thanks largely to fertilizer runoff from farms and pond leakage from fish farms, coastal waters around the world are effectively dead - that is, they no longer contain enough oxygen to support life.although the area affected is small compared to total ocean volume, the affected areas are prime fisheries. also, many folks that have come into contact with water from the dead zones have developed skin lesions and other illnesses.
unfortunately, unless we push the dept. of agriculture to limit the amount and kinds of fertilizers that commercial farms can use - which the current administration is resisting - the dead areas will continue to grow at their current rate, doubling in size every 10 years.