Hypoxia Endangers Biodiversity
like clams, oysters, corals, sponges etc. who have very important roles by mostly inhabiting the bottom of the food chain. (14)There are also endangered species such as certain kinds of sea turtles and dolphins who are in need of a safe, well balanced habitat in order to stabilize their dwindling populations to evade extinction; such an environment the Gulf of Mexico once embodied.
Why past tense? 1972 was the year of the first documentation of a hypoxic zone in the Gulf of Mexico (10). It has then grown to cover about 6,000 to 7,000 square miles in the last few years. (3) Every summer brings an increase in the zone’s area as a result of runoff nutrients in the freshwater from the Mississippi River; these nutrients consist of fertilizers from agriculture, golf courses and homes, eroded soil, animal manure and discharges from sewage treatment plants. (10) All of the watersheds within the Mississippi River Basin encompass a large percentage of the U.S. and therefore are a large percentage of the population are contributing to the growth of the dead zone in the Gulf without even realizing it. This is because the freshwater from the Mississippi River is less dense and warmer than the water it converges with in the Gulf and so stays on the surface along with the nutrients it brought from land which prohibits the mixing of the oxygenated surface water and the oxygen deficient water further down. (10) Nitrogen and phosphorus from the pollutants in the surface water create vast algae blooms which depletes the dissolved oxygen in the area even further, a process known as eutrophication (3).
With these combined processes severely exhausting the oxygen supply in the water, the species that inhabit the Gulf in the area closest to the Mississippi River (the location of the dead zone) start to die off if they do not have the ability to migrate to a different location. Those who are affected first by the oxygen depleted water are the invertebrates because they have limited mobility which causes a reduction in fish populations because of the loss of their prey and therefore affecting the food chain as a whole. Coastal state economies can be greatly impacted by the lack of revenue created from the fishermen who have a harder time catching fish which impacts the seafood industry as well. (3). The over 15,000 recorded species known to the Gulf become at risk for population shortages because of the significant loss of the invertebrates who make up the bottom of the food chain.
The impacts of the dead zone in the Gulf of Mexico adversely affect the very nation who play a role in its creation. Such a fact is reason enough to support local governance over ecosystem centric coastal zone management as well as initiatives one can take on personally to help reduce emitted pollutants to the Mississippi river. (2) The Gulf of Mexico may not be able to return to it’s original state before the dead zone in the foreseeable future, but the zone itself can be reduced if action is taken today. See our solutions page for more ways to help.
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