Gulf Oil Spill ESSM 651 1
Problem statements Introduction The gulf oil spill started on April 20, 2010 when an explosion occurred on the rig, killing 11 workers. The oil spill continued for months until the well was capped on July 15 of the same year. The estimated amount of oil that was spilled into the Gulf of Mexico can be up to 185 million gallons (http://pubs.acs.org/cen/news/88/i39/8839notw7.html). The delay in capping the well occurred due to the depth in which the well was located. With all of the oil spilled, it may take years to determine the exact damage the spill has on the environment as well as the economy in the Gulf States (Louisiana, Mississippi, Alabama, and Florida). This report is to determine the effects that the oil spill had on some selected factors in the region: sea turtles, shrimp, mottled ducks, crabs, and wetlands and to determine where the areas of concern are at with these factors. The objectives of this study is: 1) determine the areas in which these factors are located at, 2) determine the extent of the oil spill, and 3) determine the areas of concern for these factors when overlaying the oil spill upon them. Sea Turtles Five of the World s seven sea turtle species are located in the Gulf of Mexico: leatherback, hawksbill, green, loggerhead and Kemp s ridley, which are all either endangered or critically endangered (http://www.iucnredlist.org/). The sea turtles populations have decreased due to hunting, and destruction of their habitat. As of November 2010, official estimate that 609 sea turtles have died due to the oil spill (http://www.restorethegulf.gov/sites/default/files/documents/pdf/consolidated%20wildlife%20t able%20110210.pdf). The reason that sea turtles were chosen as a factor for this study is because they are an endangered species and any rapid decline in population numbers can lead to extinction in the wild. Mottle Ducks Mottle Ducks (Anas fulvigula) are a dabbling duck that resided along the Gulf States. The main difference between them and other ducks is that they do not migrate. Instead, they are residential year-round along the Gulf States. Also most of the mottled ducks in the world live along the Texas and Louisiana coast (http://magblog.audubon.org/oil-spill-wildlife-spotlightducks). Although they do not feed in salt water, with the extent of the spill unknown and the exact destruction unknown as well, if the oil spill does indeed reach the ducks fragile habitat, decline in the species is imminent. The reason that this species is a factor for this study is because they are already low in numbers, and since the population does reside in fragile habitats along the Gulf, and destruction of habitat due to the spill, can be damaging. Wetlands Wetlands are defined as areas that are inundated or saturated by surface groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions (http://water.epa.gov/lawsregs/guidance/wetlands/definitions.cfm). Wetlands are vital, and fragile ecosystem. They are also among the most productive ecosystems in the world, with many different varieties of wildlife. Also wetlands play an integral role in the ecology of a watershed, in that they host so many different species and also they are able to filter the water. 2
Wetlands along shorelines are very important in that they provide a buffer to erosion and potential hurricanes. They are declining at a fast rate due to destruction and human urbanization. There are two very large wetlands in the study area: the Louisiana wetlands and the Florida Everglades. If oil from the spill does reach these two large and fragile ecosystems, many species are at risk. I chose this as a factor because wetlands are very fragile and very important ecosystems along the Gulf States, and that if they end up becoming contaminated with oil, they may be destroyed beyond repair. Shrimp and Crab Species These two invertebrates are very important in American Seafood. In 2008, commercial fisherman in the Gulf of Mexico earned $659 million in total landing revenue (http://response.restoration.noaa.gov/book_shelf/1886_fish-stocks-gulf-fact-sheetv2.pdf). For the region, the oil spill can be very extensive. Gulf States landing of shrimp is the nation s highest with the 73% of the nations shrimp supply coming from the Gulf. The Gulf s brown and inland shrimp season started right at the time the Oil Rig exploded and began to spill oil. Not only did the production of the season take a spike, the number of shrimp may have declined as well. With adult shrimp dying due to contact with oil, postlarvae will be impacted as well, which will lead to lower numbers the following year. With a big portion of the economy in this region focused on commercial fishing, the economy might take years to rebound from this. Crabs are just as important to the region as shrimp are. The most important crab for the region economically is the blue crab. Louisiana brings in approximately 26 percent of the nations blue crab, which generates $32 million (http://response.restoration.noaa.gov/book_shelf/1886_fish-stocks-gulf-fact-sheetv2.pdf). The untimely occurrence of the oil spill occurred during the offshore spawn of these species. With the crabs being a bottom feeder, not only do they have to worry about being contaminated with oil, but also contaminated with dispersants that are being used to remove the oil. Once the crabs are contaminated, they could contaminate the whole food web (fish eats crab, bird eats fish), so the ecologically impact could damage or even destroy a whole food web. The reason why I chose these two as factors is because they are a very important species both ecologically and economically. If the oil spill does reduce these species numbers, they ecosystem as well as the economy of the region will suffer. Research methods The methodology that was used for this report was the Spatial Appraisal and Valuation of Environment and Ecosystems (SAVEE) method. This method uses the emycin algorithm to combine normalized data and bounds it between two extremes of -1 and +1. The more positive the number is at a location the more favorable the area is, whereas the more negative the value is at a given location, the more unfavorable the location is. Data for each state was merge together to create data for the whole region into one. Shapefiles were then converted to rasters, using straight line. This gave the distance of each factor. Data was then normalized to 20 miles. Factors were then individually entered into the emycin algorithm to determine the areas that were favorable and unfavorable. 3
Discussion and Conclusion Figure 1 represents the final output from the algorithm, which has all the factors (sea turtles, mottled ducks, wetlands, shrimp, and crab) data in it. The following figures show the same results but at a state coastline scale, so one can see the impact that it has for each state. Based off of the algorithm, the area along the eastern Louisiana, Mississippi, and Alabama and western Florida coast was impacted the most (Figure 2, 3, and 4 shows the impact at a statewide scale). Based off of these results, this area will be hit the hardest by the impact of the spill. This report only shows the impact that the spill will have on the factors that were put into the algorithm. This means that the area of impact can change depending on the factors that are involved. Also the oil spill location was only used. To make the algorithm more accurate, using a projected raster that showed where the oil spill will most likely be at will also show areas that can be impacted by the oil spill. Although this algorithm does show the areas of impact by the oil spill, I do not believe that it is accurately represented. Majority of the factors data was within the 20 miles from the coastline of each state. The normalizing of the data gave this distance for each factor a +1. This means that the area is very favorable. However when added the oil spill to the equation, the area might slightly decrease in value, but it still considered highly favorable. I do not agree with it. I believe that the oil spill trajectory should be weighted higher than all other factors. I believe this because once the oil is in a place; the area is no longer favorable but unfavorable. In conclusion, this method does show areas that are impacted by the Gulf oil spill. However I believe that it does not accurately shows the severity that each area is impacted. I believe that with altering the factors or getting a better understanding of the algorithm will improve the accuracy of this method. 4
Figure 1. Area of impact at region scale Figure 2. Louisiana area of impact 5
Figure 3. Mississippi and Alabama area of impact Figure 4. Florida area of impact 6