O'Reilly Catherine M, Alin Simone R, Plisnier Pierre-Denis, Cohen Andrew S, McKee Brent A
Department of Geosciences, University of Arizona, Tucson Arizona 85721, USA.
Nature. 2003 Aug 14;424(6950):766-8. doi: 10.1038/nature01833.
Although the effects of climate warming on the chemical and physical properties of lakes have been documented, biotic and ecosystem-scale responses to climate change have been only estimated or predicted by manipulations and models. Here we present evidence that climate warming is diminishing productivity in Lake Tanganyika, East Africa. This lake has historically supported a highly productive pelagic fishery that currently provides 25-40% of the animal protein supply for the populations of the surrounding countries. In parallel with regional warming patterns since the beginning of the twentieth century, a rise in surface-water temperature has increased the stability of the water column. A regional decrease in wind velocity has contributed to reduced mixing, decreasing deep-water nutrient upwelling and entrainment into surface waters. Carbon isotope records in sediment cores suggest that primary productivity may have decreased by about 20%, implying a roughly 30% decrease in fish yields. Our study provides evidence that the impact of regional effects of global climate change on aquatic ecosystem functions and services can be larger than that of local anthropogenic activity or overfishing.
尽管气候变暖对湖泊化学和物理性质的影响已有文献记载，但生物和生态系统尺度对气候变化的响应仅通过操纵和模型进行了估计或预测。在此，我们提供证据表明，气候变暖正在降低东非坦噶尼喀湖的生产力。该湖历史上一直支持着高产的中上层渔业，目前为周边国家的人口提供25%-40%的动物蛋白供应。自20世纪初以来，随着区域变暖模式的出现，地表水温度上升增加了水柱的稳定性。区域风速的降低导致混合减少，深层水营养物质上涌减少，进入地表水的夹带减少。沉积物岩芯中的碳同位素记录表明，初级生产力可能已经下降了约20%，这意味着鱼类产量大致下降了30%。我们的研究提供了证据，表明全球气候变化的区域效应，对水生生态系统功能和服务的影响，可能大于当地人为活动或过度捕捞的影响。
