Advances in Understanding Landscape Influences on Freshwater Habitats and Biological Assemblages

Ecologically Relevant Structural Metrics for Complex Stream-Lake Networks

Meghan L. Allerton, Nicholas E. Jones, Stephanie J. Melles, and Bastian J. Schmidt


Abstract.—Lakes are common features on the landscape in many regions of the world and have important impacts on the ecological function and habitat conditions of connected rivers and streams. Yet lakes are rarely incorporated in studies of river and stream network structure. Using stream and lake spatial data of catchments in Ontario, metrics can be developed that quantify the spatial structure of complex stream–lake networks. This case study represents the initial step in a larger project to develop a complete, parsimonious set of metrics that would make the link between stream–lake network structure and aquatic ecosystem function at the landscape scale. We present three new metrics that capture essential information about the spatial distribution and size of lakes in aquatic networks. These metrics can be used as descriptive measures to understand differences among catchments and as explanatory variables in predictive modeling. Developing stream–lake network measures is an important first step towards integrating lakes and streams for aquatic assessments, improving our ability to effectively manage and conserve aquatic ecosystems in many parts of the world.