Last summer, lava from a Hawaiian volcano triggered a massive algae bloom in the Pacific. Photo by the U.S. Coast Guard
Sept. 6 (UPI) -- Scientists have uncovered the link between Hawaii's famous Kīlauea volcano and an algae super bloom.
Last summer, more than a billion tons of lava from Kīlauea flowed into the waters of the Pacific. The event itself wasn't out of the norm, but when scientists analyzed satellite photos of the eruption, they were surprised to see a second eruption -- an eruption of green along Hawaii's coast.
When researchers from the universities of Hawaii and Southern California investigated, they found the perfect ingredients for algae growth -- elevated nitrate levels and plenty of silicic acid, iron and phosphate.
Scientists knew lava itself wasn't the fertilizer that sparked the bloom.
"There was no reason for us to expect that an algae bloom like this would happen," geochemist Seth John, assistant professor of Earth sciences at USC, said in a news release. "Lava doesn't contain any nitrate."
Human-triggered algae blooms typically happen as a result of runoff. Commercial farms use lots and lots of fertilizer. A lot of that fertilizer, including plenty of nitrogen and phosphorous, gets washed into waterways and flushed into lakes and oceans, fueling algae blooms.
But lava isn't fertilizer.
Still, the timing couldn't be explained away as coincidence. Scientists knew the lava had triggered the algae bloom. The region's biochemistry had been fundamentally altered, even if only temporarily.
"Usually, whenever an algae grows and divides, it gets eaten up right away by other plankton," said Nicholas Hawco, a post-doctoral researcher at USC. "The only way you get this bloom is if there is an imbalance."
In analyzing the sequence of events, researchers determined the sudden flow of lava had triggered upwelling in waters off the coast of the Big Island. As the piping hot molten rock plunged deep into the Pacific, it heated cold water deep beneath the surface, causing it to rise. The water rising from the deep carried nutrients to the surface, fueling algae growth.
Scientists detailed their conclusions this week in the journal Science.
"All along the coast of California, there is regular upwelling," said John. "All the kelp beds and marine creatures that inhabit those ecosystems are basically driven by those currents that draw fertilizing nutrients up from deep water to the surface. That is essentially the same process that we saw in Hawaii, but faster."