They are called "dead zones" in certain areas of the oceans that are devoid of oxygen and therefore unable to sustain regular marine life. Dead zones are triggered by human activity and its enormous impact on nature.
The process is a direct consequence of the action of nutrients rich in nitrogen contained in the fertilizers used by farmers in their crops. The creation of dead zones begins when nitrogen from fertilizers and sewage stimulates the growth of photosynthetic plankton on the surface of coastal waters. Such nutrients, after being absorbed and carried by rivers, end up in the waters of coastal regions, very often in fishing areas.
