Scientists have identified a novel way the ocean environment responds to the introduction of lava.

When Kilauea Volcano was erupting in 2018, it injected millions of cubic feet of molten lava into the waters off Hawaii island.

Normally, the nearshore water there lacks food for algae and other organisms.

But with the lava entering the ocean, suddenly there appeared a blanket of plankton so large that it was visible from space.

What triggered the extensive plumes of microbes picked up by satellites?

Researchers from the University of Hawaii at Manoa and the University of Southern California found that the plumes resulted from unexpectedly high concentrations of nitrate, basically fertilizer. But lava itself contains a negligible amount of nitrate.

So where did it come from?

The research team determined that nitrate was brought to the surface of the ocean when the sinking lava warmed nutrient-rich deep waters and caused them to rise up, supplying the sunlit layer.

Their findings appear in the Sept. 6 issue of the journal Science.

After observing the phytoplankton bloom in satellite images, the center organized an impromptu oceanographic expedition on the UH research vessel Kaimikai- O-Kanaloa in mid-July 2018, during the height of the volcano’s activity. The team conducted round-the-clock operations in the vicinity of the lava entry region to test water chemistry and the biological response to the dramatic event.

Co-lead author Sam Wilson of the UH-Manoa Center for Microbial Oceanography: Research and Education (C-MORE) and co-lead researcher Nick Hawco, a USC researcher who will be joining the UH-Manoa oceanography department in January, found that deep and heated seawater became buoyant, and brought up nitrate that caused certain classes of phytoplankton to bloom.

It is possible that this kind of “perturbation” has led to similar ocean fertilization events in the past associated with the formation of the Hawaiian islands and other significant volcanic eruptions, the authors suggest.

“UH has a strong tradition of not only volcanic research, but also looking at its impacts on the surrounding environment such as the ocean, groundwater and atmosphere,” Wilson said in a statement Thursday. “This latest piece of research improves our understanding of lava-seawater interactions within the much broader context of land-ocean connections.”