Hawaii's Kilauea Volcano unexpectedly unleashed a huge proliferation of phytoplankton

The study, conducted jointly by Sam Wilson of the University of Hawaii (UH) in Manoa and Nick Hawco of the University of Southern California (USC), improves our understanding of phytoplankton blooms and their training conditions ( very important considering the sudden increase in the proliferation of algae!), while presenting a mechanism until then unknown, responsible for the growth of phytoplankton.

Just three days after the start of the Kilauea eruptions, scientists spotted the phytoplankton overgrowth on satellite photos in the form of a large chlorophyll green patch, a light-collecting pigment used by phytoplankton to effect the photosynthesis. Researchers from the UH Manoa Center for Microbial Oceanography: Research and Education (C-MORE) shifted to action, chartering the research vessel Ka & imikai-O-Kanaloa and visiting the site. to analyze flowering and study the effects in real time. . It was an unprecedented opportunity to study a nutrient-poor marine ecosystem and evaluate its response to a sudden, massive influx of molten lava.

From July 13 to 17, 2018, while Kilauea was still plagued by a prolonged storm crisis, researchers measured water chemistry and biological activity in areas near the point where lava was spilled into the ocean. Back in the lab, the team, with the help of scientists from the USC, learned that the process was much more nuanced than the introduction of hot water and water. lava molten.

As their laboratory experiments have shown, a key part of the process involved high concentrations of nitrates. The problem is that basaltic lava is essentially devoid of nitrogen, a natural fertilizer for terrestrial and aquatic life.

"We had no reason to think that such a proliferation of algae would occur," said Seth John, co-author of the study and geologist at USC Dornsife. , in a press release from the USC. "The lava does not contain nitrate."

Instead, the hot lava stirred the environment near the bottom of the sea, forcing the nutrient-rich waters to the surface. The phytoplankton living at the top, the sunny layer of the ocean, suddenly had a real Jacobean banquet of nutrients, which caused a binge eating that led to the spectacular growth of algae.

"We hypothesize that high levels of nitrates were caused by floating plumes of nutrient-rich deep water created by a large inflow of lava into the ocean," the authors wrote. of the study.

Indeed, the expansive green plume was suddenly packed with the ingredients necessary for the growth of algae, namely high levels of nitrates, silicic acid, iron and phosphate. It is interesting to note that this same type of upwelling of nutrients from deep waters occurs naturally along the California coast as a result of strong ocean currents rather than under the effect of hot molten lava.

The discovery "enhances our understanding of seawater-seawater interactions in the much wider context of land-ocean connections," Wilson said in a UH press release.

Three weeks after the start of the eruptions, the flowers, in a most incredible way, stretched about a hundred kilometers off the Hawaiian coast. In the months that followed, the plume increased even further. The plume persisted as the rashes continued, but it quickly disappeared once the lava stopped flowing into the ocean. For phytoplankton, the party was suddenly over.

Such an ocean fertilization event has never been documented before, but it may have occurred elsewhere in Hawaii and other active volcanic areas. Harriet Alexander, of the Woods Hole Oceanographic Institution, who is not affiliated with the new study, told The New York Times volcano that "volcanoes could be an important factor in the phytoplankton ecology in the wider ocean" .

The researchers would like to analyze the puddles that are now appearing at the bottom of the crater floor of the volcano. Much remains to be learned about the surprising ability of volcanoes to promote life.