Divers Cement Storm-Torn Corals Back Onto Hawaii's Reefs While a 45-Day Clock Runs

A broken coral head on the seabed is on a timer. Fragments knocked loose by a storm survive for roughly 45 days, which is why Hawaii's reef teams reached the water about two weeks after Hurricane Lowell, the earliest it was safe, and why they are mixing cement on boats, the Star-Advertiser reported in a story republished by The Garden Island on Saturday.

Two hurricanes, Lala in August and Lowell in September, damaged reefs across the state. Kauai's south shore, the Big Island including Kona, and leeward Oahu are among the hotspots.

How do divers reattach broken coral?

The work is closer to construction than gardening. Teams tow snorkelers slowly across a reef to survey it, then choose repair sites. On boats an assembly line mixes concrete, hands it to snorkelers, and passes it to certified scientific divers, who set the corals back on the seabed. Cementing coral directly to the bottom is the leading technique, though Kuleana Coral's Alika Garcia found that slightly raised substrate held up better.

Kuleana Coral also builds "reef stars," steel frames coated in epoxy and sand that interlock to hold loose rubble. Twelve survived the hurricane, while nearby reef areas were wrecked. Murky brown water kept divers out for up to two weeks in places.

What happened at Kauai's Koloa Landing?

At Hanakaape Bay, reached through the Koloa Landing ramp, the Kauai Coral Restoration Nursery (Hoomalu Ke Kai) and partners aimed to locate, document, reposition and cement dislodged coral heads, with more than 2,000 damaged corals the target, according to The Garden Island. Teams had assessed nearly 20 miles of reef on the island's south and west shores. Deeper Blue described an 11-day response that ran under a NOAA restoration permit, with certified divers securing heavier structures while snorkelers and freedivers watched from the surface and carried gear, it reported on 24 October.