Record Display for the EPA National Library Catalog


Main Title Benthic foraminiferal census data from Louisiana continental shelf cores, Gulf of Mexico /
Author Osterman, Lisa E.
Other Authors
Author Title of a Work
Kelly, Wendy S.
Ricardo, John P.
Publisher U.S. Dept. of the Interior, U.S. Geological Survey,
Year Published 2009
OCLC Number 320122804
Subjects Foraminifera--Mexico, Gulf of ; Drill cores--Mexico, Gulf of ; Benthos--Mexico, Gulf of ; Marine sediments--Mexico, Gulf of ; Gulf of Mexico
Internet Access
Description Access URL
Library Call Number Additional Info Location Last
EMAD  Internet Region 6 Library/Dallas,TX 09/20/2010
Collation 24 unnumbered pages : digital, PDF file, tables, map.
Cover title. Includes bibliographical references (leaf 5).
Contents Notes
An area of oxygen-depleted bottom- and subsurface-water (hypoxia = dissolved oxygen <2 mg/L-1) occurs seasonally on the Louisiana Shelf near the Mississippi River. The area of hypoxia, also known as the "dead zone," forms when spring and early summer freshwater flow from the Mississippi River supplies a large amount of nutrients to the shelf while creating a freshwater lens, or cap, above the shelf water. The excess nutrients cause phytoplankton blooms in the shallow shelf water. After the bloom ceases, the organic material sinks in the water column and uses up oxygen during decomposition. Thus, the subsurface waters become oxygen depleted. The seasonal dead zone exists until a reduction in freshwater flow, or overturning by storms, allows mixing of the water column to restore normal oxygen conditions (Rabalais and others, 1994, 1996; Rabalais, 2002). Since systematic measurement of the extent of the dead zone began in 1985, the overall pattern indicates that the area of the dead zone is increasing (Rabalais and Turner, 2001; Turner and others, 2005). Several studies have concluded that the expansion of the Louisiana Shelf dead zone is related to increased nutrients (primarily nitrogen, but possibly also phosphorous) in the Mississippi River drainage basin and is responsible for the degradation of Gulf of Mexico marine habitats (Goolsby and others, 2001). This paper presents the benthic foraminiferal data from 10 sediment cores collected from the Continental Shelf of Louisiana (table 1), obtained as part of an initiative to investigate the geographic and temporal extent of hypoxia prior to 1985 in the Gulf of Mexico.