UH Scientists Chart Seafloor of Northwestern Hawaiian Islands

Soft coral and sponges on a deep reef in the monument.

“The goal of the expedition was to fill large gaps in seafloor data in order to facilitate future research and discoveries in the region,” said Christopher Kelley, program biologist with UH Manoa’s Hawai‘i Undersea Research Laboratory and chief scientist of the expedition, which returned April 11.

PMNM is the largest protected area in the United States, encompassing an area greater than all its national parks combined, yet over half its seafloor has never been mapped in detail due to the limited availability of the advanced sonar systems required, as reported by UH.

The team mapped more than 15,445 square miles — an area four times the size of the Big Island — of previously unmapped or poorly mapped areas inside the monument. This represents approximately 11 percent of the total area of PMNM, and includes 18 seamounts and extensive banks off Pearl and Hermes, Midway and Kure atolls.

High resolution mapping in the monument has been sparse. The goal for the upcoming expeditions is to fill in as many of these white spaces as possible.

“We literally have better maps of the moon than of the ocean floor,” said Randy Kosaki,  NOAA’s deputy superintendent for research at PMNM. “These bathymetric data will go a long way toward improving our understanding of Papahanaumokuakea’s features. As natural resource managers, we can’t manage what we don’t understand.”

Carried out aboard the Schmidt Ocean Institute’s 272-foot R/V Falkor, the expedition utilized the ship’s state-of-the-art seafloor mapping sonar systems, among the most advanced mapping technology in the world. Approximately 98 percent of the monument’s area is deeper than 100 meters (328 feet), where features including seamounts, ridges and submerged banks are home to rare and likely undiscovered species of corals, fish and other animals. Mapping is key to finding these.

Gold corals hold important records of past ocean conditions, as they can grow for more than 1,000 years.

Another objective of this mapping effort is to identify likely sites of deep-sea coral and sponge beds. In 2003, scientists discovered the existence of these beds within PMNM in more than 1,000 meters (approximately 3,280 feet) of water.

“On this trip, we discovered more sites in the monument with the right type of topography to support these amazing deep sea coral gardens,” Kelley said. “We’ll have to wait until someone gets an opportunity to dive on the sites with a submersible or remotely operated vehicle to confirm they exist.”

Previous exploration of the few known beds led to the discovery of more than 50 new species of sponges and corals, according to Kelley. It is expected that more discoveries will be made as a result of the information gleaned from this trip.

A closer view of the new Wentworth Seamount map.

The region’s geology was another key focus of the expedition. Ancient coral reefs that drowned as the earliest Hawaiian Islands subsided now hold a detailed record of that process spanning millions of years. Mapping can offer a big picture view of how various features are organized, which will help researchers better understand Hawaii’s geological history.

“We established SOI in 2009 — and led the transformation of Falkor into a state-of-the-art research vessel — to support the world’s leading ocean scientists on their essential, but difficult-to-implement research,” said Wendy Schmidt, who co-founded Schmidt Ocean Institute with her husband, Eric. “The mapping and geological work conducted during this cruise and the one that follows will inform the work of Chris Kelley and his team, and through our open sharing approach, all scientists who have a stake in better understanding this region.”

In the 800 to 2,500-meter depth range, manganese and other important minerals precipitate out of seawater to form crusts like this one.

The team consisted of researchers from UH Manoa, NOAA’s Pacific Islands Fisheries Science Center, PMNM-NOAA’s Office of National Marine Sanctuaries, Schmidt Ocean Institute, the University of Sydney and the University of British Columbia.

This was the first of two expeditions slated for the spring of 2014; the second will take place from May 2 to June 6.

Visit http://www.schmidtocean.org/story/show/2216 for more information.