir.3.In wet season,the average total density and biomass of macrobenthos in the 11reservoirs were 369.1152 ind./m²and 1.3872 g/m²,respectively.In dry season,the average total density and biomass of macrobenthos in the 11 reservoirs were 567.0788ind./m²and 2.8259 g/m²,respectively.In normal water period,the average total density and biomass of macrobenthos in the reservoirs were 1067.2808 ind./m²and 7.0732 g/m²,respectively.The density of macrobenthic fauna in each reservoir ranged from 7.1111ind./m²（Zishan Reservoir）to 1694.5778 ind./m²（Luoqiao Reservoir）,and the biomass ranged from 0.1543 g/m²（Zishan Reservoir）to 16.5947 g/m²（Liuqiao Reservoir）.4.Pearson correlation analysis showed that p H,Conductivity,NO₃^--N and COD were the main environmental factors affecting the benthic community structure in the wet period,while p H,temperature,NO₃^--N and COD were the main environmental factors affecting the benthic community structure in the dry period.p H,NO₂^--N,TN and COD are the main environmental factors affecting the benthic community structure in the normal water period.5.RDA analysis showed that TN,TP and p H were the main environmental factors affecting the benthic community in Huayanghe Reservoir.p H,COD and DO were the main environmental factors affecting the benthic community structure in Liuqiao Reservoir.NH₄⁺-N,temperature and water depth were the main environmental factors affecting the benthic community structure in Qingtan Reservoir.NH₄⁺-N,water depth and TN were the main environmental factors affecting the benthic community structure in Renhezhai Reservoir.NO₃^--N and TN were the main environmental factors affecting the benthic community structure in Luoqiao Reservoir.TP,water depth,TN and p H were the main environmental factors affecting the benthic community structure in Zhouqiao Reservoir.6.The potential fish productivity of each reservoir ranked in the following order:Liuqiao Reservoir（8.8003 kg/hm²）>Luoqiao Reservoir（5.8795 kg/hm²）>Gaoan Reservoir（5.7557 kg/hm²）>Dahuanghe Reservoir（5.5633 kg/hm²）>Zhouqiao Reservoir（4.5595 kg/hm²）>Qingtan Reservoir（3.3930 kg/hm²）>Huayanghe Reservoir（2.2947 kg/hm²）>Xihe Reservoir（1.4706 kg/hm²）>Renhezhai Reservoir（1.3149kg/hm²）>Jihe Reservoir（0.4270 kg/hm²）>Zishan Reservoir（0.2160 kg/hm²）.7.The water quality of Zaoyang reservoirs was evaluated by using Shannon-Wiener diversity index,Pielou evenness index,Margalef richness index and BPI biological pollution index,and these four indexes ranged from 0 to 1.65,0 to 0.98,0 to 1.95 and 0 to4.44,respectively.By comparison,it was found that most of the water bodies in Zaoyang reservoirs were in a state of moderate to heavy pollution.