39: The Dead Zone

Question 1

What is a watershed?

Answer 1

an area of land that drains into a river (or a river system; set of rivers)

Question 2

What is the Mississippi river watershed?

Answer 2

the 4th largest in the word, it drains 32 states plus 2 Canadian provinces

Question 3

What is an estuary?

Answer 3

mouth of the river, the place where the freshwater of the river runs into the salt water of the ocean

Question 4

What are features of an estuary?

Answer 4

coastal ecosystems and biomes are incredibly productive
- complex food webs (a lot of organisms live there)
- gradient of salt concentrations

Question 5

What is the Gulf of Mexico?

Answer 5

it is home to many birds and fish, it is economically important

Question 6

What happened to the Gulf of Mexico?

Answer 6

it became a dead zone

Question 7

How did a large area of the Gulf of Mexico become a dead zone?

Answer 7

1. Mississippi river water carries nitrogen and phosphorus rich material (ex: fertilizer, urban runoff and sewage) into the Gulf
2. populations of microscopic organisms that feed on nitrogen boom (plankton)
3. overgrowth of algae/plankton
4. those organisms die and sink to the bottom, their decomposition depletes the oxygen in the water
5. algae die and decompose as bacteria feed on them, consuming a lot of oxygen
6. fish and other mobile sea creatures flee the low-oxygen zone
7. organisms that cannot flee die

Question 8

What is hypoxia?

Answer 8

low O2 levels

Question 9

What is anoxia?

Answer 9

absence of oxygen

Question 10

If the Dead Zone is caused by pollutants from the Mississippi river, during which season is it going to be at its worst?

Answer 10

summer!

Question 11

What can people do to prevent water pollution?

Answer 11

1. fertilize your garden with compost instead of commercial fertilizers
2. minimize use of pesticides
3. do not pour paints, solvents, motor oil, antifreeze down the drain or on the ground
4. do not flush unwanted medicines down the toilet