Current conceptual models of N pollution are inadequate for shallow marine ecosystems (depths < 10 m) that are typically dominated by benthic primary producers such as seagrasses, macroalgae and benthic microalgae. Major nonlinear changes in the coupling of element cycles occur in these ecosystems as they receive increasing external N loads from anthropogenic changes in surrounding watersheds. Numerous biogeochemical feedbacks can accelerate eutrophication and aggravate some of its consequences including increased incidences of harmful algal blooms.
A consortium of researchers from Cornell University, University of Virginia and The Ecosystems Center in Woods Hole, Ma will take advantage of a whole-ecosystem "experiment" in which external N loading to a 79-hectare coastal system on Cape Cod, MA, will approximately double over the next 3-5 years, as a plume of N-polluted groundwater reaches the estuary. This "experiment" reflects the transition from low to moderate, and ultimately to high, nutrient loading, and spans the continuum of eutrophication stages within the ecosystem zones. A study of the recovery of the shallow portions of a severely eutrophied ecosystem (Boston Harbor) following diversion of wastewater offshore (N-loading decreased 10-fold in 2000) will also be continued. Process and flux measurements will focus on non-linear feedbacks and interactions among the cycles of N, C, P, O, S, Fe, Mn, and Si, along with the relationship of these cycles to biotic structure during different stages of eutrophication. Modeling at both the process and whole-system scales will integrate the research, and make the results accessible to the management community.
This research has a significant broader impact since N pollution (and the resulting eutrophication) is one of the greatest threats to the ecological integrity and functioning of coastal marine ecosystems, with two-thirds of coastal rivers and bays in the U.S. moderately or severely degraded from N pollution.
