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Liliʻuokalani Ridge Seamounts likely not of Hawaiian origin

papahanaumokuakea map.png
Papahānaumokuākea Marine National Monument
Oceanographers on E/V Nautilus believe the Liliʻuokalani Ridge Seamounts (in red) are not from Hawaiian volcanic hotspots. The seamounts likely migrated from the South Pacific.

Exploration Vessel Nautilus returned from its second expedition this year. Oceanographers aboard the ship investigated the geological origins of the Northwestern Hawaiian Islands.

The 2021 expedition to an expansion area of the Papahānaumokuākea Marine National Monument was historic. The scientific exploration team on E/V Nautilus mapped the ocean floors of the Liliʻuokalani Ridge for the first time.

Nautilus ocean exploration trust
OET/Nautilus Live
A drone Stern shot from the starboard side of Nautilus.

A new team of researchers, educators and mariners returned to Liliʻuokalani Ridge to better understand the origins of the Northwestern Hawaiian Islands.

"At Liliʻuokalani Ridge, these are very far out the Hawaiian seamount chain, but they’re offset from the Hawaiian seamount chain and they’re at a different angle from the Hawaiian seamount chain. So it’s really interesting because we can trace the plate tectonics back to where we think the origin is," expedition leader Dwight Coleman explained.

Coleman said some of the underwater mountains, or seamounts, near the Northwestern Hawaiian Islands likely migrated from the South Pacific.

"The mineral makeup of these rocks will tell us the geochemistry details and pinpoint it, and it’s probably not of Hawaiian hotspot origin," Coleman said.

Another goal of the expedition was to document high definition footage of the marine biodiversity. The team captured rare videos of deep-sea corals.

Justin Umholtz, a guest educator on the ship, said deep-sea corals are "very different structures than what we would think of as shallow corals."

Many shallow reef corals have a symbiotic relationship with photosynthetic algae. Corals provide algae protection while algae offer coral food.

Deep-sea corals grow at sea levels where there is no sunlight. Instead, they grow on ridges and areas where the currents can push nutrients and small plankton into their polyps.

Native Hawaiian worldview was a key part of the expedition.

The team practiced Hawaiian ceremonies when they left the land, and another when they entered Papahānaumokuākea.

Malanai Kāne Kuahiwinui, a science communication fellow on E/V Nautilus, assisted in leading the Native Hawaiian rituals.

"This place is sacred for a number of reasons. These islands are old," Kuahiwinui said. "Mokumanamana sits on the Tropic of Cancer, so there are studies that have been done that explain that there were Hawaiians that would go there annually to observe the celestial bodies, and that would help us predict what the weather is like."

The next E/V Nautilus expedition begins Friday, May 6, south of the main Hawaiian Islands.

Zoe Dym is a news producer at Hawaiʻi Public Radio.
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