Photo E-1. Summer storm in the Arctic

The International Association of Oil and Gas Producers (OGP) in support of the Arctic Oil Spill Response Technology – Joint Industry Programme (JIP) funded this review of available information on the environmental impacts from oil spills in the Arctic and impacts that may be associated with the application of specific treatment technologies that may be applied during an oil spill response.  The objective of the review was to compile significant findings of prior investigations and suggest priority areas of work needed to improve assessment of the consequences of the various treatment strategies prior to application under Arctic conditions. The primary outcome is development of a process to integrate ecological consequence assessments within net environmental benefit analyses (NEBA) to better evaluate the environmental effects to valuable ecosystem components (VECs) within key environmental compartments (ECs) c that would result from using different response actions in the Arctic.  Specifically, development of Arctic response consequence analysis table matrices (ARCAT) and a semi-quantitative analytical tool will optimize decision-making and lessen environmental impact related to arctic oil spills in the Arctic.  The process is proactive rather than responsive to a spill event improving the ability to reduce environmental damage by chosing mitigating measures with the minimized effect on the environment.  As a result of this proactive approach there will also be broader consensus and acceptance of decisions among regulators and stakeholders.

To increase confidence in evaluations and environmental impact statement (EIS) of oil spills and oil spill response (OSR) technologies proposed for the Arctic, a comprehensive review of the existing literature was conducted to identify priority areas for future research efforts.  Because of the breadth of topic areas supporting consequence analysis approaches, this effort called for a multidisciplinary team with an understanding of food webs throughout the Arctic; behavior of oil in surface waters, at depth, and in ice; the effectiveness of OSR countermeasures in cold-water surface and subsurface environments; the toxicity of petroleum treatment residues on Arctic species; and models used to predict individual and population effects in Arctic ecosystems based on the concept of resilience.  This literature review followed a pan-arctic approach that recognizes regional similarities and differences based on peer-reviewed literature and technical reports from government and research institutions representing circumpolar interests.  The review is based on more than 650 literature citations and the personal experience of the work group participants.  To best utilize the expertise assembled on this team, representatives from different regions and disciplines worked in subgroups and all were able to review the entire document since many of the investigators have multi-disciplinary research backgrounds. The team was divided into nine technical working groups, each with a focused assessment goal and each with the assignment to identify areas of priority research:

• The Physical Environment – Summarize available literature to describe the different environmental compartments present in the Arctic and the physical characteristics of those compartments that could potentially affect the fate and effects of oil, as well as defining what response measures are an option for those environment compartments.  Seasonality in Arctic eco-regions is addressed (ice or ice-free conditions) as well as unique habitats and use of those compartments by VECs (e.g. areas with significant riverine input).  
• Arctic Ecosystems and Valuable Resources – Identify environmental compartments, food web connections within those environmental compartments, key Valuable Ecosystem Components (VEC species/taxa) within each compartment that connects those food webs and variations among VEC species/taxa between sub-regions within the Arctic.
• Transport and Fate of Oil in the Arctic – The various treatment strategies may enhance or reduce the amount of oil that is transported away from sites of surface or subsea released oil.  This section discusses the mechanisms behind short and long term transport of spilled oil in the Arctic.
• Oil Spill Response and Related Effects – Identify the implications of various response actions to increase or decrease the exposure to various treatment residuals within environmental compartments. Identify alternative response options for surface and subsurface spills of oil under Arctic seasonal conditions and describe the environmental effects of those response actions.
• Biodegradation – Identify the measurement tools that can quantify the use of oil by Arctic microbes including direct uptake and use of carbon containing petroleum compounds, mineralization of petroleum hydrocarbons to CO₂ and chemical changes of parent petroleum compounds to other compounds under different treatment options and how those changes are modified in different ECs
• Ecotoxicology of Oil and Treated Oil in the Arctic – The four lines of ecotoxicity research include acute and chronic response assessments and biomarker and body burden assessments of exposure.  Evaluate the literature to establish the environmental relevance of these four lines of evidence.  Identify gaps in experimental programs to address the ecotoxicology of oil in separate environmental compartments.
• Population Effects Modeling – Petroleum treatment residuals are environmental stressors that have the potential to produce adverse impacts on individuals or populations of VECs.  Determine which parameters are necessary components of a population impact model for VECs; identify models useful in predicting the effects of treatment options on these species/taxa.  Parameters of interest include changes in the toxicity of biodegraded oil, transfer of impact related effects to other trophic level VECs, or consideration of the resiliency of populations to recover from a stress.
• Ecosystem Recovery – The ecotoxicology and biodegradation of oil spill residuals is better understood than the ability of a compartment or VEC to recover from the impacts of a spill.  Environmental compartments have different abilities to recover from oil impacts.  Application of treatment methods need to account for and minimize the movement of oil to locations or species that have a low resiliency to respond to oil.  This section examines the duration of continued impact of an oil release and expected recovery of different environmental compartments and VECs. Response actions need to minimize encroachment on less resilient ECs and VECs.
• Net Environmental Benefit Analyses for Oil Spill Response Options in the Arctic – The environmental consequences of an oil spill response strategy will influence the overall impact of an oil spill (surface or subsurface).  In typical applications of net environmental benefit analysis (NEBA) framework, the consequences of a treatment option are generally associated with the near-term impacts and less so with consideration of the longer term consequences to recovery resulting from impacts to less resilient environmental compartments or VECs.  As an example, far-field impacts can result from not selecting a dispersant option which result in stranding of untreated oil on cobble shorelines where the effects can be observed decades after a spill.  Alternatively, selection of the dispersant option will result in greater impacts to the more resilient zooplankton community while reducing the effects on less resilient seabird and marine mammals that might contact oil on the sea surface.  The goal of this workgroup was to develop a preliminary consequence analysis of treatment decisions and demonstrate through an adaptive NEBA process the interrelationships between treatment decisions and shortening or lengthening of recovery from all forms of environmental effects, not restricted to the immediate near-field impacts.

Recent literature was reviewed for each topic area, and the information was compiled into a Microsoft Access® database.  Approximately 650 documents have been cited within the body of this report, and at this time there are over 1300 documents represented in the Access database that has been produced for recent JIP programs.  The database is searchable and can generate a list of references related to Arctic ecology, food webs, deep water food webs, petroleum-related fate and effects, biodegradation, and ecosystem-level case studies; aquatic toxicity and chemistry data can be queried via pivot graphs to dynamically represent the data compiled to date.   Based on results of these summary investigations, recommended new environmental studies are identified and prioritized. The recommended research will help reduce uncertainties related to each topic area and strengthen the NEBA approach in the Arctic.  The organizations and team members participating in this synergistic effort are presented in Figure E-1.

Figure E-1. Organizational matrix (Workgroup chairmen and co-chairmen are noted in bold text)

Currently five of the eight countries bordering the polar region are pursuing exploration and/or development of oil and gas resources in the Arctic [Canada, Greenland (Denmark), Norway, Russia, and the United States]. The changing environmental conditions in the Arctic may provide increased opportunity for development of these resources that were less accessible due to presence of ice in past decades and the improved technological advances for extracting petroleum resources. Activities of the petroleum industry are based on promulgated regulations set by each sovereign nation but there has been a move toward international cooperation and sharing of knowledge related to the technological development required to ensure safe drilling operations as well as spill response preparedness. International, federal, and local agencies from North America, Northern Europe, and Russia are in the process of developing baseline ecosystem and biodiversity assessments and research programs in order to better understand and protect the Arctic marine ecosystem and the communities that rely on these resources. For example, the Arctic Monitoring and Assessment Program (AMAP) has completed a significant effort in publishing comprehensive baseline information on Arctic geo-political activities and regulations, available drilling technologies, spill response initiatives, and potential environmental impacts (AMAP 2010). Additional cooperative research sponsored by joint industry programs (JIP) have augmented the knowledge base associated with the oil and gas industry activities (Sørstrøm et al. 2010; NewFields 2012). These efforts and convened workshops have integrated contributions from the scientific community, governmental agencies, public interest groups, and indigenous people of the Arctic.

Additionally, extensive field and laboratory studies have been conducted to examine the behavior and fate of oil and its potential effects on Arctic resources under the disparate seasonal conditions. Many recent studies have concentrated on understanding the influence of these harsh environmental conditions on the relative sensitivity of Arctic species to additional stressors, the success and rates of microbial degradation of oil compounds, and more recently the resilience of Arctic populations to recover from responses to those stressors. Similar to other parts of the world these investigations have increased our understanding of the basic behavior and movement of oil, its potential effects on VECs and the ultimate fate of released oil in various environmental compartments. The Arctic environment has added complexities resulting from seasonal patterns of ice and light that need to be considered to provide the foundation for development of strategic spill response strategies and evaluation of the environmental consequences of released oil that are very relevant today. Excellent comprehensive reviews have been published in recent years (Potter et al. 2012, Lee et al. 2012, SL Ross et al. 2010; USGS 2011).

The fundamental role of comparing the adverse biological effects of different response options in NEBA requires an information base that identifies VECs within multiple environmental compartments. The potential adverse effects and resiliency of these VEC organisms within each of these various compartments are then compared as a consequence of the OSR actions. These comparisons should examine the acute and long-term effects of spilled oil resulting from the impacts of various response options such as natural attenuation, surface-applied or subsea-injected dispersants, in-situ burning, and mechanical or naturally occurring containment methods followed up by recovery of spilled petroleum in Arctic ecosystems. Review and tabulation of published data, such as toxicity effect concentrations and population recovery times, is a key component of this review. However, the overall objective related to exploration and production projects in the Arctic is not only to tabulate this information or determine the most sensitive end-points that might be considered but to demonstrate the relative differences in the magnitude and duration of effects that might be observed at various ecosystem compartments associated with various response actions. As has been attempted for other regions where new exploration and production activities have been implemented, demonstrating these relative differences will require additional effort aimed at bridging the gap between relatively straightforward measurements of toxicity to arctic species and more complex investigations to assess ecosystem-level or population level impacts and recovery dynamics. This report considers the similarities and differences in species sensitivity between arctic and non-arctic species. To effectively monitor habitat recovery and identify ecologically relevant endpoints for remediation operations in Arctic regions there is a need to increase our knowledge on natural variability among populations and how that variability relates to vulnerability to petroleum exposure.

Prior to the granting of approvals for exploration and production activities, the public seeks increased assurances that industry and the various governmental entities have the capability to ensure safe exploration and extraction of oil as well as the capability to respond to oil spills. To meet these challenges a number of current and emerging oil spill countermeasure technologies have been identified for use in the Arctic. While use of different OSR methods can potentially reduce the impact of spills within the Arctic under various environmental conditions, not all options have been readily accepted by the public and regulators. Lack of endorsement of some OSR options is related to the perceived change in impacts and biodegradation rates that the use of these options in the Arctic marine ecosystem may bring. Several studies have been undertaken to address such concerns for different response measures; however, conflicting interpretations and conclusions impact stakeholders’ confidence. For example, the assumptions that dispersant treated oils are more toxic than undispersed oil, dispersants are more toxic than oil, dispersants reduce the ability of microbes to degrade oil, and Arctic species are more sensitive to oil than non-arctic species are incorrect although all of these assumptions may be proposed as facts by multiple stakeholders.

The purpose of the following section is to describe those key areas that the workgroup recommended for further evaluation based on their critical review of available information. The subjects for further consideration are grouped into major subject headings for this executive summary. Details of the recommendations will be found in each of the sections of the reports.

Arctic conditions influence the behavior and fate of untreated surface oil due to the low temperatures and the presence of different types of ice. Petroleum is generally immiscible in seawater and more so under colder temperatures. Surface oils with lower specific gravity accumulate on the sea surface and spread horizontally with the more volatile or soluble components quickly released into the air or into the water, respectively (NRC 1989; EPPR 2011). The surface oil also encounters disturbance by wind and wave action increasing the exposed surface area of the oil to the vertical transport processes of volatilization and solubilization. The wind and waves also adds water to oil creating oil/water emulsions that become more stable with time. The presence of broken ice with wind and waves enhances the disruption of the surface oil. These physical processes produce small globules of oil that may undergo further physical, chemical and biological weathering, creating aggregations of the heavier residual compounds that remain, eventually producing tar balls. In general, slicks formed in cold water are thicker with less exposed surface areas with reduced spatial coverage than the same oil released under temperate conditions. Laboratory trials have provided Information on key parameters that influence oil spreading under solid ice such as under-ice currents and ice roughness (Potter et al. 2012). In situations that the pour point of oil is above ambient temperature, the physical characteristics of the oil change dramatically with the wax components of the oil precipitating and forming a gel-like semi solid that is resistant to flow and spreading and which also restricts diffusion of volatiles through the slick, effectively reducing evaporation.

Untreated surface oils form slicks that are transported laterally by winds and currents and largely remain on the water surface and in the upper water column. The oil continues to spread on the surface of the ocean forming ribbons of slicks that rapidly spread to approximately 1 mm in thickness and are patchily distributed. Wind and waves break up and drive some of this surface oil into the water column in relatively large globules (>100 µm). The oil slick contains all of the chemical components of the spilled oil less those components that volatilize into the atmosphere or solubilize into the water column under the slick. The maximum concentration of oil is therefore contained in the immediate slick area, potentially exposing organisms that use the water near the air-water interface to the highest petroleum hydrocarbon concentrations that immediately follow a spill event.

The behavior and fate of released petroleum is an important consideration in understanding the potential effects of released petroleum and in evaluating the potential OSR options in the arctic. The spreading and weathering of petroleum in the arctic is complex, influenced by factors such as water temperature, local currents and wind conditions, the presence and absence of seasonal and multi-year ice, effects of pressure in deep water environments and seasonal changes in salinity during the Arctic spring. The presence of ice has been shown to slow the rate of spreading and weathering of surface oil, as well as affecting predictions of spill locations and trajectories. Migration of petroleum into brine channels or fissures in the ice can not only alter fate, but also the species that are potentially exposed and the exposure point concentration. At depth, petroleum is affected by increased pressures and decreased temperatures, resulting in phase shifts and changes in solubility as well as the dynamics of deep water currents and bathymetry. Key considerations included in the review were as follows:

• Cold water temperatures and the presence of ice can dramatically affect the weathering and natural attenuation of oil in the Arctic, but the ice can also trap oil so that OSR options and time available to implement the necessary response can be extended.
• Changes in behavior and fate of petroleum in deep sea environments associated with seeps and well blow-outs or leakage alter the bioavailability of oil components by allowing more volatile components to diffuse into the water where they may form clathrates altering the biodegradation potential and toxicity of those structures.
• Adhesion of oil to particulate matter and how this may affect the potential for uptake into tissues;
• The change in globule size and bioavailability of physically and chemically/OMA dispersed oil under Arctic conditions and,
• The behavior of oil in the absence and presence of ice and how it influences the selection of OSR options.

The microbial degradation potential of oil in the Arctic has been demonstrated and is as effective as this process occurring in lower latitudes when natural communities of Arctic microbes respond to the presence of oil. Microbial response to oil in the Arctic and deep, cold and dark waters are emerging areas of research. While microbial degradation in temperate waters has long been recognized, recent laboratory and field studies have documented microbial degradation of petroleum and dispersed petroleum in these extreme environments. Current research is using analytical chemistry, respirometry, genomics, transcriptomics, and proteomics assays to not only show the presence of oil-degrading species, but measure the response and results of microbial activity upon being exposed to oil. Key considerations included in the review are as follows:

• The presence and effectiveness of microbial communities to degrade oil in the Arctic (in open waters, in the presence of ice, along shorelines and in subtidal sediments);
• The characterization of the microbial community responses and gene expression associated with exposure to oil and aerobic and anaerobic biodegradation and use of hydrocarbons and organosulfur compounds associated with the unresolved complex mixture; and,
• The effects of biodegradation on the toxicity and availability of metabolites created during biological use of oil compounds and the changes that occur in toxicity and further biodegradation resulting from the more recalcitrant residual compounds of oil

There has been substantial research regarding the fate and effects of oil in the Arctic over the past 40 years; studies have been published in a number of different forums including peer-reviewed literature, technical reports, government studies and professional symposia. Additional data exists in a number of different languages, since research has been conducted throughout the North American, European, and Russian Arctic. Finally, important sources of data include emerging datasets from current research and older datasets that may not be as readily found in electronic search engines but nonetheless contain valuable information on environmental conditions and ecological resources. Consideration must also be given to the quality of data available for use. However, the most important aspect of making environmental consequence comparisons for OSR options is the appropriate framing of questions so that the consequences of response actions can be compared appropriately among all environmental compartments.

The physiological, morphological, and behavioral adaptations of Arctic species may alter their sensitivity to petroleum and treated petroleum. To address this concern there have been a number of recent efforts to characterize the sensitivity of Arctic species to treated and untreated petroleum. Evaluations have included pelagic and benthic species, as well as those in close association with the ice. Endpoints that have been evaluated include survival, growth, reproduction, and behavioral effects, as well as molecular, cellular, physiological responses. Custom experimental facilities have been developed for working with chemically and mechanically dispersed oil and water soluble fractions (WSF) of differently weathered oil. Methodologies have been developed by project team members to capture and maintain Arctic species of interest for controlled laboratory studies. The VEC species that have been evaluated to this point have been found to have sensitivities similar to non-Arctic species for oil exposure. Both field and laboratory data have also been integrated with population models to provide estimates of population-level effects from oil exposures (e.g. SYMBIOSES and fishery population analysis). Key considerations included in the review are as follows:

• Recent, historic and ongoing field and laboratory studies evaluating toxicity of petroleum and treated petroleum provided in Species Sensitivity Distributions to compare sensitivity of tested species.
• Different exposure scenarios facilitate different types of evaluations and can dramatically affect comparability of data. Spiked exposures followed by reducing concentrations of oil represent the exposures of stationary species or those present in the water column when oil is undergoing the initial spreading and dilution following the spill event or after application of dispersants or OMA. Exposures to constant concentrations of oil represent zones of concentrated oil observed with neuston associated species and life stages and marine mammals and seabirds that move in and out of the air/water interface. These more constant higher exposure concentrations can also occur when oil is concentrated at edges such as shorelines, convergence zones, and water/ice edges.    
• Endpoints found in the literature review range from body burden assessment to biomarker responses as well as mortality, growth, reproductive, developmental and behavioral responses. The diversity of potential end point assessments range from exposure assessment to end points that have a direct influence on estimating population level response to the oil components. For the purpose of this review, those responses that are better predictors of effects at the individual and population levels are the central focus. Mortality, growth and reproductive endpoints are those most closely associated with population level effects. Reviews on exposure markers will concentrate on demonstrating the relationship of the exposure marker to mortality, growth or reproductive endpoints.
• All toxicity assessments are surrogate measures used to predict the potential effects of oil spills on living resources. As such, data obtained using sub-arctic and temperate species representing different groups of organisms or different environmental compartments may also be useful in augmenting datasets with Arctic species. Recent comparisons of the relative sensitivity of Arctic and non-arctic species suggest that non-arctic species have similar sensitivities warranting a broader evaluation of much larger data sets.
• Additional testing of species that are long-lived, unique to selected habitat types and low in reproductive capacity that have not been evaluated in other regions have been identified during the reviews.

The toxicity of a mixture is characterized based on the analytical approach used to characterize the exposure. Variable conclusions regarding the relative toxicity of oil and water often can be tracked to the test waters being produced by different processes. The water accommodated fraction (WAF) is designed to only introduce the more soluble components into the water column while retaining the less soluble components on the surface of the water. The breaking wave water accommodated fraction (BWWAF) introduces additional physical disturbance, introducing more oil into the water as droplets with increased surface area exposure than occurs with the WAF allowing more of the soluble components to diffuse into the water from the oil droplets. The chemically enhanced water accommodated fraction (CEWAF) reduces the surface tension of the oil and produces much smaller droplets with much larger available surface area for diffusion of the soluble components of the oil. One of the objectives of the ecotoxicology section was to evaluate alternative methods of characterizing exposure.

A NEBA evaluation of OSR strategies for use in the Arctic must consider ecosystem-level consequences of the selected response. First, the effectiveness of the proposed solution(s) under the appropriate conditions to determine how much of the oil can be treated by the proposed action. Second, the consequences to various compartment VECs resulting from exposure to the untreated oil and the treated oil. Such comparisons must be made for resources in environmental compartments to determine the relative environmental benefits or risks of different response options. Third, the resilience of the populations of organisms that are being exposed as a result of no action or a response treatment needs to be addressed in order to determine the long term consequences of the decision.

Due to both logistical and environmental constraints, responses to oil spills rely on combinations of remote sensing and monitoring. The OSR options include 1) natural attenuation, 2) containment followed by recovery, 3) in-situ burning, and 4) dispersion using chemicals or oil mineral aggregates. With the exception of lower temperatures, oil spill response (OSR) options during the ice-free season are generally similar to other parts of the world. The presence of ice results in additional challenges as well as opportunities not encountered in regions without ice. The manner in which ice affects OSR effectiveness is determined in part by the ice characteristics which can differ regionally and seasonally. Recent field and laboratory studies that have evaluated the behavior, fate and effects of chemically dispersed oil, in-situ burning, OMA, and natural attenuation. Team members have evaluated spill response options in the presence and absence of ice and in both surface and deeper water environments. Both COOGER and SINTEF have led field releases of oil and studied field applications of OSRs on arctic shoreline/intertidal environments and in cold water and harsh environments including ice.

The objective of consequence analysis applied to oil spills is to provide spill responders a choice of response option(s) in terms of the lowest overall negative impact on the environment. It is likely that multiple response options will be selected and utilized for various stages of the response to reduce the exposure of VEC species. This process recognizes that once oil is spilled, some level of environmental impacts will occur, independent of the spill response options chosen. The goal of an effective response is to apply the combination of response techniques that will be effective in minimizing overall short and long term impacts. For the Arctic and other environments, this approach helps to focus technical discussions on the potential for short term and long term impacts on key ecosystem components and those resources of greatest cultural value to indigenous peoples. Assessments include comprehensive discussions of acute and chronic toxicity, food web bioaccumulation issues and reproductive and developmental impacts to exposed species. However, the discussions should focus on overall assessments at the population and community level of ecological organization, and ultimately promote a response strategy that allows for the fastest recovery of important ecosystem components. This approach has been used by governments and industry around the world to establish environmental protection priorities and spill response preparedness that will provide the greatest degree of overall environmental protection. IPIECA, International Maritime Organization (IMO), and OGP have long-supported this approach fostering development of a rational basis for setting oil spill response guidance and regulations (www.world-petroleum.org; www.imo.org; www.ogp.org).

These consequence evaluations have recently been incorporated into consensus building exercises that include all stakeholders. The process guides technical discussions and social prioritization among response planners, environmental agencies and local citizens as they compare ecological consequences of specific response options. The communication process is complex with many different opinions and levels of understanding of the effects of various response actions. The NEBA process has been particularly useful when considering use or non-use of dispersants, in-situ burning, containment and recovery of oil, as all of these present challenges with regard to potential environmental impacts. The process recognizes there will be damage during a spill but focuses on ecological consequences of different responses and compares “trade-offs” or cross-resource comparisons. Through a facilitated and structured analytical approach, participants find “common ground” for evaluating impacts and to develop defensible logic to support their conclusions. Discussion often can get stalled when there is a focus on localized and transient impacts of spills and response actions, without stepping back and trying to incorporate a longer term view of population and community recovery. Technical advisors and facilitators help guide the group to reaching their consensus among the diverse stakeholders by using a series of analytical tools specifically developed for use in a group environment. Knowledge regarding oil spill response capabilities and strategies gained by participants in the consensus-building process facilitates real-time decision-making in the event of actual spill incidences.

Resiliency of VEC communities is a critical component to evaluating the consequences of OSR that needs to be further addressed in non-Arctic as well as Arctic environments. The direct, toxic effects of oil on individuals among the VECs are better understood than the resiliency of the populations and communities of these valuable ecosystem resources within various environmental compartments. Each environmental compartment is at a different level of risk resulting from response actions. Their resiliency is related to biological, physical and chemical attributes of the compartment and the species living in that compartment. The arctic environment is variable and harsh, featuring water temperatures that can range from -2 °C to greater than 5 °C, a light regime ranging from total darkness to total light, and regions that are covered in ice year-round and areas that cycle from being ice-covered to being ice-free. These widely varying conditions require behavioral, physiological, and morphological adaptations that may affect the sensitivity of some species to released petroleum as well as the dynamics of the population during recovery. The Arctic is considered to have relatively short food webs, with the higher trophic levels dominated by mammals and birds. Many of these species are dependent on rich populations of plankton that bloom heavily in spring in close association with ice break-up or upwelling zones. Key considerations included in the review were based on the following observations:

• The projected damages to VEC populations are based on application of each OSR option. Use of OSRs changes the fate of oil; whatever OSR (including no response) is selected will alter the communities of organisms exposed to the oil at concentrations that can result in adverse effects. Damages include acute and chronic toxicity responses to oil. Additionally, the potential for recovery from oil contamination is also influenced by physical/chemical attributes that control the distribution and availability of the oil in each of the compartment as well as the availability of the oil to microbial degradation. Environmental compartment attributes that influence oil availability and ongoing biodegradation vary and need to be well quantified when establishing the long term consequences of OSR options.
• The focus of the section on recovery potential is to document the available knowledge and identify uncertainties in our understanding for VECs in different environmental compartments. Species found in arctic waters have a number of unique physiological and morphological adaptations to allow them to tolerate the cold water temperatures and the extensive periods of ice cover and absence of sunlight and associated food resources. The data reviews in the ecotoxicology section shows that these factors may influence the time period for demonstration of effects after exposure. However, the responses of Arctic VECs are similar to non-Arctic test species.
• The reproductive potential of Arctic VEC species is the key factor in assessing the ability of their populations to recover from stress/damage. In terms of recovery times, this resilience will vary from very short periods of hours in the case of microbial populations to many decades in the case of marine mammals and seabirds. This resilience and recovery potential for VECs in the Arctic is similar to what has been characterized in other regions of the world.
• Communities and food webs change dramatically during periods of open water or iced over water resulting in seasonal modifications of the available environmental compartments. During the winter the annual ice environmental compartments increase while during the spring and summer the melting ice adds more open water pelagic compartments. Seasonal OSR evaluations need to consider the change in the availability of these compartments, as well as the associated seasonal changes in effectiveness of the response options.
• There are specialized and unique species that live under and within ice, including larval forms of important water-column species. While the communities under the multi-year ice are becoming better known the ecological importance of the annual undersea ice is less understood.
• There are also deep-water Arctic communities that feature unique species and communities, including deep water corals and sponges. The extent of these communities under multi-year ice is not well characterized but the presence of ridge topography determined by geophysical means indicate there is a potential for these species to be more broadly distributed than is known at the present time.
• There are also regional and seasonal differences across the arctic which is principally associated with some of the higher trophic level species. The rationale for selection of VEC species is to emphasize those which are pan-arctic species that support these higher trophic levels. Unique species are also examined to determine associations with specific environmental compartments.
• In general, there is less knowledge of ecological processes occurring during the Arctic winter season.

Current oil spill contingency and response models representing transport, fate, and limited effect-based components have been used to support ecosystem evaluations. A key area of additional research recommended by the work groups is to augment Arctic NEBA assessments with an environmental compartment approach in order to evaluate the short and long term consequences of oil potentially impacting the resources in those compartments (Figure ES-2). Resiliency of the inhabitants using different environmental compartments will govern the recovery from oiling and is the key focus for the recommended new work.

The review of Arctic literature found many high quality assessments at the laboratory, mesocosm, and field scales on the efficacy of the treatment options (natural recovery; containment and product recovery; use of chemical dispersants or OMA; and in-situ burning). These studies provide information for efficacy estimates and for application to transport models providing good estimates of the movement of residuals from one EC to another within the Arctic. There are also high quality toxicological effect and biodegradation studies conducted under Arctic conditions that indicate the relative acute sensitivity of Arctic species are equivalent to sub-Arctic, temperate and tropical species and that biodegradation of oil by indigenous Arctic microbes is efficient and more rapid than anticipated based on the cold inclement conditions in the Arctic. The priority recommendations of each workgroup are included at the end of each section. A list of the high priority work elements within each section is appended to the summary of recommendations. Several of the recommendations apply to local operations and should be incorporated in baseline monitoring programs, Environmental Impact Assessments and operational oil spill response plans. These recommendations have not been prioritized here, but should be considered by the individual operators.

Four overarching areas of research were identified and were considered by the scientific panel of experts to be of the highest priority to advancing NEBA applications in the Arctic:

1. Increase availability of the vast amount of data on the impacts of oil spill response techniques and on the resilience of VECs reviewed in the current study by developing and populating matrices, or Arctic Response Consequence Analysis Tables (ARCATs), in support of Arctic NEBA processes.
2. Determine influence of oil on unique Arctic communities within EC interface habitats as well as corresponding response consequences (resiliency, sensitivity, and exposure potential)
3. Further investigate in-situ biodegradation of oil and oil residues
4. Further explore consequences of acute and chronic toxicity from oil exposure through use of population modeling

All response actions, including natural recovery, result in adverse effects on some portion of the environment and to some species. The consequences of those actions need to be compared holistically among all ECs and VECs. Direct ecotoxicological responses to the oil spill residuals is an important aspect of these considerations but the long term recovery potential of the ECs and VECs is even more important. The relationships between EC resilience and the sensitivity and resilience of VECs within those ECs is an important area that needs to be addressed in OSR consequence analysis. A way to consistently summarize and present available data on the impacts of oil spill response techniques on selected VECs within ECs would be through the development of information matrices that collate the relevant available data to support Arctic NEBA processes. These ARCATs (Arctic response consequence analysis tables) summarize the relevant information from literature to focus on the initial and long term consequences of oil spill response actions so that impacts to ECs and VECs that are less resilient and which take the longest time to recover are avoided. To accomplish that goal a number of tasks are suggested.

1. Develop a format for ARCAT matrices that will address the potential effects of oil spill response treatment residuals on ECs and VECs
2. Describe the OSR actions, ECs and VECs that will be used to develop the ARCAT matrices.
3. Map the EC locations that are relatively permanent and indicate the areas for seasonal positions of other ECs.
4. Document the use of ECs by VECs on a seasonal basis with the assumption that EC usage by VECs occurs during those seasons whether they are observed or not during a spill event.
5. Provide biological attributes that influence exposure potential (e.g. skim feeding, haul-out locations), reproductive capacity (e.g. time to adult, progeny production rates that may be influenced by age, daily natural mortality rates of populations), and immigration potential that augment recovery potential.
6. Document physiological and behavioral characteristics of VECs that increase or decrease exposure potential especially for mobile species (e.g. large fish marine mammals and seabirds).
7. Document assumptions of the population sizes and age classes of VEC components.
8. Document those characteristics that will be used to compare the resiliency of EC and VEC response to oil spill residuals.
9. Summarize the responses of species to OSR that are less studied (e.g. ISB, OMA, and chemical herding).
10. Demonstrate food web complexity in the Arctic using stable isotope ratios to demonstrate structure or unstructured aspects of key food webs

Figure E-2. Arctic ecosystem (surface microlayer, ice, nearshore continental shelf, pelagic and deep water communities) [Most literature is representative of the pelagic community, outlined in red]

An understanding of the transport, fate, and exposure potential of oil spill treatment residuals is an ongoing need for convergence zone communities. Convergence zones include shorelines, air/water, sediment/water, ice/water, and water/water interfaces. The VECs that occupy these convergence zones or that move in and out of these zones undergo exposures that are not similar to the better understood open pelagic water exposures. The areas of additional work suggested by the work group include a better understanding of toxicology and biodegradation for two convergence zones air/water and ice/water:

1. Describe the ecological relevance of interface zones, specifically the surface of the ocean and the ice water interface edges.
2. Describe the seasonal use of these two interface zones by VECs.
3. Develop testing protocol for exposure evaluations at these two interfaces. Consider Early Life History of fish, Arctic algal/kelp, sediment, deep water hard substrate, and fouling exposures, bioaccumulation and lipid characterization.
4. Develop or provide analytical chemistry methods for OSR residuals and degradation products in water, sediment and tissues.
5. Describe the differences in exposure of VECs to OSR residuals and the modes of toxic action encountered in the surface microlayer (neuston) and water/ice interface environments.
6. Initial responses by pelagic organisms to oil spills are relatively well understood and predictable. However, the long term consequences of an oil spill and subsequent effects on the recovery potential of sites, species or communities is less well developed. A better understanding of the factors that control the physical, chemical and biological attributes that control VEC and EC resiliency, which ultimately controls the amount of time for recovery needs to be developed.
   1. Define and establish measurements of resilience and develop methods to combine resiliency metrics into compartment specific short and long term recovery assessments.
   2. Compare EC population sizes for VEC in EC so that the relative importance of the air/water and ice/water interface environments can be assessed.
   3. Toxicity responses to exposure from accommodated fractions of fresh oil and chemically dispersed oil have predictable results based on the measured concentrations of oil in the liquid phase of these preparations. The responses are relatively consistent from experiments performed on tropical, temperate and Arctic species. Less is known about the toxicity of other OSR residuals (ISB, OMA, chemical herders) and weathered OSR residuals.

Biodegradation of fresh and chemically dispersed oil using indigenous organisms from pelagic Arctic environments has been demonstrated to occur at rates similar to those observed in deep and surface waters throughout the marine environment. Biodegradation of oil and OSR residuals when they are concentrated at interfaces (e.g. air/water and ice/water) is less well understood but assumed to be slower based on the reduction in surface area of the oil when it is re-concentrated in these convergence zones. The recommended areas of research for these areas are:

1. Establish a method to evaluate biodegradation occurring at interface environments (air/water and ice/water).
2. Compare biodegradation success for OSR residuals using this method.
3. Evaluate –omics procedures for application to OSR residual assessments.
4. Consider the implications of the storage of OSR residuals within convergence zones. This should not only include the air/water and ice/water but also shoreline stranding and the influence of shoreline sediment type on short and long term storage of OSR residuals.
5. Produce a GIS or EC database that addresses recovery potential of those ECs impacted by OSR residuals.
6. Evaluate food web structure within areas of oil/gas seeps and demonstrate the presence or absence of food webs that are oil/gas based and whether those food webs are supplementary to detrital based food webs in the same area.
7. Demonstrate whether these oil/gas based food webs provide communities that are pre-adapted and more resilient to exposure of OSR residuals.

Key attributes to determining the importance of acute and chronic responses of organisms to OSR residuals are measures of the natural resiliency of individuals, populations of species, and structure of food webs. Modeling of the transport, fate and effects of oil spills is relatively well known and predictable. Toxicity at interface environments is much higher due to the concentration of contaminants at these locations but the population influence of that concentrated contaminant exposure is less well understood. The areas of research suggested to provide improvement in the understanding of population impacts to VEC from exposure to OSR, especially at these interface habitats is provide in the following:

1. Establish the natural structural, functional and population dynamics measures for VECs within key ECs, including comparing the interface environments of air/water and ice/water interfaces.
   1. Determine whether the ‘sustainable’ reduction of 20% used in resiliency assessments for fishery harvests is applicable and whether that level of effect can be determined within the natural population fluctuations of VECs.
   2. Evaluate whether a 20% reduction of a VEC population would influence success of food web structure.
2. Obtain population dynamics, age-related characteristics of populations of key components leading to VECs (daily mortality rates, age/size population structure, variation in population size/standing crop, seasonal sequestration of significant portions of populations, emigration/immigration potential of individuals, etc.).
   1. Refine those characteristics for populations of these species living in different ECs.
3. Establish food web connections based on literature and alternative measures (e.g., stable isotope ratios).
4. Provide a predictive modeling diagram that incorporates knowledge of spilled materials, transport and fate of OSR residuals, influence of biological transport of contaminants within the water column, toxicity assessment and consequence analysis of the application of alternative OSR actions.
5. Develop factors to address transport and fate of OSR residuals along ice edges, under ice and near sea-surface.
6. Modify models based on new input parameters obtained from these research areas.

Each review team arrived at similar overall conclusions. They observed that there were high quality assessments on the efficacy of various response options. Those assessments were conducted under different physical conditions representing the Arctic at laboratory, mesocosm, and field scales. It was also generally recognized that strong transport models exist and are applicable to some Arctic conditions, including broken ice but some necessary adjustments to include information on currents, and transport under multi-year and annual ice conditions may be required. However, past estimations of the effects of various response actions have been generally isolated to a single environmental compartment or species based on acute toxicity responses using pelagic species or age classes. These response data have been used to predict ecosystem level effects in different habitats by modeling the concentrations of oil as it moves through the environment and interacts with new species or age classes. Although the research on the acute effects is generally well done, the long term consequences to different environmental compartments and species has not been well developed. This includes chronic toxicity responses but more importantly the overarching physical and chemical resiliency of environmental compartments and the biological recovery potential for species or age classes living in those compartments that are exposed to weathered and treated or untreated oil. Resiliency of environmental compartments and population to oil exposure is less well known not only in the Arctic but also non-Arctic environments. These longer term factors in recovery are key components needed to provide a better balance to evaluations of the consequences of oil spills and use of alternative treatment options.