KAILUA-KONA — Coral bleaching is already occurring in West Hawaii waters, and things are likely to get worse as Hawaii’s reefs enter a major bleaching event within the next two months — if not sooner.
Warm ocean temperatures are the major contributing factor in bleaching and data from the National Oceanic and Atmospheric Administration’s Coral Reef Watch program indicates ocean temperatures around Hawaii aren’t getting any cooler.
“Ocean temperatures are extremely warm right now across Hawaii. They’re about 3 degrees warmer than what we typically experience in mid-August,” NOAA scientist Jamison Gove said. “If the ocean continues to warm even further as predicted, we are likely to witness a repeat of unprecedented bleaching events in 2014 and 2015.”
Corals bleach under stress, and severe or prolonged stress can lead to death. Although corals can recover from moderate levels of heat, if it is prolonged, it proves fatal. But scientists say that reducing secondary stress on corals during these bleaching events can improve the chances of coral survival.
The worst bleaching event in state history occurred in 2015. Higher than usual ocean water temperatures that year resulted in an average of 60% of corals in West Hawaii bleached, with some reefs experiencing up to 90% mortality.
In February, The Nature Conservancy said coral reefs in West Hawaii were stabilizing and poised to recover.
But, on Friday, Nikki Sanderlin, acting aquatic biologist for the Department of Land and Natural Resources Division of Aquatic Resources West Hawaii district office, provided a not-so-positive update.
“We’re already observing bleaching of corals in West Hawaii, along with some paling of other species at some of our long-term monitoring sites,” she said.
At Kahaluu Bay, which draws hundreds of thousands annually, some bleaching is currently visible, though the recent drab weather appears to have provided some reprieve thanks to cooler temperatures, said Cindy Punihaole, executive director of The Kohala Center, which oversees the Kahaluu Bay Education Center and ReefTeach programs.
“Right now, Kahaluu Bay is dying,” she said Friday. “Though it is still bountiful with fish, we can see the degradation in our corals.”
And with ocean temperatures predicted to increase in the coming months, there’s no way to stop the bleaching from settling in, and possibly killing off coral, said Brian Neilson, Division of Aquatic Resources administrator.
“We know this bleaching event is coming and it’s probably going to be worse than the ones we experienced four and five years ago,” Neilson said. “We’re asking for everyone’s help in trying to be proactive and to minimize any additional stress we put on our corals.”
That includes not touching coral while diving, snorkeling or swimming and definitely not standing or resting on the marine invertebrates. Boaters should use mooring buoys, and if they must anchor, do it in a sandy area and keep the anchor chain off the reef.
And, as always, use reef-safe sunscreen. Right now, it’s a choice to use the products not containing reef-harming chemicals oxybenzone and octinoxate. Come Jan. 1, 2021, the sale, offer of sale, and distribution of sunscreens containing those ingredients becomes illegal in Hawaii.
“That’s a stressor we can change in a minute — unlike climate change,” said Punihaole, noting that 2018 testing of water at Kahaluu Bay found oxybenzone levels to be 262 times greater than considered high-risk by the U.S. Environmental Protection Agency.
She also reminded the public that what happens up mauka (mountain) reaches the kai (ocean).
“If you are using chemical-based sunscreens on the mauka lands, hiking or playing sports, when you go wash off it goes right into wastewater and back into the ocean,” Punihaole stated.
The DLNR also advises anglers to reduce or stop take of herbivores, such as parrotfish (uhu), surgeonfish and sea urchins. These critters clear reefs of algae, which can overgrow, blocking light and killing corals during bleaching events.
Taking extra precaution to prevent potential contaminants like fertilizers, soaps and detergents, and motor oil from getting to the ocean is another way to assist. Dirt from poorly managed construction sites is also another culprit that stresses reefs.
“These are actually things we should be doing all the time, but it’s especially important now,” said Neilson. “We’d also like swimmers, snorkelers, and divers to report when and where they see both bleaching and healthy corals. Those healthy corals may provide valuable information about how some corals are better able to survive these types of events.”
In October, the Department of Land and Natural Resources said it will introduce an initiative aimed at tour operators to inform their guests about good reef practices.
The department and NOAA are also using new technology to better understand the real-time extent of predicted bleaching events. Arizona State University, which created and is maintaining the Hawaii Coral Website, is providing weekly satellite imagery to help identify bleaching areas.
The information is publicly available online at www.hawaiicoral.org.
Residents who spend time in the water can also use that website to report their findings of bleaching.