Residents of Hawaii’s Big Island are holding their breath, and it’s not just the humans. After months of hot lava spewing from the Kilauea volcano since an eruption began on May 3, 2018, the flow has slowed and the National Park is reopened. The hot volcanic rock traveling down the volcano impacted all the ecosystems it encountered—from homes to local vegetation and bird populations. The lava eventually made its way to the sea where the ocean literally boiled. 

These conditions can have a devastating effect on marine life. Fish, sea turtles, and other creatures often cannot escape the lava flow. Steven Colbert, a marine geologist at the University of Hawaii at Hilo, explains that the area where the lava from Kilauea entered the sea is “a series of tide pools with restricted flow so that organisms are trapped and cannot get away quickly.”

The dominant ecosystem in this particular seascape are shallow water coral reefs. John Burns, a marine biologist also at University of Hawaii at Hilo, says that the “coral reefs covered by the lava flow are completely destroyed” and those on the border of the flow “are very likely to be stressed.” Two things the eruption has plenty of are hot water and elevated sedimentation—both are known stressors to coral reefs. The destruction stretches along the Hawaiian coastline for over two miles. 

The Hawaiian archipelago is no stranger to lava. Formed from volcanic processes over the last 30 million years, the islands are made up of layers of dirt and rock that form a “floating” crust on top of the planet’s molten, play-doh-like mantle. These tectonic plates of crust shift and create earth’s geologic features. The tectonic plate beneath Hawaii is slowly migrating northwest and moving over a stationary hot spot, where magma from near the core is bubbling up to the surface. Over time, molten rock flowing out of Hawaiian volcanoes cooled and formed new, bare substrate that enlarged the island chain. 

Kilauea is located on the youngest island in the chain which is still being established beneath the waves as the lava erupts and flows into the sea to cool. The new substrate forming will eventually be colonized by organisms in the ecological process of succession. Fleshy macro-algae are usually the first colonizers of bare substrate in the ocean and there is a risk that algae will leave no room for coral to settle and grow. Burns explains that a balance is provided by “having an abundance of herbivores and having low levels of nutrients and sediment in the water.” Nutrients in the water fuel algae growth, while a lack of plant-eating fish means the algae can grow unhindered. Sediment in the water prevents coral larvae from receiving the sunlight necessary to survive. 

But, if conditions combine properly, new coral larvae settle on the substrate and a functioning coral reef ecosystem appears. Current global environmental conditions may impact the reefs growth, however. “Large-scale global stressors such as increasing temperatures and ocean acidification may impact the ability of corals to come back in the form we saw prior to the lava flow,” Burns says. 

Kilauea’s eruption presents a unique opportunity for scientists to research coral reef succession and growth in a changing ocean. It also presents an opportunity to look at the flow itself using modern technology. Scientists from the University of Hawaii, the U.S. Geological Survey, Hawaii Volcanoes Observatory, and other organizations teamed up with a company called Liquid Robotics to study the lava flow using seafaring robots. These “Wave Gliders” allow researchers to get up close to the boiling sea without endangering human life. 

About the size of a stand-up paddleboard, the Wave Gliders are equipped with a variety of instruments to measure oceanic and atmospheric variables. Researchers programmed the gliders to zigzag along the edge of the lava flow where an underwater sail that extends 16 feet below the waves allows for measurements at both the surface of the ocean and at depth. The accumulated information is helping Colbert and other scientists make a 3D map of the hydrothermal plume of water streaming from the lava flow zone to better understand where it is going and how it moves over time. 

Hot, muddy water from the eruption is expected to stay near the shoreline due to a swift current running along the southern coast of Hawaii. Initially, scientists were concerned this fast current might carry the hot water along the coast causing destruction as it went. Colbert says that instead, “the hot water moves out to sea and new water comes into the shoreline.” This new, cooler water often wells up from the depths and could act as a “buffer to surrounding ecosystems.” 

This natural, cyclical process of erupting lava streaming along land and into shore is how an island gets built. It allows for new growth of ecosystems and has been ongoing for millions of years. Colbert, Burns and other scientists are taking advantage of the Kilauea eruption to study the geologic and ecological changes to the Hawaiian environment as they happen, this time with human influences in the mix.