University of Hawai‘i research voyage explores marine links across North Pacific

A research trip by University of Hawaiʻi at Mānoa scientists to Wake Island and Johnston Atoll – two remote spots in the Pacific – will provide insights into the historic and potential future role of these two places as biological stepping-stones for movement of marine species between the Hawaiian Islands and other archipelagoes of the North Pacific Ocean.

Wake and Johnston are isolated coral atolls 2,300 miles and 800 miles southwest of Honolulu, respectively. Both share many species in common with Hawaiʻi, and the apparent biogeographic connection has important implications for understanding how often species disperse via Johnston and Wake to and from Hawaiʻi, versus dispersing directly to Hawaiʻi from more distant archipelagoes, such as the Marianas, Line and Marshall islands.

In July 2024, the University of Hawaiʻi at Mānoa team collected thousands of tissue samples from several species of sea urchins, seawater samples and water and plankton samples from the surface layers of the ocean as they transited between Guam, Wake, Johnston and back to Hawaiʻi. DNA will be extracted from all of the samples to understand connections at gene, whole genome, species and community levels of organization.

Access to the coral reef communities at Wake and Johnston has been limited by a long history of military activity at each atoll. Comprehensive species lists have not been completed, especially with respect to organisms that are not easily detected visually. Genetic analysis has been limited to a handful of species.

Scientists are studying sea urchins because their larvae float in the ocean, making them easy to observe in labs. This helps researchers understand how long these baby sea urchins can survive while drifting in the complicated currents of the North Pacific Ocean.

Working with NOAA scientists, who are using computers to map how ocean currents move these larvae, the research team can predict where the baby sea urchins might end up. They can then test these predictions by looking at the DNA of sea urchins from different areas to see if they’re related.

Environmental DNA, or eDNA, will be extracted from seawater samples taken from around each atoll and be used similarly to study the genetic similarities of populations of species found in Hawaiʻi, Wake and Johnston.

The expedition was funded by the National Science Foundation and conducted from the University-National Oceanographic Laboratory System research vessel Thomas G. Thompson.

The trip was a collaboration between faculty, staff, and students from the University of Hawai‘i Mānoa School of Life Sciences, University of Hawai‘i Diving Safety Program, NOAA, University of Hawai‘i Marine Center and University of Washington Marine Operations, the latter which operates the Thompson.