Betini Gustavo S, Roszell Jordan, Heyland Andreas, Fryxell John M
Department of Integrative Biology , University of Guelph , Guelph, Ontario , Canada N1G 2W1.
R Soc Open Sci. 2016 Dec 7;3(12):160537. doi: 10.1098/rsos.160537. eCollection 2016 Dec.
Predicting the ecological responses to climate change is particularly challenging, because organisms might be affected simultaneously by the synergistic effects of multiple environmental stressors. Global warming is often accompanied by declining calcium concentration in many freshwater ecosystems. Although there is growing evidence that these changes in water chemistry and thermal conditions can influence ecosystem dynamics, little information is currently available about how these synergistic environmental stressors could influence the behaviour of aquatic organisms. Here, we tested whether the combined effects of calcium and temperature affect movement parameters (average speed, mean turning frequency and mean-squared displacement) of the planktonic , using a full factorial design and exposing individuals to a range of realistic levels of temperature and calcium concentration. We found that movement increased with both temperature and calcium concentration, but temperature effects became considerably weaker when individuals were exposed to calcium levels close to survival limits documented for several species, signalling a strong interaction effect. These results support the notion that changes in water chemistry might have as strong an effect as projected changes in temperature on movement rates of , suggesting that even sublethal levels of calcium decline could have a considerable impact on the dynamics of freshwater ecosystems.
预测气候变化的生态响应极具挑战性，因为生物体可能会同时受到多种环境压力源协同效应的影响。在许多淡水生态系统中，全球变暖常常伴随着钙浓度的下降。尽管越来越多的证据表明，水化学和热条件的这些变化会影响生态系统动态，但目前关于这些协同环境压力源如何影响水生生物行为的信息却很少。在此，我们采用全因子设计，让个体暴露于一系列现实的温度和钙浓度水平下，测试了钙和温度的联合效应是否会影响浮游生物的运动参数（平均速度、平均转向频率和均方位移）。我们发现，运动随着温度和钙浓度的升高而增加，但当个体暴露于接近几种物种记录的生存极限的钙水平时，温度效应会显著减弱，这表明存在强烈的交互作用。这些结果支持了这样一种观点，即水化学变化对浮游生物运动速率的影响可能与预计的温度变化一样强烈，这表明即使是亚致死水平的钙下降也可能对淡水生态系统动态产生相当大的影响。
