The Gulf Of Mexico
The Gulf of Mexico is home to the second largest zone of coastal hypoxia, the largest being the Baltic Sea. The hypoxic conditions had began to appear around last century and had become amplified since the 1950's when the amount of nitrate that was flowing from the Mississippi River had tripled. The oxygen depleted waters are found near the outflows of the Mississippi and Atchafalaya Rivers. It occurs between the inner and mid-continental shelf of the northern area of the Gulf, covering approximately 6000-7000 square miles and expands westwards to the upper Texas coast. In this particular location, there are many factors that contribute to the formation of the dead zone, such as water discharge, wind mixing and regional circulation.(https://serc.carleton.edu/microbelife/topics/deadzone/visited 2/03/2014)
Figure 6:
Figure 6 is a map from NOAA that graphs the amount of dissolved oxygen in waters in the Gulf Of Mexico using contours on June 11 to July 16 2008. In the areas near the coast of Louisiana, the map shows that the dissolved oxygen level is around 0.00-1.00 mg/L, referring to the legend on the right side of the map. This indicates that the rate of marine life perishing in that area is noticeably higher than other places. The highly affected areas also seem to be more adjacent to the coast and to the mouth of the Mississippi River, which suggests that severe hypoxic conditions may be influenced by activities associated with the mainland areas around the Mississippi River. On the other hand, map also shows that the areas along the coast of Texas and the waters away from the mainland seem less severe, only having dissolved oxygen levels of around 5.0 to 6.5 mg/L.
Steve Machan. (2010). What is Causing Ocean Life to Beach Itself in an Attempt to Breathe?. http://www.technorati.com/lifestyle/green/article/what-is-causing-ocean-life-to1. Last accessed 20th March 2014.
Figure 6 is a map from NOAA that graphs the amount of dissolved oxygen in waters in the Gulf Of Mexico using contours on June 11 to July 16 2008. In the areas near the coast of Louisiana, the map shows that the dissolved oxygen level is around 0.00-1.00 mg/L, referring to the legend on the right side of the map. This indicates that the rate of marine life perishing in that area is noticeably higher than other places. The highly affected areas also seem to be more adjacent to the coast and to the mouth of the Mississippi River, which suggests that severe hypoxic conditions may be influenced by activities associated with the mainland areas around the Mississippi River. On the other hand, map also shows that the areas along the coast of Texas and the waters away from the mainland seem less severe, only having dissolved oxygen levels of around 5.0 to 6.5 mg/L.
Steve Machan. (2010). What is Causing Ocean Life to Beach Itself in an Attempt to Breathe?. http://www.technorati.com/lifestyle/green/article/what-is-causing-ocean-life-to1. Last accessed 20th March 2014.
What Caused The Dead Zone?
Human activity has been a major component of the formation of the Gulf Of Mexico dead zone. The actions of humans had dramatically increased the flux of phosphorus and nitrogen from the Mississippi River. Nutrient enrichment of mostly phosphorous and nitrogen, which are caused by the various watersheds and drainage basins within the Mississippi River, cause algal blooms to develop, the food chain to alter and ultimately deplete dissolved oxygen in the area. The source of the input of these elements are the major farming states in the Mississippi River Valley. The fertilisers, soil erosion, animal waste and sewage through the act of farming on the banks of the river caused increased amounts of nitrogen and phosphorus to enter the river. The input of these nutrients could also originate from the addition of sediments, soil and rocks from the atmosphere or the advection of deeper nutrient-rich oceanic waters.
Rabalais, N, (Turner, R, & Wiseman, W 2002, 'GULF OF MEXICO HYPOXIA, A.K.A. "THE DEAD ZONE"', Annual Review Of Ecology & Systematics, 33, p. 235, Academic Search Premier, EBSCOhost, viewed 5 March 2014.)2
Rabalais, N, (Turner, R, & Wiseman, W 2002, 'GULF OF MEXICO HYPOXIA, A.K.A. "THE DEAD ZONE"', Annual Review Of Ecology & Systematics, 33, p. 235, Academic Search Premier, EBSCOhost, viewed 5 March 2014.)2
Emily Tripp. (2012). All You Need to Know About the Gulf of Mexico ‘Dead Zone’ Read more: http://marinesciencetoday.com/2012/10/21/all-you-need-to-know-about-the-gulf-of-mexico-dead-zone. Last accessed 24th March 2014.
Figure 7:
Figure 7 depicts a map which shows the several locations of the cities and farms located around the Gulf Of Mexico area. It mainly shows the cities and farms that situated near to the Mississippi basins and the tributaries that branch off from them. From this image, we can interpret that the hypoxic zones in the Gulf Of Mexico area are mainly caused by human activities, since the tributary networks are all linked to the main Mississippi River, which is the main source of phosphorus and nitrogen input. The active use of farms and cities along the banks of water bodies provide rich sources of phosphorus and nitrogen and they all share one common exit through the Gulf of Mexico as illustrated in the figure above. It can be concluded that the uses of cities and farms along the tributaries are a major aspect regarding the cause of the Gulf of Mexico dead zone.
Figure 7:
Figure 7 depicts a map which shows the several locations of the cities and farms located around the Gulf Of Mexico area. It mainly shows the cities and farms that situated near to the Mississippi basins and the tributaries that branch off from them. From this image, we can interpret that the hypoxic zones in the Gulf Of Mexico area are mainly caused by human activities, since the tributary networks are all linked to the main Mississippi River, which is the main source of phosphorus and nitrogen input. The active use of farms and cities along the banks of water bodies provide rich sources of phosphorus and nitrogen and they all share one common exit through the Gulf of Mexico as illustrated in the figure above. It can be concluded that the uses of cities and farms along the tributaries are a major aspect regarding the cause of the Gulf of Mexico dead zone.
Effects
The major effect of the hypoxic areas in the Gulf Of Mexico dead zone is caused by Eutrophication, which is an increase in the rate of supply of organic matter in an ecosystem. This causes many concerns for the economy and the health of marine life in these areas. Hypoxic areas only have a small supply of oxygen since nutrient enrichment depletes most of the oxygen in that area when the dead zone had formed. This indicates that it could only support significantly fewer living organisms, such as fish, because they require oxygen to survive and it leads to the numerous amounts of marine life to perish.
Among the dying population of marine life, are fish and crustaceans, which are considered to be an extremely valuable resource. Since marine creatures have drastically disappeared in numbers, it creates huge negative impacts on seafood production and recreation. Fishing industries have suffered economically in huge measures, due to the limited amount of supplies in the ocean, since there are fewer marine life and the risk of causing extinction through over fishing have increased. The Gulf of Mexico's seafood industry accounts for more than 40 per cent of the nations seafood and the deficiency of these industries could cause devastating impacts on the economy. Some fish and crustaceans have migrated further outwards into the ocean due to the lack of oxygen in the hypoxic area though. This suggests that it is more difficult for seafood companies to gather sufficient resources to not become heavily affected economically.
The lack of marine life in the Gulf of Mexico could create more dents in the economy relating to recreational activities. The Gulf Of Mexico resembles an ideal spot for fishing. Whether it is fishing for food or sport fishing, the lack of fish due to depleted oxygen levels have made recreational fishing less popular. This can create a negative impact on the economy in various ways. There are several fishing businesses around the Gulf that provide fishing gears and supplies and with recreational fishing becoming unpopular, their businesses have also fallen in popularity. Another possibility is the reduction of tourism. Recreational activities are an important aspect of tourism and since recreational fishing have become less viable, it is possible for the amount of tourists visiting the Gulf to decrease, creating a dent in the economy.The Nature Conservancy.
(2014). The Gulf "dead zone" threatens seafood production, recreation and marine life. - See more at: http://www.nature.org/ourinitiatives/regions/northamerica/areas/gulfofmexico/explore/gulf-of-mexico-dead-z. Last accessed 24th March 2014.
Among the dying population of marine life, are fish and crustaceans, which are considered to be an extremely valuable resource. Since marine creatures have drastically disappeared in numbers, it creates huge negative impacts on seafood production and recreation. Fishing industries have suffered economically in huge measures, due to the limited amount of supplies in the ocean, since there are fewer marine life and the risk of causing extinction through over fishing have increased. The Gulf of Mexico's seafood industry accounts for more than 40 per cent of the nations seafood and the deficiency of these industries could cause devastating impacts on the economy. Some fish and crustaceans have migrated further outwards into the ocean due to the lack of oxygen in the hypoxic area though. This suggests that it is more difficult for seafood companies to gather sufficient resources to not become heavily affected economically.
The lack of marine life in the Gulf of Mexico could create more dents in the economy relating to recreational activities. The Gulf Of Mexico resembles an ideal spot for fishing. Whether it is fishing for food or sport fishing, the lack of fish due to depleted oxygen levels have made recreational fishing less popular. This can create a negative impact on the economy in various ways. There are several fishing businesses around the Gulf that provide fishing gears and supplies and with recreational fishing becoming unpopular, their businesses have also fallen in popularity. Another possibility is the reduction of tourism. Recreational activities are an important aspect of tourism and since recreational fishing have become less viable, it is possible for the amount of tourists visiting the Gulf to decrease, creating a dent in the economy.The Nature Conservancy.
(2014). The Gulf "dead zone" threatens seafood production, recreation and marine life. - See more at: http://www.nature.org/ourinitiatives/regions/northamerica/areas/gulfofmexico/explore/gulf-of-mexico-dead-z. Last accessed 24th March 2014.
Remediation
The Gulf Of Mexico dead zone problem needs to be remediated, because it has become a serious issue in terms of damaging the economy and marine wildlife. The crucial thing to reducing the Gulf dead zone is to target its sources. The hypoxic location is generally caused by farming on the banks of tributaries that branch off from the Mississippi River, so by addressing the farming situations, we can effectively minimise the dead zone.