Overview of Project

P.I.: Clare E. Reimers, Rutgers University

TITLE: The dynamics of oxygen uptake by shelf sediments

Project Objectives: Our main objective is to understand, via direct, in situ measurements, the role of advective versus diffusive exchange in benthic community oxygen consumption and organic carbon cycling in two distinct subenvironments of the continental shelf of the Mid-Atlantic Bight. These environments are the Inner Shelf (10-20 m) offshore of Little Egg Inlet (LEO-15) and the mid-shelf (30-60 m) of the New York Bight Apex.

The specific questions we will address are:

1. What processes are the most important in transporting oxygen to the sea bed at LEO-15 and sites at 30, 45 and 60 meters within the New York Bight Apex during seasonally variable, wave-current and bottom stress conditions?
2. How deep into the sediment is turbulence-induced advection observed under different natural bottom boundary conditions?
3. How different are in situ sediment oxygen profiles (including the diffusive sublayer) within and between the sediments of the New York Bight Apex, an area influenced by primary production associated with the Hudson River effluent, the Hudson Shelf Valley and a recent history of sludge disposal, and the more pristine and shallow LEO-15 area?
4. Can localized summer hypoxia be linked to increased rates of oxygen consumption at the sea bed of the continental shelf?

Summary of Research: We will determine whether molecular diffusion, physical advection or bioturbation dominate benthic oxygen exchange on the inner and mid-continental shelf using an in situ microelectrode profiling instrument, bottom mounted CTD-O2-turbidity sensors and a time-lapse video camera system. We will also sample water from the benthic boundary layer and collect cores for determining pore water distributions and for shipboard oxygen uptake measurements.