Although our understanding of the complexity of the microbial food web has increased tremendously over the past several years, there has been little appreciation to date of the effects of trophic dynamics on the regenration of nitrogen. Dr. Glibert's work to date leads us to believe that total nitrogen regeneration in a natural food web is greater than that contributed by the component popultions, and that this effect is a nonlinear function of macrozooplankton density. This hypothesis has important consequences for how we measure the regeneration of nitrogen, and implies that commonly-used size-fractionation techniques may lead to underestimates of total regeneration. If the magnitude of this bias is large, even if only under certian conditions, then our perspective of the balance between "new" and "regenerated" nitrogen may also be biased. In these studies Dr. Glibert and collaborators will use several newly-developed techniques to determine the magnitude of the effect of these interactions under a range of conditions and the major processes contributing to this effect. The significance of these studies lies in elucidating the complex role of macrozooplankton in controlling the regeneration of nitrogen and how their interactions with other components of the plankton food web regulate the flow of nitrogen.
