General impacts of warming on reciprocal subsidies between aquatic and terrestrial ecosystems

Freshwater and terrestrial ecosystems are fundamentally connected; insect emergence from streams provides an important energy resource to terrestrial riparian communities (Paetzold et al. 2004), and subsidies from the terrestrial ecosystem often support in-stream production (O’Gorman et al. 2016). Subsidies are likely to be altered by environmental warming, with evidence for greater aquatic insect emergence into terrestrial landscapes (Hannesdottir et al. 2013) and increased activity of terrestrial invertebrates and thus potential in-fall to streams (Dell et al. 2011). This potential for increased energy flow between aquatic and terrestrial systems could offset some of the higher metabolic demands of organisms in each environment under warming. Therefore, it is important to examine the impact of warming on cross-ecosystem linkages and quantify energy flow between habitats to better model and predict the effects of climate change on ecosystems. This project builds on my previous research conducted at the Hengill geothermal valley in Iceland, increasing the generality of findings from this field site by studying additional natural temperature gradients in Alaska and Greenland.