摘要
气候变化很可能作为一种多重胁迫因子,对水生生态系统造成累积的和/或协同的影响。预测的温度上升以及由此带来的降水季节性特征的改变将会增加污染物流入水生生态系统的量,并且会独自提高水生生物体对污染物暴露和影响的易感性。对生物区系造成的结果在多数情况下是加和的(累积的)或倍增的(协同的),其总的结果必然是污染物负荷加重,生物放大作用(指有毒化学物质在食物链各环节中的毒性渐进)加强。同温层中臭氧和紫外线辐射季节性特征的变化也会对水生生态系统的结构和功能产生累加或协同的影响。与预测的同温层臭氧量减少这一原因相比,冰层覆盖度的降低可能对水下紫外线暴露产生更为重大的影响。紫外线辐射水平的大幅升高会导致对生物体的损伤增强(生物分子学、细胞学和生理学上的损害,以及物种组成的变化),而生物区系分配用于抵抗紫外线伤害的能量和资源也会增加,有可能使营养水平上的生产力降低。通过光化学途径,元素的通量将会增加。
Climate change is likely to act as a multiple stressor, leading to cumulative and/or synergistic impacts on aquatic systems. Projected increases in temperature and corresponding alterations in precipitation regimes will enhance contaminant influxes to aquatic systems, and independently increase the susceptibility of aquatic organisms to contaminant exposure and effects. The consequences for the biota will in most cases be additive (cumulative) and multiplicative (synergistic). The overall result will be higher contaminant loads and biomagnification in aquatic ecosystems. Changes in stratospheric ozone and corresponding ultraviolet radiation regimes are also expected to produce cumulative and/or synergistic effects on aquatic ecosystem structure and function. Reduced ice cover is likely to have a much greater effect on underwater UV radiation exposure than the projected levels of stratospheric ozone depletion. A major increase in UV radiation levels will cause enhanced damage to organisms (biomolecular, cellular, and physiological damage, and alterations in species composition). Allocations of energy and resources by aquatic biota to UV radiation protection will increase, probably decreasing trophic-level productivity. Elemental fluxes will increase via photochemical pathways.
