Much of the organic carbon in lakes originates from surrounding terrestrial ecosystems. Degradation of this terrestrial carbon in lakes implies that lake food webs are potentially supported by external sources, rather than solely by internal primary production. Prior experiments in small lakes using inorganic carbon-13 additions revealed significant terrestrial support of aquatic food webs. This project will directly address the relative importance of terrestrial support of food webs in lakes 4-10 times the size of lakes studied previously. Carbon-13 will be added to two large lakes and analyzed with several models developed by the investigators. Results will determine the importance terrestrial subsidies in these larger lakes that are in the top quartile for size in the Northern Highlands of Wisconsin and Michigan and representative of a large class of temperate lakes globally.
This research will contribute to understanding lakes in a landscape context by assessing whether differences in lake size influence food webs and carbon cycling. Broader impacts of this project include promoting public understanding of lake ecosystems as well as research training for graduate and undergraduate students. Results will be incorporated into an ongoing outreach effort on the future of the Northern Highland Lake District.
