Dead Zones in Oceans

A dead zone is an area that has a concentration of oxygen in the water that is so low that animals cannot live there because they suffocate when they stick around too long.

One of the largest dead zones is on the Gulf of Mexico. This dead zone fluctuates every spring because that is when runoff from farmers crops and fertilizers wash away into the Gulf. In 2014 the dead zone on the Gulf of Mexico reached the size of Connecticut. This is not only detrimental to the animals that live in that ecosystem, but it costs the United States $82 million dollars every year due to reduced tourism and fishing yield. No one wants to visit a place that smells like rotting fish. This is similar to what happened at Salton Sea. The Gulf of Mexico is an example of a time where human interference was the cause of this dead zone, but there are places where they occur naturally. There are over 200 dead zones in the United States. Because of our human pollution we are creating more dead zones faster than nature can fix them. Worldwide there are over 400 known dead zones, this means that in the United States we have half of all the dead zones in the world. This should be a sign of how badly we need to change in the United States. Sewage, not fertilizer, is a main issue in South America and Africa. This is better because we know how to create a proper sewage and wastewater treatment plan in a city so this problem can be fixed once the proper funds are moved towards fixing it. Another contributor to dead zones is airborne nitrogen pollution. The main sources of nitrogen pollution come from vehicles and power plants.

Climate change has aided to the creation of many dead zones across the globe. If the water continues to increase, it will only create more dead zones because the higher the temperature of the water the less dissolved oxygen it can hold. Scientists have found that by the end of the century areas with severe oxygen deficiency will see a 2-degree Celsius increase which will only worsen existing problems and potentially increase the perimeter of these dead zones. Many hypoxic zones are created or enhanced by humans. Another way that humans can create dead zones is through wastewater that is piped into rivers which eventually hit the oceans. These excess nutrients create algae blooms which use a lot of the dissolved oxygen in the water leaving nothing for the animals that live there causing them to die. When things die in the water they decompose, which uses more dissolved oxygen in the water and their bodies provide even more nutrients on which the algae can grow. This algae blooming issue is more common to areas with still water such as lakes, so it is harder for this to occur in oceans where the water moves around. If farmers used less fertilizer then this would not create as big of a problem.

http://oceanservice.noaa.gov/facts/deadzone.html

http://www.onearth.org/earthwire/devil-deep-blue-sea

http://www.teachoceanscience.net/teaching_resources/education_modules/dead_zones/learn_about/