1. Dead Zones

2. Dead Zones
Apply your understanding of the core ideas of population dynamics and resource use, as well as human impacts on Earth, to the issue of dead zones.
Apply understanding of watersheds and estuaries to a situation where abiotic and biotic factors are being changed.

3. Open your notebook to page 27
Let’s read the first two paragraphs.
Dead zone: an area or body of water where the water at the bottom has little or no dissolved oxygen. (underline this in the paragraph)
How are dead zones created?
Fertilizer run-off
Lots of nutrients added to water
Extra plankton die, sink, and are eaten by decomposers
Bacteria increases and uses all the dissolved oxygen available – other organisms died

4. Where does this watershed drain into?
Gulf of Mexico
Think back to our watershed activity…what all is included in a watershed?
Rivers, streams, lakes, groundwater, and run- off (from farms, factories, etc…)

5. Working at your table, take minutes to complete #s 1 and 2 on pages 27 and 28 of your notebook.
You are analyzing and interpreting two graphs.

6. 1a. What patterns did you notice?
As the streamflow increased, the total nitrogen input increased as well.

7. 1b. What do you think explains the patterns?

8. 1c. What pattern do you expect to see in the size of the dead zones in the Gulf of mexico? Explain why you expect to see these patterns.

9. 2a. What patterns do you notice?
Some years the nitrogen input and streamflow correlate with the size of the dead zones, in some years the correlation is not as clear.
There are likely other factors affecting the size of the dead zones.

10. 2b. Does the data in the graph match the prediction you made in step 2 about patterns in the size of dead zones in the Gulf of Mexico?

11. http://www. pbslearningmedia. org/resource/envh10. sci. life. eco
ultural-runoff-and-the-gulf-of-mexico-dead-zone/

12. What environmental impact does agricultural run-off have?
Creation of dead zones  causes aquatic animals to dies  impacts the food web of that ecosystem.
What economic impact does agricultural run-off have?
Fishermen rely on catching shrimp and fish for their livelihood
Increase run-off  decrease fish pops  less money to be made
Less money made  less money to invest back into community (houses, food, shopping)

13. What social impact does agricultural run-off have?
fewer fishermen being able to make a living  employment will decline  population growth will decline  poverty increases

14. Focus on bottom page 28 of notebook
At your table, read “Gulf of Mexico Dead Zone” on pages 28 and 29.
Answer the following question on the bottom of 29 after reading –
How do humans affect the size of dead zones?
Answer in complete sentences – refer to graphs, the video, and the reading to answer

15. Exit Slip
What are the abiotic and biotic factors that are affected in a dead zone? How do they differ from a healthy ecosystem?
How might an increase in the size of the dead zone in the Gulf of Mexico affect the red snapper fishery or other fisheries?

16. What are the abiotic and biotic factors that are affected in a dead zone? How do they differ from a healthy ecosystem?
In a dead zone abiotic factors that are affected include oxygen levels and the amount of nitrogen. The oxygen levels are much lower than in a healthy ecosystem and the nitrogen levels are much higher. The biotic factors that are affected are the amount of plankton, bacteria, and fish and other organisms. The plankton increase because of the higher nitrogen levels. When the plankton die they feed the bacteria, which increase and consume more oxygen. This causes the fish and other organism to either die or leave the ecosystem. In a healthy ecosystem the plankton do not increase like this, so the bacteria stay at healthy levels leaving plenty of oxygen for the fish and other organisms.

17. How might an increase in the size of the dead zone in the Gulf of Mexico affect the red snapper fishery or other fisheries?
An increase in the dead zones might cause a decrease in the red snapper fishery, or other fisheries in the Gulf of Mexico, because there would not be enough oxygen for the fish to survive. This would mean fewer fish, and that the fisherman would not have as much to catch so they would make less money.