Yang Yalan, Wang Huan, Yan Shuwen, Wang Tao, Zhang Peiyu, Zhang Huan, Wang Hongxia, Hansson Lars-Anders, Xu Jun
State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, P. R. China.
Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, P. R. China.
Environ Sci Technol. 2023 Aug 15;57(32):11767-11778. doi: 10.1021/acs.est.3c02257. Epub 2023 Aug 3.
Climate change and eutrophication are two environmental threats that can alter the structure of freshwater ecosystems and their service functions, but we know little about how ecosystem structure and function will evolve in future scenarios of climate warming. Therefore, we created different experimental climate scenarios, including present-day conditions, a 3.0 °C increase in mean temperature, and a "heatwaves" scenario (i.e., an increase in temperature variability) to assess the effects of climate change on phytoplankton communities under simultaneous stress from eutrophication and herbicides. We show that the effects of climate warming, particularly heatwaves, are associated with elevated cyanobacterial abundances and toxin production, driven by a change from mainly nontoxic to toxic spp. The reason for higher cyanobacterial toxin concentrations is likely an increase in abundances because under the dual pressures of climate warming and eutrophication individual toxin-producing ability decreased. Eutrophication and higher temperatures significantly increased the biomass of , leading to an increase in the cyanobacterial toxin concentrations. In contrast, warming alone did not produce higher cyanobacterial abundances or cyanobacterial toxin concentrations likely due to the depletion of the available nutrient pool. Similarly, the herbicide glyphosate alone did not affect abundances of any phytoplankton taxa. In the case of nutrient enrichment, cyanobacterial toxin concentrations were much higher than under warming alone due to a strong boost in biomass of potential cyanobacterial toxin producers. From a broader perspective our study shows that in a future warmer climate, nutrient loading has to be reduced if toxic cyanobacterial dominance is to be controlled.
气候变化和富营养化是两种环境威胁，它们能够改变淡水生态系统的结构及其服务功能，但我们对在气候变暖的未来情景下生态系统结构和功能将如何演变知之甚少。因此，我们创建了不同的实验气候情景，包括当前状况、平均温度升高3.0°C以及“热浪”情景（即温度变异性增加），以评估在富营养化和除草剂的同时胁迫下气候变化对浮游植物群落的影响。我们发现，气候变暖的影响，尤其是热浪，与蓝藻丰度升高和毒素产生有关，这是由主要从无毒种类向有毒种类的转变所驱动的。蓝藻毒素浓度较高的原因可能是丰度增加，因为在气候变暖和富营养化的双重压力下，个体产生毒素的能力下降了。富营养化和较高温度显著增加了蓝藻的生物量，导致蓝藻毒素浓度升高。相比之下，仅变暖不会导致蓝藻丰度或蓝藻毒素浓度升高，这可能是由于可用营养池的枯竭。同样，单独使用除草剂草甘膦不会影响任何浮游植物类群的丰度。在营养物质富集的情况下，由于潜在蓝藻毒素生产者的生物量大幅增加，蓝藻毒素浓度比仅变暖时高得多。从更广泛的角度来看，我们的研究表明，在未来气候变暖的情况下，如果要控制有毒蓝藻的优势地位，就必须减少营养物质的负荷。
