Tracing the Fate of Nitrogen Inputs from Watersheds to EstuariesEPA Grant Number: R824767
Title: Tracing the Fate of Nitrogen Inputs from Watersheds to Estuaries
Investigators: Deegan, Linda A. , Peterson, Bruce J.
Institution: Marine Biological Laboratory
EPA Project Officer: Hiscock, Michael
Project Period: January 1, 1996 through December 1, 1997
Project Amount: $232,323
RFA: Water and Watersheds (1995) Recipients Lists
Research Category: Water and Watersheds , Water
Description:The objective of this project is to determine experimentally the fate of watershed-derived nitrogen and organic matter in the interface where rivers first encounter tidal waters: the oligohaline zone. In this region, river-borne dissolved and particulate nitrogen undergoes major transformation, including uptake by planktonic and benthonic algae, freshwater marshes and macrophytes, and conversion by bacteria and consumers. The dynamic oligohaline production cycle supports high consumer biomass and growth rates, and nourishes a vital and productive faunal habitat that is a nursery for fish species important to commerce and recreation. Transformations of watershed-derived nutrients and organic matter in the oligohaline zone are currently modeled superficially because they are difficult to quantify at the ecosystem scale.
The importance of nutrients and organic matter from the watershed to the oligohaline food web will be examined experimentally by adding 15N-enriched nitrate to the oligohaline reach of the Parker River (MA), the site of an ongoing Land Margin Ecosystem Research (LMER) program. By adding the tracer to this critical estuarine zone, questions about the transformations of materials from watersheds as they enter tidal waters, and about the influences of changing land use on important fauna of coastal waters, can be answered simultaneously.
The experiment will provide information to test complex food web models that are otherwise very difficult to confirm.