Native fish found with spinal deformities in California’s Sacramento-San Joaquin Delta in 2011 had been exposed to high levels of selenium from their parents and food they ate as juveniles in the San Joaquin River, new analysis has discovered.
The finding featured in Environmental Science and Technology indicates that some fish in the area may experience harmful ranges of selenium. Selenium is a naturally found mineral that is essential to life but turns poisonous and might inflict deformities at high levels.
Deformities had been present in birds exposed to selenium accumulated in the agricultural runoff in the same space in the Eighties.
Biologists collected the juvenile fish, minnows known as Sacramento splittail, from a pumping station in the Sacramento-San Joaquin River Delta in 2011. They realized that over 80% of the roughly 1,000 amassed fish showed spinal deformities.
Scientists raised the fish in tanks for several years. In the meanwhile, they coined laboratory methods to examine the ear bones of the fish for clues about where they’d found the selenium. Called otoliths, the ear bones show chemical traces of the situations the fish experience as they grow.
Researchers used high-intensity X-rays at Cornell University’s Cornell High Energy Synchrotron Source to trace selenium concentrations in the otoliths.
They revealed that the fish had swallowed selenium from their mothers, and while feeding as juveniles in the San Joaquin River.