Katie Fisher, Utah State University
Arctic lakes are very sensitive to the effects of climate change. It is important to understand the current food web dynamic and energy flow within these lakes to better understand how they will change in the future due to the effects of a rapidly changing climate. In order to understand the current conditions in arctic lakes, this project consists of an analysis of stable isotopes of carbon (13C) and nitrogen (15N) from invertebrates among fish and fishless lakes in arctic Alaska to compare their trophic level positions and primary energetic sources. In order to carry out this analysis, I collected pelagic invertebrates were collected from 6 different lakes, 3 of which have resident fish populations and 3 of which are fishless. Samples collected in 2011 were analyzed for stable isotope composition by a mass spectrometer at University of California Davis. Results from samples collected in 2012 are pending at Washington State University. I will analyze and correlate the stable isotope results with isotopic data collected from other related projects. With this analysis, I will create food webs to 1) assign trophic positions to each species in each lake and compare those positions across lakes, 2) assess the potential effect fish predation has on pelagic invertebrate community structure. I hypothesize that fish predation will determine zooplankton community structure (e.g., dominant taxa) and alter trophic linkages (e.g., secondary trophic level predation rates).