Abstract：
Climate change threatens freshwater fish species due to predicted changes in thermal, sedimentary and hydrological properties of stream ecosystems. Gravel-spawning fish are particularly sensitive to such alterations as warming, higher inputs of fine sediment and low-flow all have potentially negative effects on the functionality of their reproductive habitat, the hyporheic zone. Multiple stressors can interact in synergistic and antagonistic manners, causing surprise-effects that cannot be predicted from the additive consideration of individual stressors. For obtaining reliable, yet realistic data on the climate change stressor effects warming (+3-4 °C), fine sediment (increase in <0.85 mm by 22 %) and low-flow (eightfold discharge-reduction), we constructed a unique large-scale outdoor-mesocosm facility consisting of 24 flumes to study individual and combined stressor responses in a fully-crossed, 3-way-replicated design. To acquire representative results reflecting individual susceptibilities of gravel-spawning fish species due to taxonomic affiliation or spawning seasonality, we studied hatching success and embryonic development in the three fish species brown trout (Salmo trutta L.), common nase (Chondrostoma nasus L.) and Danube salmon (Hucho hucho L.). Fine sediment had the most significant single negative effect on both hatching rates and embryonic development (-80 % in brown trout, -50 % in nase, -60 % in Danube salmon). When fine sediment was combined with one or both of the other stressors, we observed strongly synergistic stressor responses, being distinctly stronger in the two salmonid species than in the cyprinid nase. Danube salmon was most susceptible to synergistic effects due to warmer spring water temperatures exacerbating the fine sediment-induced hypoxia, hence leading to complete mortality of fish eggs. This study highlights that individual and multiple-stressor effects depend strongly on life-history traits of respective species and that climate change stressors have to be assessed in combination to obtain representative results due to the high level of synergisms and antagonisms detected in this study.
摘要：
由于预测的热量变化，气候变化威胁着淡水鱼种，河流生态系统的沉积和水文特性。砾石产卵鱼对变暖等变化特别敏感，较高的细沉积物输入和低流量都对其繁殖栖息地的功能产生潜在的负面影响，hyporheic区。多种应激源可以以协同和拮抗的方式相互作用，造成意外的影响，这是无法通过对个体压力源的加性考虑来预测的。为了获得可靠的，然而，关于气候变化压力源影响变暖(+3-4°C)的现实数据，细沉积物(增加<0.85mm22%)和低流量(减少8倍流量)，我们建造了一个独特的大型户外中观设施，由24个水槽组成，以研究完全交叉的个体和组合压力源反应，3路复制设计。为了获得反映由于分类学隶属关系或产卵季节性而产生的砾石产卵鱼类物种的个体敏感性的代表性结果，我们研究了三种褐鳟鱼（SalmotruttaL.）的孵化成功和胚胎发育，普通纳斯鱼（ChondrostomanasusL.）和多瑙河鲑鱼（HuchohuchoL.）。细沉积物对孵化率和胚胎发育的影响最明显（褐鳟鱼的-80％，-50%的Nase,-60％的多瑙河鲑鱼）。当精细沉积物与其他压力源之一或两者结合时，我们观察到强烈的协同应激源反应，在两种鲑鱼中明显比在鲤科动物中更强。多瑙河鲑鱼最容易受到协同效应的影响，因为春季水温升高加剧了细沉积物引起的缺氧，从而导致鱼卵完全死亡。这项研究强调了个体和多重压力源效应在很大程度上取决于各自物种的生活史特征，并且由于本研究中检测到的高水平的协同作用和拮抗作用，因此必须结合评估气候变化压力源才能获得代表性结果。
