CHAPTER FIVE

Ecosystem Services in the Gulf of Mexico

INTRODUCTION

In Chapter 2 we outlined the general concept of ecosystem services and the basic principles and challenges of applying an ecosystem services approach to damage assessment for an event of the magnitude and duration of the Deepwater Horizon (DWH) oil spill. Chapter 3 explored the concept of resilience in the context of ecosystem services and the challenges faced by managers in attempting to restore or increase the resilience of the Gulf of Mexico (GoM) ecosystem. Chapter 4 reviewed the response technologies used during and after the DWH oil spill and their impacts on GoM ecosystem services. This chapter brings the discussion of ecosystem services into focus by examining in more detail the specific ecosystem services provided by the GoM. The chapter begins by considering the characterization of GoM ecosystem services within a geospatial context and how ecosystem services vary as a function of scale and in response to changes in the physical and environmental setting.

The remainder of the chapter is dedicated to presentation of four case studies representing each of the primary ecosystem service types—supporting, regulating, provisioning, and cultural—and chosen to capture the opportunities and challenges that emerge when applying the ecosystem services approach to assessing the impact of the DWH spill on the GoM. For each of these case studies, the committee identifies key ecosystem services, considers how they may have been impacted by the DWH oil spill, examines methods for taking baseline measurements, and explores the adequacy of existing baseline data for the GoM. Additionally, the committee offers suggestions for additional measurements that can enhance an ecosystem services approach to damage assessment (Tables 5.5, 5.6, 5.7, and 5.8).

ECOSYSTEM SERVICES IN THE GULF OF MEXICO

As a starting point for examining ecosystem services specific to the GoM, the committee utilized a list of GoM ecosystem services that was developed by a panel of regional experts during a workshop convened in Bay St. Louis, Mississippi, in June 2010 (Yoskowitz et al., 2010). The workshop panel, composed of representatives from academic institutions, nongovernmental organizations, the private sector, and state and federal agencies, defined ecosystem services as the “contributions from GoM marine and coastal ecosystems that support, sustain and enrich human life.” As shown in Table 5.1, the panel identified 19 ecosystem services provided by the GoM natural infrastructure and grouped them under the four primary types of ecosystem ser-



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CHAPTER FIVE Ecosystem Services in the Gulf of Mexico INTRODUCTION In Chapter 2 we outlined the general concept of ecosystem services and the basic prin- ciples and challenges of applying an ecosystem services approach to damage assessment for an event of the magnitude and duration of the Deepwater Horizon (DWH) oil spill. Chapter 3 explored the concept of resilience in the context of ecosystem services and the challenges faced by managers in attempting to restore or increase the resilience of the Gulf of Mexico (GoM) ecosystem. Chapter 4 reviewed the response technologies used during and after the DWH oil spill and their impacts on GoM ecosystem services. This chapter brings the discussion of ecosystem services into focus by examining in more detail the specific ecosystem services provided by the GoM. The chapter begins by considering the characterization of GoM eco- system services within a geospatial context and how ecosystem services vary as a function of scale and in response to changes in the physical and environmental setting. The remainder of the chapter is dedicated to presentation of four case studies represent- ing each of the primary ecosystem service types—supporting, regulating, provisioning, and cultural—and chosen to capture the opportunities and challenges that emerge when apply- ing the ecosystem services approach to assessing the impact of the DWH spill on the GoM. For each of these case studies, the committee identifies key ecosystem services, considers how they may have been impacted by the DWH oil spill, examines methods for taking baseline mea- surements, and explores the adequacy of existing baseline data for the GoM. Additionally, the committee offers suggestions for additional measurements that can enhance an ecosystem services approach to damage assessment (Tables 5.5, 5.6, 5.7, and 5.8). ECOSYSTEM SERVICES IN THE GULF OF MEXICO As a starting point for examining ecosystem services specific to the GoM, the committee utilized a list of GoM ecosystem services that was developed by a panel of regional experts during a workshop convened in Bay St. Louis, Mississippi, in June 2010 (Yoskowitz et al., 2010). The workshop panel, composed of representatives from academic institu­ ions, nongovernmen- t tal organizations, the private sector, and state and fed­ ral agencies, defined ecosystem services e as the “contributions from GoM marine and coastal ecosystems that support, sustain and enrich human life.” As shown in Table 5.1, the panel identified 19 ecosystem services provided by the GoM natural infrastructure and grouped them under the four primary types of ecosystem ser- 103

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L TABLE 5.1  Gulf of Mexico Ecosystem Services by Millennium Ecosystem Assessment Category Supporting services Nutrient balance Hydrological balance Biological interactions Soil and sediment balance Regulating services Pollutant attenuation Water quality Gas regulation Climate regulation Hazard moderation Provisioning services Air supply Water quantity Food Raw materials Medicinal resources Ornamental resources Cultural services Aesthetics and existence Spiritual and historic Science and education Recreational opportunities vices (supporting, regulating, provisioning, and cultural) defined by the Millennium Ecosystem Assessment (MEA, 2005). Panelists in the Bay St. Louis workshop (Yoskowitz et al., 2010) recognized that the coastal and marine habitats of the GoM also constitute a natural infrastructure that contributes to the provisioning of ecosystem services. When ecological production functions are not well under- stood, integrated assessments of ecosystem services tend to use natural structures such as habitats to map the complex interactions of different components of the ecosystem. The scale for assessing an ecosystem service must be determined by the threshold at which changes in ecosystem functioning (or its habitats) can be detected (measured) and at which the ecosys- tem sustains functions that contribute to its resilience (as discussed in Chapter 3). Table 5.2 organizes a number of important GoM ecosystem services by habitat, which could be used to guide efforts in delineating and determining changes in ecosystem services after the DWH oil spill. Ecosystem services can also be classified according to their spatial characteristics (see Ta- ble 5.3). Each of the 19 ecosystem services provided by the GoM can be mapped to at least one of the five different spatial classes (global nonproximal, local proximal, directional flow-related, in situ or point of use, and user movement-related) proposed by Costanza (2008). For example, 104

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Ecoystem Services in the Gulf of Mexico TABLE 5.2  Synthesis of Services Provided by the Gulf of Mexico by Service Category and Habitat Ecosystem Service Category Habitat Example in the GoM Supporting services Soil and sediment balance Brackish marsh Upper Barataria estuary, Louisiana Dunes/beaches Barrier islands, Texas Forested coastal ridge Chenier Forest/Woodlands, Louisiana Intertidal sediments Mud flats in Laguna Madre, Texas Subtidal sediments Widespread throughout the Gulf Mangroves Everglades, Florida Nutrient regulation Brackish marsh Upper Barataria estuary, Louisiana Freshwater marsh Rockefeller State Wildlife Refuge, Louisiana Macroalgae Floating and beached Sargasso Swamp/bottomland hardwood Maurepas Swamp, Louisiana Subtidal sediments Widespread throughout the Gulf Regulating services Water quality Oyster reef Mobile Bay, Alabama Seagrass Redfish Bay, Texas Hazard moderation Oyster reef Barataria Bay, Louisiana Salt marsh Mississippi River Delta, Louisiana Freshwater marsh Barrier island freshwater marshes, Texas Swamp/bottomland hardwood Sabine River floodplain swamp, Texas and Louisiana Dunes/beaches South Pacific Island, Texas Forested coastal ridge Chenier Forest/Woodlands, Louisiana Mangroves Everglades, Florida Provisioning services Food Oyster reef Galveston Bay, Texas Seagrass Laguna Madre, Texas Open water Widespread throughout the Gulf Offshore shoals and banks Sabine Bank, Texas and Louisiana Subtidal sediments Widespread throughout the Gulf Raw materials Oil and gas fields/reservoirs Shelf/slope of central, western planning areas of the Gulf Offshore shoals and banks Sabine Bank, Texas and Louisiana Cultural services Aesthetics and existence Spiritual and historic Shell middens throughout the Gulf Coral reefs Florida Keys National Marine Sanctuary, Florida Dunes/beaches St. George Island State Park, Florida continued 105

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L TABLE 5.2 Continued Ecosystem Service Category Habitat Example in the GoM Recreational opportunities Coral reefs Florida Keys National Marine and tourism Sanctuary, Florida Salt marsh Northern Barataria Bay, Louisiana Forested coastal ridge Grand Isle, Louisiana Intertidal sediments Bays and estuaries anywhere in the Gulf Open water Widespread throughout the Gulf Offshore shoals and banks Florida Middle Grounds, Florida Science and Education Widespread throughout the Gulf SOURCE: Modified from Yoskowitz et al., 2010. TABLE 5.3  Gulf of Mexico Ecosystem Services by Spatial Characteristics Global nonproximal (does not depend on proximity) Climate balance Gas balance Air supply Existence Spiritual and historic Local proximal (depends on proximity) Hazard moderation Pollutant attenuation Biological interactions Directional flow-related: flows from point of production to point of use Water quality Water quantity Sediment balance Nutrient balance Hydrological balance In situ (point of use) Soil balance Food Raw materials Ornamental resources User movement-related: flow of people to unique natural features Medicinal resources Recreational opportunities Aesthetic Science and education 106

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Ecoystem Services in the Gulf of Mexico a service such as gas balance (an intermediate input to climate regulation) is classified as “global nonproximal” because carbon sequestration occurs across the entire GoM and beyond. “Local proximal” services, on the other hand, are dependent on the spatial proximity of the eco- system service to the human beneficiaries. For example, “hazard moderation” requires that the ecosystem service be proximal to the human settlements and assets being protected. “Direc- tional flow-related” services are dependent on the flow from upstream to downstream, as is the case for water quality and water quantity. An examination of the spatial relationships of ecosystem services highlights the need to identify and manage natural infrastructure at scales that improve its ability to withstand chronic or acute impacts, such as those associated with the DWH oil spill. If the natural infra- structure is damaged, then human communities that benefit from the services provided by these ecosystems will likely become more vulnerable, therefore decreasing their overall well- being and resilience. Any degradation of the ecosystem structure and function may lead to a reduction in the supply of the essential services that will be needed to help communities build the resilience needed to withstand damages and recover after the spill (see discussion of so- cioeconomic resilience in Chapter 3). Examples of spatially specific benefits in the GoM region that could be severely impacted by an oil spill include storm mitigation by coastal wetlands and food provisioning by commercial fisheries. Consideration of the spatial characteristics of ecosystem services is important not only when assessing damages, but also when deciding which services to restore. Tradeoffs will be necessary, and recognizing which communities or sectors may benefit (or lose) from restoration efforts will be useful when priorities are set by the Trustees and stakeholders. CASE STUDIES The committee conducted four case studies to explore specific GoM ecosystem services in detail, to highlight some of the opportunities and challenges that emerge when applying an ecosystem services approach to damage assessment, and to demonstrate how to apply such an approach under various conditions and across wide levels of understanding regarding the services in question. These conditions and levels include the amount and utility of available data, the value of the service in market and nonmarket terms, and the range of the impacts of the spill on the services. In addition, the selected ecosystem services were considered in the context of the linkages between ecosystem services and the constituents of well-being identi- fied in Chapter 2 (see Figure 2.1). Coastal wetlands, which cover a large region in the northern GoM, are the subject of the first case study. Half of the nation’s coastal wetlands are found along the GoM, and, of these, approximately 40 percent are in Louisiana. Unfortunately, many wetlands were among the clos- est land points (only about 40 miles) from the Macondo well (NOAA, 2012b). Coastal wetlands, including salt marshes and mangrove plant communities, provide a wealth of supporting, regulating, provisioning, and cultural services that include maintenance of soil and sediment (shoreline stabilization), regulation of nutrients and water quality, provisioning of food, recre- 107

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L ational opportunities, and hazard moderation (Barbier et al., 2011; Shepard et al., 2011). This case study focuses primarily on the regulating service of hazard moderation (specifically storm mitigation) to illustrate the opportunity that exists in using the ecosystem services approach when the underlying ecosystem science and the particular ecosystem service are well known and supported by a rich literature. The ecosystem service of storm mitigation also benefits from having been monetized—that is, the costs of storm damage and reductions in losses due to wetland buffers can be quantified. The second case study focuses on fisheries, a provisioning service with a rich literature about its valuation and assessment. In recent times, this service has been considered to be a good candidate for a holistic integration of management at an ecosystem scale that includes both ecological and human components. Although the field has been developing this integra- tion by promoting an ecosystem approach to fisheries management, it does not yet consider ecosystem services as a guiding principle. Fisheries, however, offer many examples of quan- tification of human impacts on the ecosystem structure and of ecological and economical productivity. This case study specifically explores the provision of seafood by the GoM and how the ecosystem services approach may help to quantify the possible impacts of oil spills on seafood provision. Bottlenose dolphins were chosen as the subject for the third case study for numerous reasons, including their role in three of the four types of ecosystem services—regulating, sup- porting, and particularly cultural. This case study allowed for the exploration of approaches to estimating the value of passive use and existence—a key, but difficult-to-establish, metric for cultural ecosystem services. The stranding of many dolphins in the GoM before, during, and especially after the DWH spill has stimulated considerable public concern, which speaks to our cultural needs and sensitivities regarding their value as an ecological resource and ecosystem service. Bottlenose dolphins are capable of self-recognition, which ranks them highly on a cogni- tive scale (Reiss and Marino, 2001). As apex predators, a role they share with humans, they play a role in regulating the GoM food web and their health and well-being serve as important indicators of the health of the GoM and oceans in general. More is known about this species than virtually any other cetacean. The world’s longest-running study of a wild dolphin popula- tion, spanning five generations, focuses on Sarasota Bay in the eastern GoM (Wells, 2003). Their position as the most studied and arguably the most popular and charismatic marine mammal makes them a centerpiece for conservation science, education, and ecotourism. Finally, the deep GoM was selected as the subject for the last case study in part because of its location with respect to the DWH blowout and spill. The deep sea was also selected because of increasing concern about the risk posed by the energy industry’s activities as it employs the cutting edge of engineering in the most poorly understood of the impacted habitats. The biota of the surrounding seafloor at 1,500-m depth and of the water column through which a plume of hydrocarbons and dispersants flowed received the most immediate impact of the uncon- trolled discharge. Although there has been some habitat mapping of the deep GoM, the data are quite sparse and the ecological consequence of a spill is incompletely understood. 108

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Ecoystem Services in the Gulf of Mexico Wetlands Introduction Coastal wetlands, including salt marshes and mangroves, provide a wealth of supporting, regulating, provisioning, and cultural services that include soil and sediment maintenance (shoreline stabilization), nutrient regulation, water quality regulation, provision of food and other biological resources, recreational opportunities, and hazard moderation (Barbier et al., 2011; Shepard et al., 2011). The marshes of the Mississippi River Delta comprise almost 40 percent of the coastal wetlands in the 48 contiguous states, support 30 percent of the na- tion’s commercial fishery production, and protect important oil and gas reserves and refiner- ies (Mendelssohn et al., 2012). During the DWH oil spill, coastal salt marshes were significantly affected, with 1,100 linear miles of wetland impacted at some time during the event (NOAA, 2012b). Crude oil can smother vegetation by coating leaf surfaces and can cause toxic effects, particularly from the light fractions of the oil that are more water soluble. With wetlands, the values of some of its ecosystem services, such as storm mitigation, can be quantified within an order of magnitude, while for others, such as nursery habitat for com- mercial marine resources, the values are much more difficult to quantify. The following discus- sion focuses on hazard mitigation because it represents an example of ready application of the ecosystem services approach using the existing knowledge base. Regulating Services Hazard Moderation  Several wetland characteristics are positively correlated with the regulat- ing ecosystem services of both wave attenuation and shoreline stabilization, including vegeta- tion density, biomass production, and marsh size (Shepard et al., 2011). The topography of wetlands (including plant architecture) provides enhanced friction, which tends to decrease wind speed, wave height, storm-driven steady currents, and storm- surge height. Wetlands can also decrease tropical storm intensity by inhibiting the transfer of heat from the ocean to the atmosphere. It is this latter energy transfer that serves as the basic engine that drives a tropical storm. Reduction of wave energy depends on the structure of the plant canopy, its height and density, and the cross-shore and along-shore extent of the wetland (Koch et al., 2009; Krauss et al., 2009; Massel et al., 1999; Narayan and Kumar, 2006; Shepard et al., 2011; Vosse, 2008). The velocity of water traveling within a plant canopy is relatively lower than above the canopy. Can- opy height in relation to water depth is relevant because water flowing through the vegetation encounters a higher friction than does the water above the vegetation. Therefore, the total friction in the water column will change with the depth of vegetated and nonvegetated areas. Because a mangrove canopy is taller and exerts more drag than a salt marsh community, man- groves are more effective at reducing water inflow and waves than are salt marshes. Quartel et al. (2007) suggested that the drag force exerted by a mangrove forest can be approximated by 109

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L the function CD = 0.6e0.15A, where CD is the coefficient of drag and A is the projected cross- sectional area of the submerged canopy. For the same muddy surface without mangroves, the drag is a constant 0.6. Mazda et al. (1997) observed that a 100-m-wide strip of mangrove forest was capable of reducing wave energy by 20 percent. Reduction in water levels across a man- grove area in Florida was 9.4 cm/km (Krauss et al., 2009). Wave energy is also affected by topography. In a modeling study of sea level rise and storm surge across the Louisiana coast, Vosse (2008) found that when the relative land elevation was decreased by 20 cm and 50 cm, wave heights increased 5–10 cm and 10–20 cm, respectively, across the model domain. The conclusion is that friction by the plant canopy dissipates energy and reduces wave heights, but the effect of the wetland surface depends on water depth. Con- sequently, the relative elevation of a coastal wetland, not simply its presence or absence and structure, is a determinant of its effectiveness in storm hazard mitigation. Like waves, storm surge can be reduced by the presence of wetlands because of the increased dissipation. The U.S. Federal Emergency Management Agency (FEMA) provides estimates of the impact of various types of wetland vegetation on frictional dissipation (FEMA, 1985). United Research Services (URS) used the FEMA estimates and a well-validated numerical model to examine the impact of vegetation on surge height. It found a 25 percent reduction in the inland surge simply by assuming the marshland was composed of long grass instead of short grass (Ayres Associates, 2008). Along with these reductions in surge height are substantial secondary benefits. For example, the current velocity is reduced and so is the wave height be- cause larger waves require higher surge, all else being equal. Finally, a reduction in wave height reduces the wave setup, which is a contributor to the surge. Although there is ample evidence that wetlands reduce surges and waves, the evidence is less clear for winds. One problem is that storm winds (as well as surges and waves) can severely alter the vegetation during the course of a storm. Dingler et al. (1995) discuss this issue, using data collected during Hurricane Andrew, which hit the Mississippi River Delta in 1992. They found that wind dissipation was higher over the wetlands than over the ocean, but only when wind speeds exceeded 20 m/s. This effect occurred despite the fact that the wetlands in the study area were composed primarily of Spartina and bulrushes, which would have “flattened” during the stronger winds. Somewhat in contrast to Dingler et al. (1995), FEMA (1985) sug- gested factors that show a substantial increase in wind dissipation over open-ocean values for all types of wetlands and wind speeds. In total contradiction of the other two researchers, Speck (2003) showed a decrease in dissipation with rising wind speed above 1 m/s over 4-m reeds compared to open ocean. In short, no consistent picture emerges from the research regarding wind dissipation, which is no doubt partially due to the facts that the vegetation type in these studies was highly variable and that the dissipation effectiveness varies over the course of a storm as vegetation is damaged by wind, wave, and current. Wetlands may also have an effect on tropical storms by mitigating storm intensity. As ex- plained by Emanuel (1987), the intensity of a tropical cyclone is driven by a Carnot cycle (a ther- modynamic cycle) that requires warm, humid air near the sea surface. Anything that disrupts that supply will reduce storm intensity. Wetlands clearly have that potential, especially if they contain a high percentage of vegetation. Cubukcu et al. (2000) used a numerical model to ex- 110

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Ecoystem Services in the Gulf of Mexico amine the effects of land and found a significant weakening in the surface winds in large part because the storm entrains much drier air. However, Shen et al. (2002) showed that not much water (0.5 m deep) was required to substantially counter this weakening effect, a finding that supports anecdotal evidence from numerous tropical storms that have cut across the wetlands of southern Florida without losing a great deal of intensity. In summary, the general trend is for wetlands to reduce the severity of a storm and its as- sociated wind and waves through numerous physical processes, most of them related to the enhanced friction, which serves as an energy sink. Changing Baselines Although the DWH oil spill had multiple impacts on wetlands (discussed below), the most serious threat to GoM wetlands is their inability to keep up with relative sea level rise (Boesch et al., 1994). The reasons for this inability have been discussed in numerous publica- tions (Boesch et al., 1984; Britsch and Kemp, 1990; Day et al., 2009; Dokka et al., 2006; Mallman and Zoback, 2007; Meade, 1982; Reed, 2002; Reed and Wilson, 2004; Turner, 1997). One notable problem is a reduction in sediment supply caused by the construction of levees and dams. Peri- odic overbank flooding supplied large pulses of sediment to marshlands behind natural levees, but these sediment supplies have been all but eliminated by the hardening and extension of the levees for flood control and navigation. GoM coastal wetlands have also been extensively dredged to provide access to oil and gas platforms, which has seriously degraded freshwa- ter wetlands by providing a conduit for saltwater intrusion (Turner et al., 1982). The piling of dredge spoils on the banks of wetlands adjacent to the canals has also disrupted the natural flow of surface water and sediments across the marshes. The Mississippi River Delta consists of an estimated 25,000 km2 of wetlands, open water, distributaries, and beach ridges. Of the remaining coastal habitat, there has been a net loss of approximately 4,800 km2 over the past century (Day et al., 2005). The loss rate decreased from a high of about 80 km2/year in the 1970s to about 45 km2/year by the turn of the century (Barras et al., 2003; Bernier et al., 2007). It is not clear if the recent decline in loss rate is due to varia- tion in sea level rise (e.g., Bernier et al., 2007; Kolker et al., 2011), subsidence (e.g., Morton et al., 2002), the resolution of GIS technology, the reduction of dredging activities in the marshes, or other factors. The National Oceanic and Atmospheric Administration (NOAA) gauge on Grand Isle, Louisiana, has registered a variable, long-term relative rate of sea level rise of 6.7 mm/year (Figure 5.1). More recently, a 2005 coastwide analysis indicated that more than 4,714 km2 of the pre-storm coastal wetland area experienced a substantial decline in vegetation density and vigor after Hurricane Katrina, with the majority of persistent damage through November 2006 in the western areas (Steyer, 2008). In addition, the background rate of marsh loss is not uniform across the coast, and is especially acute in the region most impacted by the DWH oil spill (Figures 5.2 and 5.4). Current literature supports the conclusion that wave and storm surge attenuation and damage avoidance are related to wetland area, either nonlinearly with diminishing returns 111

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L FIGURE 5.1  Linear regression of mean (±1 SD) annual sea level at Grand Isle, Louisiana (NOAA station 8761724). NOTE: Annual means were computed from monthly means. SOURCE: http://tidesandcurrents. noaa.gov/sltrends/sltrends_station.shtml?stnid=8761724. to scale (Barbier et al., 2008) or linearly (Costanza et al., 2008). Consequently, change in total wetland area is the most direct and practical measurement of change in ecosystem services in 5-1 Gulf Coast wetlands. To quantify changes in wetland area, remote sensing is a highly effective R02473 method for analyzing estuarine and coastal landscapes (Kelly and Tuxen, 2009; Klemas, 2001; Phinn et al., 2000). Remote sensing isbitmapped, uneditable used to efficiently map, monitor, and detect changes in wetlands (Ramsey et al., 2011; Zhang et al., 1997). New satellites carry sensors with spatial resolutions of 1–5 m and spectral resolutions of 200 nm, providing the capability to accurately detect changes in coastal habitat and wetland health (Bourgeau-Chavez et al., 2009; Klemas, 2001, 2011; Ozesmi and Bauer, 2002). The classification of wetland areas and plant communities is also improving as data from satellites are combined with those collected from fixed-wing aircraft. LiDAR (light detection and ranging), an optical system that can measure the distance to a target and other proper- ties using pulses from a laser, is one of the sensors now commonly used on fixed-wing aircraft. This tool is used to construct digital elevation models and to develop digital profiles of plant canopies (e.g., Omasa et al., 2006). Classification schema based on combinations of these data 112

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FIGURE 5.2  Land loss change in coastal Louisiana. SOURCE: http://www.nwrc.usgs.gov/upload/landloss11X17.pdf. 113 5-2 R02473

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L Chemical Production The GoM was once a major source of elemental sulfur extracted as a molten liquid by super-heated steam (the Frasch process), but the last offshore facility ceased operation in 2000 because sulfur could be recovered more cheaply as a byproduct of ore processing (Kyle, 2002). Fossil-water brines extracted along with oil are a potential source of halides, but they are currently discharged into the ocean and regulated as toxic waste. The prevalence of the petrochemical industry in the northern GoM coastal zone is not due solely to the proximity of hydrocarbons. Salt domes within the zone are mined for halogens, primarily chlorine, by means of hydraulic dissolution. Chlorinated hydrocarbons are produced as solvents and feedstock for plastics manufacturing. The GoM is so geologically complex because of salt tectonics that the presence of igneous and hydrothermal ore bodies cannot be discounted. With the exception of a few xenoliths, exotic basement rock carried upward by salt movement (Stern et al., 2011), no deposits have been found to date. The DWH blowout did not impact the existing chemical industry or potential deep GoM chemical industry, but an increased regulatory environment for oil and gas exploration will eventually impact these industries. Cultural Services Aesthetics and Existence When you stare into the abyss the abyss stares back at you. Friedrich Nietzsche I asked them to look into the Abyss, and, both dutifully and gladly, they have looked into the Abyss, and the Abyss has greeted them with grave courtesy of all objects of serious study, saying: “Interesting, am I not? And exciting, if you consider how deep I am and what dread beasts lie at my bottom. Have it well in mind that a knowledge of me contributes materially to your being whole, of well-rounded, men.” Lionel Trilling, 1961 essay “On the Teaching of Modern Literature” As Lionel Trilling’s essay describes, the Abyss has become a powerful metaphor in recent literary history. Vast, dark, and inhabited by seemingly terrible beasts, to Nietzsche it stood for total meaninglessness, but to the more modern writer with a nod to oceanography, it is fascinating. The public at large retains a fascination with the deep ocean and its exploration by pioneers such as William Beebe and modern visionaries such as James Cameron. There is a spiritual or cerebral satisfaction in knowing deep-sea animals or ecosystems exist, evidenced by the unwillingness to use marine mammals as a source of food and measurable as the will- ingness to pay for conservation. It can be argued that the deep GoM, as with the entire vast and remote deep ocean floor, has a high existence value, but this argument requires an examination of how high that value is perceived to be. The usual pattern in society is to ascribe a high existence value to habitats 156

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Ecoystem Services in the Gulf of Mexico that are both desirable in some manner as well as dwindling in supply. Thus, there is often an implied connection between perceived value and rarity. Preservation of scenic wilderness otherwise threatened by overly exploitative encroach- ment in the National Park System is a prime example. Protection of a watershed to ensure the survival of a rare endangered species in either a technical or legal sense is another. Rare species abound in the deep ocean, and they are endangered by ongoing and planned resource exploitation that includes destructive trawling and habitat removal similar to strip mining (Carney, 1995; Ramirez-Llodra et al., 2011). The deep ocean is certainly wilderness, and human experience will be restricted to telepresence, except for scientists working with government support and explorers with access to substantial wealth. However, the vastness of the deep sea, the largest ecosystem on the planet, combined with the low level of human awareness of the system have the effect of making the existence value of the system unrecognized. Public interest and curiosity have somewhat effectively been focused on special subsystems such as hydrothermal vents, hydrocarbon seeps, and coral-supporting deep hardgrounds, but these are a tiny fraction of the total area of the deep seafloor. For management of the vast mud bottoms, the assumption of homogeneity has been clearly proven wrong by existing information on zoogeography and biodiversity (Menot et al., 2010; Rex and Etter, 2010). Cultural Artifacts Submerged cultural artifacts in the deep GoM provide an aesthetic benefit to people. The lifetime of such artifacts is prolonged by conditions in the deep sea (e.g., colder temperatures, higher pressure, reduced rates of biological activity) compared to those in shallow waters, making the extended preservation of submerged cultural artifacts an ecosystem service of the deep sea. MMS/BOEM includes in its responsibility the protection of cultural artifacts under the provisions of Section 106 of the National Historic Preservation Act of 1966. The initiation and early implementation of the program in the GoM and decisions about necessary technol- ogy were fully explained by Irions (2002).5 In the deep GoM, cultural artifacts consist primarily of shipwrecks that occur at all ocean depths, although usually clustering on the continental shelf along navigation routes between ports. More than 400 shipwrecks dating from 1625 to 1951 have been verified (BOEM, 2010) in the GoM. The deep GoM shipwrecks represent a broad historical span from colonial times to World War II, including the sinking of a German U boat. Especially noteworthy cultural artifact studies supported by MMS/BOEM are Church et al. (2007) and Church et al. (2009), which were carried out by multi-institutional partners, includ- ing oil companies and the offshore service industry. These studies have led to the formulation of more effective archaeological survey techniques employing high-resolution seismics and the implementation of spatial restrictions intended to provide protection for the artifact. In most cases, industry submits the required surveys to BOEM as part of the permitting process, 5  Current information about the program is available online at http://www.boem.gov/Environmental-Stewardship/ Archaeology/Gulf-of-Mexico-Archaeological-Information.aspx. This link provides access to relevant documents such as survey requirements placed on industry in 2005 and revised in 2011. 157

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L although BOEM does support surveys for its own use. Industry-collected survey data are considered proprietary, but they have been shared with independent researchers on occa- sion. The coordinates of shipwrecks are not shared with the public because of concerns about site destruction. The BOEM Gulf of Mexico Archaeology program continues to be proactive in outreach to make the public aware of the deep artifacts. This effort is carried out through the agency’s websites and through partnerships with the NOAA Ocean Exploration Program. Deep-water oil and gas activities have definitely increased knowledge of submerged arti- facts due to discovery and investigation using the advanced tools of the industry. BOEM speci- fications for survey and safe distances during development afford a high degree of protection. Impacts to artifacts caused by a seafloor blowout are probably limited to damage of physical structures in proximity to the well. No report of damage to a submerged cultural artifact has been reported as a result of the DWH oil spill. Impacts of the DWH Spill on the Deep Sea Simplistically and under ideal circumstances, environmental impacts are assessed through comparison of baseline data for the before-impact state to data for the after-impact state (Schmitt and Osenberg, 1996). The degree to which pre-spill data constitute an adequate base- line requires a more complex examination than can be undertaken here. The data for possible impacts are considered first, followed by the data that constitute the available baseline. Much of the study of the impacts of the DWH oil spill on the deep sea has been conducted under the auspices of the NRDA process, and, at the time of this writing, the full NRDA results for the deep GoM have not been released. A general account of deep-sea activities is available in a status report of April 2012 (NOAA, 2012b). More detailed findings from 2010 are included in Opera- tional Science Advisory Team’s 17 December 2010 Summary Report for Sub-Sea and Sub-Surface Oil and Dispersant Detection: Sampling and Monitoring (OSAT, 2010).6 Research cruise activities have overlapped, but generally it can be said that water column sampling with the intent of detecting oil and understanding its trajectories began in early May 2010, with a later inclusion of faunal studies that might allow for the assessment of impacts. Taking advantage of ongo- ing deep-coral studies, a work plan was accepted in July 2010 for NRDA investigation of that habitat based primarily on imaging and observation of hardgrounds in the vicinity of the spill. Related investigations of hardgrounds have continued into 2012. During phase I, May–August 2010, approximately 4,000 water and sediment samples, taken at depths greater than 200 m, were collected offshore with the primary purpose of detecting and quantifying the presence of spilled oil. These samples provided the basis of findings in OSAT (2010), in which hydrocarbon levels were consistent with those from submerged-plume models and rarely exceeded levels associated with injury except within 3 km of the blowout site. Plans for investigation of soft-bottom impacts were put forward in July 2011 (Deepwa- ter Benthic Communities Technical Working Group, 2011). These involved new sampling and 6  Partially redacted study plans are available at http://www.gulfspillrestoration.noaa.gov/oil-spill/gulf-spill-data. 158

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Ecoystem Services in the Gulf of Mexico analysis of 65 sites selected from previous studies: 17 within 3 km of the spill, 23 within 25 km, 15 sites more than 25 km away along the modeled route of a deep hydrocarbon plume, 2 sites more than 25 km under the known route of the surface slick, and 8 reference sites previously sampled in the Deep Gulf of Mexico Benthos (DGoMB) study (Rowe and Kennicutt, 2009). The sampling resembled traditional infaunal surveys with supporting geological and chemical analysis. A multicorer was proposed as the primary sampling device. Supplementing these traditional deep-sea approaches has been the use of a sediment-profiling camera, a device useful for assessing the thickness of deposited layers. Macrofauna would be examined at each site in three cores with a surface area of 0.03 m2, and meiofauna from a single core with an area of 0.01 m2. A workplan to investigate large animals living on the sediment surface at 10 sites using remotely operated vehicle (ROV) imaging surveys of bottom and water column was ap- proved in October 2011. Plankton studies were initiated offshore in November 2010, but they seldom included samples deeper than the 200-m upper limit of the deep ocean. A work plan to sample deep mesopelagic and bathypelagic fish using midwater trawls was submitted on November 30, 2010. In terms of the supporting and regulating ecosystem services, the primary impacts to the deep system will include reductions of dissolved oxygen and nitrate and toxic effects on biota. A blowout at the seafloor of a deep-water oil well has been recognized by regulatory agencies as a worst-case scenario since the onset of deep drilling (Carney, 1998), with the subsurface behavior of plumes examined during an experimental release (Johansen, 2000). Study of the acute effects on the deep-water column, deep bottom, and surface were initiated as part of the NRDA process as well as by separately funded independent scientists. As noted earlier, NRDA findings were not public as of this writing, but publicly available, peer-reviewed results provide a basic scenario. Because the hydrocarbons forcefully jetting into the bottom waters consisted of a wide range of particle sizes, a subsurface plume of slowly rising droplets as well as a soluble fraction was expected. Camilli et al. (2010) confirmed and documented this expec- tation, with little early indication of microbial consumption and associated oxygen reduction. An extensive amount of soluble component was subsequently reported (Reddy et al., 2011), as well as microbial consumption accompanied by drawdown of oxygen (Camilli et al., 2010; Val- entine et al., 2012) and nitrate (Hazen et al., 2010). Thus, the DWH oil spill is highly likely to have impacted regional gas exchange and nutrient dynamics. Hydrocarbons, unlike natural detritus, lack nutrients such as nitrogen and phosphorus. Microbial shifts to consuming hydrocarbons will thus alter the cycling of these essential nutrients. Larger-scale mixing will reduce these impacts over time. Such an event was anticipated and modeled by BOEM-supported research- ers prior to the spill using the smaller Ixtoc 1 oil spill from 1979 as an input example, along with mixing models of the GoM (Jochens et al., 2005). Among the damage assessments for the water column, mud bottoms, and hardgrounds, only results for the latter two have been reported. At the time of the blowout, the MMS (now BOEM) was supporting exploration and study of deep coral aggregations in the northern GoM in conjunction with regulation development. That effort was redirected to impact assessment. Dead and dying corals with brown, flocculent material on them were reported, which was 159

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L reasonably attributed to exposure to hydrocarbon/dispersant plumes (White et al., 2012). Three months after the Macondo well was capped, nine sites of deep-sea coral communities, located more than 20 km from the well and at depths of 290 to 2,600 m, were investigated using a ROV, the Jason II (White et al., 2012). These sites included seven that had been observed in 2009, and all were healthy, showing no impact from the spill. However, one site at 11 km southwest of the well and 1,370 m deep, which would have been in the path of the hydrocarbon plume, was covered by brown flocs and had coral colonies exhibiting obvious signs of stress such as bare skeleton, tissue loss, sclerite enlargement, excess mucous production, and abnormally colored or malformed commensal ophiuroids (White et al., 2012; WHOI, 2012). Of 43 corals, 46 percent showed impacts extending to more than half of the colony, and 25 percent showed impacts exceeding 90 percent of the colony at this one site only. Strongly reinforcing the interpreta- tion of a spill impact was the analysis of hopanoid petroleum biomarkers isolated from the floc collected from the impacted corals: comprehensive two-dimensional gas chromatography revealed a high degree of similarity with Macondo well oil (Boehm and Carragher, 2012). Some experts contend that these observed effects on the coral colony are due to nearby natural seeps or submarine landslides (Boehm and Carragher, 2012) rather than to the DWH oil spill, but the possibility of these alternatives is low, given the extensive surveys of the area in ques- tion (White et al., 2012). Information indicating impacts on the large fauna on the extensive mud bottom are based on analysis of ROV video recordings (Valentine and Benfield, 2013). The bottom was surveyed at four locations north, south, east, and west 2,000 m from the DWH blowout preventer (BOP); a fifth site was 500 m north of the BOP. Faunal density, species richness, and species composition varied spatially in a manner consistent with impact at the 500-m site and at the western and southern 2,000-m sites. The conclusion that impacts had occurred was reinforced by observa- tion of low numbers of apparently dead holothuroids and sea pens at those locations. Impact to mid-water zooplankton was indicated by the presence of dead pyrosomes and salps on the seafloor at all locations. Unlike the observations of impacted corals on deep hardgrounds (White et al., 2012), no collected specimens or sediments were taken for hydrocarbon analysis. The reported impact on corals and soft-bottom biota are consistent with these observa- tions. Effects might be sufficiently great so as to influence potential commercial upper-ocean pelagic species, which are somewhat dependent on the biomass aggregations of the deep- scattering layer and on the seafloor. Spill impact on the nonliving resources of the deep GoM may come through increased regulation and prohibitions intended to prevent environmental damage. Finding 5.17. The generally low level of understanding about the deep GoM makes it very difficult to assess the full impact of the DWH oil spill on ecosystem services. There are few, if any, ways in which the spill will have altered the larger-scale physics of the deep GoM, leaving only the biological and biogeochemical processes subject to major effects. It is, however, possible to consider the likely impact scenarios on supporting, regulating, and provisioning services. The cultural impacts of the spill are more nebulous, but they include what might best be called a loss of wilderness. 160

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Ecoystem Services in the Gulf of Mexico Baseline Data for the Deep GoM The U.S. Department of the Interior has the authority to manage seafloor mineral resources in federal submerged lands to the extent of the EEZ. Since receiving the initial mandate, the required tasks have been carried out under different organizational arrangements, beginning with the Bureau of Land Management and then followed by the Minerals Management Service (MMS) and the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE). Following the DWH oil spill, BOEMRE was divided into the Bureau of Ocean Energy Manage- ment (BOEM) and the Bureau of Safety and Environmental Enforcement. The critical task of identifying information needed to ensure protection of the natural and human environment has been the primary responsibility of the Environmental Studies Program (ESP), which was initiated in 1973 (NRC, 1992) and is currently a component of BOEM. ESP has a headquarters division and regional programs in the GoM, the Pacific, and Alaska.7 ESP has a scientifically trained staff, but it lacks a dedicated research component and, in most instances, supports information gathering by means of the Department of Interior pro- curement authority, which includes competitive bidding, cooperative agreements, and memo- randa of understanding. Contracts to carry out studies in deep water have traditionally gone to various combinations of academic institutions and the offshore service industry. Partnerships within government have made use of research platforms and staffs of NOAA and the Biological Resources Division of the U.S. Geological Survey. As a result of the continuing efforts of ESP and its partners and contractors, the GoM is one of the most extensively studied regions of the world’s oceans on a relative basis (volu- metrically, most of the global ocean remains unexplored). As will be discussed later, data gaps and inadequately addressed phenomena prevent the establishment of ecological production functions for the deep GoM. However, a basic of understanding of species inventory and the physical environment has been established for the continental shelf and the deep basin. Until the late 1980s, the primary sources of information about the deep GoM came from the sam- pling programs directed by Willis Pequegnat at Texas A&M University between 1964 and 1973 and were supported without regard to oil and gas development primarily by the U.S. Navy’s Office of Naval Research. With the intention to bring these results into the decision-making process for pioneering deep oil leases, BOEM supported an initial synthesis of results from 111 sampling stations above 1,000 m in the U.S. EEZ between Brownsville, Texas, and Desoto Can- yon (Pequegnat et al., 1976). Subsequently, a Gulf-wide synthesis of 246 stations was supported (Pequegnat, 1983). The stations were sampled primarily for megafauna on the continental slope to a basin depth of 3,658 m. Extensive hardgrounds on the West Florida Escarpment and Yucatan Peninsula prevented investigation of these eastern and southeastern regions. The Pequegnat et al. (1976) sampling efforts collected some hydrographic data, but it was primarily a zoogeographic study and biodiversity inventory. As such, it lacked the more comprehensive suite of measurements that became standard in BOEM-initiated baseline studies on the continental shelf. These more comprehensive investigations included the South 7  http://www.boem.gov/About-BOEM/BOEM-Regions/Index.aspx. 161

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L Texas Outer Continental Shelf Study, the Mississippi Alabama Florida study, and the Southwest Florida Shelf study, which included sediment hydrocarbon and metal contaminant measure- ments along with biological surveys (Carney, 1995). These studies were ecologically compre- hensive in that they examined both the seafloor (benthos) and water column (pelagos). A BOEM deep-sea baseline-type study was initiated and carried out on five cruises between 1983 and 1985. The primary results of the Northern Gulf of Mexico Continental Shelf Study (NGMCS) were presented in its third- and fourth-year annual reports (Gallaway, 1986, 1987). The sampling design was not hypothesis-driven in a formal sense; rather, it incorporated Pequegnat’s system of faunal zones and the need to compare eastern, central, and western planning regions. In ad- dition to benthic fauna, alkanes were analyzed for indication of petroleum hydrocarbon, along with metals. Pelagic work was limited to water column hydrology and chemistry. The 10 years following the completion of the NGMCS study saw the initiation of sufficient deep-oil drilling that a second comprehensive benthic study was initiated in 1999, the DGoMB project. Sampling was carried out between 2000 and 2002. Major results were published in a special volume of Deep-Sea Research (Rowe and Kennicutt, 2008) and a final report issued by Rowe and Kennicutt (2009). Although lacking a substantial analysis of the water column, the DGoMB study is notewor- thy with respect to future transition from habitat characterization to an ecosystem services approach. It included ecosystem function and model development in addition to the more traditional biological surveys. Sampling design was structured around specific hypotheses and included stations in close proximity to the DWH site. Primary productivity and carbon flux to the bottom, although not directly measured, were estimated from surface chlorophyll data. Benthic microorganisms were included as well as animal taxa. BOEM has contracted three major studies of seep communities and has afforded this special habitat protection through issuance of a Notice to Lessees (BOEM, 2012; National Ocean Service, 2012). When protection of deep coral habitat became a major issue in the European Union, BOEM contracted a series of studies to map and assess similar systems in the GoM and elsewhere within the U.S. EEZ. The second large study of deep corals, “Lophelia II,” was under way at the time of the DWH blowout and was converted into an NRDA task. Role of Industry in Baseline Development People generally familiar with environmental permitting may assume that the offshore industry carries out substantial environmental surveys prior to any drilling activity. Were that the case, a baseline would have been determined for the thousands of wells already drilled. In fact, the Department of the Interior, in the role of manager of nationally owned offshore lands, carries out studies and prepares reports that meet National Environmental Policy Act require- ments. The offshore industry has relatively minimal requirements to contribute to the overall understanding of the ecology of either the deep or shallow GoM. Much of the data developed by industry and submitted as a part of the permitting and planning process are proprietary and not available for review. The primary requirement in deep water is that the proposed drill- 162

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Ecoystem Services in the Gulf of Mexico ing must avoid sensitive habitats such as seep or hardgrounds. As evidence that such systems are being avoided, BOEM accepts geophysical or video recordings of the bottom taken by ROVs. The industry does from time to time exceed BOEM’s minimal baseline requirements. Any ecological data gathered, however, are considered proprietary or otherwise are not made avail- able for independent scientific analysis. A particularly noteworthy program in which industry makes a major contribution to data gathering and understanding of deep circulation is the BOEM Deepwater Current Monitoring on Floating Facilities program initiated in 2005. With few exceptions, floating facilities in water deeper than 400 m must acoustically monitor water movement through most of the water column. The data are publicly available online from the National Data Buoy Center (Bender and DiMarco, 2008). The Heavily Studied But So-Poorly-Known Contradiction Given that BOEM studies have provided so much information about the deep GoM, it is critically important to understand why the region has often been characterized as “poorly known” during and after the DWH spill. Beyond a lack of familiarity with GoM studies on the part of some spill responders, four causes can be suggested and corrected: (1) sparse data, (2) data less suited to serving as a baseline, (3) limited ability to access data collected over three decades, and (4) lack of conceptual frameworks that produce useful syntheses of existing data. With respect to sparse data, a major challenge to managing the deep GoM or any other portion of the United States’ deep EEZ is the problem of obtaining adequate data density to support management decisions and to provide a baseline from which to assess any damage due to exploitation. The deep GoM is a very large area that must be sampled by very small devices for understanding ecology and ecosystem services. This is especially the case for biotic inventories, sediment analyses, and benthic metabolism. How little of the actual deep habitat is actually sampled can be seen from an examination of the two major biological surveys of the deep GoM bottom: the NGMCS study (Pequegnat et al., 1990) and the DGoMB study (Rowe and Kennicutt, 2008). In the relatively recent DGoMB study, the sedimentary biota was sampled with a corer 271 times for a total area sampled of only 46 m2 (Wei et al., 2010b). The older NGMCS study took 324 cores for similar analysis, but these were of a smaller size and the total area sampled was only about 20 m2. Thus the major portion of deep GoM sampling that has contributed to habitat classification and that might be used as a baseline for the deep sedi- mentary environment has covered a seafloor area of less than 70 m2. Given that the deep GoM is not a homogeneous region, it remains grossly undersampled. The deep water column biota has largely been ignored: there are few pre-spill data sets to either characterize the habitat or serve as a baseline. With respect to collecting relevant data, management agencies such as BOEM are faced with the challenge of balancing regulatory obligations and limited budgets with evolving strategies of natural systems management and an incomplete understanding of what parts of natural systems are most important. Based on prior recommendations to increase data density 163

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L and gather data relevant to ecosystem functioning (NRC, 1992), it might be useful to assess the progress and limitations of deep GoM understanding of the past 20 years. As part of that as- sessment, the data requirements of the ecosystem services approach can be determined. With respect to data access, all reports produced by ESP since its inception are available online at the Environmental Studies Program Information System.8 Studies completed prior to the use of digital media are available as scanned images. The lack of a central topic index and the lack of geospatial information other than regional seriously limit the utility of these reports. The extent to which the reports include the critically important raw and processed data is highly variable. BOEM partners with the National Oceanographic Data Center (NODC) of NOAA for data archival. Much oceanographic data collected before 1995, however, remain in the Multi-Discipline Archives Retrieval System format, which is no longer supported. In addition to ESP studies, BOEM obtains information about the deep environment from industry during the process of approving exploration and development plans. This information includes video surveys to determine if protected habitats are present and seismic data for multiple purposes. Although of considerable ecological relevance, these data are proprietary and unavailable for independent analysis. Whether or not we can obtain and facilitate access to more data of greater relevance de- pends upon how the data are to be utilized. As more and more data are being collected, there is a growing need for an integrative process for search, retrieval, and analyses. Finding 5.18. As discussed throughout this report, contemporary management of deep-sea resources will benefit from the adoption of new perspectives such as ecosystem-based man- agement, ecosystem services approach, and management for resilience. For each of these per- spectives, new ideas are being proposed and critically examined. Meshing this process of idea evaluation with appropriate and adequate field data is a critical activity that should engage the participation of the academic community, federal agencies, and the offshore industries. BOEM’s deep-water program initiated a limited geospatial ecological synthesis effort in the form of Grid Programmatic Environmental Assessments (GPEAs). The deep GoM was divided initially into 17 and later 18 regions (Richardson et al., 2008). Depending primarily upon propri- etary data submitted as part of exploration and development plans, BOEM would determine the adequacy of existing information. For example, DWH’s Mississippi Canyon lease block 252 is in grid cell 16. MMS issued an environmental assessment for this lease block in 2002 (MMS, 2002), indicating that the data were judged to be adequate—a conclusion that might profit- ably be reexamined in light of events. The effectiveness of GPEA executions prior to the DWH oil spill can be argued, but with more careful examination of criteria and with all data available and accessible, a similar approach may be useful going forward. 8  http://www.data.boem.gov/homepg/data_center/other/espis/espismaster.asp?appid=1. 164

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Ecoystem Services in the Gulf of Mexico Deep-Sea GoM Conclusions The DWH oil spill occurred within the deep habitats of the GoM, producing a sustained buoyant plume that rose to the surface, crossing the density gradient (pycnocline) and con- taminating both the slowly mixed lower and more rapidly mixed upper water column. In addition, nonbuoyant plumes remained in the lower volume, contaminating water and bottom areas as these plumes intersected the continental slope. The environmental impacts of these contaminations are being investigated as part of the NRDA process, but few results had been released at the time of this writing. That work requires the time-consuming processing of samples of small fauna. In the case of deep corals that are more easily observed in the field, however, areas of injury consistent with exposure to deep plumes have been documented. Because of the increasing exploitation of deep-water areas, including the GoM, deep habitats will be increasingly at risk. With respect to the deep-sea environment of the GoM, an ecosystem services approach affords the potential to greatly improve the effectiveness of environmental management, espe- cially as the ecosystem services approach is refined to better consider the ecological functions of this very large but poorly understood system. In addition, this approach is directed at an understanding of ecosystem interactions rather than the promotion of species inventory and habitat classification. It is likely that microbial and faunal contributions to hydrocarbon attenu- ation, carbon sequestration, and nutrient recycling are critical ecosystem services that may require careful management. Actual assessment of ecosystem services and their distribution across the deep GoM will, however, require substantial innovation both conceptually and tech- nologically. Work needs to be done from a thoughtfully developed conceptual base, guiding careful sampling, with access to integrative tools for analysis and synthesis. Of the ecosystem services considered, the linked biological, geochemical, geological, and physical systems of the GoM interact to provide critical supporting and regulating services. The exact nature, rates, and distribution of the interactions and resulting services present many critical questions. How does the complex circulation across two sills and the Caribbean prevent deep hypoxia within the GoM basin under normal and spill-impacted conditions? How does the complex deep circulation interact with the Loop Current to determine the distribution of recycled nutrients within the GoM and the larger Atlantic? From a comprehensive perspective, what is the carbon balance of the GoM: is the deep a net sink or a net source? Of very special interest is the ability of the microbial system, closely linked to the physical system, to consume naturally seeping liquid and gas hydrocarbons. How does this attenua- tion capacity vary within the GoM, as well as other regions of the global ocean? How does it impact nutrient and gas balance in slowly mixed deep water? Can this capacity be decreased by industrial accidents or other mismanagement? Through the development of broad-based knowledge of the ecosystem dynamics of the deep GoM, required for an ecosystem services approach, we can hope to answer many of these fundamental questions. 165

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A S S E S S I N G T H E I M PA C T S O F T H E D E E P WAT E R H O R I Z O N O I L S P I L L SUMMARY The four case studies presented in this chapter (wetlands, fisheries, marine mammals, and the deep sea) were chosen to provide examples of how an ecosystem services approach may be applied to assess the impact of the DWH oil spill on several key ecosystem services in the GoM. They represent a range of conditions with respect to the amount and utility of available data, our fundamental understanding of the functioning of the ecosystem subcomponents, the values of the services in market and nonmarket terms, and the range of the impacts of the spill on the services. As such, they serve as exemplars of how an ecosystem services approach can add to the ability to capture the full impact of an event such as the DWH oil spill and, at the same time, illustrate the challenges faced when attempting this approach. The case studies should make it clear that, within the GoM, some ecosystem services (e.g., storm mitigation from wetlands) are associated with years of research and baseline measure- ments, which creates a situation in which adequate ecological production functions and valu- ation processes exist to carry out an ecosystem services approach to damage assessment, with a high likelihood that the result will provide a more holistic view of the impact of the DWH oil spill and a wider range of restoration options. In the case of the ecosystem services provided by fisheries, valuation techniques are well established (at least for the provisional services) and a significant amount of baseline data exist, but these data suffer from a lack of spatial specificity, which affects the ability to assess impacts on the current and future productivity of the fisher- ies. The final two examples (marine mammals and the deep GoM) highlight the difficulties in estimating the full range of impacts when the current database, level of understanding of eco- system interactions, and approaches to valuation are clearly inadequate. Nonetheless, in each case, the potential benefits of an ecosystem services approach are outlined. The next chapter discusses the research efforts that are needed to realize these benefits. 166