University of Hawaii researchers get grant for limu study

Researchers from the University of Hawaii at Manoa have received a grant to study a new species of limu found only in the Hawaiian archipelago’s deep and dimly lit waters.

The National Science Foundation has awarded $792,021 to a team of researchers from UH Manoa, Bishop Museum and the Western Australian Department of Parks and Wildlife to describe the species in detail.

The team anticipates it will be able to describe more than 60 new species of limu, also known as marine algae, from the waters of the Hawaiian archipelago, using a combination of DNA techniques and anatomical studies.

“This is one of the most extensive studies of mesophotic (existing in low light) algae to date,” said Alison Sherwood, a botany professor and principal investigator of the grant, in a news release. “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 Hawaii and will aid understanding of floras across the entire Indo-Pacific.”

Technical divers collected the specimens from mesophotic coral ecosystems at depths of 100 to 500-plus feet, which are among the least explored marine ecosystems on Earth.

The reefs represent a new frontier, given that they are at greater depths than conventional scuba divers can safely venture but at shallower depths than where most submersible-based explorations go. The specimens were collected from the entire 1,600-mile stretch of the Hawaiian archipelago.

Besides serving as food, the limu are “photosynthetic protists” used in food additives, cosmetics, paints, toothpaste and biofuels.

“The limu form beds and meadows in this deep, blue water, and some appear to form habitat for fish and invertebrates,” said co-principal investigator and postdoctoral fellow Heather Spalding. “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.”