Ecological Networks as a Framework for Understanding and Predicting Contaminant Movement Across the Land- Water Interface

Abstract

Models of interaction networks among species (i.e., network models) can be used to predict behavior of complex adaptive systems, such as ecosystems at the land-water interface. As theoretical and empirical understanding of ecological networks continues to grow, network models are increasingly used to quantify and predict ecosystem stability, metapopulation dynamics, disease spread, and social behavior. Here, we propose that ecological networks can also be used to synthesize many of the dynamics that regulate the movement of contaminants between aquatic and terrestrial systems. We discuss how network models can predict aquatic-terrestrial contaminant transport via food-web interactions, animal movement, and mutualistic interaction webs. In addition, we discuss how knowledge of social-ecological networks can help address contaminant exposure and risk to humans. To illustrate an application of network models in the field of contaminants and subsidies, we provide an empirical example of the responses of ecological networks to dam removal in a temperate river system. In this example, we observed that shifts in species composition (especially losses of larger-bodied, often predatory, sport fish) and subsequent changes to feeding relationships could reduce biomagnification of contaminants in the food web and thus reduce exposure to humans and other terrestrial consumers in the short term. In summary, we propose that ecological networks will be a valuable framework for understanding and forecasting temporally and spatially dynamic aquatic to terrestrial contaminant transport.