RUI: A Geomorphic-Tropic Hypothesis for Benthic-Pelagic Coupling in Arctic Lakes

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RUI: A GEOMORPHIC-TROPHIC HYPOTHESIS FOR BENTHIC-PELAGIC COUPLING IN ARCTIC LAKES Studies of lakes have traditionally focused on control of phytoplankton, or pelagic, production by nutrients or food webs. However, there is growing recognition that algal and invertebrate production on the lake bottom, or benthic habitat, and benthic-pelagic coupling are also important to lake food webs and whole-lake productivity. Furthermore, the role organic matter from the surrounding terrestrial plant community in fueling lake food webs has been underemphasized. In arctic lakes, recent research has shown that coupling to the terrestrial landscape and benthic-pelagic coupling may be especially important to lake food webs and productivity. The project will examine landscape control of lake food webs, the distribution of algal productivity between pelagic and benthic habitats, and coupling of those habitats through food web and chemical and physical processes. Approaches include whole-lake tracer experiments using 15N, a stable nitrogen isotope, comparison of lakes with contrasting fish communities in constrasting landscape settings, microcosms manipulations of organic matter sources and food webs, and modeling. This research will result in improved understanding of landscape control and benthic-pelagic coupling to lake food webs and productivity. The work will train undergraduate and graduate students, and will be used by natural resource managers in Alaska and other northern regions where pristine lakes are currently being threatened by global warming, eutrophication, and other disturbances.