If you live on a sandy beach here in Hawaii then you may come to love the giant finger corals because they just may help save your house from falling into the sea someday soon! Pohaku puna the finger coral is nature’s natural seawall and one of the most common reef building corals in the Hawaiian Islands. This white to grey colored coral makes up about 80% of the reef surrounding Waikiki and the entire town of Honolulu is resting on an ancient bed of fossil pohaku that was once a massive live healthy reef years ago when the sea levels were higher.
Finger corals grow quickly and like shallow calm water so they usually grow on the inside of the reef and not the outer edge. When they are small they look just like small white fingers growing upwards but as they grow large they get a more rounded shape and they can grow as large as a car then grow together to form an entire coral reef! I did growth rates on some baby finger corals at Anini Beach in Kauai and measured them growing over six inches a year! At best our sea levels are rising less than one half of an inch a year so pohaku puna can grow upwards faster than sea level rise if it is nourished and kept healthy.
Finger coral is also the reef building condominium that houses millions of baby fish and invertebrates like lobster. Certain fish like the yellow tangs live in or near finger corals and reefs in Molokai’i that are made of huge beds of finger coral are just covered in golden schools of yellow tangs! Some of the Hawaiian finger corals are way over 500 years old and may have been growing even before the Tahitians set sail for Hawai’i 1800 years ago! This really makes pohaku puna a true Hawaiian local and that demands our care and respect as they were here first!
Most of us are well aware of the houses falling into the sea on the north shore of Oahu between Sunset Beach and Rocky Point as they are in the news quite often. In 2012 I started scuba diving on the shallow reefs at Sunset Beach and I started to see the finger corals become diseased.
Their beautiful white fingers were turning brown and the corals were becoming coated in a brown turf algae which means they are losing their immune system and becoming sick.
I shot some movies of the corals and called the Hawaii TV news and did a story on the beach at Sunset and said if this coral reef dies the reef will lower in height. Along with rising sea levels the waves will have more energy hit the beach removing the sand which will cause the homes to fall into the sea.
Many people laughed at my prediction at the time but now that the finger corals did die by 2015, over 10 million dollars of property has been lost into the sea! Simple cause and effect and understanding pure physics. Lower reef equals more beach erosion!
What can kill an entire coral reef made up of thousand year old finger corals? Well actually many things and some we are just now starting to understand. Corals are made of living animal tissue called polyps that grow algae in their tissue for food and secrete a hard calcium carbonate structure that acts like the walls of our homes we live in on the beach. If mud flows out onto the reef it can coat the live coral killing it. If there are leaking cesspools in the area the sewage can coat the reef killing it.
If there are farm chemicals and fertilizers flowing out onto the reef that could also kill the coral. We now know that military helicopter and submarine activity discharges electricity into the sea and that also can kill the coral. One thing we know for sure is when the coral dies the waves break up the dead coral and the reef lowers in height. This changes how the waves break causing more energy of the waves to hit the beach, removing the sand and causing homes to fall into the sea! I am documenting this process happening real time underwater out on the reef, on the beach and with drones and satellites in the air for an educational movie series about Hawaiian beach erosion.
If we were to nourish our coral reefs once again and have the pohaku puna grow back at Sunset Beach the underwater coral seawall will protect the beach and slow down erosion even as sea levels rise so it may be cheaper to regrow a reef then try to save a beach. Finger corals grow so quickly we know we do not need to transplant or farm these native Hawaiian corals. We just need to remove the stress that killed the corals to begin with and they will grow back all on their one! We have shown this to be true on many of the coral reefs around Kauai.
How can we save and help regrow pohaku puna? To begin with, remove all cesspools that are on or near the beach. Due ongoing chemical test to make sure sewage, farm chemicals and fertilizers are not flowing out onto the reef.
When rebuilding roadways, homes and businesses near the coastline make sure no mud flows off into the sea from the construction project. Restore our native wetlands because these areas filter the rainwater before it flows out onto the reef. Stop all military helicopter and submarine activity in shallow water and move these harmful activities out into deep water where they won’t affect the corals.
This may be a lot to ask but by helping nature regrow here coral reefs around Hawaii will save over 70 billion dollars in shoreline damage due to sea level rise! Nature knows how to deal with sea level rise as she has done so for millions of years here in Hawaii but we have to clean up our act and give her a healthy environment to grow in. We have show by doing day by day coral growth measurements in Kauai on over 10,000 corals that our coral reefs can grow back with five to ten years and once again act as a healthy natural barrier protecting our coastline from excessive erosion, plus create a healthy ocean once again to surf, dive, swim in and fish in.
Just look at our ocean as our blood and the coral reef as our bones. The Earth spins, pumping our blood as our heart does. If you poison your blood with chemicals or radiation then your bones will dissolve and you will simply fall apart. The Earth is one large single living system so lets start treating it that way!
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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 www.reefguardianshawaii.org.
