Why the waters off Santa Barbara mysteriously turned turquoise: Scientists discover algae was to blame for sudden color change four years after the baffling phenomenon
- Scientists say they discovered the cause of a change to water color in California
- An algae bloom released calcium carbonate which distorts light
- The results were a Caribbean-like turquoise hue off the coast of Santa Barbara
- These light-distorting blooms grew large enough to be seen from space
- A new method of studying the algae may help detect toxic blooms preemptively
Four years after coastal waters near Santa Barbara, California inexplicably turned bright blue, researchers say they have determined the cause.
According to new research, the culprit behind the drastic and mysterious color change is one of the world’s smallest organisms — a single-celled algae called coccolithophores, stemming from a large bloom.
In a paper published in the Journal of Geophysical Research: Oceans, scientists describe how physical characteristics of the algae turned the otherwise dark blue waters into shades of turquoise.
After four years, scientists say they have gotten to the bottom of the sudden bright blue water off the coast of California in the summer of 2015
‘When the water off the coast of California starts to look like you’re in the Caribbean, that’s really weird,’ said lead author Paul Matson a postdoctoral student who worked on the research in a statement.
Unlike their algae-relatives, diatoms, which are coated in silica, coccolithophores, specifically a specie called Emiliania huxleyi or E. hux, are shrouded in tiny specks of calcium carbonate.
As they shed these specks, the material interacts with the light to cause a light-blue hue.
While the water-tinting algae observed by scientists is found most everywhere, the researchers say algae blooms like the one that caused the phenomenon are at uncommon at latitudes like those in Santa Barbara.
Algae blooms caused the introduction of calcium carbonate which distorts the light and changes the appearance of the water color. Above, E. huxleyi as seen through a scanning electron microscope
Part of what stoked the unusual occurrence was a large formation of warm water, which researchers aptly named ‘the Blob,’ that entered the northeast Pacific Ocean in 2013.
The waters persisted into 2016, according to the researchers, and were coupled with an El Niño weather event that further increased the water temperature.
Temperatures rises first gave rise to a bloom of the often toxic algae, Diatom, which feeds on silica, but as the diatoms burned up their silica reserves, E. hux, which don’t need the compound to survive were ready to shine.
The E. hux fed off the dying diatom algae according to the researchers and exploded, growing large enough to be seen from space.
‘We had this extended period of time when we had extremely warm waters. We had low nutrient availability, and just strange things were happening,’ Matson said.
Blooms grew so large that they could be seen from space and were aided by E. hux’s toxic cousin
Scientist were able to come to their conclusion using an innovative mix of satellite imagery and radar arrays that study surface currents to create hourly maps of of the algae.
The new method can also detect where blooms are about to occur, which gives them insight into how the algae began to spread in the first place.
They hope that the approach could be used to identify more harmful algae blooms in the future.
Blooms like those produced by diatoms which starve off swaths of water bodies of nutrients and oxygen are deadly to animals, and also harmful to humans — algae can be spread through the air and inhaled unintentionally.
