Confidence in Assessments

Workshop in Anchorage, Alaska

26 and 27 March, 2008

Lines of Evidence

Environmental Compartments

Assessment of Effects

Trajectory

Evaluating Effects

Environmental Compartments

– Degree Of Effect

• Short and long term impacts

– Area Of Effect

• Size of impact zone small or large

– Rate Of Recovery

Components within Food Web (s)

Degree and Area of Effect within the Environmental Compartments

• Sea Surface including Microlayer – Neuston, marine birds, marine mammals

• Pelagic Zone

– Marine mammals, invertebrates, fish

• Sediment

– Benthic community, demersal fish and invertebrates, marine mammals and other species

• Near Shore and Intertidal

– Juvenile fish and invertebrates, shellfish, birds, terrestrial animals, anadromous and forage fish

Rate of Recovery

Parameters SML Pelagic SedimentNear Shore

& Intertidal

Resource Type(s) Number of compartments involved

Site Conditions Complexity relative to weathering

Size of the Spill Small to larger impact on weathering

Type of Petroleum Light to more complex crude oils

Depth of Water Potential to affect more compartments

Proximity to Shore or ASBS

Distance relative to transport and weathering

Predicting Dispersion

Level of Testing Required to Predict Impact to Receptors

Establish a Process:• How many tests and how many times• Different phyla • Food web components• Realistic conditions• Endpoints• Transport, fate, and changing toxicity