Under the collaboration of:

Bob Howarth, Roxanne Marino, and Melanie Hayn (Cornell University)
Ken Foreman, Anne Giblin, and Jane Tucker (Marine Biological Laboratory)
Peter Berg and Karen McGlathery (University of Virginia)

Overview: Shallow marine systems are more biogeochemically complex than are deeper coastal systems, due to a greater diversity of forms among primary producers, greater importance of sediment processes, and a tight coupling of element cycling to ecological structure. Nonetheless, much of the current understanding of how nutrient pollution affects coastal ecosystems is based on studies of deeper systems. We hypothesize that major non-linear changes in the coupling of element (C, N, P, S, O, Si, Fe) cycles occur in shallow systems during eutrophication, with linked shifts in community structure. As part of a new NSF biocomplexity grant, we take advantage of a whole-ecosystem N enrichment to a coastal bay (West Falmouth Harbor, MA). External N loading will increase by ~ 2-fold over the next few years, as a plume of N-polluted groundwater reaches the estuary, then will gradually decrease as N removal is implemented. This “experiment” spans a transition from low to moderate, to ultimately high N loading, and the continuum of eutrophication stages within ecosystem zones. We are making process and flux measurements to elucidate feedbacks and interactions among element cycles, and the relationship of these cycles to changing biotic structure during different stages of eutrophication.