Spatial-temporal characteristics of zooplankton community structure and analysis for the impact factors in the Shanmei Reservoir,Fujian Province

Abstract

山美水库既是福建省泉州市饮用水源地，也肩负着为台湾省金门县供水的功能，但春夏季过高的pH值影响了水库水质.为此，从2020年起，调整水库鱼类放养结构和捕捞策略，并研究鱼类群落调控后山美水库浮游动物群落结构的响应及其与环境因子的关系.本研究于2020年和2021年连续两年的1月（冬季）、4月（春季）、7月（夏季）、10月（秋季）调查山美水库21个采样点的浮游动物群落结构和水环境因子.结果共鉴定出浮游动物68属102种，其中轮虫21属41种（40.20%），原生动物32属41种（40.20%），枝角类8属13种（12.75%），桡足类7属7种（6.86%）.2020—2021年山美水库浮游动物平均密度为（1443.05±360.02） ind./L，平均生物量为（1.21±0.27） mg/L，2021年浮游动物密度和生物量显著高于2020年，其中，2021年枝角类和桡足类的密度分别显著高于2020年枝角类和桡足类的密度，2021年库首、库中和库尾区域枝角类生物量显著高于2020年对应区域；2021年桡足类生物量显著高于2020年.春冬季浮游动物群落的优势种主要为原生动物，夏秋季浮游动物群落的优势种主要为轮虫.根据浮游动物密度和生物量评价水体营养状态，夏季山美水库处于中营养状态，春、秋和冬季处于贫营养状态.影响浮游动物群落结构分布的主要环境因子为电导率、水温、溶解氧、硝态氮、透明度和高锰酸盐指数.研究表明调整鱼类放养和捕捞措施提高了浮游动物密度和生物量，基于此提出了通过调整鱼类群落结构改变浮游动物群落结构，进而改善水环境的建议，可为湖泊水库水环境保护和水生生物资源高效利用提供科学依据.;The Shanmei Reservoir is the drinking water source of Quanzhou City, Fujian Province, and it also provides water to Jinmen County, Taiwan Province. However, high pH in spring and summer in the reservoir affects water quality. Therefore, from 2020 on, we studied the response of zooplankton community structure to fish assemblage regulation by manipulating fish stocking and capture strategy and its relationship with environmental factors in the Shanmei Reservoir. Zooplankton community and environmental factors were seasonally investigated in January (winter), April (spring), July (summer), and October (autumn) for two years in 2020 and 2021. A total of 102 species were identified, belonging to 68 genera, including 41 Rotifera species (40.20%), 41 Protozoa species (40.20%), 7 Copepoda species (6.86%), and 13 Cladocera species (12.75%). The average density of zooplankton in the eight seasons was (1443.05±360.02) ind./L and the average biomass was (1.21±0.27) mg/L. The density and biomass of zooplankton in 2021 were significantly higher than those in 2020. Specifically, the density and biomass of cladocerans and copepods in 2021 were significantly higher than that in 2020. The biomass of cladocerans in the lower, middle, and upper sections of the reservoir in 2021 was significantly higher than that in the corresponding area in 2020. The dominant species of the zooplankton community were protozoa in spring and winter, and rotifers in summer and autumn. Based on the zooplankton density and biomass, the water quality of the Shanmei Reservoir was classified as a mesotrophic state in summer and an oligotrophic state in other seasons. The main environmental factors affecting the zooplankton community structure were electrical conductivity, water temperature, dissolved oxygen, nitrate-nitrogen, transparency and permanganate index. Our results indicated that manipulation of fish assemblage structure increased the density and biomass of zooplankton in the Shanmei Reservoir. Based on this, we proposed measures to change the zooplankton community structure by manipulating fish assemblage structure for improving water quality, which could provide scientific grounds for environment protection and efficient aquatic bio-resources utilization in lakes and reservoirs.