Steve Dollar, a researcher from the University of Hawaii and a CORAL co-investigator, leads a team of divers taking photos off Heron Island on Australia’s Great Barrier Reef. The team captured about 1,000 images of each 32-by-32 foot (10-by-10 meter) study area. Back on land, researchers use computer software to stitch the photos together to create high-resolution photo mosaics. Scientists then use these images, combined with data collected by the airborne PRISM instrument, to describe the benthic (seabed) communities of the reef ecosystem. Photo Credit: Stacy Peltier, Bermuda Institute of Ocean Sciences
After six weeks in Australia, NASA’s COral Reef Airborne Laboratory (CORAL) has completed its campaign along the world’s largest reef structure—the Great Barrier Reef. Eric Hochberg, BIOS reef scientist and CORAL principle investigator, says he’s pleased with the “successful conclusion to the first of four field campaigns designed to shed light on the condition and function of representative reef ecosystems around the world.”
To achieve this objective, CORAL uses a special instrument called PRISM (Portable Remote Imaging SpectroMeter) that was developed by NASA’s Jet Propulsion Laboratory (JPL) specifically to study coastal environments. Housed in a Tempus Applied Solutions Gulfstream-IV airplane, the PRISM instrument operates during flight to measure light values, or spectra, of the seafloor that are used to signal the type and condition of the reef community. The result is a set of maps that represent the relative densities of coral, algae, and sand in each area, as well as rates of primary productivity (photosynthesis) and calcification (the process by which coral skeletons are formed), both of which are indicators of coral health.
Beginning on September 5, the flight team worked around local and regional weather patterns to cover six sectors that provide nearshore to offshore, and north to south, gradients of the Great Barrier Reef: Townsville, Mackay, Heron Island, Lizard Island, Torres Strait, and Northeast Torres Strait. During this time, three field teams were deployed to Lizard Island and Heron Island to make additional measurements of benthic cover (what the bottom habitat looks like), reef metabolism (photosynthesis and calcification), and water optics (the physical properties of the water column that influence how light travels from the surface to the bottom). Data from the field teams will be used to validate the airborne data collected by the PRISM instrument.
On September 9 and 17 the CORAL flight team conducted flight lines over Lizard Island and Heron Island, respectively, allowing the in-water teams to make concurrent measurements. The water optics field team, led by Brandon Russell (University of Connecticut) and Rodrigo Garcia (University of Massachusetts Boston), was able to capture measurements that accurately reflect properties of the water column at the time of the flyover. These “match-ups” are valuable opportunities to obtain data from the air and water simultaneously, which is particularly important for conditions that can change rapidly, such as water chemistry and optics.
As the PRISM instrument is flown above the water it collects images as strips, each correspondnig to a flightline. Each image is adjusted to provide a consistent scale and then matched with latitude and longitude from the flight log. This is a mosaic of the 16 flightlines conducted in the vicinity of Lizard Island in the northern portion of Australia's Great Barrier Reef. CORAL scientists will then process these images to learn more about fundamental reef processes, such as primary productivity and calcification, on an ecosystems scale. Photo credit: Eric Hochberg and NASA JPL.
A third “match-up” took place on October 6 in coordination with the Commonwealth Scientific and Industrial Research Organization (CSIRO) research vessel Investigator. While on a multi-project scientific cruise, CSIRO scientist Karen Wild-Allen was able to make in-water measurements of water optical properties during CORAL’s overflight process.
During the time on Lizard and Heron Islands the reef metabolism team, led by Bob Carpenter (California State University, Northridge), studied a total of 20 sites (10 at each location) in the lagoon and outer reef that encompassed a variety of bottom types, including mixed coral, sand, and algae habitats. Data from these sites will help CORAL scientists better understand how reef ecosystems uptake and recycle carbon.
The benthic cover team, led by Steve Dollar (University of Hawaii), surveyed 38 sites at Heron Island, in addition to the 36 sites previously surveyed at Lizard Island, resulting in thousands of high resolution photographs that will be stitched together by state-of-the-art computer software to produce larger-scale mosaics of reef habitat.
Presently, the field teams have returned to their respective institutions and are in the process of collating and analyzing data collected during the Great Barrier Reef campaign. The flight team departed Cairns, Australia early Wednesday, October 19 and returned home to Maine by way of the Marshall Islands, Honolulu, Hawaii, and Burbank, California.
Preparations are now underway for the next campaign to the main Hawaiian islands. “We accomplished and learned a lot during our time in Australia and we’re excited to see what the data from our 2017 field campaigns will show,” Hochberg said.
For continued updates on CORAL, including future campaigns in 2017 to the Hawaiian Islands, Guam, and Palau, visit Facebook (@coralreefairbornelaboratory) and online at www.coral.bios.edu and www.coral.jpl.nasa.gov.
The CORAL team would like to extend thanks to its many supporters and collaborators who made this mission successful, including Hawker Pacific, CSIRO, the University of Queensland, the Great Barrier Reef Marine Park Authority, Daintree Air Services, Allstate Boat Licensing & Training, Lizard Island Research Station and Heron Island Research Station.