Causes and Consequences of Spatial Heterogeneity in Lakes

Lakes, far from being the homogeneous environments we might expect, offer a rich and dynamic heterogeneity at multiple spatial and temporal scales that we are just beginning to understand. At the within-lake scale, a complex set of phenomena such as internal waves and stream intrusions leads to both horizontal and vertical heterogeneity. Developing an understanding of whether and how this heterogeneity affects ecosystem processes is in its early stages, but nutrient movement both horizontally and vertically may be more structured than previously conceptualized and will depend on interactions among nutrient loading, stratification, surface meteorology, and basin morphometry.Within a landscape, lakes often differ from each other both in their average characteristics and in their among-year dynamics. Much of this heterogeneity has been linked to how water flows across the landscape. In landscapes dominated by groundwater flow, there is often more heterogeneity in lake characteristics and response to climatic events than in landscapes where exposed bedrock leads to rapid horizontal transport of water. Humans can affect heterogeneity across lakes by causing changes in land use and cover and within lakes by simplifying the physical structure of the littoral zone.