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.