Researchers survey a high-priority coral reef area off Maui

By John Rooney
R/V AHI. NOAA photo

R/V AHI. NOAA photo

A team of scientists from the Coral Reef Ecosystem Division (CRED) of the NOAA Pacific Islands Fisheries Science Center on Tuesday began a mission to conduct acoustic and optical surveys of the waters of coral reef ecosystems in Maui. The team shipped their 8-m survey launch R/V AHI, equipped with a diesel generator to provide power and a Reson 8101ER multibeam echosounder, to Maui from O’ahu last week to support this survey effort.

Optical surveying will focus on one of two high-priority coral reef sites in Hawai’i identified by the Hawai’i Department of Land and Natural Resources (DLNR) and NOAA’s Coral Reef Conservation Program (CRCP): an area near Kahekili off West Maui (see map below at left). In 2013, the U.S. Geological Survey (USGS) conducted shallow-water mapping in the area, generally at depths of 10–40 m. The present survey effort on Feb. 4–21 will collect video and still photographs of the seafloor at depths of 30–100 m to overlap with and extend the USGS maps out to the 3-mile boundary of state waters or to a depth of ~100 m.

The red box in this map indicates the survey area where the camera sled will be deployed. This area off Kahekili, Maui, has been designated by the Hawai’i Department of Land and Natural Resources and NOAA’s Coral Reef Conservation Program as one of two high-priority sites in the state.

The red box in this map indicates the survey area where the camera sled will be deployed. This area off Kahekili, Maui, has been designated by the Hawai’i Department of Land and Natural Resources and NOAA’s Coral Reef Conservation Program as one of two high-priority sites in the state (click image for a larger version).

For the surveys, members of the CRED ecospatial information team will use an underwater camera sled, called the “TOAD,” for towed optical assessment device (see photo below at right). The data collected during these TOAD surveys will enable the team to map the dominant seafloor structures (e.g., pavement, patch reef, and sand) and the major classes of biologic cover (e.g., coral and macroalgae) in the area. The extended maps will provide DLNR and other management agencies and coastal and marine stakeholders with the spatial data needed to make informed decisions about the management of nearshore marine resources and habitats.

The second goal of this survey mission is to fill gaps in existing maps that depict seafloor depths, or bathymetry, with a high degree of detail. No type of seafloor map is of higher value to more people than are maps of high-resolution bathymetry. However, gaps in existing maps (see map below) inhibit their use for many purposes.

To collect data to fill some of those gaps, the survey team will operate the multibeam echosounder on the R/V AHI. They’ll first fill remaining gaps in the data for the Kahekili high-priority site, and then they will spend the remaining time surveying in the most windward and exposed sites in which they are able to operate.

The video and still photographs collected by the towed optical assessment device (TOAD), the camera sled shown being deployed from a ship in this photo, can be analyzed to help map the character of benthic habitats. NOAA photo

The video and still photographs collected by the towed optical assessment device (TOAD), the camera sled shown being deployed from a ship in this photo, can be analyzed to help map the character of benthic habitats. NOAA photo

After the mission, the team will clean and process the data and then provide them to NOAA’s National Geophysical Data Center to be made publicly available for download. The data also will be provided to the School of Ocean and Earth Science and Technology (SOEST) at the University of Hawai’i at Mānoa for inclusion in the synthesis of high-resolution bathymetry data that SOEST has maintained for many years.

Funding for this project was provided by the CRCP. We thank the Hawai’i DLNR for graciously providing logistical support and the USGS for going out of their way to send us copies of their existing data and publications.

Follow this link for a PDF version of this story about the latest mapping surveys off Maui.

For more information about this mission and CRED benthic habitat mapping, contact John Rooney, program manager for the ecospatial information team, at john.rooney@noaa.gov.
This map shows existing high-resolution bathymetry collected around Maui, color coded by depth and superimposed over a nautical chart.

This map shows existing high-resolution bathymetry collected around Maui, color coded by depth and superimposed over a nautical chart.

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