Coral bleaching widespread but not as severe as predicted

  • Coral Bleaching monitoring took place recently at Kaneohe Bay on Oahu. (Courtesy /DLNR)

KAILUA-KONA — The widespread coral bleaching event predicted by the National Oceanic and Atmospheric Administration did impact reefs across Hawaii.

But, the agency said, the bleaching that began with warm ocean temperatures in the summer and fall wasn’t as severe as predicted.

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“Conditions for corals are now improving with sea surface temperatures beginning to drop,” Gerry Davis, with NOAA Marine Fisheries, said in a press release issued Tuesday by the Department of Land and Natural Resources. “While bleaching this year was not as devastating as the events seen across the Hawaiian Islands in 2014 and 2015, the DAR surveys, along with NOAA observations and reports from ocean users to the Hawaii Coral Bleaching Tracker, show there still was substantial bleaching found on all islands.”

As much as half of live coral bleached in the most heavily affected areas.

For the past two months, teams from the DLNR Division of Aquatic Resources, NOAA, The Nature Conservancy, the Hawaii Institute of Marine Biology and the Arizona State University Center for Global Discovery and Conservation Science, conducted rapid assessments of coral health along coral reef tracts throughout the state. They reported cauliflower and rice corals were most impacted.

On Hawaii Island, the majority of the sites surveyed by the DAR teams showed some level of bleaching.

The areas most affected by the by bleaching were along the Kona Coast, with an average of 40% live coral bleached in many survey locations. Several locations there were heavily bleached in the 2015 event which resulted in high mortality.

“This has resulted in less coral cover in 2019 as previous bleaching has reduced the amount of live coral in some of these places,” Brian Neilson, DAR administrator, said in the release.

Heather Howard, who co-founded Kona-based Coral Reef Education Institute with partner Paul Badgley, concurred.

The past few weeks have been particularly bad at the eight dive sites monitored along the Kona Coast. At Kealakekua Bay, coral bleaching was evident at 100 feet, she said.

“September and October were rough months and we have been seeing in our monitoring a lot of coral mortality,” Howard said. “A lot of the small coral babies that have been growing since the 2015 bleaching (event) — specifically the cauliflower coral — have bleached.”

On Maui, bleaching surveys showed that the amount of coral impacted was less than in 2014 and 2015, but areas with low coral from previous events were more severely impacted this year.

For instance the near-shore reef at Paia, where the live coral cover is only 5%, more than three-quarters of the live coral left, bleached. As reported earlier, reefs in Molokini’s crater experienced upwards of 50% of corals bleached. At Olowalu, routine monitoring in August did detect numerous Porities corals bleached and overgrown with turf algae.

Several locations on Oahu were surveyed for bleaching the first time this year, in what were the most extensive islandwide surveys yet conducted by DAR aquatic biologists and technicians.

At Lanikai, in Windward Oahu, a beach known for its white sand and heavy visitation draw, bleaching has covered an estimated 55% of live corals. This is a higher percentage than reported during the last bleaching event.

Also on Windward Oahu, surveys teams looked at numerous patch reefs in Kaneohe Bay.

DAR Aquatic Biologist Kim Fuller led the efforts there and at other locations around the island.

“On the patch reefs, bleaching was patchy,” she reported. “On some reefs more than 50% of the corals have turned the tale-tale snowwhite color which makes it easy to spot bleached corals, while on other reefs nearby, maybe only 10-20% was bleached.”

“Kauai’s reefs mirrored this year’s statewide trend with extensive bleaching in some areas and less in others, but overall the 2019 event appears to be less severe than those of four and five years ago,” Fuller added.

The reefs along Molokai’s south shore were also surveyed and also showed the same trend, where cauliflower and rice corals experienced the worst of it.

“We hope that greater awareness of the constant stresses we all put on our coral reefs and the steps we can take to reduce those impacts, helped the corals persist during this event,” DLNR Chair Suzanne Case said.

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The department on Tuesday also issued a coral pledge for people to follow to help save the reefs: Let Fish Protect Reefs; Corals Like Their Space; Stand on the Sand; Use Reef-Safe Sunscreen; Contain Any Chemicals; Anchor Away from Reefs)

“This is why we encourage everyone, especially commercial tour operators who take people into the ocean, to sign The Coral Pledge,” she said. “Our efforts to protect, preserve and perpetuate Hawaii’s coral reefs as the foundation of the ocean will take knowledge and constant awareness from all of us.”

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