El Niño is causing spikes in ocean temperatures that scientists say could damage Hawaiʻi’s reefs.
The National Weather Service officially declared the start of El Niño, a climate phenomenon that can drive extreme weather events, in early June. During El Niño, sea surface temperatures heat up, which puts corals at a higher risk of bleaching.
Madeleine Sherman, the project manager for the Coral Resilience Lab at the Hawaiʻi Institute of Marine Biology, said the threshold at which local corals start to bleach is about 82 degrees. Already this summer, researchers have recorded temperatures of up to 83 degrees in Hawaiʻi’s nearshore waters.
“The fact that we're seeing these elevated temperatures this early in June is a bit of a concern, especially because the ocean takes time to absorb the rest of the heat coming in through the summer,” said Sherman.
In 2015, another El Niño event wreaked havoc on local reef systems. Sherman said that heat stress caused about two-thirds of Hawaiʻi’s corals to bleach or pale. She and her colleagues are bracing for the possibility of similar effects this summer.
While concern is high, Sherman said El Niño may also offer valuable research opportunities. She and her team hope to determine whether outplantings of selectively bred corals around Oʻahu prove resilient to temperature spikes.
These corals were bred from thermally tolerant parents and have been analyzed in lab settings, but El Niño will be the real test of their ability to withstand rising temperatures.
“We've kind of been almost waiting for a natural bleaching event to be able to monitor if the work that we are doing is worth our time, money, [and] energy,” Sherman said.
