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It has often been said that generals prepare for the next war by re-fighting the last. The Deepwater Horizon (DWH) oil spill was unlike any previous – an underwater well blowout 1,500 meters deep. Much has been learned in the wake of DWH and these lessons should in turn be applied to both similar oil spill scenarios and those arising from “frontier” explorations by the marine oil industry. The next deep oil well blowout may be at 3,000 meters or even deeper. This volume summarizes regional (Gulf of Mexico) and global megatrends in marine oil exploration and production. Research in a number of key areas including the behavior of oil and gas under extreme pressure, impacts on biological resources of the deep sea, and the fate of oil and gas released in spills is synthesized. A number of deep oil spills are simulated with detailed computer models, and the likely effects of the spills and potential mitigation measures used to combat them are compared. Recommended changes in policies governing marine oil exploration and development are proposed, as well as additional research to close critical and emerging knowledge gaps. This volume synthesizes state-of-the-art research in deep oil spill behavior and response. It is thus relevant for government and industry oil spill responders, policy formulators and implementers, and academics and students desiring an in-depth and balanced overview of key issues and uncertainties surrounding the quest for deep oil and potential impacts on the environment.



Correction to: Linking Abiotic Variables with Macrofaunal and Meiofaunal Abundance and Community Structure Patterns on the Gulf of Mexico Continental Slope

The book was inadvertently published without including the name of Michael G. Reuscher as a co-author of Chapter 5.
Paul A. Montagna, Jeffrey G. Baguley, Michael G. Reuscher, Gilbert T. Rowe, Terry L. Wade

Part I


Chapter 1. Introduction to the Volume

Ultra-deep water production of oil and gas – from depths greater than 1 mile (1500 m) – comprises an ever-increasing proportion of the world’s supply of hydrocarbons. In the Gulf of Mexico, ultra-deep production now exceeds that from shallower waters. The ultra-deep domains of the world’s oceans are home to unique and highly sensitive communities of animals, are characterized by extremes in environmental conditions (low temperatures, high pressures), and are exceedingly challenging regions in which to work safely. Deepwater Horizon (DWH) was the world’s first and largest ultra-deep water well blowout and likely not the last. In the wake of that incident, scientific research and industrial development have been focused to better understand the ultra-deep domain, to lessen the likelihood of accidents there, and to better respond to future incidents. This volume summarizes trends in the development of ultra-deep drilling, synthesizes the state of knowledge relevant to ultra-deep oil spill prevention and response, and contrasts the effects of simulated ultra-deep spills in the frontier regions of the Gulf and elsewhere. Recommendations for additional research and public policy changes to lessen the likelihood and impacts of future spills and to improve oil spill response are provided.
Steven A. Murawski, Cameron H. Ainsworth, Sherryl Gilbert, David J. Hollander, Claire B. Paris, Michael Schlüter, Dana L. Wetzel

Chapter 2. Deepwater Oil and Gas Production in the Gulf of Mexico and Related Global Trends

The marine oil industry in the Gulf of Mexico (GoM) began in 1938 with the construction of the first oil well platform built in 4 meters of water, a mile off the Louisiana coast. The Mexican marine oil industry began in the 1950s with exploration and low-level production off the city of Tampico in the state of Tamaulipas. The discovery of the massive Cantarell oil field off Campeche in 1976 led to rapid expansion of the Mexican industry, surpassing US production of GoM-derived oil. Total annual oil production from the GoM peaked in 2003 at 1.6 billion barrels, but has since declined to about 1.2 billion barrels. Production at the Cantarell field peaked in 2004 and has since declined by 90%. Both the US and Mexican oil industries have focused more recently on deepwater plays to support production. The US oil production by lease depth showed a steady offshore migration through the 1990s but a dramatic rise in ultra-deep (e.g., ≥1500 m water depth) production beginning in the 2000s. In 2017, 52% of US oil production was from ultra-deep wells. Beginning in 2013, Mexico liberalized its policies to allow international cooperative ventures for exploration and production, particularly focusing on deepwater sources. Several large discoveries off Mexico since 2015 portend higher offshore production in the 2020s when these fields come online. In the US GoM, marine-derived natural gas production has declined by 79% since 1997, to about 1 trillion ft3 in 2017, reflecting rapid increases in land-based gas sources from hydraulic fracturing, which are less expensive to produce that marine-derived gas. Over the next decade, shallow-water sources of oil and gas in the US GoM will be phased out or reduced in importance as additional ultra-deep sources are developed. In the US GoM these include plays in depths to 3000 m and potentially deeper off Mexico. Ultra-deep sources occurring in the “Golden Triangle” between West Africa, Brazil, and the GoM will likely dominate global ultra-deepwater production, but other frontier regions will doubtlessly be explored. The inherent risks of catastrophic well blowouts at extreme depths will increase as the productivity of oil facilities increases exponentially with water depth.
Steven A. Murawski, David J. Hollander, Sherryl Gilbert, Adolfo Gracia

Chapter 3. Spilled Oil Composition and the Natural Carbon Cycle: The True Drivers of Environmental Fate and Effects of Oil Spills

Rachel Carson’s 1962 landmark book, Silent Spring, describing the toxic effects of the persistent organic pesticide, DDT, was instrumental in bringing awareness to the notion of environmental pollution (Carson, Silent spring. Houghton Mifflin, Boston, 1962). This work was a catalyst that began the advancement of the global environmental pollution movement and the concern for persistent chemical pollutants (POP). By intentional design, POPs are chemically nonreactive and are resistant to degradation in aerobic environments. It is important to realize that oil pollution and toxicity derived from the polycyclic aromatic hydrocarbon (PAH) components in crude oil are fundamentally different from the chemistry of persistent organic pollutions and its bioaccumulation and magnification that were learned in the 1960s and 1970s. Petroleum hydrocarbons are not stable; they are, in fact, quite reactive in aerobic environments via microbial (Varjani, Bioresour Technol 223:277–286, 2017; Atlas and Hazen, Environ Sci Technol 45:6709–6715, 2011; Salminen et al., Biodegradation 15:29–39, 2004; Widdel and Rabus, Curr Opin Biotechnol 12:259–276, 2001) and photochemical (D’Auria et al., J Hazard Mater 164:32–38, 2009; Plata et al., Environ Sci Technol 42:2432–2438, 2008; Garrett et al., Environ Sci Technol 32:3719–3723, 1998; Overton EB, Laseter JL, Mascarella SW, Raschke C, Nuiry I, Farrington JW (1980) Photochemical oxidation of IXTOC I oil, pp 341–383. In: Proceedings of symposium on preliminary results from the September 1979 Researcher/Pierce IXTOC I Cruise. Key Biscayne, Florida, June 9–10, 1980, NOAA Office of Marine Pollution Assessment, Boulder, CO) oxidations. To understand the implications of oil spills, we need to recognize that we are dealing with the reduced form of a pollutant that can readily react in most of the environments. The goal of this chapter is to present the dynamics of an oil spill from the molecular level with a description of the carbon cycle, the role of photosynthesis, diagenetic production of oil, its ultimate conversion back to carbon dioxide, and the fundamental carbon cycle processes in environmental chemistry. Only by understanding what happens chemically to spilled oil can we accurately predict and understand the biological consequences of these spills and the harm done by exposures to hydrocarbons from oil.
Edward B. Overton, Dana L. Wetzel, Jeffrey K. Wickliffe, Puspa L. Adhikari

Part II


Chapter 4. An Overview of the Geologic Origins of Hydrocarbons and Production Trends in the Gulf of Mexico

The Gulf of Mexico (GoM) region is one of the most important hydrocarbon-producing sedimentary basins in the world. Triassic rifting leads to formation of this small ocean basin characterized by the accumulation of thick salt deposits followed by a thick succession of continental- and marine-derived deposits that combined to generate and trap abundant hydrocarbons. This chapter presents a very brief overview of factors related to hydrocarbon accumulation and production trends in US waters. The offshore GoM has been producing from shelf to deep water for the past ~70 years. Ultra-deep-water drilling was reached in the late 1980s and progressed to depths near 3000 m by the 2000s. Although the extraction of the GoM’s oil and natural gas is in its mature phase, studies indicate that oil and gas reserves are significant and that the GoM will be producing for many decades into the future.
Stanley D. Locker, Albert C. Hine

Chapter 5. Gulf of Mexico (GoM) Bottom Sediments and Depositional Processes: A Baseline for Future Oil Spills

The deposition/accumulation of oil on the seafloor is heavily influenced by sediment/texture/composition and sedimentary processes/accumulation rates. The objective of this chapter is to provide a baseline of Gulf of Mexico sediment types and transport/depositional processes to help guide managers where oiled sediments may be expected to be deposited and potentially accumulate on the seafloor in the event of a future oil spill. Based solely on sediments/processes/accumulation rates, regions most vulnerable to oil deposition/accumulation include the deep eastern basin, followed by the western/southwestern basin, and north and west continental margins. The least vulnerable regions include the northwest Cuban shelf and the carbonate-dominated west Florida shelf and Campeche Bank. This is intended to be used as a general, “first cut” tool and does not consider local variations in sediments/processes.
Gregg R. Brooks, Rebekka A. Larson, Patrick T. Schwing, Arne R. Diercks, Maickel Armenteros, Misael Diaz-Asencio, Adrian Martínez-Suárez, Joan-Albert Sanchez-Cabeza, Ana C. Ruiz-Fernandez, Juan Carlos Herguera, Libia H. Pérez-Bernal, David J. Hollander

Chapter 6. Benthic Faunal Baselines in the Gulf of Mexico: A Precursor to Evaluate Future Impacts

This chapter provides a comparison between recently developed, post-oil spill baseline measurements throughout the Gulf of Mexico (GoM) and previous, pre-oil spill baselines for benthic foraminifera, meiofauna, and macrofauna for areas impacted by the Deepwater Horizon (2010) and Ixtoc 1 (1979–1980) oil spills. This comparison will provide two primary outcomes: (1) assessment of any lasting changes in benthic faunal assemblages caused by the Deepwater Horizon and Ixtoc 1 oil spills in the Gulf of Mexico and (2) augmentation of pre-oil spill baselines or establishment of “new normal” post-oil spill baseline measurements that can be utilized to quantitatively assess impact, response, and recovery of benthic fauna in the event of a future oil spill.
Patrick T. Schwing, Paul A. Montagna, Maria Luisa Machain-Castillo, Elva Escobar-Briones, Melissa Rohal

Chapter 7. Linking Abiotic Variables with Macrofaunal and Meiofaunal Abundance and Community Structure Patterns on the Gulf of Mexico Continental Slope

The Deep Gulf of Mexico Benthos (DGoMB) program was designed to determine patterns of abundance and diversity of meiofauna and macrofauna in the northern Gulf of Mexico continental slope between 300 m and 3700 m depth. Abundance of all taxa was significantly influenced by the particulate organic carbon (POC) flux. The abundance of meiofauna, macrofauna, crustaceans, and mollusks increased with increasing clay content, but clay had no significant effect on harpacticoid or polychaete abundance. Polychaete diversity was significantly correlated to POC flux, but mollusk diversity was correlated to sediment properties. Polychaetes had the highest average abundance and species richness. Harpacticoids were the least abundant of the four taxa, but had the highest values of Hill’s diversity index and Pielou’s evenness index. Harpacticoids and Crustaceans had high species turnover rates, resulting in low similarities of the respective faunas between sampling stations, whereas mollusks and polychaetes were more similar between different sampling stations. Overall, there were interannual differences in abundance patterns of meiofauna and macrofauna, similar community structure patterns among the taxa, and unique distributions of diversity with respect to depth and longitude.
Paul A. Montagna, Jeffrey G. Baguley, Michael G. Reuscher, Gilbert T. Rowe, Terry L. Wade

Chapter 8. The Asphalt Ecosystem of the Southern Gulf of Mexico: Abyssal Habitats Across Space and Time

Recent findings cap more than a decade of research on habitats for chemoautotrophic fauna that are generated by hydrocarbon seepage at abyssal depths in the southern Gulf of Mexico. Extensive pavements (3300 m2) of asphalt, created by repeated, slow discharges, are sparsely colonized by tubeworms that tap reduced sulfur compounds through cracks and fissures in the solidified material. At depths greater than 3000 m, gas hydrate forms instantaneously, generating frozen mounds 10 m or greater in diameter. These deposits are apparently stable for decades or longer, because they are colonized by massive arrays of tubeworms. The asphalt ecosystem of the southern Gulf poses special challenges for expanding deep-water oil production and many potential chemosynthetic habitats remain unexplored.
Ian R. MacDonald, Adriana Gaytan-Caballero, Elva Escobar-Briones

Chapter 9. Geochemical and Faunal Characterization in the Sediments off the Cuban North and Northwest Coast

This chapter provides a summary of the scientific knowledge about sediments and fauna in the margin of northwest Cuban shelf. Little scientific information is publicly available, and so much of what is discussed here is the result of the scientific expedition to the region in May 2017 on board the R/V Weatherbird II as part of the GoMRI consortium, C-IMAGE (see Foreword, this book). The goal was to set broad environmental baselines against which to evaluate the impacts of any potential future oil spill or other disturbance in the Gulf of Mexico (GoM). The chapter is organized in three parts: (1) overview of the geographical setting of Cuban margin of GoM; (2) sediment characterization including texture, composition, and geochronology of sediment cores; and (3) characterization of key bioindicators of oil impact: mollusks, meiofauna, and foraminifera.
Maickel Armenteros, Patrick T. Schwing, Rebekka A. Larson, Misael Díaz-Asencio, Adrian Martínez-Suárez, Raúl Fernández-Garcés, David J. Hollander, Gregg R. Brooks

Chapter 10. Mapping Isotopic and Dissolved Organic Matter Baselines in Waters and Sediments of the Gulf of Mexico

The Deepwater Horizon oil spill released petroleum hydrocarbons that were depleted in δ13C and Δ14C at depth into the Gulf of Mexico. Stable-carbon and radiocarbon isotopic values and high-resolution mass spectrometry were used to follow the distributions of this petroleum and to track its transformation into petrocarbon, a term used to describe crude oil or transformed crude oil following biodegradation, weathering, oxygenation, or loss of lighter components. The term petrocarbon includes oil- or methane-derived carbon assimilated or incorporated into microbial biomass or into the food web as well as degraded and undegraded petroleum constituents. Here we report (1) the increase in the relative abundance of oxygen-containing carbon compounds making up the dissolved organic matter (DOM) with increasing depth through the water column, indicating the biodegradation of DOM as it was transported to depth in the water column, (2) the finding of 14C depletion in DOM indicating petrocarbon inputs, and (3) the decrease and subsequent increase of 14C in the isotopic composition of sinking particles indicating the capture of petrocarbon in sediment traps. In addition, we discuss the 14C depletion of this material once it is sedimented to the seafloor and the implications for oil spill budgets of seafloor petrocarbon deposition.
Jeffrey P. Chanton, Aprami Jaggi, Jagoš R. Radović, Brad E. Rosenheim, Brett D. Walker, Stephen R. Larter, Kelsey Rogers, Samantha Bosman, Thomas B. P. Oldenburg

Chapter 11. Toward a Predictive Understanding of the Benthic Microbial Community Response to Oiling on the Northern Gulf of Mexico Coast

Benthic ecosystems often act as a repository for oil contamination that washes ashore or is deposited onto sediments following a major oil spill. Sedimentary microorganisms mediate central ecosystem services on the coast, such as carbon and nutrient cycling, and these services may be adversely impacted by oil perturbation. Thus, during the response to the Deepwater Horizon (DWH) oil discharge in the Gulf of Mexico, considerable effort went into characterizing the response of benthic microbial communities to oil deposition on shorelines of the Northern Gulf where oil came ashore. Oil perturbation elicited a pronounced microbial response in coastal ecosystems, altering the abundance, diversity, and community composition of sedimentary microorganisms. Next-generation gene sequencing and metagenomic approaches, which were not available during previous large oil spills, have revolutionized the field of microbiology, providing new insights into the microbial response after the DWH discharge. This review centers on a case study of the fate of oil contamination in Pensacola Beach sands, which sheds light on the mechanisms of microbially mediated hydrocarbon degradation and the impacts of oiling to ecosystem functions. Analysis of field and laboratory results is discussed along with the technological advances that made these observations possible. Metagenomics enabled the application of ecological theory, thereby building a stronger foundation for the effective prediction of baseline microbial community structure/function and response to oiling. Oil perturbation was shown to resemble a press ecosystem disturbance according to the disturbance-specialization hypothesis. Benthic microbial communities were shown to be resilient, maintained ecosystem functions, and recovered quickly after oil disturbance.
Joel E. Kostka, Will A. Overholt, Luis M. Rodriguez-R, Markus Huettel, Kostas Konstantinidis

Chapter 12. Combining Isoscapes with Tissue-Specific Isotope Records to Recreate the Geographic Histories of Fish

After the Deepwater Horizon (DWH) oil spill, interest in marine animal movement was heightened by recognition that some individual animals had been cryptically exposed to the oil, and that some of these exposed individuals later moved, introducing oil contamination to geographic areas that were beyond the initial domain of direct oil impact. Forensic methods based on internally recorded stable-isotope records can be used to address the issue of movement by contaminated individuals. Different tissues provide stable-isotope histories that reflect different periods in the individual’s history, ranging from just a few recent days in the case of blood plasma to the entire lifetime in the case of eye lenses and otoliths. Isotopic offsets between tissue types (e.g., liver and muscle) within the same individual can be used to measure the relative site fidelities of different individuals. Among individuals that have low site fidelity, geographic movements can be estimated by comparing lifetime isotope trends with background maps of isotope variation (isoscapes). The process of isotope conservation within the vertebrate eye lens is described, and practical application of forensic methods and data interpretation are discussed.
Ernst B. Peebles, David J. Hollander

Chapter 13. The Utility of Stable and Radioisotopes in Fish Tissues as Biogeochemical Tracers of Marine Oil Spill Food Web Effects

Direct exposure to petroleum compounds was widely reported for a variety of taxa following the DWH. Evidence of exposure ranged from oiling of skin, shells, or feathers, depending on the taxa, to observation of ingested oil in small translucent, invertebrates, to biomarkers of petroleum compounds within an organism’s tissues, such as PAHs in the hepatopancreas of invertebrates or the liver of fishes, or metabolic products of PAH catabolism in the bile of various vertebrate taxa. Development of natural biogeochemical tracers to examine indirect effects, especially over long (months to years) time scales, can be much more problematic. In this chapter, we describe the utility of employing stable isotopes and radioisotopes to 1) examine whether food web effects can be inferred from shifts in stable isotope values measured in vertebrate taxa; 2) examine the assimilation and trophic transfer of petrocarbon in marine food webs; and, 3) serve as long-term biogeochemical tracers either of petrocarbon assimilation or trophic shifts that are indicative of food web effects of marine oil spills. Data and analyses are largely drawn from DWH-related studies but with broader implications to marine oil spills in general.
William F. Patterson III, Jeffery P. Chanton, David J. Hollander, Ethan A. Goddard, Beverly K. Barnett, Joseph H. Tarnecki

Chapter 14. Modernizing Protocols for Aquatic Toxicity Testing of Oil and Dispersant

The goals of this chapter are to discuss, compare and contrast these new or altered protocols with the initial Chemical Response to Oil Spills: Ecological Effects Research Forum (CROSERF) methods. Although we do not advocate for any specific approach, we do provide a summary of updated guidelines and present recommendations for improvements to the standard protocols for future aquatic toxicity testing with oil and/or chemical dispersants.
Carys L. Mitchelmore, Robert J. Griffitt, Gina M. Coelho, Dana L. Wetzel

Chapter 15. Polycyclic Aromatic Hydrocarbon Baselines in Gulf of Mexico Fishes

The lack of baseline data has hindered the assessment of impacts from large-scale oil spills throughout their history. Baseline data collected before an adverse event such as an oil spill are critical for quantifying impacts and understanding recovery rates to pre-spill levels. In the case of the two largest oil spills in the Gulf of Mexico (GoM), Deepwater Horizon and Ixtoc 1, the lack of comprehensive contaminant baselines limits our ability to project when the ecosystem will return to pre-spill conditions and assess the short- and long-term impacts of contamination on ecosystems. Beginning in 2011, we initiated comprehensive sampling in the GoM to develop broad-scale and Gulf-wide hydrocarbon contaminant baselines primarily targeting continental shelf fishes in the USA, Mexico, and Cuba. We also developed a time series of collections over 7 years from the region in which DWH occurred. In the event there is another oil spill in the GoM, the samples from these baselines will provide broad-scale but not installation-specific baseline information for the assessment of impact and recovery. This chapter provides a summary of historical sampling and current baseline data for pelagic, mesopelagic, and demersal fish in the GoM. Further, we outline the importance of ongoing and more specific collection of monitoring data for hydrocarbon pollution.
Erin L. Pulster, Adolfo Gracia, Susan M. Snyder, Isabel C. Romero, Brigid Carr, Gerardo Toro-Farmer, Steven A. Murawski

Chapter 16. Case Study: Using a Combined Laboratory, Field, and Modeling Approach to Assess Oil Spill Impacts

The Deepwater Horizon (DWH) spill was the largest oil spill in US history, requiring an assessment of injuries to nearshore habitats and estuarine organisms. Developing a model of appropriate complexity is critical in an environmental assessment; models should be complex enough to adequately address the assessment objectives without being more complex than is needed. We present an approach that starts with a sensitivity analysis of an initial assumption-based model to prioritize model parameters and focus research efforts to reduce model uncertainty. We then develop a targeted research strategy that utilized laboratory, field, and intermediate modeling efforts to parameterize a final set of models of varying complexity to evaluate risk. We demonstrate this process in a case study of the small estuarine fish, the sheepshead minnow (Cyprinodon variegatus), exposed to weathered oil in Barataria Bay, LA, following the DWH oil spill.
Sandy Raimondo, Jill A. Awkerman, Susan Yee, Mace G. Barron

Part III


Chapter 17. Testing the Effect of MOSSFA (Marine Oil Snow Sedimentation and Flocculent Accumulation) Events in Benthic Microcosms

In multispecies experiments performed in microcosms with natural sediment, it was investigated how the presence of marine snow affects the fate and ecological impact of deposited oil residues. The response of different taxonomic groups like nematodes, foraminifera, crustaceans and molluscs onto the presence of marine snow with or without oil was compared with the impact of deposited oil residues without marine snow. Also the effect of the presence of marine snow on oil biodegradation and transfer of oil-derived compounds to selected biota was studied. Although not designed to mimic the specific deep sea conditions in the Gulf of Mexico, the outcome of the experiments gave new insights in how a MOSSFA event can affect the benthic community. In general the experiments indicate that at field realistic oil-derived compound concentrations, the adverse impact of the marine snow on the sediment surface has a stronger impact on the benthic ecosystem than the oil’s toxicity on its own. In addition, the presence of marine snow reduces the degradation of the oil and can create an exposure route for animals that consume oiled marine snow and thus potentially enhances the ecological impact further.
Edwin M. Foekema, Justine S. van Eenennaam, David J. Hollander, Alette M. Langenhoff, Thomas B. P. Oldenburg, Jagoš R. Radović, Melissa Rohal, Isabel C. Romero, Patrick T. Schwing, Albertinka J. Murk

Chapter 18. Physical Processes Influencing the Sedimentation and Lateral Transport of MOSSFA in the NE Gulf of Mexico

Accurate predictions of the transport and fate of oil spilled in the marine environment are essential for response and mitigation efforts. The sedimentation of oil-associated marine snow (MOS) has been shown to be an important pathway by which Deepwater Horizon (DWH) oil was removed from the water column; thus, information is needed on the vertical and lateral dispersion of MOS. Here, we simulated the physical environment in the NE Gulf of Mexico using the Connectivity Modeling System (Paris et al., Environ Model Softw 42:47–54, 2013). Field measurements of marine snow provided initial conditions for the simulations. High Mississippi River (MR) discharge during 2010 and 2013 resulted in strong eastward flowing fronts along the shelf break to the east of the MR, and an anticyclonic eddy at the shelf break retained and aggregated particles, which acted to enhance MOS sedimentation. Forward simulations suggested that particles with high sinking rates (200 m d−1) reached the seafloor within <5–15 days and settled within 0–30 km of their origin, while particles with low sinking rates (30 m d−1) were dispersed up to 110 km away from their origin. Suspended particles (no sedimentation rate) may be transported over 300 km from their origin.
Kendra L. Daly, Ana C. Vaz, Claire B. Paris

Chapter 19. Simulating Deep Oil Spills Beyond the Gulf of Mexico

As deep-sea oil exploitation increases worldwide, the probability of another Deepwater Horizon (DWH) blowout also increases. The DWH disaster directly impacted the coastal communities of the Gulf of Mexico (GoM) with 11 deaths and the release of 172.2 million gallons of gas-saturated oil, covering over 1000 miles of coastline and contaminating an estimated 300,000 million cubic meters of GoM water. In the aftermath of the DWH blowout, the question of what a similar event would look like outside the GoM is of fundamental importance. Anticipating the extent and potential environmental impact of major spills in other locations becomes important for effective oil preparedness and response, including coordination of emergency response between neighboring countries. Avoiding deep-sea drilling in environmentally sensitive and some of the world’s most biodiverse and productive fishing areas is also of upmost importance. The west coasts of Cuba and West Africa may be two of the most environmentally sensitive areas across the North Atlantic, yet exploitation of deepwater oil reservoirs has already started or is imminent. Northwest Cuba holds abundant coral reefs characterized by uniquely high diversity and fish biomass, and the region is also home of multi-species spawning aggregations, crucial for the persistence of fish populations. In addition, this area contains Cuba’s most important lobster fishery grounds. A major oil spill occurring in NW Cuba is thus likely to have deleterious impacts on the biodiversity and seafood resources of the region. The West African coastal upwelling system is an extremely productive area, harboring one of the world’s main “hot spots” in terms of fish abundance and biomass. This important system is most likely also a crucial mechanism regulating the climate, and an oil spill in this area could thus have severe local and global impacts.
Here we simulate a DWH-like spill in two deepwater prospect blocks offshore Cuba and Senegal, West Africa, and evaluate their extent and impact against the DHW oil spill hindcast as a benchmark. These two hypothetical spills are not locally contained and are both severe, yet we find distinctive differences between their impact on the coastline, the seafloor, and the water column. Overall, the Senegal deep blowout scenario seems to be the most impactful with the highest sedimented and beached oil mass; the Cuba deep blowout scenario is the second worst, with the highest impact in terms of oiled area and volume. In this context, our study demonstrates that if another DWH occurred in a different region, poorly regulated emergency responses for international waters at the time of the spill could result in more detrimental impacts on marine ecosystems and coastal communities compared to the DWH. Here, we bring forward, quantify, and visualize the possible outcomes of another mega-spill similar to the DWH in two strategic locations to increase the awareness of decision-makers and the public to such implications. Since oil exploration is not expected to decrease in the near future, we urge governments to focus on establishing international agreements protecting sensitive marine resources and areas.
Claire B. Paris, Ana C. Vaz, Igal Berenshtein, Natalie Perlin, Robin Faillettaz, Zachary M. Aman, Steven A. Murawski

Part IV


Chapter 20. Comparison of the Spatial Extent, Impacts to Shorelines, and Ecosystem and Four-Dimensional Characteristics of Simulated Oil Spills

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.
Igal Berenshtein, Natalie Perlin, Cameron H. Ainsworth, Joel G. Ortega-Ortiz, Ana C. Vaz, Claire B. Paris

Chapter 21. A Predictive Strategy for Mapping Locations Where Future MOSSFA Events Are Expected

A MOSSFA (marine oil snow sedimentation and flocculent accumulation) event was the reason that substantial amounts of the spilled oil were transported to the seafloor during the Deepwater Horizon (DWH) oil well blowout. The region-wide sinking and flocculent accumulation of marine oil snow on the sediment surface changed redox conditions, slowed down the biodegradation of the oil, and increased the spatial and temporal impacts on the benthic community and habitat suitability. Recent field research has confirmed that, in addition to the DWH MOSSFA event in the northern Gulf of Mexico (nGoM), another extensive MOSSFA event occurred in a biologically sensitive area in the southern Gulf of Mexico (sGoM) during the 1979–1980 Ixtoc 1 oil well blowout. Thus, MOSSFA events are not unexpected and have the potential to not only alter sediment chemical conditions but also to extend, expand, and intensify the ecological impact of an oil spill. Consequently this risk should be taken into consideration when preparing response strategies for potential future oil spills and subsurface oil well blowouts. To illustrate this approach, MOSSFA-sensitive areas were identified in offshore areas where deepwater oil production and exploration are occurring. Based on the newly gained insights into the factors that can initiate and contribute to a MOSSFA event, global maps showing the presence of oil/gas platforms, phytoplankton biomass, and suspended mineral matter are developed in order to infer the probability that future MOSSFA events are likely to occur. These maps are of particular importance for oil spill responders who will be deciding locations and which oil spill response strategies (i.e., applying large volumes of dispersants, burning in situ burnings, increasing riverine inputs of nutrients, and fine-grained clay particles) would result in the development of a MOSSFA event.
Albertinka J. Murk, David J. Hollander, Shuangling Chen, Chuanmin Hu, Yongxue Liu, Sophie M. Vonk, Patrick T. Schwing, Sherryl Gilbert, Edwin M. Foekema

Chapter 22. Connectivity of the Gulf of Mexico Continental Shelf Fish Populations and Implications of Simulated Oil Spills

The Gulf of Mexico (GoM) marine ecosystem is experiencing acute stressors. Natural (e.g., hurricanes, harmful algal blooms) or anthropogenic (e.g., oil spills), these stressors have the potential to impact fish populations and decrease biodiversity that may be difficult to recover unless the ecosystem is resilient.
One of the most effective factors governing the resilience capacity of sensitive Gulf fish species is the degree of connectivity and network modularity among spatial sub-units of species occupying the continental shelf. This chapter is a meta-study that looks at the relationship between the Lagrangian dynamical geography of the GoM regions, the community structure of demersal fish, and the potential for larval connectivity. We use adult fish movement from tagging data, larval fish migration from biophysical modeling, and oceanographic patterns from satellite-tracked Lagrangian drifters to quantify the degree of connectivity and modularity of the GoM ecosystem. We evaluate the biophysical model output with 20+ years of data from the Southeast Area Monitoring and Assessment Program (SEAMAP) ichthyoplankton survey and use the drifter inferred dynamics provinces to access mechanisms underlying retention or exchange for each species and GoM province. The tagging analyses reveal a modular network structure consistent with the Lagrangian oceanographic provinces. While the oceanographic dynamic patterns drive self-recruitment levels and the size and location of these provinces, they do not constrain connectivity patterns between distant locations within the GoM. In contrast, larval transport and migration between the provinces and subregions drive the patterns of connectivity and community structure similarity. Ultimately, it is the combination of within-scale functional redundancy and cross-scale species connectivity that can amplify resilience and speed of recovery and minimize the potential for catastrophic regime shifts in ecological meta-communities such as in the GoM. The importance of such studies to natural resource management and oil spill preparedness outcomes is discussed.
Claire B. Paris, Steven A. Murawski, Maria Josefina Olascoaga, Ana C. Vaz, Igal Berenshtein, Philippe Miron, Francisco Javier Beron-Vera

Chapter 23. Evaluating the Effectiveness of Fishery Closures for Deep Oil Spills Using a Four-Dimensional Model

During the Deepwater Horizon (DWH) oil spill, extensive areas of the Gulf of Mexico (GoM) were closed for fishing due to the risk of seafood contamination and fishers’ health. The closures were determined daily according to the estimated extent of the spill relying mainly on satellite imaging. These closures were largely limited to the northern GoM. Yet, evidence from the field indicates a presence of oil beyond the closures, in some cases at toxic concentrations. With the advancement of oil transport modeling, together with the availability of new in situ data, we examine the 4D extent of the DWH spill, along with the effectiveness of the fishery closures in capturing the oil spill extent. We use the oil application of the Connectivity Modeling System (oil-CMS), cross-checked against in situ BP Gulf Science Data (GSD) and other published studies. The oil-CMS indicates that DWH extended well beyond the satellite footprint and fishery closures, with the closures capturing only ~55% of the total extent of the spill. With an increasing global shift toward deep-sea drilling, our findings are important for the safety of coastal communities and marine ecosystems around deep-sea drilling areas.
Igal Berenshtein, Natalie Perlin, Steven A. Murawski, Samatha B. Joye, Claire B. Paris

Chapter 24. As Gulf Oil Extraction Goes Deeper, Who Is at Risk? Community Structure, Distribution, and Connectivity of the Deep-Pelagic Fauna

The habitat and biota most affected by ultra-deep oil spills in the Gulf of Mexico (GoM) will necessarily be in the deep-pelagic domain. This domain represents ~91% of the GoM’s volume and almost certainly contains the majority of its metazoan inhabitants. Ultra-deep oil spills may or may not reach the surface or the seafloor but will occur entirely within the deepwater column domain at some point and likely for the longest duration. Recent research has shown the deep-pelagic GoM to be extremely rich in biodiversity, both taxonomic and functional. Indeed, the GoM is one of the four “hyperdiverse” midwater ecosystems in the World Ocean. This biodiversity is functionally important. For example, well over half (58%) of all fish species known to exist in the GoM spend all or part of their lives in the oceanic domain. Recent research has also shown the deep-pelagic GoM to be highly connected vertically, as well as horizontally (onshore-offshore). This vertical connectivity provides an increasingly valued ecosystem service in the form of atmospheric carbon sequestration via the “biological pump.” In this chapter, we summarize the GoM deep-pelagic nekton (fishes, macrocrustaceans, and cephalopods) that have been, and would be, affected by ultra-deep oil spills. We also discuss key aspects of distribution and behavior (e.g., vertical migration). These behaviors and distributions are key elements of ecosystem assessments before and after oil spills. For example, some deep-pelagic taxa show affinities for oceanic rim habitats (i.e., continental slopes), where ultra-deep drilling is most intense. Lastly, we summarize what is known about hydrocarbon contamination in the deep-pelagic biota and its possible ecosystem consequences.
Tracey T. Sutton, Tamara Frank, Heather Judkins, Isabel C. Romero

Chapter 25. Evaluating Impacts of Deep Oil Spills on Oceanic Marine Mammals

The Deepwater Horizon (DWH) oil spill may be indicative of future large, deep spills that may occur in the coming decades. Given that future deepwater spills are possible, critical considerations include (1) establishing baselines for oceanic marine mammal and populations in at-risk areas, (2) understanding the implications of response choices for oceanic marine mammals, (3) designing studies with adequate coverage for post-spill monitoring, and (4) identifying effective strategies for oceanic marine mammal restoration. In this chapter, we consider these four stages in the context of a series of hypothetical oil spill scenarios, identifying ways that lessons learned from the DWH oil spill and prior events can be applied to future disasters.
Kaitlin E. Frasier

Chapter 26. Comparative Environmental Sensitivity of Offshore Gulf of Mexico Waters Potentially Impacted by Ultra-Deep Oil Well Blowouts

Environmental sensitivity indices (ESIs) have long been used to identify coastal and shoreline resources particularly vulnerable to oil spills and ensuing mitigation measures. In the Gulf of Mexico, oil production by the United States and Mexico has increasingly focused on deepwater sources. As oil exploration and production continue further offshore, deepwater and open ocean pelagic resources increasingly become the focus of susceptibility to oil well blowouts. Methodologies are proposed to spatially quantify ESIs specifically for offshore living marine resources. A multi-attribute utility model is proposed to integrate biological resource sensitivity measures and measures of potential economic losses to define spatially explicit environmental sensitivity. Model sensitivity is examined using three weighting schemes for various environmental attributes. The relative environmental sensitivities of four simulated deepwater blowouts in the Gulf of Mexico were analyzed and compared. While differences were found between four oil well blowout scenarios in terms of the overall sensitivity and to the individual attributes, results were relatively insensitive to the weights assigned to various attributes. The uses of ESIs in optimizing oil production locations to minimize potential impacts on sensitive ecological resources and economic uses are discussed.
Emily Chancellor, Steven A. Murawski, Claire B. Paris, Larry Perruso, Natalie Perlin

Part V


Chapter 27. Preparing for the Inevitable: Ecological and Indigenous Community Impacts of Oil Spill-Related Mortality in the United States’ Arctic Marine Ecosystem

While hydrocarbon exploration and extraction in the Arctic ebb and flow, reduced sea ice has opened new travel routes across the Arctic. The opening of the Northwest Passage has allowed larger ships (including oil tankers) and higher traffic into remote regions. More ice loss is expected in the future. With this comes the potential for hydrocarbon spills. To quantify the ecosystem impacts of a spill in the Alaska North Slope region, an Ecospace model using the Ecopath with Ecosim software was developed. We highlight the impacts of four potential hydrocarbon contamination scenarios: a subsurface crude oil pipeline release, a surface platform oil spill, a surface cruise ship diesel spill, and a surface tanker oil spill. Hydrocarbon contamination was modeled using SIMAP (Spill Impact Model Analysis Package), which was developed from the oil fate sub-model in the Natural Resource Damage Assessment Model for the US Department of the Interior and under the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA). Spatial-temporal SIMAP results were coupled to the Ecospace model. We show that in all four hydrocarbon contamination scenarios, there are spatial changes in harvested species resulting in long-term declines in harvest levels for the communities within the model area (Nuiqsut, Kaktovik, and Barrow Alaska), depending on the severity of the scenario. Responses to hydrocarbon events are likely to be slow in the Arctic, limited by the ice-free season. We highlight this area for scenario testing as ecological impacts are also an issue of food security to the local communities and human health issue.
Paul M. Suprenand, Carie Hoover, Cameron H. Ainsworth, Lindsey N. Dornberger, Chris J. Johnson

Chapter 28. Summary of Contemporary Research on the Use of Chemical Dispersants for Deep-Sea Oil Spills

Mitigation options for deep-sea oil spills are indeed few. In the open ocean, far from land, booming, burning, and mechanical pickup of oil at the sea surface may be of limited value due to wave and wind conditions. The use of chemicals to disperse oil into smaller droplets is predicated on the assumptions that smaller droplets are more easily dissolved into surrounding waters and that smaller droplets are degraded by bacterial action more rapidly than are larger droplets. During the Deepwater Horizon accident, a novel use of dispersants injected directly into the subsurface source of the blowout was undertaken to treat the oil prior to surfacing. The presence of subsurface “plumes” of small droplets and dissolved oil observed during DWH raised the issue of active measures to sequester oil in the subsurface vs. allowing it to surface. Reducing the concentration of volatile organic compounds surfacing near workers was also a stated objective of subsurface dispersant injection (SSDI) application. Aquatic toxicity testing has evolved significantly from a sole focus on short-term mortality to evaluate a variety of sublethal physiological, genotoxic, and immunogenic impacts affecting animal health and fitness of exposed populations. In this chapter we consider a number of pressing – and heretofore unresolved – issues surrounding the use of dispersants as an oil spill mitigation tool. Further, we advocate continued, targeted research to help resolve ongoing controversies regarding dispersant use.
Steven A. Murawski, Michael Schlüter, Claire B. Paris, Zachary M. Aman

Chapter 29. Perspectives on Research, Technology, Policy, and Human Resources for Improved Management of Ultra-Deep Oil and Gas Resources and Responses to Oil Spills

This chapter considers a series of research, technology, policy, and human resource-relevant recommendations aimed at identifying ultra-deep wellsite locations that may be problematic for risk of an oil spill, as well as enhancing prevention, preparedness, response, and subsequent injury assessment associated with ultra-deep oil spills. While various groups have offered research and process improvement recommendations, numbering in the high hundreds, this chapter focuses on 20 key research gaps and 4 policy changes that would improve outcomes for ultra-deep oil spill prevention and response. Recommended policy changes include (1) inclusion of site-specific risk assessments as an element of lease sale identification and approval, (2) collection of environmental baselines (both broadscale and installation-specific) and ongoing monitoring of oil contaminants, (3) improved transparency and data sharing for oil facility management and accidental releases, and (4) more formal international engagement in siting, oil spill preparedness, response, and impact assessment.
Steven A. Murawski


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