Pathways of Contaminant Transport Across the Aquatic-Terrestrial Interface: Implications for Terrestrial Consumers, Ecosystems, and Management

Abstract

The role of freshwater ecosystems as a source of nutrients, energy, and contaminants to terrestrial ecosystems is relatively underappreciated compared with the impact of catchment properties on inputs to receiving surface waters. Aquatic contaminants can reach terrestrial ecosystems through biologically mediated pathways, such as emerging adult aquatic insects or aquatic prey consumed by terrestrial predators. Alternatively, contaminant transfer from aquatic to terrestrial ecosystems occurs through abiotic pathways such as aqueous-phase or particle-bound contaminants transported via flood events to the surrounding terrestrial habitats. Once contaminants reach the terrestrial ecosystem, they may lead to top-down (consumer-driven) or bottom-up (producer-driven) effects on the terrestrial ecosystem/food web, yet our knowledge of these effects is still limited. In this chapter, we review the relative importance of these pathways of contaminant exposure in driving effects of aquatic contaminants on terrestrial ecosystems. We also summarize current knowledge about the effects of these exposures on terrestrial food webs. In this context, we discuss how the use of tools, such as stable isotope analysis, that untangle the complexity of aquatic contaminant effects on terrestrial ecosystems may support informed decision-making as part of chemical risk assessment or ecosystem management.