Dissertation Research: Linking Lakes with the Landscape: The Fate of Terrestrial Organic Matter in Planktonic Food Webs

Dartmouth College, Hanover NH

Investigators

Abstract

A key goal of ecology is to understand how ecosystems process materials and energy. In this proposal, we focus on the energetic importance of terrestrially-derived dissolved organic matter (DOM) for lake ecosystems. Using laboratory-based studies, we will assess how terrestrial DOM quantity and quality influence the production and growth efficiency of pelagic bacteria. These two processes ultimately dictate how much terrestrial DOM enters lake food webs. We will then incorporate the laboratory data into a simulation model that will predict conditions under which terrestrial DOM is likely to be energetically important for higher trophic levels. We are particularly interested in using the model to assess terrestrial carbon flow in lakes with contrasting food webs and trophic states. Finally, we will test model predictions by examining the stable isotopic signatures (delta 13 C) in zooplankton from a wide array of New England lakes. Results from this study will clarify the energetic importance of spatially linked ecosystems and broaden our understanding of how allochthonous inputs influence food web dynamics. In addition, our studies will aid in decision-making regarding land use activities that modify carbon export to lakes such as agriculture, shoreline development, forestry, and wetland delineation.