New causal factor in the Mass Extinctions of the pastAlongside well-known and well-studied causes fo
New causal factor in the Mass Extinctions of the pastAlongside well-known and well-studied causes for mass extinctions of the past, such as global volcanic eruptions and the asteroid that hit what is now the Yucatan peninsula, new research proposes that global drops in the abundance of the trace element, selenium (Se), may have been partly responsible for three of the planets biggest extinction events: the end-Ordovician (443 million years ago), the Late Devonian (359 million years ago), and the end-Triassic (201 million years ago).Selenium is a key trace element, a “micronutrient”, that is required by all animal and most plant life, playing a role in many biological processes such as antioxidant processes, thyroid function, and reducing the effects of mercury toxicity. The richest ordinary dietary source of selenium is Brazil nuts. It has been shown to be vital in photosynthesis in phytoplankton.Global spikes in selenium have been linked to periods of high productivity, while inability to access selenium results in fatal deficiencies and immunity problems across wide ranges of organisms. Within the last few years, selenium deficiencies in large parts of China and Africa have been linked to mass outbreaks of viral diseases.Researchers who published an article in Gondwana Research last month (http://bit.ly/1QBy8gz) matched global drops of selenium in the oceans with three of the planet’s mass extinction events, posing a possibly critical affect on food chains and their subsequent collapse. As ocean levels dropped, selenium transfer to terrestrial ecosystems was also critically affected. The idea is controversial, but understanding the factors that play a role in these extinctions is key because of the overwhelming impact on biodiversity as a result.AshMain scientific article credit: http://bit.ly/1QBy8gzSource credit: http://bit.ly/1MDrUGUSource credit: http://bit.ly/1QBya84Image credit: https://flic.kr/p/spCdQb, selenium naturally occurring in sandstoneImage credit: http://bit.ly/20Sj1E2, showing extinction events and their corresponding Extinction Intensity (% species loss) -- source link
#science#geology#mass extinction#selenium#biology#trace element#chemistry#ocean#thyroid#antioxidant#micronutrient