| Zooplankton can respond quickly to changes in water environment,and seasonal dynamics of their community structure are affected by environmental factors.In Huaibei city,Anhui province,many small closed lakes are formed after coal mining collapsed,and coal gangue and fly ash are filled in lake sediments.Because the main functions in lakes are different,the characteristic of each lake is quite different.From August 2020 to September 2021,seasonal variations of zooplankton community structure were studied in three coal mining collapsed lakes in Huaibei city(LakeNanhu,Lake Donghu and Lake Qianlong),and the relationships between zooplankton and physi-chemical factors were analyzed.Our results will reveal the main environmental factors in three coal mining collapsed lakes affecting the community structure and succession of zooplankton,and provide theoretical basis for ecological management and environmental restoration of coal mining collapsed lakes.The main results are as follows:1.In the three coal mining collapsed lakes,the community structures of crustacean zooplankton have all obvious seasonal variations,and the differences among lakes are also obvious.Diaphanosoma brachyurum and Mesocyclops leuckarti were dominant species in the three lakes in summer and autumn.The density and biomass of crustacean zooplankton in different seasons had significant differences between Lake Nanhu and Lake Qianlong(P<0.05).In Lake Nanhu,15 species of crustacean zooplankton are identified,among which 7 species belong to 6 genera in cladocera and 8 species belong to 7 genera in copepods.The density and biomass of crustacean zooplankton varied from 0.7-16.8 ind·L-1 and 0.03-0.521 mg·L-1,with an average of 3.9 ind·L-1 and 0.141mg·L-1,respectively.Daphnia galeata and Sinocalanas dorrii were dominant species in winter and spring,which were positively correlated with dissolved oxygen.Moina micrura and Schmackeria forbesi were also dominant species in summer and autumn.In Lake Qianlong,11 species of crustacean zooplankton were recorded,among which5 species belong to 5 genera in cladocera and 6 species belong to 4 genera in copepods.The density and biomass of crustacean zooplankton varied from 1.3-85.6 ind·L-1 and0.039-2.443 mg·L-1,with the mean values of 22.6 ind·L-1 and 0.664 mg·L-1,respectively.In Lake Donghu,11 species of crustacean zooplankton were recorded,among which 4 species belong to 4 genera in cladocera and 7 species belong to 6 genera in copepods.The density and biomass of crustacean zooplankton varied from 0.01-28.9ind·L-1 and 0.0003-0.844 mg·L-1,with an average of 4.4 ind·L-1 and 0.126 mg·L-1,respectively.Bosmina sp.was also the dominant species in Lake Donghu in summer and autumn.The density of S.dorrii was low during the sampling period.Our results suggested that water temperature was the main factor affecting the seasonal variation of crustacean zooplankton community structure in the three coal mining collapsed lakes.Secchi depth and phosphate were important factors affecting crustacean zooplankton in Lake Nanhu,nitrate nitrogen and chlorophyll-a were important factors in Lake Qianlong,and secchi depth and chlorophyll-a were important factors in Lake Donghu.2.There were significant differences on rotifer density,biomass and dominant species in the three coal mining collapsed lakes.A total of 26 species belong to 15genera in rotifer were recorded in Lake Nanhu.The density and biomass of rotifer varied from 0.6-682 ind·L-1 and 0.0002-0.295 mg·L-1,with an average of 132.5 ind·L-1 and 0.073 mg·L-1,respectively.Polyarthra trigla was correlated with phosphorus concentrations.A total of 28 species belong to 18 genera in rotifer were recorded in Lake Qianlong,and their densities and biomass varied from 13.3-5620 ind·L-1 and0.003-2.868 mg·L-1,with an average of 1835.5 ind·L-1 and 0.884 mg·L-1,respectively.P.trigla was negatively correlated with dissolved oxygen and chlorophyll-a.Both Trichcerca pusilla and Keratella valga were negatively correlated with nitrate nitrogen.In Lake Donghu,a total of 24 species belong to 17 genera in rotifer were recorded.The density and biomass of rotifer varied from 1183.3-16123.3 ind·L-1 and 0.582-5.167mg·L-1,with an average of 6219.2 ind·L-1 and 2.412 mg·L-1,respectively.P.trigla,T.pusilla and Brachionus angularis were all positively correlated with nitrate nitrogen,but they were negatively correlated with water temperature.Philodina erythrophthalma were positively correlated with chlorophyll-a but negatively correlated with secchi depth.Both density and biomass of rotifer in different seasons were all significantly differences between Lake Nanhu and Lake Qianlong(P<0.05).3.Based on the evaluation standard of water trophic status,the trophic status of Lake Nanhu,Lake Qianlong and Lake Donghu were mesotrophy to light eutrophication,light eutrophication and light to medium eutrophication,respectively.Based on the Margalef richness index,the pollution levels of Lake Nanhu,Lake Qianlong and Lake Donghu were clean,moderately polluted and moderately polluted,respectively.Compared with the previous investigations,the community structure,density and biomass of zooplankton varied in Lake Nanhu and Lake Qianlong.In addition,fisheries aquaculture affected the seasonal variation of zooplankton community structure and dominant species in the three coal mining collapsed lakes.In conclusion,water temperature,secchi depth,chlorophyll-a and nutrient were the main factors affecting zooplankton community structure in the three coal mining collapsed lakes in Huaibei city.Human activities such as fisheries aquaculture were important factors influencing the seasonal variation of zooplankton community structure and water quality difference in the three coal mining collapsed lakes. |
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