The Abiotic and Biotic Controls of Arctic Lake Food Webs: A Multifaceted Approach to Quantifying Trophic Structure and Function

• Main Author: Klobucar, Stephen L.
• Format: Text
• Language: unknown
• Published: DigitalCommons@USU 2018
• Subjects: predator-prey interactions; fish ecology; food webs; lakes; arctic; Terrestrial and Aquatic Ecology; Arctic; Arctic Lake; Salvelinus alpinus; Zooplankton
• Online Access: https://digitalcommons.usu.edu/etd/7293; https://doi.org/10.26076/5322-f835; https://digitalcommons.usu.edu/context/etd/article/8407/viewcontent/2018_Klobucar_Stephen.pdf

The Arctic is warming faster than any other region of the globe. To conserve and manage many thousands of lakes across arctic landscapes, scientists need to understand historic and present conditions within these lakes to predict how the lakes, and the organisms that inhabit them, may respond to a changing climate. The goal of my research was to improve our understanding of what physical, chemical, and biological factors contribute to: 1) how lake food webs are assembled; and, 2) how these food webs may change in the future. First, I used long-term observations and lab experiments to determine how fish food, including zooplankton and snails, may respond to a warming climate. I then used field measurements of arctic char (Salvelinus alpinus) body characteristics, genetic samples, and fish diets to investigate if, and potentially why, populations of arctic char across a series of lakes achieve different maximum body sizes. Finally, as a method of monitoring population-level changes of fish abundance, I collected samples of arctic char DNA in lake water to test if estimated arctic char population abundances within a given lake correspond to the amount of DNA collected. Fish will require more food to eat as their metabolism increases with warming lake temperatures. Based on a thirty-year period of record, I determined zooplankton abundance increases in warmer years, indicating there is likely to be enough food for fishes in the future. Accordingly, zooplankton and snail abundance and development was also faster in warmer treatments of my lab experiments. My field observations indicated these are important prey items for arctic char. Small arctic char eat more zooplankton and large arctic char eat more snails, and these observations were consistent whether or not other predators are found in the particular lake. Similarly, my analyses did not indicate morphological or genetic differences between small and large arctic char within the same lake, suggesting arctic char size structure is determine by biological ...