Early Registration Deadline
12 February 2010
Travel Award & Grant Recipients Notified
Lennon, J. T., Michigan State University, W.K. Kellogg Biological Station, Hickory Corners, USA, firstname.lastname@example.org
Jones, S. E., Michigan State University, W.K. Kellogg Biological Station, Hickory Corners, USA, email@example.com
Terrestrial ecosystems export large quantities of dissolved organic carbon (DOC) to nearby aquatic ecosystems. Food web and ecosystem theory predict that such donor-controlled resource inputs should influence the stability of recipient ecosystems. We tested these predictions by manipulating terrestrial DOC loading to a series of ponds. As expected, our ponds became increasingly heterotrophic with increasing DOC loading, owing in part to light limitation of gross primary productivity. Using dynamic linear models, we identified a strong non-linear relationship between P uptake dynamics and DOC supply rate. Specifically, phosphorus uptake was much more rapid in ponds with low DOC loading than ponds with high DOC loading. Using a combination of simulation modeling and reciprocal transplant experiments, we conclude that terrestrial DOC inputs reduce ecosystem stability via light limitation of phytoplankton. Although terrestrial DOC inputs subsidized heterotrophic bacteria to some degree, microbes remained carbon limited and were thus incapable of compensating for episodic increases in phosphorus availability. Our results suggest that lakes may become less resilient to nutrient perturbations in the future given the observed trends of increasing DOC around the globe.
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