The 2007 Cosco Busan disaster, which spilled 54,000 gallons of oil into the San Francisco Bay, had an unexpectedly lethal¹（致命的） impact on embryonic² fish, devastating³ a commercially and ecologically important species for nearly two years, reports a new study by the University of California, Davis, and the National Oceanic and Atmospheric⁴ Administration. The study, to be published the week of Dec. 26 in the early edition of the Proceedings⁵ of the National Academy of Sciences, suggests that even small oil spills can have a large impact on marine⁶ life, and that common chemical analyses of oil spills may be inadequate⁷.

"Our research represents a change in the paradigm⁸（范例） for oil spill research and detecting oil spill effects in an urbanized estuary⁹（河口，江口） ," said Gary Cherr, director of the UC Davis Bodega Marine Laboratory and a study co-author.

On the foggy morning of Nov. 7, 2007, when the container ship collided with the San Francisco-Oakland Bay Bridge, bunker oil contaminated spawning¹⁰ habitats for the largest U.S. coastal¹¹ population of Pacific herring -- a month before spawning season.

The new study, which analyzed¹² Pacific herring embryos¹³ following the spill, highlights the effects of bunker oil on fish embryos in shallow water, the potential significance of sunlight interacting with oil compounds, and the extreme vulnerability of fish in early life stages to spilled oil.

Specifically, the study found that components¹⁴ of Cosco Busan bunker oil accumulated in naturally spawned¹⁵ herring embryos, then interacted with sunlight during low tides to kill the embryos. Laboratory-fertilized eggs, caged in deeper waters, were protected from the lethal combination of sunlight and oil, but still showed less severe abnormalities associated with oil exposure.

Crude oil is naturally occurring, liquid petroleum¹⁶. Bunker oil is a thick fuel oil distilled¹⁷（蒸馏） from crude oil and burned on ships to fuel their engines. It is contaminated with various, sometimes unknown, substances.

The study builds on research following the 1989 Exxon Valdez spill, which released up to 32 million gallons of crude oil into the comparatively pristine¹⁸（原始的） environment of Prince William Sound, Alaska. That research established a new paradigm for understanding the effects of oil toxicity¹⁹ on fish at early life stages.