Out of sight out of mind? Implications of winter vs. summer conditions for lakes on the northern Great Plains.

加拿大大草原上的湖泊是极好的模式系统，可以促进我们对气候对湖泊食物网影响的理解。在小空间尺度上，区域地貌和气候共同导致湖泊形态、物理和化学特征的巨大多样性。因此，不同湖泊的分类丰富度、食物网复杂性和物种组合差异很大。此外，最近加强的土地利用可能对湖泊产生不利影响，包括夏季有毒藻类大量繁殖和冬季鱼类死亡。一个独特且迅速发展的理论是，冬季湖泊的状态对决定夏季食物网的动态至关重要(“冬季控制”)。该项目的第一个目标是量化冬季条件对这些湖泊中食物网结构的影响，并开发新的量化模型来预测冬季杀手的风险。其次，我们将继续我们的长期湖泊调查，以对比夏季和冬季条件对当前气候制度的重要性，并通过实验测试它们对浮游动物群落的影响。第三，我们将通过将过去100年重建的生产力和食物网模式与气候和土地利用的同步变化进行比较，来评估长期变化。最终，基于这里建立的食物网组成与气候和土地利用的关联，我们将使用现有的气候变化情景来预测这些湖泊的未来条件。这项研究的结果将有助于改善和调整这些湖泊的管理办法，如水质保护和渔业。此外，这项研究还将对淡水湖的功能及其对气候变化的脆弱性产生重要的新见解。虽然草原湖泊在环境条件方面可能是极端的，对气候变化更敏感，但淡水湖中的生物群应该对水文和水化学的变化做出类似的反应，特别是因为在分类学上与北方湖泊有广泛的相似之处。

Lakes across the Canadian prairies are excellent model systems to advance our understanding of climate effects on lake food-webs. Together, regional geomorphology and climate result in a tremendous diversity in morphological, physical and chemical lake characteristics on a small spatial scale. As a result, taxonomic richness, food-web complexity and species assemblages vary dramatically among lakes. Additionally, recently intensified land-use can have detrimental impacts on lakes, including toxic algal blooms in the summer and fish kills in the winter. A unique and rapidly developing theory is that the state of lakes in the winter is critically important in determining the dynamics of food webs in the summer ("winter control"). The first goal of this project is to quantify the impacts of winter conditions on food-web structure in these lakes and develop novel quantitative models to predict the risk of winterkill. Second, we will continue our long-term lake surveys to contrast the importance of summer vs. winter conditions for current climate regimes, and experimentally test their respective impacts on zooplankton assemblages. Third, we will evaluate long-term changes by comparing reconstructed productivity and food-web patterns over the past 100 yrs with simultaneous changes in climate and land-use. Ultimately, based on the here established associations of food-web composition with climate and land-use, we will use existing climate change scenarios to predict future conditions in these lakes. The results of this study will be instrumental in improving and adapting management approaches for these lakes, such as water-quality protection and fisheries. Furthermore, this study will also generate important new insights into the functioning of freshwater lakes and their vulnerability to climate change. While prairie lakes can be extreme in respect to environmental conditions and are more sensitive to climate change, the biota in freshwater lakes should respond similarly to changes in hydrology and water chemistry, particularly as there are broad taxonomic similarities to boreal lakes.