Native fish discovered with spinal deformities in California’s Sacramento-San Joaquin Delta in 2011 were exposed to high levels of selenium from their parents and food they ate as juveniles in the San Joaquin River, new research has found.
Native fish discovered with spinal deformities in California’s Sacramento-San Joaquin Delta in 2011 were exposed to high levels of selenium from their parents and food they ate as juveniles in the San Joaquin River, new research has found.
The finding published in Environmental Science and Technology indicates that some fish in the region may experience harmful levels of selenium. Selenium is a naturally occurring mineral that is essential to life but turns toxic and can cause deformities at high levels. Deformities were also found in birds exposed to selenium concentrated in agricultural runoff in the same area in the 1980s.
Biologists collected the juvenile fish, minnows known as Sacramento splittail, from a pumping station in the Sacramento-San Joaquin River Delta in 2011. They soon realized that more than 80 percent of the approximately 1,000 collected fish exhibited spinal deformities.
“This was not just a few fish, it was the majority of them,” said Fred Feyrer, a research fish biologist at the U.S. Geological Survey’s California Water Science Center and co-lead of the research.
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Photo: Captured in the wild and raised in tanks at UC Davis, Sacramento splittail show spinal deformities traced to exposure to selenium. Scientists used the fishes' ear bones, called otoliths, to track their exposure to selenium. Photo credit: Fred Feyrer/US Geological Survey; fish in Rachel Johnson’s hands.
