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# The Dead Zone

## On Again, Off Again — The Dead Zone: Hypoxia

For the past few summers, newspapers have carried at least one story per year about the “Dead Zone” along Louisiana’s coast west of the Mississippi River in the Gulf of Mexico. In fact, the duration, number and size of dead zones throughout the world are increasing. Coastal waters are not actually ‘dead.’ They are hypoxic, meaning having a low level of oxygen. The term ‘dead zone’ refers to the risk of death for many organisms living in an area where pollution has caused a reduction in the oxygen level. What is hypoxia, what causes it, and how can people control or reduce it?

## The Dead Zone: Hypoxia in the Gulf of Mexico Dead Zone Mapping Activity: Graphing Hypoxia

For the Teacher

Introduction:
There are several useful publications and websites that describe the dead zone in the Gulf of Mexico (see: Dead Zone websites). For specific background on the phenomenon, see these sites and materials. The primary purpose of this package is to provide activities that address the dead zone for middle and high school students. The mapping activities use data that are available on the Internet at www.aoml.noaa.gov/ocd/necop/. The data were collected during scientific cruises in the Gulf of Mexico in July 1993. Included in this package are:

Notes:
To set up the graphing for Activities #1 and 2, DO will be plotted on the x axis beginning with zero at the x,y intercept and depth will be plotted on the y axis with zero at the top of the graph to show depth. Maximum depth for all stations should be noted and a line drawn to indicate the Gulf bottom.

Students plot points on graph paper and interpolate between each point to draw the dead zone boundary. Draw a line across the graph at <2mg/l where hypoxic values begin. Any plots below this line will be in the hypoxic zone.

## Dead Zone Mapping Activity: Graphing Hypoxia Graphing Dissolved Oxygen from 1993 Cruise Data in the Gulf of Mexico

Purpose:
The purpose of the following series of activities is to help students visualize the dead zone and to provide them with dissolved oxygen (DO) data to analyze and interpret. Students will plot and analyze DO from the July 23-28, 1993, scientific cruise in the Gulf of Mexico. The activities are designed to engage the students individually, within a group and as a class to plot, observe, analyze and interpret several different spatial slices of the dead zone. In addition, these graphing activities can also be used to graph other variables such as salinity, density and temperature. The five graphing and mapping activities are described in order from simplest to most complex.

Activities:

• Activity #1 – Profile mapping of dissolved oxygen (DO) by depth for each station - Individual student
• Activity #2 – Cross section map of the hypoxic zone by transect - Student groups
• Activity #3 – Constructing a master location map using transects and stations - Student groups
• Activity #4 – Mapping the area of the dead zone - Student groups or whole class
• Activity #5 – Building a 3-dimensional model of the dead zone - Student groups or whole class

Materials to Complete all Activities:

 Louisiana offshore map* Station data sheets* Ruler Scissors Pencils, paper Colored pencils Colored markers Graph paper Calculator Colored paper Long sheets of paper Tape String or colored thread Wooden shish kabob sticks (10") or straws Blue, black and red permanent marker Hard foam, styrofoam sheets or copier paper box Clay, play dough, other modeling material Garden clippers (optional) Crepe paper Wood or metal poles or stakes

* The enlarged map of the Louisiana’s offshore area with latitude, longitude, transects and station labeled will be prepared in Activity #2.

The Data:
The data provided for these activities were downloaded from the U.S. Department of Commerce/National Oceanic and Atmospheric Administration’s (NOAA) Nutrient Enhanced Coastal Ocean Productivity Program (NECOP) website, www.aoml.noaa.gov/ocd/necop/. The website has several data sets which consist of physical, chemical and biological parameters from cruises in the Gulf of Mexico. A condensed version of the July 23-28, 1993, data is provided with these materials (see file names below). The data set has been reduced and formatted in Microsoft Excel to be student and teacher friendly for these activities. The activities are set up as pencil and paper exercises. However, some of the graphing activities can be conducted using Excel graphing options. Data sets from additional years on the NECOP website can also be downloaded and used for class activities on the dead zone.

File names to use for these activities:

PDF versions of files for easy printing:

Notes:
There are 14 transects with 82 stations in the July 23-28, 1993, cruise data set. Provide data sheets for one or more stations to each student. Each student will plot the oxygen vs. depth profile for his or her data set. You may wish to determine a standard range of values for the graphing activities for the class. Provide students with the range of values for their graphs, so that they are all comparable and can be used in all activities.

Data set variables included in the data files are: transect (trn.), station (stn.), depth (m), dissolved oxygen (DO, mg/l), salinity (sal., ppt), temperature (temp., ºC), and latitude (lat) and longitude (long) in degrees, whole/hundredth minutes.