Mechanism for transport of oil-contaminated groundwater into pink salmon redds

Exposure of pink salmon embryos to dissolved polynuclear aromatic hydrocarbons delays development, prolonging vulnerability to mechanical damage

“…Two mechanisms placed embryos in contact with toxic dissolved oil constituents, tidally driven water flow from oiled intertidal gravel into stream channels and shifts in stream channel position. Tidal cycles and resultant hydraulic gradients provided a mechanism for groundwater transport of PAHs from oiled intertidal gravel to pink salmon embryos (Carls et al, 2003(Carls et al, , 2004a. The laboratory procedures in this and similar studies were designed to emulate this mechanism (Marty et al, 1997a,b;Heintz et al, 1999;Incardona et al, 2005).…”

“…(1) direct mortality as a result of oil exposure (Rice et al, 2001;Carls et al, 2003) and (2) differential shock resistance resultant from hypothetical differences in run timing among oiled and reference streams (Brannon and Maki, 1996). The latter hypothesis was developed because eggs were hydraulically pumped from stream substrate and the authors were concerned that observers did not discriminate among previously dead eggs and those killed by sampling.…”

“…The incidence of embryo mortality, determined by hydraulically pumping eggs from natural substrate, remained greater in oiled streams than in reference streams before merging about 5 yr post-spill. Two principal hypotheses have been advanced to explain this phenomenon: (1) direct mortality as a result of oil exposure (Rice et al, 2001;Carls et al, 2003) and (2) differential responses in shock resistance based on hypothetical differences in run timing among oiled and reference streams (Brannon and Maki, 1996). The goal of this study is to examine the possibility that protracted susceptibility to mechanical damage caused by oilinduced, developmental delays indirectly contributed to the observed disparity in mortality between oiled and reference streams in PWS.…”

Restoration of oiled mussel beds in Prince William Sound, Alaska

“…This study clearly demonstrates that natural processes transport oil within the intertidal system. The potential for tidally-driven transport of oil constituents dissolved in water was demonstrated near intertidal streams (Carls, Thomas, & Rice, 2003) and both field and laboratory studies demonstrate that PAH move from oil into water (e.g., Marty et al, 1997;Neff & Stubblefield, 1995;Short & Harris, 1996;). Harris, Rice, Babcock, and Brodersen (1996) reported that oil distributions within mussel beds were not static.…”

Slightly Weathered Exxon Valdez Oil Persists in Gulf of Alaska Beach Sediments after 16 Years

“…Intertidal sediments of PWS and the GOA usually contain <5% total organic carbon (22), and sedimentary oil refuges armored by boulders are stable, porous and well-flushed by ∼5 m tides and wave exposure, especially in the GOA (11,12,23). Low concentrations of nitrate in seawater during warm seasons (24) may also retard biodegradation.…”