Volcanoes are often feared for their destructive power, but a new study reminds us that they can promote new growth.
A year ago, in July, researchers from the USC Dornsife College of Letters, Arts and Sciences and the University of Hawaii rushed on a boat for the famous Hawaii Vulcano K? Lauea to collect samples of the surrounding northern Pacific Ocean. They were trying to determine why so many algae had started to grow in the water as they poured around 1 billion tons of hot lava.
Looking at the satellite photos of the NASA eruption, the scientists noticed that the ocean water around the volcano was turning green. The satellite had detected enormous amounts of chlorophyll, the green pigment of algae and other plants that convert light into energy.
The new study, published September 5 in the journal Science, shows that the green plume in the ocean around the volcano contained the perfect cocktail for plant growth – a fertile mix of higher levels of nitrates, silicic acid, iron and phosphate.
"There was no reason for us to expect an algae bloom like this to happen," said the geochemist Seth John, assistant professor of Earth sciences at USC Dornsife and author of the study. "Lava contains no nitrates".
How the eruption of K? Lauea has triggered the flowering of algae
Nitrogen is a natural fertilizer for plants, even on the ground. In such rich conditions, the algae bloom exploded, expanding up to hundreds of miles in the Pacific Ocean, the researchers said.
"Usually, whenever an alga grows and divides, it is immediately eaten up by other plankton," said Nicholas Hawco, a researcher at the USC post-doctoral study Dornsife. "The only way to get this bloom is if it's an imbalance."
The researchers believe that the nitrogen has probably been awakened from the deep ocean. As hot lava poured in, it forced a cooler, deeper ocean water source. When the water rose, it carried nitrogen and other particles on the surface that helped the algae grow.
"Along the entire California coast, there is a regular recovery," John said. "All the algae beds and sea creatures that populate those ecosystems are basically driven by those currents that absorb nutrients from deep water to the surface. This is essentially the same process we saw in Hawaii, but faster. "
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