KAILUA-KONA — Coral in the typically crowded Kahaluu Bay is getting a reprieve from human traffic through today.
The county closed the bay to allow for a coral spawning event that scientists predicted was most likely to occur Monday and today.
“It’s so critical for these to be able to successfully reproduce in order, basically, for the population to survive,” said Kathleen Clark, of the Kahaluu Bay Education Center’s ReefTeach program.
The park was off limits for two half-days in 2018, but officials decided to increase it to two full days this year, with Clark describing the endeavor as sort of a “pilot program” to gauge the possibility of similar closures at other sites in the future.
Human presence can be disruptive during a spawning event, during which corals release gametes, both sperm and egg, into the water, where fertilization occurs. They form planulae, which Clark described as coral in an embryonic state.
Planulae swim about until environmental cues dictate they settle, a process that typically takes between 24-48 hours. In Kahaluu Bay, Clark said, they often settle on lava rock covered in calcareous algae or a bio film — the same places swimmers and snorkelers think it’s OK to stand because there’s no live coral.
West Hawaii reefs lost roughly 95% of their cauliflower coral in a 2015 mass bleaching event. Clark said that last year and this year are the first years the coral has been healthy enough to spawn. That’s why the closure is important.
It likely will be a couple of years, however, before the impact of the 2018 and 2019 closures on the coral can be accurately assessed, but Clark said there have been positive omens in recent months.
“We are seeing some new, small juvenile coral out there, which is a really great sign,” she said.
Email Max Dible at mdible@westhawaiitoday.com.