Coral bleaching could be on the way

  • Graphic courtesy of National Oceanic and Atmospheric Administration

    This shows the coral bleaching alert levels as of August 11, with some alerts going up a step in the next four months.

LIHUE — Another coral bleaching event could hit Hawaii in the next four months, according to the National Oceanic and Atmospheric Coral Reef Watch.

The entity monitors and maps thermal stress conditions that contribute to bleaching events. Sunday, NOAA Coral Reef Watch upgraded current alert levels from “watch” to “warning.”

Alert levels for mid-September through about November are now at the highest setting, “Alert Level 2”.

CRW is predicting a 60% likelihood of bleaching thermal stress to corals around most of the main Hawaiian Islands from the latest four-month coral bleaching thermal stress outlook.

In early August, the National Weather Service announced El Nino in the Pacific is ending, which would mean waters are cooling down, opposite of what CRW is saying. However, marine heat waves can still move through an ENSO-neutral ocean.

Hawaii’s first statewide bleaching event was triggered in 2015 by a marine heat wave, nicknamed The Blob. It coincided with the 2015-16 El Nino.

The upgrade in alert status was based on the coral bleaching outlook, a climate forecast system which was released publicly on the CRW website in March 2018. It’s updated weekly based on daily sea surface temperatures from NOAA.

“In a normal year, the outlook forecasts no potential for bleaching,” according to a statement from NOAA CRW. “When the forecasted SST exceeds bleaching thresholds over a long enough period to cause bleaching, the outlook maps display the bleaching potential.”

The predictions can change rapidly, CWR says, but the tool helps inform leadership and researchers of the steps needed to monitor the activity.

Hawaii organizations, like Eyes of the Reef, are already putting the word out to citizen scientists to watch coral health over the next few months and report their findings.

According to NOAA, bleached corals aren’t necessarily dead — they just expel the algae living in their tissue. That’s why bleached corals are usually white. However, if it persists, it can lead to coral death.

Hawaii Island’s corals were hit hard in the 2015 bleaching event, as were areas on Oahu and some corals on Kauai.

Researchers say some of those corals are back and doing well.

On Kauai, there are reports of corals thriving inside Anini’s outer reef and at Wainiha. Other places are reportedly still struggling after the 2018 storm runoff deposited silt and other debris downstream and into the ocean.

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