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.