Four New Limu Species Discovered in Hawai‘i’s Deep Waters 

A new species of deep see algae discovered at Kure Atoll. Courtesy of NOAA

Scientists working with NOAA’s Office of National Marine Sanctuaries announced earlier this week the discovery of four new species of deep-water algae from Hawaiʻi.

Marine algae, or limu, are very important in Hawaiian culture, used in foods, ceremonies and as adornments in traditional hula. The new species of limu were collected between 200 and 400 feet, depths not typically known for marine algae.

“I was astounded at the abundance and size of these algae, which resembled something you would see in a shallow-water lagoon, not at 400 feet.” Said Heather Spalding, Ph.D., postdoctoral researcher at the University of Hawaiʻi Department of Botany and lead author of the study.

Heather Spalding is seen here examining a limi specimen in the lab. Courtesy of NOAA

Spalding has been collaborating with NOAA’s Office of National Marine Sanctuaries for several years, studying samples collected by NOAA divers working in Papahānaumokuākea Marine National Monument. She and her colleagues at UH and University of Washington’s Friday Harbor Laboratories conducted DNA analyses that showed the species are very different than those found in Hawai‘i’s shallow waters, even though they are very similar in appearance.

“If you picked up one of these algae on the beach, you couldn’t tell if it was from a nearby rock or washed up from the deep, the species look that similar,” Spalding said.

The newly discovered species are similar in appearance to limu pālahalaha (Ulva lactuca), or sea lettuce.

Scientists consulted with the Native Hawaiian community to develop meaningful names for the new species to honor the great importance they have in Hawaiian culture. One species was named Ulva iliohaha, which refers to the foraging behavior of ʻīlioholoikauaua, the endangered Hawaiian monk seal, one of the best-known residents of Papahānaumokuākea.

A new deep-water algae named Ulva ohiohilulu. Courtesy of NOAA

The species were sampled during surveys between 2013 and 2015 in Papahānaumokuākea Marine National Monument by NOAA divers using advanced SCUBA diving technologies, and during past NOAA expeditions from 2006 to 2014 throughout the Main Hawaiian Islands using submersibles operated by the Hawaiʻi Undersea Research Laboratory.

Scientists anticipate many additional new species of algae will be described in the coming years from samples collected by NOAA divers on future expeditions to the monument.

A new species of deep-water is seen here during collection. Courtesy of NOAA

“These findings redefine our understanding of algal distributions in Hawaiʻi, and hint at the great number of other new species that are likely to be discovered in the future from these amazing deep-water reefs,” said Daniel Wagner, Papahānaumokuākea research specialist with NOAA’s Office of National Marine Sanctuaries.

The study describing the new species of limu was published in the latest issue of the Journal of Phycology. The article, titled “New Ulvaceae (Ulvophyceae, Chlorophyta) from mesophotic ecosystems across the Hawaiian Archipelago,” is featured as the journal’s cover story and can be accessed in its entirety at http://onlinelibrary.wiley.com/doi/10.1111/jpy.12375/full.