Ocean Dead Zones Lead To Suffocating Consequences
More than 400 oxygen-deprived dead zones are abundant in the world seas and oceans, resulting in the wipeout of marine life, according to a report released by the World Resource Institute (WRI), a global resource and environmental research and analysis nonprofit organization. The number of dead zones throughout the world has doubled every decade since the ‘60s. Most dead zones appear in coastal shallow areas (between 20 and 100 feet in depth) and gulf waters.
Man-made pollutants trigger the growth of dead zones. They include agriculture fertilizer and sewage waste runoffs; as a result algae are overfed and overgrow. The overfeeding rapidly increases the natural life cycle of the aquatic plant. Because algae grow and die at a faster rate, coastal waters are invaded with decomposing plants disrupting marine life and their environment. During the algae decomposition phase, the plants submerges to the ocean floor “eating up” oxygen in the water, resulting in little to no oxygen - making it almost impossible for marine life to survive. The lack of oxygen destroys delicate marine habitat in which many organisms make their home. If there is no oxygen in the water, there are no fish, turtles, snails, et cetera, it is literally a desert in the ocean abandoned and empty with no life.
Dead zones do not happen overnight, much experience a progressive lack of oxygen. however, if the environment is increasingly harmful to marine life and nutrients continue to overpopulate (excessive amount of nutrients feed marine plants), the area become a permanent dead zone resulting in the death or migration of marine life. "Most fish and other marine animals have to move or die," said Janet Sprintall, a scientist at the Scripps Institution of Oceanography in La Jolla. "They cannot live in these low-oxygen conditions."
The world’s largest dead zone is in the Baltic Sea, which experiences lack of oxygen year-round. In the United States the largest dead zone is the Gulf of Mexico which covers more than 8,500 square miles. Its size fluctuates during the year; it becomes larger during the summer when floodwaters flush nitrogen-rich fertilizers down the Mississippi River ending at the Gulf of Mexico. When the nitrogen-rich fertilizers reach ocean waters they feed marine plants causing them to grow and multiply.
Unfortunately, the oxygen deprived zones are often ignored until they starts to affect larger creatures such as fish or lobsters, commonly consumed by humans. When oxygen severely decreases the natural food chain cycle that supports bottom feeders such as shrimp, clams and snails is disrupted. Ocean areas that lack oxygen force marine life to relocate or are left with no oxygen as a result they die. As a result, marine habitat is disturbed or destroyed and organisms in the ocean are no longer available to serve as a food sources to larger creatures higher up the food chain.
The death of fish and their food sources are the direct results these dead zones have on marine life. The indirect results are: changed migration patterns, reduction in healthy habitats, increased vulnerability to predation (a process where an organism “hunts” and feeds on its prey) and disruption of spawning (the fertilized eggs of aquatic animals).
The Black Sea and Baltic Sea have been severely affected by dead zones; most of their fisheries have either been eliminated or severely stressed.
Dead zones affect the ability of coastal communities to provide valuable services such as tourism, recreation, providing of fish and shellfish for local consumption, sport fishing, and commercial fishing. In addition, reduced oxygen levels may have dramatic consequences for coastal economies.
Fortunately, the effects might be reversible and the Black Sea is a great example. It was once the largest dead zone in the world; it had 26 commercially fish species in the 1960s, and in the 1980s it was down to just five. The growth of the Black Sea oxygen deprived zone was caused by the increase of agriculture in the former Soviet Union. However, it is no longer the largest dead zone in the world and it has been in “recovery” mode since the 1990s largely due to the massive reduction in fertilizer use.
The key solution, is to "keep fertilizers on the land and out of the sea," said Robert Diaz, an oceans expert at the US Virginia Institute of Marine Science, in a study released by the institute in 2008. “Scientists and farmers need to continue working together to minimize the transfer of nutrients from land to sea." Hopefully scientist and farmers can work together, therefore dead zones do not keep on doubling, but instead start decreasing each decade.
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