U.S. Department of the Interior Minerals Management Service Gulf of Mexico OCS Region Technical Announcement

Northeastern Gulf of Mexico Chemical Oceanography and Hydrography Study:
Synthesis Report

OCS Study MMS 2002-055

This report presents the findings and results from nine cruises completed from November 1997 through August 2000 over the northeastern Gulf of Mexico.  An important finding is that interannual variation overwhelms the seasonal changes.  This occurs because the offshore circulation that affects the inner shelf circulation is not seasonal and the wind regime, while seasonal, has large interannual variability.  In addition, freshwater input is very complex.  The largest amount of freshwater lies over the continental slope.  The chemical property distributions reflect the interplay between the circulation and the regional biological processes.  Near-surface oxygen reflects the effects of salinity and temperature on solubility and primary productivity.  Hypoxic conditions were not observed in the area despite very low concentrations at some places.  Chemical property distributions also reflect lateral (east-west) variations related to river discharge, particulate matter, light penetration, and resuspension of bottom materials.  Finally, by the use of pigment data, the major algal groups were identified.  Chlorophyll-a showed a seasonal variation opposite to that of offshore waters: low in fall-winter and high in spring-summer.

For more information about this study or the Environmental Studies Program in general, contact the Environmental Sciences Section (MS 5430), 1201 Elmwood Park Boulevard, New Orleans, Louisiana 70123-2394, telephone (504) 736-2752.

You can obtain copies of the report from the Minerals Management Service, Gulf of Mexico OCS Region, at a charge of $25.00 by referencing OCS Study MMS 2002-055.  You will be able to obtain this report also from the National Technical Information Service in the near future.  Here are the addresses.  You may also inspect copies at selected Federal Depository Libraries.