Coastal Dead Zones: Causes of Coastal Dead Zones

More and more dead zones are plaguing the World. Although, these dead zones are not horrendous. These zones are such areas of coastal water bodies that are deprived of oxygen. Hence, most of the aquatic life has ceased to exist in such areas. Read on to know more about these coastal dead zones.

A prime example is the

Gulf of Mexico

which experiences a dead zone every summer. At this time, this area is bereft of any aquatic life including fishes. This dead zone is expanding over the years and now spans nearly 21,000 square kilometers. Another example is the

Chesapeake bay

. From the 70s, a formation of dead zone is an yearly event. This effects nearly 40% of the bay on some occasions.

Causes of Coastal Dead Zones

In the coastal regions, what exactly is killing the fish and other aquatic organisms? The blame goes to certain complex events. But it begins with farmers keen to grow more crops to provide for the growing world’s population.

The fertilizer’s helps crop to grow by providing nutrients, but when this excess fertilizer is washed off the fields along with rain water into the rivers and seas, the nutrients promote the growth of microscopic plants in the water bodies. A massive bloom of algae and phytoplanktons can occur due to the high concentrations of phosphorus and nitrogen in the water. This deprives the dissolved oxygen levels in the water.

This causes an interference in the aquatic life conditions. The aquatic organisms like fish abandon the dead zones by swimming away from such low oxygen areas.

Coastal Dead Zones in the U.S.

43% of the known dead zones of the world are present in the US coastal regions

. The world’s 2nd largest dead zone is the Gulf of Mexico. This severely disrupts the productivity of fishery which provides nearly 18% of the annual US catch.

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