WA4 Indirect Effects of Stressors on Organisms and Communities
204 Oregon Ballroom
8:00 AM - 12:00 PM, Wednesday
() Exxon Valdez oil spill: Chronic exposure and indirect effects.
Rice, S1, Short, J1, Heintz, R1, Esler, D2, Bodkin, J3, Ballachey, B3, Irons, D4, Peterson, C5, 1 Auke Bay Laboratory, NOAA, Juneau, Alaska, USA2 Simon Fraser University, Burnaby, British Columbia, Canada3 U S Geological Survey, Anchorage, Alaska, USA4 Fish and Wildlife Service, Anchorage, Alaska, USA5 University of North Carolina, Morehead City, North Carolina, USA
ABSTRACT- The Exxon Valdez oil spill in 1989 had tremendous direct effects resulting in severe habitat contamination and direct mortalities. In the following decade, oil contamination generally declined, but not to zero. Pockets of persistent oil on intertidal beaches have provided low-level, chronic exposure to key species such as pink salmon embryos, sea otters, and harlequin ducks that spawn or feed in these areas of persistent oil. Extensive studies directed at these three species in the 1990s provide the best evidence linking chronic oil exposure with indirect effects and limited population recovery. Large-scale exposure tests with pink salmon embryos subsequently released to the ocean demonstrate how delayed effects on growth result in lower fitness and greater predation of individual fish leading in turn to poorer adult returns to the natal streams. These controlled laboratory tests corroborate field observations of increased embryo mortalities and reduced escapements. Sea otter exposure to chronic oil through feeding on oiled invertebrates has continued for more than 10 years, and recovery has been poor in some localized areas despite the abundance of food. Harlequin ducks in the same oiled areas struggle similarly, and extensive winter tracking data demonstrate the homeothermic challenges for small species in a cold environment. While the documented direct mortalities in the first year were staggering, the chronic effects from the spill coupled with indirect effects may rival the initial losses of some specific species.
Key words: chronic effects, Exxon Valdez, oil spill, indirect effects