Recognition of the microbial loop in marine and freshwater ecosystems is changing the view of trophic dynamics and energy flow in these environments. This project will focus on the structure and grazing impact of microbial food webs in arctic aquatic systems of the Toolik Lake region and its response to nutrient and predator manipulations. During the first year, samples will be taken for determination of seasonal microplankton abundance in both control and experimental lakes. Fluorescently labelled algae will be used to assess trophic links within the microbial loop. During the second year of the study, grazing rates of microplankton will be assessed by uptake of algae in control and experimental lakes. During both years, epilithic protozoan communities in control and experimental reaches of an arctic river will also be monitored. All research will be coordinated with the Toolik Lake Long Term Ecological Research (LTER) group for synoptic sampling. This study will provide insight for a tropic component which is fundamental for an understanding of the functioning of aquatic ecosystems but is not currently being addressed in the Toolik Lake LTER study.
