Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
Hypoxic refers to an environment or condition that has low levels of dissolved oxygen, which can be harmful to aquatic organisms. It occurs when there is insufficient oxygen to support normal life functions.
Anoxic refers to an environment or condition completely devoid of dissolved oxygen. It is even more severe than hypoxia and can lead to the death of most aquatic organisms.
The oxygen sag curve represents the decrease in dissolved oxygen levels downstream from a pollution source. It shows how organic pollutants consume oxygen as they decompose, leading to hypoxia or anoxia if not properly managed.
Dead Zone: A dead zone is an area in a body of water where there is little or no dissolved oxygen, resulting in the death or displacement of marine life. Dead zones often occur due to excessive nutrient pollution from human activities like agriculture and sewage runoff.