University of Hawaiʻi Researchers Discover New Limu Species

A new study on Hawaiian limu led to the discovery of new limu species that can be only found in deep, dark waters.

A team of researchers from the University of Hawai‘i at Mānoa, Bishop Museum, and the Western Australian Department of Parks and Wildlife received a $792,021 grant from the National Science Foundation to describe these new species of limu. They anticipate the description of more than 60 new species of limu from the Hawaiian archipelago.

“This is one of the most extensive studies of mesophotic (existing in low light) algae to date,” said Alison Sherwood, a UH Mānoa professor in the Department of Botany principal investigator of the grant. “We have nearly 2,000 specimens of limu collected from 100 to more than 600 feet deep across the entire Hawaiian Archipelago. This will redefine our understanding of limu diversity in Hawai‘i and will aid understanding of floras across the entire Indo-Pacific.”

These deep limu samples were collected from coral reefs at depths of 100 to 500-plus feet. The researchers say these areas are among the most poorly explored of all marine ecosystems on Earth and pushes boundaries for coral-reef research.

The limu were collected from the entire 1,600-mile extent of the Hawaiian Archipelago, from Kure Atoll to Hawai‘i island. Technical divers used advance SCUBA and underwater equipment to collect the samples. NOAA’s National Centers for Coastal Ocean Science, Papahānaumokuākea Marine National Monument, Coral Reef Conservation Program, Office of Ocean Exploration and Research and the Hawai‘i Undersea Research Laboratory funded the collections. With support from the NSF, the researchers will use a combination of techniques to describe these new species.

“The limu form beds and meadows in this deep, blue water, and some appear to form habitat for fish and invertebrates,” said Heather Spalding, a co-principal investigator on the NSF grant. “These new species aren’t just tiny fuzz on the reef—they’re huge blades of brightly-colored red, brown and green limu. It’s like a garden down there, with new species poking up around every reef. We’re just on the tip of the iceberg in terms of understanding algal diversity in the mesophotic.”

The project will involve a team of undergraduate and graduate students, as well as postdoctoral fellows. Mary Ade, a Research Experience for Undergraduate student who is working in the Sherwood Lab this summer through the DNA-based Discoveries in Hawaiian Biodiversity project, is one of the first to join the project. Her summer research project will wrap up with a description of several new species of brown algae.

For more information on the project, contact Alison Sherwood at (808) 956-4115

PhD student Rachael Wade, PI Heather Spalding, REU student Mary Wade, and PI Alison Sherwood. Photo Courtesy of University of Hawaiʻi Mānoa.