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Dead Zone

Dead Zone:

National Oceanic and Atmospheric Administration (NOAA) is forecasting an above-average summer “dead zone” in the Gulf of Mexico covering approximately 5,827 square miles.

  • The term “dead zone” or “hypoxia” refers to low-oxygen areas in the world’s lakes and oceans.
  • Because most organisms need oxygen to live, few organisms can survive in hypoxic conditions.
  • That is why these areas are called dead zones.
  • Hypoxic zones can occur naturally, but human activities can also lead to the creation of new dead zones or the enhancement of existing ones.
  • Dead Zone occurs as a result of eutrophication, which happens when a body of water is inundated with too many nutrients, such as phosphorus and nitrogen.
  • At normal levels, an organism called cyanobacteria – or blue-green algae – feeds on these nutrients.
  • With too many nutrients, it can cause an overgrowth of algae in a short period of time, also called algae blooms.
  • Dead zones form when the algae die, sink to the bottom, and are decomposed by bacteria—a process that strips dissolved oxygen from the surrounding water.
  • Dense algal blooms also block sunlight, which prevents underwater grasses from growing.
  • In turn, the animals that depend on these grasses for food and shelter suffer, as well.
  • Human activities mainly cause these excess nutrients to be washed into the ocean, which is why dead zones are often located near inhabited coastlines.