Dead zone

Definition

Dead zones are areas in oceans or large lakes where oxygen levels are so low that most marine life cannot survive. They are often caused by nutrient pollution leading to excessive algae growth, followed by decomposition which depletes oxygen.

5 Must Know Facts For Your Next Test

1. Dead zones are primarily caused by nutrient runoff from agriculture and wastewater.
2. The process leading to dead zones is called eutrophication.
3. Once established, dead zones can last for months or even years if conditions do not improve.
4. The largest dead zone in the United States is located in the Gulf of Mexico.
5. Dead zones can significantly impact local fisheries and biodiversity.

Review Questions

• What are the primary causes of dead zones?
• How does eutrophication lead to the formation of dead zones?
• What is the impact of dead zones on marine life and local economies?

Related terms

Eutrophication:

The process where water bodies receive excess nutrients that stimulate excessive plant growth.

Hypoxia:

A condition in which oxygen levels drop below what is necessary to sustain most animal life.

Nutrient Pollution: The presence of excess nutrients, primarily nitrogen and phosphorus, often from agricultural runoff or wastewater discharge, that leads to ecosystem imbalances.