Bottom-up and top-down effects on codetermination of the dominant phytoplankton functional groups in Lake Erhai

浮游动物牧食、水温及营养可利用性均可影响优势浮游植物功能群的转变,但这些驱动因素的交互作用尚不清楚。为了解云南高原湖泊--洱海浮游植物优势功能群的分布特征及其主要驱动因素,于2018年1月-2020年12月进行月度采样,结合聚类分析、方差分析和冗余分析等,分析驱动浮游植物优势功能群转变的主要因素。结果表明,共鉴定浮游植物7门96属,划分为27个浮游植物功能群,其中优势功能群有15个。聚类分析结果表明,根据浮游植物功能群密度数据可将优势功能群转变过程分为3个由不同类型藻类主导的时期(S期、M期和P期),其中S期(为期18个月)以功能群S1和H1(代表藻为假鱼腥藻、浮丝藻和长孢藻等丝状蓝藻)为主,M期(为期10个月)以功能群M(微囊藻群体)为主,P期(为期8个月)以功能群P和M(脆杆藻和单个微囊藻等)为主。RDA分析及变差分解分析结果表明,卡尔森营养状态指数(TSI)(主要是总磷)是影响以丝状藻类为主的浮游植物功能群的主要驱动因素,TSI和水温是影响以微囊藻为主的浮游植物功能群的重要驱动因素。因此,在富营养化初期湖泊中,降低湖泊营养负荷是首要任务。同时可以考虑增加浮游动物丰度的策略,以增强浮游动物在削减丝状蓝藻或微囊藻生物量(下行效应)中的作用和重要性。;The shift of dominant phytoplankton functional groups (FGs) can be driven by zooplankton grazing, water temperature and nutrient availability, but the interactive effects these driving factors are not well understood. To understand characteristics FGs their major in Lake Erhai, a subtropical highland lake China, monthly sampling was conducted from January 2018 to December 2020. The main were analyzed combining cluster analysis, variance partitioning analysis redundancy respectively. In this study, 7 families 96 genera identified divided into 27 FGs, among which 15 identified. results showed that abundance could classified three periods (S, M P Periods) dominated different types phytoplankton. S Period (which contained 18 months) S1 H1 (representative species filamentous cyanobacteria such as Pseudanabaena sp., Planktothrix Dolichospermum sp.). While Microcystis colonies) high dominance 10 months), Fragilaria sp. individual Microcystis, respectively) during 8 months). Our also confirmed Carlson trophic state index (TSI) (mainly total phosphorus) drivers affecting predominant algae studied lakes, while TSI significant sp.. Therefore, top priority for lakes experiencing early eutrophication is reduce loading. And strategies aimed at increasing considered enhance role importance biomanipulation (top-down effects) or blooms.