SAN FRANCISCO, Dec. 27 (UPI) -- Spilled oil can be unexpectedly lethal to fish embryos in shallow, sunlit waters, U.S. scientists studying the effect of a spill in San Francisco Bay said.
Researchers at the National Oceanographic and Atmospheric Administration said Pacific herring embryos in shallow waters died in unexpectedly high numbers following a 2007 spill when a container ship released 54,000 gallons of bunker diesel fuel oil into the bay.
An interaction between sunlight in shallow water and the chemicals in oil might be responsible, a NOAA release said Monday.
"Based on what we know about the effects of crude oil on early life stages in fish, we expected to find live embryos with abnormal heart function, so it was a surprise to find so many embryos in the shallow waters literally falling apart," John Incardona, a toxicologist with NOAA's Northwest Fisheries Science Center, said.
"The study has given us a new perspective on oil threats in sunlit habitats, particularly for translucent animals such as herring embryos," he said.
"The chemical composition of residual oils can vary widely, so the question remains whether we would see the same thing with other bunker fuels from around the world."
Bunker fuel is used in maritime shipping worldwide, and accidental bunker spills are more and more common and widespread than large crude oil spills, NOAA said.
