Biodiversity and Climate Changes in East Africa: Lake Victoria IDEAL Limnology

莱曼维多利亚湖是地球上第二大湖泊，近几十年来经历了惊人的变化。水的透明度、氧浓度、营养物质、藻类和鱼类群落都与历史条件相比发生了显著变化。该湖现在支持的引进鱼类种群的物种多样性比其原生状态减少，渔业的未来产量令人怀疑。为了解释这些变化，人们提出了三个假设：(1)大气来源和区域土地利用加速了养分的输入；(2)区域气候的变化改变了湖泊的物理混合，使分层和脱氧的时间延长；(3)鱼食性鱼类的引入破坏了食物网，减少了鱼类的总生物量。本研究将对假设(1)进行严格检验，并在该假设被证明是错误的情况下，为后续检验其他假设提供依据。这项研究是东非湖泊国际十年计划的一部分。对这些假设的辨析可以促使采取补救措施，可以预测湖泊的未来状态及其生产可收获蛋白质的潜力，并提供评估和解释古地层记录的数据。这项研究的结果将有助于重建维多利亚湖在过去一个世纪中的变化，并在更长的时间内校准大陆地区对全球和区域气候变化的响应。

9318035 Lehman Lake Victoria, the second largest lake on earth, has experienced striking changes during recent decades. Water transparency, oxygen concentrations, nutrients, algae, and fish communities have all changed markedly from historical conditions. The lake now supports an introduced fish fauna of reduced species diversity than in its indigenous state, and the future yield of the fishery is in doubt. Three hypotheses have been advanced to account for these changes: (1) nutrient inputs have accelerated from atmospheric sources and regional land use, (2) changes in regional climate have altered physical mixing of the lake, permitting prolonged periods of stratification and deoxigenation, and (3) the introduction of piscivorous fish has disrupted food webs reducing total fish biomass. This research will test hypothesis (1) critically, and provide a basis for subsequently testing the others if this hypothesis proves false. %%% This research is part of the goals of IDEAL, the International Decade for East African Lakes. Discrimination of these hypotheses could prompt remedial action, permit prediction of future states of the lake and its potential to produce harvestable protein, and provide the data to evaluate and interpret paleostratigraphic records. The results from this research will be instrumental in a reconstruction of the changes in Lake Victoria during the past century, and in calibrating the responses of continental regions to global and regional climate change over much longer time periods.