Seasonal oxygen depletion in continental-shelf waters of Louisiana: Historical record of benthic foraminifers

Research Article| March 01, 1996 Seasonal oxygen depletion in continental-shelf waters of Louisiana: Historical record of benthic foraminifers Barun K. Sen Gupta; Barun K. Sen Gupta 1Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803 Search for other works by this author on: GSW Google Scholar R. Eugene Turner; R. Eugene Turner 2Department of Oceanography and Coastal Sciences, and Coastal Ecology Institute, Louisiana State University, Baton Rouge, Louisiana 70803 Search for other works by this author on: GSW Google Scholar Nancy N. Rabalais Nancy N. Rabalais 3Louisiana Universities Marine Consortium, Chauvin, Louisiana 70344 Search for other works by this author on: GSW Google Scholar Author and Article Information Barun K. Sen Gupta 1Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803 R. Eugene Turner 2Department of Oceanography and Coastal Sciences, and Coastal Ecology Institute, Louisiana State University, Baton Rouge, Louisiana 70803 Nancy N. Rabalais 3Louisiana Universities Marine Consortium, Chauvin, Louisiana 70344 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1996) 24 (3): 227–230. https://doi.org/10.1130/0091-7613(1996)024<0227:SODICS>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Barun K. Sen Gupta, R. Eugene Turner, Nancy N. Rabalais; Seasonal oxygen depletion in continental-shelf waters of Louisiana: Historical record of benthic foraminifers. Geology 1996;; 24 (3): 227–230. doi: https://doi.org/10.1130/0091-7613(1996)024<0227:SODICS>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract A strong spring and summer oxygen depletion is induced in nearshore bottom waters of the Louisiana continental shelf by density stratification and by the carbon flux from phytoplankton production, which, in turn, is related to the nutrient load of the Mississippi and Atchafalaya rivers. In an attempt to read the historical record of this shelf hypoxia during the past two centuries, we compared the stratigraphic signals of benthic foraminifera (as reflected in a relative-dominance index for two common species of Ammonia and Elphidium) in 210Pb-dated cores, and we found evidence of an overall rise in oxygen stress (in intensity or duration), especially in the past 100 yr. This implies a progressive increase in the influence of river-borne nutrients, particularly anthropogenically influenced nitrates. Judging by our results, foraminiferal indices based on appropriate species ratios should prove useful in testing hypotheses about long-term environmental stresses, including eutrophication and paleohypoxia, on other marine shelves. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.