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The Dead Zone

Ecology and Oceanography in the Gulf of Mexico



Co Authors:

Kathleen Archer
Biology Department
Trinity College
EKathleen.Archer@trincoll.edu

Lauren Sahl
Corning School of Ocean Studies
Maine Maritime Academy
lauren.sahl@mma.edu

Abstract:

This interrupted case study focuses on the seasonal hypoxic area in the Gulf of Mexico known as the Dead Zone. It follows Sue, a college student, whose father is a commercial fisherman affected by the lack of fish in his usual fishing grounds in the summer.  In her quest to determine why the fish disappear, Sue learns about both the biological and physical forces that produce, maintain, and eventually dissipate the hypoxic zone. The case introduces students to the marine food web, the aquatic microbial loop, the impact of exogenous nutrients, and the physical forces that affect oxygen content and water stratification. It could be used in introductory biology or ecology courses or in an oceanography course.

Objectives:
  • Understand the close integration of biological and physical influences on an aquatic environment and the outcome when nutrient inputs are elevated.
  • Understand the structure of an aquatic food web.
  • Understand the role of the microbial loop.
  • Understand the role of salinity and temperature in creating water column density structure.
  • Understand how the interaction between biological processes and water column structure can cause hypoxia.
  • Read and interpret graphical data.
Keywords: Gulf of Mexico; microbial loop; dissolved oxygen; aquatic hypoxia; nutrients; fertilizer; algae; marine food web; phytoplankton; nitrogen; water column; seawater; salinity
Topical Area: Policy issues
Educational Level: Undergraduate lower division, Undergraduate upper division
Formats: PDF
Type/Method: Interrupted, Demonstration
Language: English
Subject Headings: Ecology   Environmental Science   Earth Science   Marine Science / Oceanography   Botany / Plant Science  
Date Posted: 05/07/09
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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I really like this case, in part because it nicely replicates how science works, gradually narrowing the possible explanations and using data to eliminate ideas and reinforce others. For a recent update on this issue, read the following article: http://www.desmoinesregister.com/article/20121028/NEWS/310280045/Runoff-from-Iowa-farms-growing-concern-Gulf?nclick_check=1


Eric Ribbens
Biology
Western Illinois University
Macomb, IL
e-ribbens@wiu.edu
10/2/2013



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