How Important Are Prey Subsidies for Fishes in Arctic Freshwater Ecosystems?

Freshwater ecosystems in the Arctic are among the least studied and understood ecosystems on the globe, yet are crucial foraging and spawning grounds for many fishes, including Arctic Grayling (Thymallus arcticus). We’ve undertaken a series of studies on the Arctic Coastal Plain of Alaska to identify the major trophic pathways, and relative importance of resource subsidies for Arctic Grayling, one of the most abundant freshwater salmonids on the Arctic. As winter ice melts grayling disperse from deep-water overwintering areas to summer-available shallow, productive foraging habitats, where they feed and grow. Subsidies of terrestrial invertebrates to freshwater habitats are of relatively minor importance there, compared to other ecosystems around the globe, but are important prey for small grayling.  Aquatic invertebrates, especially chironomids and caddisflies, are also key prey for small grayling. Conversely, Ninespine Stickleback (Pungitius pungitius) occur at extraordinarily high densities in nearly all types of aquatic habitats, and are key prey resource for large grayling. These somewhat simple food webs support high densities of a relatively small number of species, at multiple trophic levels. Climate change and petroleum development are predicted to change food web productivity in Arctic Alaska in ways that may be both beneficial and detrimental to fishes.