Broken Corals and Coral Reef Recovery by Nature

When we dive, our intrusion into the wild ocean life means that we “poke the sea”. Coral damage, surprisingly, isn’t the end of the world, as Bob Halstead discovers. Corals do bounce back to restore vibrant reefs once again, and you can do your part in re-growing new reefs.

Bob, too deep for too long.By Bob Halstead

Bob, too deep for too long.By Bob Halstead

I'll fix this moron! I silently vowed as I viewed the mutilated brain coral. Not only had a diver been ignorant and careless enough to vandalise its exquisite and perfect maze surface, he was dumb enough to do it by scratching his name and the date in the coral - and I recognised the name.

So, having been brought up with Superman, the Saint, NAUI and other unofficial forces for justice, I went out of my way to meet with the man that employed him as a diver, and dobbed him in. I was of course overcome with a feeling of righteousness, which did wonders for my ego. I mean I had just saved the world's coral reefs, right? If only others would care like me - and take action! (like me)

Vandalised coral.

Brain corals are fascinating living sculptures. I love to look at them and play maze games or just marvel at their art. So when I returned to the same reef a couple of years later I remembered the mutilated brain coral and tried to find it. Sure enough, it was gone - I searched in vain for the carved coral, but it had disappeared.

Same coral after a year.

I thought my worst fears had come true, the coral must have died of its injuries and turned to an ugly rotting algae infested rock. But I could not find one of those either - then I realised that the perfect specimen right in front of my eyes was the very same. It had healed! There were no scars, it was the exquisite, outrageous, wonderful brain coral that it had been before the vandal struck.

I do enjoy reading magazines that run reviews on various dive operations round the world - they have helped me discover what divers consider essential qualities in dive boats and have enabled me to fine-tune Telita Cruises. I learned for example that the anchor we were using was "too heavy". I also learned that we did not have enough chairs on our top deck so bought some more and observed that guests prefer to sit around on the deck and lockers.

I was fascinated to find out that some guests thought we should fit mirrors under the top bunks in the Honeymoon cabins and also that I was "irascible" - but I think this must have been a simple typing error, the word, surely, was meant to be "irresistible".

A while ago one of these magazines reviewed the Manta, an unpretentious mini live aboard that operated out of Rabaul in PNG. I cannot remember if they spelt Rabaul correctly, but if so it was probably the first time any reviewer ever did, before or since. The reviewer commented on the wrecks in the harbour and noted that they were littered with rocks which detracted from their charm, then a few sentences later castigated the Manta for anchoring on a reef when, in the reviewer's politically correct view, he should have used a mooring.

Moorings can save a reef from damage.

The irony of this is that if you wish to guarantee the destruction of a reef in PNG all you need to do is put a mooring on it with a surface buoy. (The splendid moorings now used by all members of the PNG Diver's Association are all buoyed sub-surface and located with GPS not sight so I am really talking history here).

Fishermen with rocks for weights.

Fishermen with rocks for weights.

Local fishermen in their canoes love the convenience of a mooring - such as those on the wrecks in Rabaul harbour. They tie up and proceed to fish from them. The most popular method is to take a rock about the size of a small fist and tie a palm leaf around it so that about half a metre of leaf sticks out from the rock.

The baited hook is then pushed through the end of the palm and then the whole mess dropped to the bottom. On the bottom the hook is given a jerk and pulls free of the palm to float above the bottom and thus avoid getting snagged. A single fisherman can easily get through 50 to 100 rocks in one night's fishing - and the reef or wreck looks like an avalanche has fallen on it.

Then the Rabaul volcano erupted - completely burying a couple of the best wrecks with a billion or so rocks. Such are the forces of nature.

Modern moorings are very practical for the regular dive sites. But when we first operated Telita in the 1980s we had over 150 sites that we returned to, many sites that had been dived just once but had not been returned to - and many places yet to dive. On the dive sites where coral damage was possible our procedure was to find the least attractive part of the reef, a relatively dead area or a sand patch, and always anchor in that same area thus preserving the best part of the reef, just a short swim away for the divers.

On one reef a large ship ran aground so Telita always anchored where the ship damaged the reef. Our reward for taking this care were occasional complaints that the reef was looking in bad shape in the areas we anchor! MV Golden Dawn has a great system of instant mooring when it is exploring new sites. It sends down a diver with a metal sling attached to a mooring line and lassos a convenient coral head or rock producing minuscule damage.

Rocks on seabed.

Rocks on seabed.

Once, on an exploratory dive, I was saddened to see that our chain had drifted through a beautiful stand of cabbage coral and had broken some of it. When the divers returned I re-anchored the boat in a barren area I had found nearby, and went back to inspect the damage.

I was able to collect the broken pieces and prop them up back in their right positions - less than a year later the corals had rejoined and it was impossible to see where they were damaged.

Coral grows over rock.

You can do this too - if you ever see a fallen sea fan or overturned coral or damaged reef, whether caused by careless divers, anchor chain, or more often the forces of nature, try to repair the damage. This really does work.

At Deacon's Reef in Milne Bay I have been repairing small sea fans for twenty years - replanting sections of fan kicked to the bottom by careless divers swimming through a narrow gap. (Just jam the stalk into a small hole in the coral - it makes its own foot again). Now the area is a forest of sea fans.

Notice how reality differs from the views of the guilt mongers who proclaim that every coral touched then dies (presumably in agony). Do they realise that billions of fish and other marine creatures, including coral polyps, are slaughtered every day?! And do they know who is responsible? Well actually it is… fish and other marine animals.

Bob's replanted coral garden.

What is more they usually chomp on each other's live and twitching flesh, and particularly go for the weak and sick. I am not saying (yet) that we could learn from them, but it might do well for those dreamy idealists to open their eyes and see what actually goes on in nature. Try following a school of bump headed parrot fish around for a day and see the damage they cause to corals - but you know what, the corals recover, rapidly!

About ten years ago a plague of crown of thorns sea stars invaded Milne Bay. It was a little hard to blame people for this since commercial exploitation and pollution of the reefs was non-existent. Nevertheless I saw some of my favourite reefs destroyed by the sea star. Corals disappeared, and with them the abundant fish life. It was sickening.

I simply stopped diving on the reefs that were affected and found other reefs not so badly damaged. Recently I revisited one reef that had been absolutely devastated to find it stacked with vibrant live corals, including layers of plate corals several feet across, and buzzing with fish. I could hardly believe it - the reef was even better than it had been to start with.

So it is with other forms of damage that divers and boats and storms and, yes, fish do - if there is time for the reef to renew, and the water quality has not been affected, the reefs come back better than ever.

More than this, old reefs tend to be dominated by just a few species. When they are wiped out all sorts of corals recolonise the same area and biodiversity increases dramatically. When I dived the B17 bomber "Blackjack" after a rare cyclone had passed right over it, I was astonished to see that it was adorned with a carpet of colourful soft corals. It looked fantastic- it is amazing what some wild seas and massive rainfall can do.

Coral reefs may be fragile in that they depend on unpolluted water and are easily broken, but in other ways they are incredibly dynamic and resilient. And corals grow FAST if the conditions are right, I have seen reefs recover from being barren to having healthy coral cover in as little as five years.

Corals thrive again after invasion by crown of thorns.

I believe that it would be a dismal life if we lost our right to go underwater and see nature at work even though it is impossible to do this without affecting the underwater world in some way.

This is Halstead's Uncertainty Principle - just by diving underwater we change what we go to see. It is good to minimise this change but we should realise that by diving we INEVITABLY "Poke The Sea".

Sometimes it pokes us back, and fair enough too. I enjoy the wildness of the ocean and the fact that there are no "human rights" there. The marine world just carries on doing its own thing as best it can and what we rely on to avoid injury, or become part of the food chain, is education and a lot of bluff.

Photos by Bob Halstead. 

Bob Halstead is author of the “Coral Sea Reef Guide” with underwater photo identification of over 1000 marine animals found in PNG and the Coral Sea region.