Excessive exposure to selenium is linked to the severe deformity in the spines of an jeopardize California migratory minnow .
The Sacramento splittail ( Pogonichthys macrolepidotus)is only witness in the waters between the Sacramento - San Joaquin Delta and the San Francisco Estuary and is considered a mintage of “ special care ” by the State of California . During a 2011 fishery discipline , researchers regain that more than 80 percent of 1,000 juvenile splittail collected near a pumping station showed signs of spinal deformities . Their finding are published inEnvironmental Science and Technology .
" This was not just a few fish , it was the majority of them , " said Fred Feyrer , a research Pisces life scientist at the US Geological Survey ’s California Water Science Center and co - track of the research , in astatement
Seleniumis a course occurring vestige factor and is essential to the growth of man and animate being , but gamey levels can be toxic and have been show to get deformity in fish , birds , and mammals through both maternal transportation and collection through dieting . In some slip , the element can be more toxic than arsenic , as was the vitrine during a aggregative death rate case that killed some 15,000 sea bird near the Salton Sea in 1992,reportedin the Los Angeles Times .
Rice - sized ear bones known as otoliths phonograph recording chemical substance tracing that fish are exposed to much like tree diagram ring leave records of the plant ’s environment . Researchers examine the Pisces ’ otoliths using high - intensiveness X - rays to measure selenium concentration to specify where and at what compass point the minnows were being give away .
" We constitute that the otoliths record a diary of selenium pic from parturition to death , and were the key to unraveling this secret , " said hint generator Rachel C. Johnson , a research biologist at NOAA Fisheries ' Southwest Fisheries Science Center and the University of California Davis .
Though individuals varied widely in the number of days they were divulge to the element , researcher found that the fish had absorb selenium from “ both guidance ” – both from their parent during fertilized egg development and while feeding as juveniles . In an earlierstudy , the researcher observed gamy concentrations of selenium in some adult splittails feeding in the San Francisco Estuary that exceeded protective criteria localise forth by the US Environmental Protection Agency .
Oil refineries within the estuary and agrarian practices upstream are the two leading causal agent of human - influenced selenium in the region between the river and estuary where splittail feed , migrate , and reproduce . Splittails are roll in the hay to procreate during soaked years like 2011 , which also see engorged river spread into floodplains to open up new habitats . What is unclear is whether splittails are encounter higher levels of atomic number 34 during these surfactant years or consistently over time – a hard theory to test as ill-shapen fish are less abundant in the wild because of their heighten fatality rate pace .
The researcher sum up that understand how Pisces encounter selenium could inform management agencies ’ policies on migratory specie and pave the path for diagnosing sources , nerve pathway , and possible avenues for excessive atomic number 34 photo .
