There is something in the water in California that is causing deformities that are radically altering the body shape of fish and scientists are concerned that it may spread to birds and mammals.
Houston we have a problem…But it’s not coolsculpting Houston that is creating this curvy new body shape among fish in California waters. The bodies of fish are being altered in strange ways by severe spinal deformities that have been linked to a toxic mineral.
The findings are the result of study conducted by the US Geological Survey’s (USGS) California Water Science Center that was published in the journal Environmental Science and Technology, which looked at the severe deformities that are being found in an endangered fish called the Sacramento splittail (Pogonichthys macrolepidotus), which is only found in California and is a migratory minnow.
“This was not just a few fish, it was the majority of them,” said Fred Feyrer, a research fish biologist at the USGS and the co-lead of the research.
The toxic mineral found in high amounts in California water is selenium. Excessive amounts of selenium have been linked to causing severe deformities in fish.
While selenium is a naturally occurring trace element, which is essential to the development of humans and animals, high levels of the mineral can be toxic.
Selenium has been shown to cause deformities in fish, birds, and mammals in high doses that can be received through both parental transfer and accumulation end diets.
In some cases, selenium can even be more toxic than arsenic. For example, there was a mass mortality event due to toxic levels of selenium that killed around 15,000 seabirds near the Salton Sea in 1992.
Fish have a unique characteristic in their ear bones that will leave a record, in patterns very similar to tree rings, showing chemical traces of whatever they have been exposed to in their environment.
These rice-sized ear bones in fish are called otoliths, and scientists can use high-intensity x-rays to see these ring patterns and measure selenium concentration to determine at what point and where the minnows were being exposed to the mineral.
“We found that the otoliths record a diary of selenium exposure from birth to death, and were the key to unraveling this mystery,” said Rachel C. Johnson, a research biologist at National Oceanic and Atmospheric Administration (NOAA) Fisheries’ Southwest Fisheries Science Center and the University of California Davis and the lead author of the USGS study.
The study found that the fish had absorbed selenium in “both directions,” from their parents during embryo development and while feeding as juveniles.
The study found high concentrations of selenium in some adult splittails that had been feeding in the San Francisco Estuary which exceeded environmental protective criteria set forth by the Environmental Protection Agency (EPA).
It is the activity of humans that is increasing the amount of selenium in the environment.
Both oil refineries and agriculture practices that are occurring upstream have been determined to be the two leading causes of introducing access selenium into the region between the river and the estuary where the splittail feed, migrate, and reproduce.
The researchers say that understanding how fish encounters selenium could be extremely beneficial in informing management agencies, such as the EPA, on how to adjust their policies to protect migratory species and diagnosing the sources, pathways and other potential avenues that are leading to excessive selenium exposure.
This will not only be beneficial in protecting fish, but protecting other species such as birds, mammals, and even humans, as authorities develop greater knowledge of where selenium is coming from and how toxic levels of the mineral seeps into water sources.
