How does eutrophication affect the role of grazers in harmful algal bloom dynamics?
How does eutrophication affect the role of grazers in harmful algal bloom dynamics?
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DOI：
10.1016/j.hal.2008.08.009
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发表时间：
2008-12-01
期刊：
影响因子：
6.6
通讯作者：
Buskey, Edward J.
中科院分区：
文献类型：
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作者：
Buskey, Edward J.
有害藻华物种的种群动态既受到影响其生长速率的因素“自下而上”的调节，又受到影响其损失率的因素“自上而下”的调节。虽然似乎很明显，富营养化对影响浮游植物生长速度的因素（养分供应、光照可用性）影响最大，但在有害水华动态研究中，不能忽视包括食草动物和病原体在内的自上而下控制的作用。浮游植物和浮游动物种群生长之间的滞后，或不利环境条件对浮游动物种群的破坏，可能是富营养化条件下浮游生物大量繁殖的重要因素。避免捕食有害物种并积极捕食竞争物种的食草动物也可能在水华萌芽中发挥重要作用。不受浮游植物毒素影响且生长速度与浮游植物相当的食草动物（例如原生食草动物）可能具有控制水华发生的潜力。如果对食草动物的抑制随有毒浮游植物水华的细胞密度而变化，则富营养化可能会增加水华达到食草动物抑制阈值密度的机会。此外，富营养化的二次影响，包括缺氧和 pH 值变化，可能会对食草动物种群产生不利影响，并进一步使 HAB 物种脱离自上而下的控制。德克萨斯州褐潮（Aureoumbra lagunensis）水华为食草动物破坏在水华起始中的作用以及高密度褐潮细胞在持续抑制食草动物中的重要性提供了证据。 (C) 2008 Elsevier B.V. 保留所有权利。
Population dynamics of harmful algal bloom species are regulated both from the "bottom-up" by factors that affect their growth rate and from the "top-down" by factors that affect their loss rates. While it might seem apparent that eutrophication would have the greatest impact on factors affecting growth rates of phytoplankton (nutrient supply, light availability) the roles of top-down controls, including grazers and pathogens, cannot be ignored in studies of harmful bloom dynamics. Lags between the growth of phytoplankton and zooplankton populations, or disruption of zooplankton populations by adverse environmental conditions may be important factors in the initiation of plankton blooms under eutrophic conditions. Grazers that avoid feeding on harmful species and actively graze on competing species may also play important roles in bloom initiation. Grazers that are not affected by phytoplankton toxins and have growth rates comparable to phytoplankton (e.g. protozoan grazers) may have the potential to control the initiation of blooms. If the inhibition of grazers varies with cell density for blooms of toxic phytoplankton, eutrophication may increase the chances of blooms reaching threshold densities for grazer inhibition. In addition, secondary effects of eutrophication, including hypoxia and change in pH may adversely affect grazer populations, and further release HAB species from top-down control. The Texas brown tide (Aureoumbra lagunensis) blooms provide evidence for the role of grazer disruption in bloom initiation and the importance of high densities of brown tide cells in continued suppression of grazers. (C) 2008 Elsevier B.V. All rights reserved.