Scientists who raced to study Kilauea’s lava as it fueled rare phytoplankton bloom find surprise

Results from a rapid-response oceanographic expedition in the North Pacific reveal a surprise about how lava from the K?lauea Volcano, which erupted on the island of Hawai’i during the summer of 2018, triggered a vast phytoplankton bloom. The study – a unique opportunity to study this rarely observed phenomenon in real time – informs how nutrient-poor marine ecosystems respond to both a massive influx of molten lava and nutrients. Beginning just three days after K?lauea’s lava first began to pour into the ocean, a rapidly growing bloom of phytoplankton formed in the waters nearby, persisted throughout the two-month duration of the volcano’s eruption and rapidly dissipated when the lava ceased to flow. At the height of K?lauea’s discharge of lava into the ocean, Samuel Wilson and colleagues set sail to determine the cause and composition of the curious phytoplankton bloom. Using a suite of shipboard and subsea glider-based instruments, Wilson

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. sampled the seawater chemistry and phytoplankton diversity in different areas of the extensive bloom and revealed that unexpectedly high concentrations of nitrate played a key role in the particularly strong biological response to the influx of lava into the ocean. Lava, however, contains very little nitrogen indicating a non-volcanic source of micronutrients. The authors instead suggest that the rare phytoplankton bloom was fed by the lava heating water far below the surface and triggering the upwelling of nutrient-rich deep-water to the surface. Hugh Ducklow and Terry Plank highlight the implications of the novel biogeophysical process revealed by Wilson

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. in a related Perspective.

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