Dead Zones baMEL

The Dead Zones baMEL asks students to investigate whether and how aquatic dead zones may be repaired. A dead zone is an area of water that is low in oxygen. Aquatic life cannot survive in a dead zone.

The Models

Model A: We should balance the use of nutrients in agriculture and communities. It is important to eliminate dead zones and the damage they cause.
Model B: Agricultural science and engineering solutions can reduce the damage caused by nutrient use. This can reduce the impacts caused by dead zones.
Model C: The use of nutrients that create dead zones can provide benefits that make up for the harm they cause.

Student Handouts


Lines of Evidence

Evidence #1: Methods to maintain healthy nutrient levels in bodies of water do not always work. Water nutrient levels return to normal when human overuse of fertilizer stops.
Evidence #2: Over the past 50 years, the number and the size of dead zones have increased. Over the same time, fertilizer use has also increased.
Evidence #3: Eutrophication can increase fish populations. More algae means more food for fish to grow and reproduce. Fish will die when oxygen in water goes down.
Evidence #4: Fertilization and soil tillage helps to grow healthy crops. Efficient farming practices can help avoid excess fertilization and runoff into bodies of water.
Evidence #5: Algae blooms change the amounts of dissolved carbon and oxygen, and other toxins, in seawater. These changes can harm marine organisms.
Evidence #6: Farming, forestry, and fishing practices can be part of a region's economy. The health of these practices can impact the economy in both positive and negative ways.
Evidence #7: Marine life needs dissolved oxygen in water to live. As oxygen levels decrease in water, fewer and fewer organisms can survive. Dead zones occur when levels of dissolved oxygen in the water fall below 2 milligrams per liter (mg/L).
Evidence #8: Not all dead zones are caused by farming. Urbanization and overfishing can also cause dead zones.


Student Handouts