Lürling Miquel, van Oosterhout Frank, Faassen Elisabeth
Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 50, 6700 AB, Wageningen, The Netherlands.
Toxins (Basel). 2017 Feb 11;9(2):64. doi: 10.3390/toxins9020064.
Eutrophication and warming are key drivers of cyanobacterial blooms, but their combined effects on microcystin (MC) concentrations are less studied. We tested the hypothesis that warming promotes cyanobacterial abundance in a natural plankton community and that eutrophication enhances cyanobacterial biomass and MC concentrations. We incubated natural seston from a eutrophic pond under normal, high, and extreme temperatures (i.e., 20, 25, and 30 °C) with and without additional nutrients added (eutrophication) mimicking a pulse as could be expected from projected summer storms under climate change. Eutrophication increased algal- and cyanobacterial biomass by 26 and 8 times, respectively, and led to 24 times higher MC concentrations. This effect was augmented with higher temperatures leading to 45 times higher MC concentrations at 25 °C, with 11 times more cyanobacterial chlorophyll- and 25 times more eukaryote algal chlorophyll-. At 30 °C, MC concentrations were 42 times higher, with cyanobacterial chlorophyll- being 17 times and eukaryote algal chlorophyll- being 24 times higher. In contrast, warming alone did not yield more cyanobacteria or MCs, because the in situ community had already depleted the available nutrient pool. MC per potential MC producing cell declined at higher temperatures under nutrient enrichments, which was confirmed by a controlled experiment with two laboratory strains of Nevertheless, MC concentrations were much higher at the increased temperature and nutrient treatment than under warming alone due to strongly promoted biomass, lifting N-imitation and promotion of potential MC producers like . This study exemplifies the vulnerability of eutrophic urban waters to predicted future summer climate change effects that might aggravate cyanobacterial nuisance.
富营养化和气候变暖是蓝藻水华的关键驱动因素，但它们对微囊藻毒素（MC）浓度的综合影响却鲜少被研究。我们验证了以下假设：气候变暖会促进自然浮游生物群落中蓝藻的丰度，而富营养化会增加蓝藻生物量和MC浓度。我们将富营养化池塘中的天然悬浮物在正常、高温和极端温度（即20、25和30°C）下进行培养，添加或不添加额外营养物质（富营养化），模拟气候变化下预计夏季风暴可能带来的脉冲效应。富营养化使藻类和蓝藻生物量分别增加了26倍和8倍，并导致MC浓度升高24倍。这种效应在较高温度下会增强，在25°C时导致MC浓度升高45倍，蓝藻叶绿素增加11倍，真核藻类叶绿素增加25倍。在30°C时，MC浓度升高42倍，蓝藻叶绿素升高17倍，真核藻类叶绿素升高24倍。相比之下，仅气候变暖并不会产生更多的蓝藻或MC，因为原位群落已经耗尽了可用的营养池。在营养富集条件下，较高温度下每个潜在MC产生细胞的MC含量下降，这在对两种实验室菌株的对照实验中得到了证实。然而，由于生物量的强烈增加以及对N的模拟和对潜在MC生产者（如 ）的促进，在温度和营养处理增加的情况下，MC浓度比仅气候变暖时要高得多。这项研究例证了富营养化的城市水域对预测的未来夏季气候变化影响的脆弱性，这种影响可能会加剧蓝藻滋扰。
