CRITTER: Record coral growth recorded at Anini Beach

For the last five years myself and the Reef Guardians Hawai‘i nonprofit research team have taken over 500 kids in our Reef Camp out to see the beautiful yellow antler corals growing about 100 yards offshore from the boat ramp at Anini Beach.

We all have a smile on our face when we get close to more than 50 bright yellow antler corals that only grow in this part of the lagoon. All up and down the coastline on Kaua‘i’s North Shore, the antler corals are usually brown or green — not yellow.

Once we swim out to this amazing coral garden, we will dive down about 3-4 feet and lay a footlong measuring stick close to each coral to document the size and growth rate of the corals. On my own, I have gone out to this coral garden over 50 times in the last seven years shooting video and pictures of the growing antler corals. I now have over 7,000 pictures of Anini corals dating back to 2006.

What we found after measuring the antler corals every few months is an abnormal growth rate. According to NOAA, Hawaiian corals can grow at a rate of an inch a year. up to about 6 inches a year in isolated locations. But a growth rate of 2 inches a year is considered very good.

I have done coral growth studies all around the Pacific Ocean from Palau to Bora Bora and to the Galapagos Islands.

The researchers I dove with have never documented corals with a growth rate of over 4 inches a year.

From 2012 to 2015, over 90 percent of the corals died at Anini Beach. I documented this death rate along with a research team from NOAA, USGS and UH. It was devastating.

We never found out for sure what killed all the corals, but in this time frame the U.S. Navy was practicing submarine electronic surveillance operations off Anini Beach. We now know from lab studies an electrical current discharged into saltwater can kill corals. We were very disturbed by the coral dying, but it turned out to be a gift for research because we got to document a coral reef growing back.

For the first time we know of, as a biologist I was able to video document a healthy coral reef from 2008 to 2012, then document this entire reef dying from 2012 to 2015, then growing back within six years.

In 2015 the Navy moved activities 50 miles offshore, and all of the Anini corals started to grow back.

In 2016, the baby yellow antler corals were only a few inches tall. By 2022 these corals were 18 inches tall and over 24 inches wide. Some of the corals grew over 6 inches a year from 2016 to 2022.

Recently, at Reef Camp, I once again measured the antler corals and they are still growing quickly. Some are so huge they cannot grow any taller due to the shallow lagoon, so they are growing wider.

What is causing this coral garden to grow so fast? This is what I asked the kids in Reef Camp to help me figure out because if a coral reef can grow so quickly, we need to know why in order to help save coral reefs all around the world.

With the student at the beach, we went over some theories about the amazing growth of the corals. I mapped the entire Anini reef with my drone helicopter and found a channel in the reef where clean deep ocean water flows into the lagoon.

That is where these corals are growing fast, so maybe they are in an area that does not have sewage from cesspools, boat fuel or touristswimming.

The corals are growing in shallow water so they are in a lot of sunshine. There are several factors that may explain why the corals grow so fast in this area, but we still don’t understand all of the reasons.

So I asked our young Reef Guardians to help us find answers. I will continue to measure the growth rates of our rare Anini yellow antler corals! Many coral reefs in the world are dying, but our Anini corals are growing so let’s find out why.

Just maybe the corals at Anini Beach Kaua‘i are trying to tell us something.

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Terry Lilley is a marine biologist living in Hanalei Kaua‘i and co-founder of Reef Guardians Hawai‘i, a nonprofit on a mission to provide education and resources to protect the coral reef. To donate to Reef Guardians Hawaii go to reefguardianshawaii.org.