An Ecosystem Services Approach to Assessing the Impacts of the Deepwater Horizon Oil Spill in the Gulf of Mexico (2013) / Chapter Skim
Currently Skimming:
5 Ecosystem Services in the Gulf of Mexico
5 Ecosystem Services in the Gulf of Mexico
Pages 103-166
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 103... ...
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)
|
From page 104... ...
. 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.
|
From page 105... ...
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
|
From page 106... ...
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)
|
From page 107... ...
"Directional 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.
|
From page 108... ...
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, supporting, and particularly cultural.
|
From page 109... ...
. 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)
|
From page 110... ...
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.
|
From page 111... ...
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)
|
From page 112... ...
. Consequently, change in total wetland area is the most direct and practical measurement of change in ecosystem services in 5-1 Gulf Coast wetlands.
|
From page 113... ...
FIGURE 5.2 Land loss change in coastal Louisiana. SOURCE: http://www.nwrc.usgs.gov/upload/landloss11X17.pdf.
|
From page 114... ...
and now possibly to the DWH oil spill. Distinguishing the background trends and noise associated with storms, droughts, and other factors from oil-spill-related effects will be challenging (Figure 5.5)
|
From page 115... ...
. 5-4 R02473 bitmapped, uneditable FIGURE 5.5 Dark grey denotes the extent of the oil slicks in the vicinity of Barataria Bay, Louisiana, based on satellite observations made on (a)
|
From page 116... ...
Data collected at each site include information on sediment accretion and plant community metrics. DWH Spill Impact on Wetlands A review of the effects of oil spills on wetlands in general can be found in Mendelssohn et al.
|
From page 117... ...
(2012) discussed impacts specific to the DWH oil spill.
|
From page 118... ...
However, in view of numerous studies that document a rapid recovery from oiling and a relatively low sensitivity of perennial marsh vegetation to hydrocarbons, marsh vegetation can be expected to suffer little or no long-term impairment from the spill in areas where roots and rhizomes survived the initial impact of oil fouling. Seven months after oil from the DWH oil spill came ashore in the salt marshes of Bay Jimmy in northern Barataria Bay, Louisiana, the concentration of total petroleum hydrocarbons at a sediment depth of 2 cm was as high as 510 mg/g, causing almost complete mortality of Spartina alterniflora and Juncus roemerianus (Lin and Mendelssohn, 2012)
|
From page 119... ...
The next step in the ecosystem services approach is to attempt to attribute a monetary value for this service. Two methods for doing so include quantifying the costs avoided, as in the case of storm mitigation, or the replacement costs, as in the case of engineered defenses.
|
From page 120... ...
Finding 5.3. The ecological production function for storm mitigation from wetlands relates changes in wetland area to changes in coastal protection.
|
From page 121... ...
In contrast, the ecosystem services approach may offer a broader range of options to restore ecosystem services and enhance wetland resilience. As depicted in Table 5.5, application of the ecosystem services approach in the GoM is fairly simple from a concep TABLE 5.5 Provision and Valuation for Wetland Storm Mitigation NRDA Practices Resource Wetlands (salt marsh)
|
From page 122... ...
An ecosystem services approach can develop production and valuation functions, which calculate a net present value of the incremental loss of wetlands and human-engineered structures due to storms. This approach allows for identification and comparison of alternative mitigation options to find the preferred restoration option, which may increase resilience more so than simply restoring the damaged wetland to its original state.
|
From page 123... ...
Fisheries clearly offer an important cultural ecosystem service through recreational fishing, which will be considered only briefly here. Like for wetlands, substantial baseline data for fisheries exist, and significant efforts have been made to develop ecological production functions through various fisheries models (see Chapter 2)
|
From page 124... ...
. As a result, a wide array of GoM fishery resources may have come in contact with substrates or waters polluted by the DWH oil spill or the spill responses.
|
From page 125... ...
, while the reduction in value for 2010 may be attributed to the DWH oil spill. Most fishery models describe the productivity of a fish population as a function of population dynamics (Quinn and Deriso, 1999)
|
From page 126... ...
(2011) estimated spatially explicit abundance for migratory fish; however, their model still does not resolve abundance at scales smaller than FIGURE 5.7 Historical sustainability indices for some of the most important fish stocks in the Gulf of Mexico that may have been affected by the oil spill or by the fishing closures imposed after the oil spill.
|
From page 127... ...
Although population assessments do not estimate spatially explicit population abundance, there are indices of relative abundance for some species that have some measure of spatial resolution. Many of the indices of relative abundance for fish populations in the GoM use the National Marine Fisheries Service (NMFS)
|
From page 128... ...
have shown that it is possible to design robust management strategies despite the lack of knowledge about all of the factors that affect the productivity of species such as bluefin tuna. In theory, it should be possible to design and implement precautionary management measures that acknowledge the uncertainty of the impacts of the DWH oil spill on fishery resources and therefore ensure sustainable provision of seafood into the future.
|
From page 129... ...
. DWH Spill Impact on Fisheries As already discussed in this report, the impacts of the DWH oil spill can be far-ranging and long-lasting.
|
From page 130... ...
and abnormalities in locomotor behavior, sensory and motor axon pathfinding, somitogenesis, and muscle growth. In addition, heavily weathered oil from the DWH oil spill has also been implicated in reproductive impairment and aberrant protein expression in gill tissues (physiological impairment)
|
From page 131... ...
Fishery closures in response to the DWH oil spill serve as one limited measure of the impacts to fisheries. Another impact of the spill and the subsequent closures was the public's concern about the safety of seafood from the GoM, despite efforts by federal and state governments to establish a comprehensive protocol to ensure the safety of GoM seafood.
|
From page 132... ...
. Prior to the DWH oil spill, oil spills have typically been local events that affect mostly the vicinity of the incident where oil was released.
|
From page 133... ...
Relative to the NRDA process, valuation efforts utilizing the ecosystem services approach can integrate more of the environmental variables that influence the productivity and recruitment of the fisheries, particularly the condition of the habitat that could be directly affected by an event such as the DWH oil spill. Opportunities for Restoration The ability to manage possible impacts on the provision of seafood and fish-based products as an ecosystem service also relies on our knowledge of the natural resilience of marine ecosystems.
|
From page 134... ...
Aside from application of precautionary catch limits to mitigate the potential impacts of the DWH oil spill on fisheries, habitat restoration, because of its potential to enhance a suite of ecosystem services, may prove to be one of the more effective ways to restore fishery productivity in the GoM. It is also essential that habitat restoration efforts are documented with a proper and standard set of habitat project-level metrics so that decision makers have the information they need to decide whether projects are likely to mitigate the effects of the DWH oil spill on fisheries.
|
From page 135... ...
in the northern GoM based on the unexpectedly high levels of bottlenose dolphin mortality along the coast.4 Such a designation calls for intensive data and sample collection and a rigorous, coordinated study into the cause. Investigation of the mortality event has been subsumed into the NRDA process related to the DWH oil spill.
|
From page 136... ...
Dependent calves would be of particular concern. Studies under the NRDA process may shed light on whether the DWH oil spill has affected the health of dolphins in the GoM and any links between the spill and the mortality event.
|
From page 137... ...
Expenditures that individuals make for these experiences provide some measure of their minimum value. Revenues from these operations are uncertain, but relevant information is available from other parts of the country and could be used to help model/extrapolate values for this GoM ecosystem service.
|
From page 138... ...
Researchers have consequently studied this species extensively for decades, which allows for exploration of their role in providing a number of ecosystem services. Changing Baselines Estimating changes in the ecosystem services provided by dolphins will ultimately require an understanding of the underlying ecological production functions for dolphins and of the impacts of the DWH oil spill on the population dynamics of GoM dolphins.
|
From page 139... ...
Finding 5.11. Substantial uncertainty regarding the abundance of GoM dolphins and of the range of stressors that affect them will complicate the assessment of the true impact of the DWH oil spill on their populations and on the ecosystem services that they provide.
|
From page 140... ...
(2003) conducted one of the most extensive studies to measure the impact of an oil spill on passive-use values, with regard to the Exxon Valdez oil spill of 1989.
|
From page 141... ...
Opportunities for Restoration Under the current Marine Mammal Protection Act in the United States, there are no specific restoration plans in place for bottlenose dolphins. If the NRDA findings establish a linkage between the recent mortality event of dolphins in the GoM and the DWH oil spill, then a major opportunity will exist to establish a plan to protect and restore dolphin habitat and to reduce mortality caused by human activities, such as bycatch from fishing.
|
From page 142... ...
If a determination is made that the recent dolphin mortality event is linked to the DWH oil spill, then an opportunity may exist to establish a plan that includes the protection and restoration of dolphin habitat as well as the reduction of dolphin mortality from human activities. The Deep Gulf of Mexico Introduction The final case study focuses on the GoM deep sea, defined by this committee as ocean depths of 200 m and greater (effectively beyond the continental shelf )
|
From page 143... ...
There is sufficient knowledge of deep-sea processes and availability of GoM-specific information to begin to identify ecosystem services of this deep-sea habitat, consider how these services may have been impacted by the DWH oil spill, examine methods of measuring baselines, determine what baseline data already exist for the GoM ecosystem, and identify gaps in those data. At present, the gaps in knowledge of the GoM deep-sea inhibit the ability to apply an ecosystem services approach in a quantitative way, leaving development of ecological production functions and the most effective use of valuation tools (Figure 2.1 in Chapter 2)
|
From page 144... ...
Achieving effective science-based management is challenging due to the unique characteristics of the deep GoM, including novel geochemistry, slope instabilities, and steep escarpments. Environmental Protection During Petroleum Development The Outer Continental Lands Act of 1953, amended in 2000, has a primary intent of developing offshore hydrocarbon resources, but also includes sections requiring that the natural and human en vironment be protected.
|
From page 145... ...
. On the International Front In contrast to the United States' fragmented program of deep-ocean management is the European Union's highly organized approach, which adds an ecosystem services component to traditional conservation and protection (Armstrong et al., 2011; Tinch et al., 2012)
|
From page 146... ...
This Gulf Loop Current links the surface water to the larger Atlantic and causes local processes to have far-distant effects. Presumably, much more will be learned about transport and mixing from the extensive studies following the DWH oil spill.
|
From page 147... ...
Nutrient Resupply in Support of Primary Productivity The most extensive studies of primary productivity in the GoM have been carried out in shallow coastal waters, especially associated with the discharge of the Mississippi River. High levels of productivity have been observed over the deep GoM using sea-surface color imagery (Biggs et al., 2008; Müller-Karger et al., 1991)
|
From page 148... ...
Some existing models, targeting other goals such as trophic transfers of carbon and nitrogen (Rowe and Deming, 2011; Rowe et al., 2008; Wei et al., 2012a) , may provide starting points for developing the more complex systemwide models ultimately required to evaluate supporting ecosystem services of the deep GoM.
|
From page 149... ...
Its location within the larger North Atlantic circulation and its abundance of special habitats make the deep GoM a likely source -- and center of distribution -- for seep and hardground fauna. This conjecture is now under examination.
|
From page 150... ...
, but was unknown for the deep-sea water column prior to the DWH oil spill. The release of crude oil from the spill site, creating a plume of hydrocarbons in the deep GoM, provided unique impetus and resources for a scientific evaluation of the ability of natural communities of marine bacteria to attenuate hydrocarbons in situ in deep water.
|
From page 151... ...
also occur throughout the other anoxic sediments of the GoM, including those impacted by the DWH oil spill. Just as indigenous hydrocarbon-degrading bacteria responded to an injection of oil into deep waters (Abbriano et al., 2011)
|
From page 152... ...
As described earlier in this case study, the GoM is well equipped to handle the breakdown of hydrocarbons into smaller organic compounds. Hydrocarbon-degrading bacteria, present in the plethora of natural seeps in the deep GoM, responded rapidly when the plume was formed, which demonstrated that the GoM environment does have the ability to attenuate pollution, specifically hydrocarbons.
|
From page 153... ...
The unusual geomorphology and physical oceanography of the deep GoM may give it important roles in nutrient resupply, a critical supporting service of the deep sea, and thus in carbon dioxide fixation and carbon sequestration. The important question of whether the deep Gulf is a net repository or source of carbon to 153
|
From page 154... ...
The extent to which an oil spill of the magnitude of the DWH oil spill may impact seafloor carbon sequestration (or hydrocarbon attenuation) in the deep GoM is unknown.
|
From page 155... ...
Relative to the combined value of all deep GoM reservoirs, the loss of commodity can be seen as small. The blowout did, however, alter the regulatory environment and cause temporary delays in new production through drilling moratoria and extended permitting times (NRC, 2011)
|
From page 156... ...
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
|
From page 157... ...
.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)
|
From page 158... ...
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.
|
From page 159... ...
. Thus, the DWH oil spill is highly likely to have impacted regional gas exchange and nutrient dynamics.
|
From page 160... ...
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.
|
From page 161... ...
. Following the DWH oil spill, BOEMRE was divided into the Bureau of Ocean Energy Management (BOEM)
|
From page 162... ...
. Although lacking a substantial analysis of the water column, the DGoMB study is noteworthy with respect to future transition from habitat characterization to an ecosystem services approach.
|
From page 163... ...
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.
|
From page 164... ...
, indicating that the data were judged to be adequate -- a conclusion that might profitably 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.
|
From page 165... ...
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.
|
From page 166... ...
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 measurements, which creates a situation in which adequate ecological production functions and valuation 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.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.