Abstract：
Cyanobacteria can reach high densities in eutrophic lakes, which may cause problems due to their potential toxin production. Several methods are in use to prevent, control or mitigate harmful cyanobacterial blooms. Treatment of blooms with low concentrations of hydrogen peroxide (H2O2) is a promising emergency method. However, effects of H2O2 on cyanobacteria, eukaryotic phytoplankton and zooplankton have mainly been studied in controlled cultures and mesocosm experiments, while much less is known about the effectiveness and potential side effects of H2O2 treatments on entire lake ecosystems. In this study, we report on three different lakes in the Netherlands that were treated with average H2O2 concentrations ranging from 2 to 5 mg L-1 to suppress cyanobacterial blooms. Effects on phytoplankton and zooplankton communities, on cyanotoxin concentrations, and on nutrient availability in the lakes were assessed. After every H2O2 treatment, cyanobacteria drastically declined, sometimes by more than 99%, although blooms of Dolichospermum sp., Aphanizomenon sp., and Planktothrix rubescens were more strongly suppressed than a Planktothrix agardhii bloom. Eukaryotic phytoplankton were not significantly affected by the H2O2 additions and had an initial advantage over cyanobacteria after the treatment, when ample nutrients and light were available. In all three lakes, a new cyanobacterial bloom developed within several weeks after the first H2O2 treatment, and in two lakes a second H2O2 treatment was therefore applied to again suppress the cyanobacterial population. Rotifers strongly declined after most H2O2 treatments except when the H2O2 concentration was ≤ 2 mg L-1, whereas cladocerans were only mildly affected and copepods were least impacted by the added H2O2. In response to the treatments, the cyanotoxins microcystins and anabaenopeptins were released from the cells into the water column, but disappeared after a few days. We conclude that lake treatments with low concentrations of H2O2 can be a successful tool to suppress harmful cyanobacterial blooms, but may negatively affect some of the zooplankton taxa in lakes. We advise pre-tests prior to the treatment of lakes to define optimal treatment concentrations that kill the majority of the cyanobacteria and to minimize potential side effects on non-target organisms. In some cases, the pre-tests may discourage treatment of the lake.
摘要：
蓝藻在富营养化湖泊中可以达到很高的密度，这可能会导致问题，由于其潜在的毒素生产。几种方法正在使用，以防止，控制或减轻有害的蓝藻水华。用低浓度的过氧化氢（H2O2）处理水华是一种有前途的应急方法。然而,H2O2对蓝藻的影响，真核浮游植物和浮游动物主要在受控培养和中观实验中进行了研究，尽管人们对H2O2处理对整个湖泊生态系统的有效性和潜在副作用知之甚少。在这项研究中,我们报道了荷兰的三个不同湖泊，这些湖泊用平均H2O2浓度从2到5mgL-1进行处理以抑制蓝藻水华。对浮游植物和浮游动物群落的影响，关于氰毒素浓度，并对湖泊中的养分利用率进行了评估。每次H2O2处理后，蓝细菌急剧下降，有时超过99%，虽然Dolichospermumsp.的花朵。,Aphanizomenonsp.,和planktothrixrubescens比planktothrixagardhii开花受到更强烈的抑制。真核浮游植物没有受到H2O2添加的显着影响，并且在处理后比蓝细菌具有初始优势，当充足的营养和光线可用时。在所有三个湖泊中，第一次H2O2治疗后几周内出现了新的蓝藻水华，因此，在两个湖泊中进行了第二次H2O2处理，以再次抑制蓝细菌种群。除H2O2浓度≤2mgL-1外，在大多数H2O2处理后，轮虫都强烈下降，而枝节角类仅受到轻度影响，co足类受添加的H2O2的影响最小。为了应对治疗，氰毒素微囊藻毒素和Anabaenoptin从细胞中释放到水柱中，但几天后就消失了.我们得出的结论是，低浓度H2O2的湖泊处理可以成为抑制有害蓝藻水华的成功工具，但可能会对湖泊中的一些浮游动物类群产生负面影响。我们建议在湖泊处理之前进行预测试，以确定杀死大多数蓝细菌的最佳处理浓度，并最大程度地减少对非目标生物的潜在副作用。在某些情况下,预测试可能会阻碍对湖泊的处理。
