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Environmental factors controlling phytoplankton dynamics in a large floodplain river with emphasis on cyanobacteria
River Research and Applications ( IF 2.2 ) Pub Date : 2020-07-06 , DOI: 10.1002/rra.3658
Shawn M. Giblin 1 , Gretchen A. Gerrish 2
Affiliation  

Harmful algal blooms are occurring in large river ecosystems and at the mouth of large rivers with increasing frequency. In lentic systems, the chemical and physical conditions that promote harmful algal blooms are somewhat predictable but tracking prevalence and conditions that promote harmful algal blooms in lotic systems is much more difficult. We captured two of the most extreme discharge years within the last 20 years occurring in the Upper Mississippi River, allowing a natural experiment that evaluated how major shifts in discharge drive environmental variation and associated shifts in phytoplankton. Statistical models describing significant environmental covariates for phytoplankton assemblages and specific taxa were developed and used to identify management‐relevant numeric breakpoints at which environmental variables may promote the growth of specific phytoplankton and/or cyanobacteria. Our analyses supported that potentially toxin‐producing cyanobacteria dominate under high phosphorus concentration, low nitrogen concentration, low nitrogen‐to‐phosphorus ratio, low turbulence, low flushing, adequate light and warm temperatures. Cyanobacteria dominated in 2009 when low discharge and low flushing likely led to optimal growth environments for Dolichospermum, Aphanizomenon and Microcystis. Rarely will a single factor lead to the dominance, but multiple positive factors working in concert can lead to cyanobacteria proliferation in large rivers. Certain isolated backwaters with high phosphorus, low nitrogen, warm water temperatures and low potential for flushing could benefit from increased connection to channel inputs to reduce cyanobacterial dominance. Numerous examples of this type of habitat currently exist in the Upper Mississippi River and could benefit from reconnection to channel habitats.

中文翻译:

控制大型泛滥河中浮游植物动态的环境因素,重点是蓝细菌

大型河流生态系统和大型河流口中有害藻华的发生频率越来越高。在透镜系统中,促进有害藻华大量繁殖的化学和物理条件在某种程度上是可以预测的,但要追踪在抽水系统中促进有害藻华大量繁殖的条件和条件要困难得多。我们捕获了过去20年中密西西比河上游发生的两个最极端的排放年,从而进行了一项自然实验,评估了排放的主要变化如何驱动环境变化以及浮游植物的相关变化。建立了描述浮游植物组合和特定类群的重要环境协变量的统计模型,并将其用于识别与管理相关的数字断点,环境变量可能会在这些断点处促进特定浮游植物和/或蓝藻的生长。我们的分析表明,在高磷浓度,低氮浓度,低氮磷比,低湍流,低潮气,充足的光照和温暖温度下,可能产生毒素的蓝细菌占主导地位。蓝藻在2009年占据主导地位,低排放和低冲洗可能导致最佳的生长环境。低氮磷比,低湍流,低冲洗,充足的光照和温暖的温度。蓝藻在2009年占据主导地位,低排放和低冲洗可能导致最佳的生长环境。低氮磷比,低湍流,低冲洗,充足的光照和温暖的温度。蓝藻在2009年占据主导地位,低排放和低冲洗可能导致最佳的生长环境。多孢子Aphanizomenon微囊藻。很少有因素会导致主导地位,但多个积极因素共同作用会导致大型河流中的蓝细菌繁殖。某些隔离的死水具有高磷,低氮,温水温度和低冲水潜力,可受益于与通道输入的连接增加,以减少蓝藻的优势。密西西比河上游目前存在许多此类生境的例子,可以从重新连接到河道生境中受益。
更新日期:2020-07-06
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