CASE STUDY: Gulf of Mexico Dead Zone

CASE STUDY: Gulf of Mexico Dead Zone

Kristi Hannam, SUNY-Geneseo

Poll

What do YOU think might be the reason why shrimp have disappeared from local waters?

• Overfishing has depleted shrimp populations.

• Pollution has killed off shrimp populations.

• Rising water temperatures caused by climate change have made the habitat inhospitable to shrimp.

• Hurricane Katrina (Aug 2005) destroyed all the shrimp and their habitat.

Open Ended

The four working hypotheses for the Dead Zone are:

-Hurricane Katrina (Aug 2005)

-Pollution

-Climate change

-Overfishing

Can you think of other hypotheses?

Multiple Choice

Which hypothesis does this graph NOT support?

• Hurricane Katrina

• Pollution

• Climate Change

• Overfishing

Poll

Which hypothesis does the evidence in this image support?

• Hurricane Katrina

• Pollution

• Climate change

• Overfishing

Locations go form the north to south.

Multiple Choice

What do these figures tell you about the runoff to the Mississippi River basin over time?

• Annual nitrate concentrations have increased over time.

• Stream flow has remained constant over time.

• The biggest source of nitrates is the area farthest from the Gulf of Mexico.

• Only A and C.

• A, B, and C are true.

And she recalled another figure...

Multiple Choice

What is the most likely source of nitrogen in runoff?

• Fossil fuel emissions.

• Organic matter.

• Leaching of nitrates from nitrification.

• Fertilizer runoff.

Poll

When the freshwater river flows into the saltwater Gulf, what do you predict will happen?

• The freshwater and the saltwater will mix, lowering the overall salinity of the Gulf.

• The warmer freshwater will sink to the bottom of the Gulf, and the colder saltwater will float above.

• The less dense freshwater will float on top of the more dense saltwater.

• The amount of freshwater entering the Gulf is so small compared to the total volume of the Gulf that there will be no noticeable effect of the freshwater input.

https://www.smm.org/deadzone/causes/dead-zone.html

Poll

Is there evidence of hypoxia in the Gulf of Mexico?

• Yes

• No

Poll

Does the evidence you’ve seen so far mean that climate change and overfishing are NOT to blame for the decline of the shrimp fishery?

• Yes

• No

Open Ended

Suppose you are on a government panel studying the Dead Zone problem. What recommendation(s) would you make for solving the problem of the Dead Zone?

Open Ended

Who should be responsible for fixing the problem, and what actions should they take?