Data from: Living in flowing water increases resistance to ultraviolet-B radiation

Ultraviolet B radiation (UV-B) is an important environmental driver that can affect locomotor performance negatively by inducing production of reactive oxygen species (ROS). Prolonged regular exercise increases antioxidant activities, which may alleviate the negative effects of UV-B-induced ROS. Animals naturally performing exercise, such as humans performing regular exercise or fish living in flowing water, may therefore be more resilient to the negative effects of UV-B. We tested this hypothesis in a fully factorial experiment, where we exposed mosquitofish (Gambusia holbrooki) to UV-B and control (no UV-B) in flowing and still water. We show that fish exposed to UV-B and kept in flowing water had increased sustained swimming performance (Ucrit), increased antioxidant defences (catalase activity and glutathione concentrations) and reduced cellular damage (lipid peroxidation and protein carbonyl concentrations) compared to fish in still water. There was no effect of UV-B or water flow on resting or maximal rates of oxygen consumption. Our results show that environmental water flow can alleviate the negative effects of UV-B-induced ROS by increasing defence mechanisms. The resultant reduction in ROS-induced damage may contribute to maintain locomotor performance. Hence, the benefits of regular exercise are "transferred" to improve resilience to the negative impacts of UV-B radiation. Ecologically, the mechanistic link between responses to different habitat characteristics can determine success of animals. These dynamics have important ecological connotations when river or stream flow changes as a result of weather patterns, climate, or human modifications.

紫外线B辐射（UV-B）是一类重要的环境驱动因子，其可通过诱导活性氧（reactive oxygen species, ROS）的生成，对动物的运动表现产生负面影响。长期规律运动可提升机体抗氧化活性，从而缓解UV-B诱导的活性氧所带来的负面效应。因此，自然状态下进行运动的动物——例如定期参与运动的人类，或栖息于流水环境中的鱼类——对UV-B的负面影响或具备更强的耐受能力。我们通过完全因子设计实验验证了这一假说：将食蚊鱼（Gambusia holbrooki）分别置于流水与静水环境，同时施加UV-B辐射与对照（无UV-B辐射）处理。结果显示，与静水环境中的个体相比，暴露于UV-B辐射且处于流水环境的食蚊鱼，其持续游泳能力（临界游泳速度Ucrit）、抗氧化防御能力（过氧化氢酶活性与谷胱甘肽浓度）均显著提升，细胞损伤程度（脂质过氧化与蛋白质羰基浓度）则显著降低。UV-B辐射与水流条件对食蚊鱼的静息耗氧率与最大耗氧率均无显著影响。本研究结果表明，环境水流可通过增强机体防御机制，缓解UV-B诱导的活性氧所带来的负面效应。活性氧诱导的细胞损伤得以减轻，或有助于维持动物的运动表现。由此可见，规律运动所带来的益处可被‘传递’，从而提升生物体对UV-B辐射负面影响的耐受能力。从生态学视角来看，针对不同生境特征的响应之间所存在的机制性关联，可决定动物的生存与繁衍成败。当河流或溪流的水流因天气模式、气候变化或人类活动干预发生改变时，这类动态过程将具备重要的生态学内涵。