Definition of the word dead zone

The term "dead zone" originally referred to an area in naval warfare where the strong magnetic fields from nearby ships could interfere with the navigational equipment of other ships, making it difficult or impossible to determine their location. This area was known as a "magnetic dead zone." As marine research advanced, the term "dead zone" was also applied to areas in bodies of water where oxygen levels are so low that fish and other marine life cannot survive. These areas are often caused by excess nutrient pollution, which leads to an overgrowth of algae and bacteria that consume the oxygen in the water. The resulting "dead zones" can be hundreds of square miles in size and last for several weeks or even months. The increasing prevalence of these underwater dead zones, which now occur in numerous coastal areas around the world, has raised concerns about the ecological health of our oceans and the impact on local fishing industries and surrounding ecosystems.