Half of Hawaii’s Coral Bleached in One Year

Scientists estimate that beaching affected 56 percent of the coral around the Big Island, 44 percent of that along West Maui and 32 percent around Oahu over a one-year period spanning 2014-2015.

Researchers recently completed an 88-day expedition aboard the NOAA Ship Hi’ialakai to survey two remote regions in the Pacific. First, they traveled to the islands of Jarvis, Howland, Baker and Wake, all part of the Pacific Remote Islands Marine National Monument. Then they traversed to the Mariana Archipelago, working their way up the island chain from the populated islands in the south to remote locations in the north.

map of mission area

During the expedition, researchers collected data to evaluate climate and ocean change, coral ecosystem health, and the extent of coral bleaching. Scientists with NOAA, the Hawaii Institute of Marine Biology, San Diego University, Scripps Institution of Oceanography, and Woods Hole Oceanographic Institution participated in the mission.

1. Coral Bleaching in the Pacific

The Pacific Islands experienced unusually warm ocean temperatures in the last few years, during the longest global coral bleaching event on record to date. Prior to the bleaching event, Jarvis Island had very high coral cover. Preliminary surveys in 2015 and 2016 indicated that most coral colonies died due to coral bleaching. While at Jarvis in 2017, researchers surveyed these coral reef communities and assessed the recovery potential from the thermal stress that caused the coral to bleach.
All images courtesy of NOAA:
Coral reef colonies near Jarvis Island; Image credit:Tate Wester

2. Bumphead Parrotfish

The giant bumphead parrotfish is an amazing fish that can live to be 40 years old, growing up to four feet long and 100 pounds. They use their large head bumps to literally bump heads during competitive displays, when large numbers of fish aggregate to spawn on a lunar cycle. Researchers saw many bumpheads during their first day at Wake Island. The bumphead parrotfish has been heavily targeted by fishing throughout much of it’s range and is now considered globally rare by the IUCN Red List of Threatened Species.
The giant Bumphead parrotfish; credit: Andrew E. Gray
 3. Reef Life

On the east side of Agrihan Island, an octopus takes off across the rocky reef after being discovered by a diver. All reef life is important, including this clever invertebrate. These fascinating creatures can rapidly change color to blend in with their surroundings, making them difficult to spot.

octopus near Agrihan Island; credit Louise Giuseffi)
 4. Crown-of-thorns Sea Stars

The scientists found many crown-of-thorns sea stars at Alamagan Island. These prickly invertebrates feed on coral tissue. Here, the sea star leaves only the skeleton of this Acropora coral in its wake. In large numbers, they can do significant damage to coral reefs, but in small numbers, they are a natural key component of the coral reef ecosystem.

Crown-of-thorns sea stars at Alamagan Island; credit: Keisha Bahr
 5. A Rare Sighting

An extremely rare sighting at Farallon de Pajaros, scientists found this female angelfish after completing their fish survey. Little is published about this species beyond aquarium enthusiast blogs. Some describe it as being endemic to the Bonin or Osagawara Islands just south of Japan, although the researchers discovered this fish within the Marianas Trench Marine National Monument waters during their expedition.

Rare anglefish species; credit: NOAA, Andrew E. Gray)
 6. Volcanic Vents

Underwater volcanic vents near the Maug Islands release carbon dioxide gas that cause surrounding waters to acidify—a localized example of how carbon dioxide emissions in our atmosphere cause global climate change and ocean acidification. Maug’s carbon dioxide vents occur near coral reef ecosystems, allowing scientists to glimpse the future of these ecosystems along a naturally occurring gradient of changing ocean chemistry conditions.

Maug's underwater volcanic vents; credit: Kaylyn McCoy)
 7. Bubble Coral

Despite their appearance, these Plerogyra corals, also known as bubble coral, are actually a type of Scleractinian, or hard coral. The tissue is soft and bubble-like, and hides the hard skeleton underneath.

Bubble coral; credit: Tate Wester
 8. Colorful Nudibranch

Autonomous Reef Monitoring Structures (ARMS) uncover many beautiful creatures, including this nudibranch. a nudibranch; credit: Ingrid Knapp)

9. Healthy Coral

Corals at Pagan Island seem to have fared much better than other areas hit hardest by the recent global coral bleaching event. Here is a close-up of an Acropora coral (typically more susceptible to bleaching events), which appears to be doing just fine.
healthy coral in Pagan; credit: Ingrid Knapp
 10. Stars in the Sand

If you look closely in the sand, sometimes you can find “star dust,” or the star-shaped skeletal remains of Foraminifera, microscopic unicellular organisms that form an important part of the marine food chain.

Star-shaped skeletal remains of Foraminifera, microscopic unicellular protists; credit: Louise Giuseffi)

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