Abstract
The ever-growing increase in deep-sea oil explorations in the Gulf of Mexico (GoM) has been raising concerns with regard to future oil spills. Major oil spills in the GoM such as the Deepwater Horizon (DWH 2010) and the Ixtoc 1 (1979) resulted in extensive pollution of the pelagic, sea-floor, and coastal ecosystems. Oil spill transport and fate models are effective tools which allow a spatiotemporally explicit reconstruction of oil spills, while accounting for key processes such as evaporation, sedimentation, biodegradation, and dissolution. Oil transport data can be fed into an ecosystem model to help estimate system-scale changes in biodiversity and impacts on the delivery of ecosystem services. The increase in deep-sea oil-drilling endeavors warrants an evaluation of the potential outcomes and effects of oil spills. However, each spill scenario is a complex 4-D problem, spanning over wide spatiotemporal dimensions, affecting various media (water, sediments, coast, air); hence it is difficult to effectively evaluate the differences between various oil spill scenarios.
In the current chapter, we examine quantifiable variables, which enable an effective comparison of the outcomes of four different scenarios: the DWH (DB_control), the DWH occurring during the fall (DB_Fall), east GoM scenario (DB_AL2), and west GoM scenario (DB_AL3). Specifically, we evaluate the total area and volume of oil-affected waters, the total water area and volume affected by toxic oil concentrations, the length of the shoreline affected by oil, and the total area of the sedimented oil. The oil transport model is coupled to Atlantis, a biogeochemical ecosystem model, to examine changes in the ecosystem biota. The depth and location of the oil vary with each scenario and so affect different habitats, species, and life stages. We consider relative impacts on pelagic and demersal food webs, shifts in age structure, changes in diet, and impacts on the sustainability of exploited species. We report the differences between the different oil spills and discuss their implications. Overall, the results differed slightly and not significantly between the four scenarios, ranked from most to least impactful: DB_AL2 > DB_control > DWH_Fall > DB_AL3. This work suggests that a “DWH” occurring at a different time or place in the GoM would result in impact fairly similar to that occurred during the actual DWH. This is relevant given the extensive petroleum-related activity in the GoM.