Abstract：
Phytoplankton communities are major primary producers in the aquatic realm and are responsible for shaping aquatic ecosystems. The dynamics of algal blooms could be determined by a succession of variable taxonomic groups, which are altered based on complex environmental factors such as nutrient availability and hydraulic factors. In-river structures potentially increase the occurrence of harmful algal blooms (HABs) by increasing water residence time and deteriorating water quality. How flowing water stimulates cell growth and affects the population dynamics of phytoplankton communities is a prioritized question that needs to be addressed for water management tactics. The goal of this study was to determine if an interaction between water flow and water chemistry is present, furthermore, to determine the relationship among phytoplankton community successions in the Caloosahatchee River, a subtropical river strongly influenced by human-controlled water discharge patterns from Lake Okeechobee. Particularly we focused on how phytoplankton community shifts influence the natural abundance of hydrogen peroxide, the most stable reactive oxygen species and a byproduct of oxidative photosynthesis. High-throughput amplicon sequencing using universal primers amplify 23S rRNA gene in cyanobacteria and eukaryotic algal plastids revealed that Synechococcus and Cyanobium were the dominant cyanobacterial genera and their relative abundance ranged between 19.5 and 95.3% of the whole community throughout the monitoring period. Their relative abundance declined when the water discharge increased. On the contrary, the relative abundance of eukaryotic algae sharply increased after water discharge increased. As water temperature increased in May, initially dominant Dolichospermum decreased as Microcystis increased. When Microcystis declined other filamentous cyanobacteria such as Geitlerinema, Pseudanabaena, and Prochlorothreix increased in their relative abundances. Interestingly, a peak of extracellular hydrogen peroxide was observed when Dolichospermum dominance was ended, and M. aeruginosa numbers increased. Overall, phytoplankton communities were strongly impacted by human-induced water discharge patterns.
摘要：
浮游植物群落是水生领域的主要初级生产者，并负责塑造水生生态系统。藻类的动态可以由一系列可变的分类群决定，这些变化是基于复杂的环境因素，如养分利用率和水力因素。河内结构可能会增加水的停留时间和水质恶化，从而增加有害藻华（HAB）的发生。流动的水如何刺激细胞生长并影响浮游植物群落的种群动态是水管理策略需要解决的优先问题。这项研究的目的是确定水流和水化学之间是否存在相互作用，此外，为了确定卡洛萨奇河浮游植物群落演替之间的关系，受人类控制的奥基乔比湖排水模式影响很大的亚热带河流。特别是我们关注的是浮游植物群落的变化如何影响过氧化氢的自然丰度，最稳定的活性氧和氧化光合作用的副产物。使用通用引物进行高通量扩增子测序，扩增蓝藻和真核藻类质体中的23SrRNA基因，结果表明，在整个监测期间，蓝藻和蓝藻是主要的蓝藻属，它们的相对丰度在整个群落的19.5％至95.3％之间。当排水量增加时，它们的相对丰度下降。相反,水排放量增加后，真核藻类的相对丰度急剧增加。随着五月水温的升高，最初占优势的Dolichospermum随着微囊藻的增加而减少。当微囊藻减少其他丝状蓝细菌如Geitlerinema时，假单胞菌,和Prochlothreix的相对丰度增加。有趣的是,当Dolichospermum优势结束时，观察到细胞外过氧化氢的峰值，铜绿假单胞菌数量增加。总的来说,浮游植物群落受到人为排水模式的强烈影响。
