Crown of Thorns 

Cancer of the Coral Reef 

The harmony of communications between all the microscopic cells of a human body keeps the system humming along. If some of the cells stop hearing the music they can start multiplying rapidly and go into a feeding frenzy, eating everything they can get their little membranes around. And when that happens, the symphony that was the individual being consumes itself from the inside out. 

In medical terms this is called cancer.

Cancer cells start out as valuable members of the community before they loose the beat.

Usually, when the balance gets upset and one type of cell starts getting too numerous, the cops show up. In the cellular community the cops are macrophages (big eaters). They devour the cells causing the problem and keep things in control. Cancer happens when the control networks break down. Even the police system can go haywire, as in Leukemia when Macrophages start eating all cells, good and bad alike.

There are several reasons why some members of living systems lose control. Human cells, for example, become cancers from stress, chemicals, smoking, radiation, and even disease organisms.

Normally, there are not very many Acanthaster on a coral reef. Maybe one every kilometer of reef or less. Many reefs don't seem to have any at all and, of course, the starfish is absent entirely from Atlantic coral reefs. 

Usually, Acanthaster live near coral reef passes. Maybe they help keep the passes open by trimming corals. Maybe they just like the current. Back before the sixties, not many people had ever seen or heard of the crown of thorns starfish. The diving biologists of the forties and fifties surveyed many miles of coral reefs and even very experienced diver/biologists had never even seen one.

As a specialist in coral reefs and echinoderms (starfish included) I discovered another infestation in Guam in 1968. It had been in progress for perhaps three years when I arrived at the University of Guam. The biologists recognized the reefs were in trouble, but were not sure what the problem was. I knew what was wrong the instant I saw the crown of thorns there on the reefs of Guam. 

Lots of them. Thousands. Hundreds of thousands. 

Stripping the living coral from the intertidal zone to the depth limits of coral growth at the rate of one kilometer of shoreline a month. There were two fonts, moving out from an epicenter at Tumon Bay. Ahead of the front the coral was alive. Behind the coral skeletons were bare, slowly being covered with a gray algae. The colorful coral reef fish moved ahead of the bands of starfish, trying to remain in their adaptive habitats, uncomfortable in the dead coral environment. The stripped reefs looked desolate, colorless, compared to the unharmed reefs.

Why did these starfish become a cancer of the reef?

I studied the problem in Guam for 6 months and began a control effort to stop the coral destruction. The results of my study were published in the July issue of Science. You can download a reprint of this study by clicking on the following link:

Chesher, R.H. 1969. Destruction of Pacific Corals by the Sea Star Acanthaster planci. Science 18 July 1969, 165, pp. 280-283

I organized a crown-of-thorns survey of the north Pacific from Hawaii to Palau, and the Northern Marianas Islands to Kapingimarangi. The expedition was supported by the U.S. Department of the Interior and managed by Westighouse Ocean Research Laboratories. I headed a team of 63 diver/scientists that were divided into groups of 10 and sent out to survey conditions in as many locations as possible. It was the largest single survey of the condition of coral reefs ever organized. I published details on how the Acanthaster survey was organized in Oceans Magazine. You can download the PDF file of this article with the following link:

Chesher, R.H. 1970. Acanthaster: Killer of the Reef. Oceans Magazine 3(5):10-17

The final report of the survey was published by the National Technical Information Service and was instrumental in obtaining millions of dollars for future research and control efforts. You can download a PDF copy of this rare report by clicking on the following link;

Chesher, R.H. 1969 Acanthaster planci, Impact on Pacific Coral Reefs. Final Report to the U.S. Department of the Interior. Westinghouse Electric Corporation.

The survey teams found other infestations of crown of thorns starfish in different stages of development in many island areas - usually in close proximity to villages or urban areas. There was no "common denominator" for the infestations. Instead, the picture that emerged was blooms occur where the reefs are stressed. And the reefs of the world are stressed by many different causes.

What sorts of things stress reefs? Increased water temperature can cause coral to eject their symbiotic algae - a process known as coral bleaching. If the temperature stays too high too long the corals die and are quickly covered with blue-green algae. The Crown of Thorns starfish spawn during the hottest months of the year and if the larvae settle on a recently bleached reef they will have a very high survival rate. Not only because of the decaying coral but because the normal diverse coral reef creatures that eat larval Acanthaster have moved into neighboring reefs where the corals are still alive. 

People blast reefs with dynamite and, as in Guam, damage the coral by dredging. The adult crown of thorns, and even their swimming larvae, are attracted to the metabolites released by damaged corals. When the adults are attracted to the damaged coral metabolites they will find plenty of partners for enhanced spawning success and of course the larvae they create will have an excellent chance of survival.

People also break coral when walking on reefs, to catch octopus, crabs, and collect shells for tourists or get coral rocks for building material.

Reefs are over-fished. At least five species of large fish eat the crown of thorns. They are gone from most reefs near people. People poison the reefs with various chemicals to kill or stun fish. Agricultural chemicals applied to island gardens or used to control mosquitoes wind up in the sea, and in the corals. This weakens the corals. When the crown of thorns eats the coral they accumulate these chemicals in their own tissues (it does not seem to harm them, the larvae actually survive better with DDT in the water). The predators of the crown of thorns, including triton shells and a beautiful little shrimp, may die or encounter breeding problems from the concentrated poisons in the starfish's flesh. Increased concentrations of carbon dioxide in the sea water reduces calcium deposition, slowing coral growth.

All of these stresses create an opportunity for the Crown of Thorns to become a cancer of the reef.

And then there is the triton. The beautiful triton.

Dr. Bob Endean said, right away, he thought the cause of the starfish explosion was because tritons were over-collected. Other biologists, including me, thought this unlikely. But now, after investigating the infestations for over 30 years, I think Bob was right after all. Or partly right. Certainly the tritons are a major predator on the starfish. And they are over-collected, even endangered or locally extinct, in most areas of the Pacific.

Many critics of the idea that triton predation is significant point out one triton can only eat one big Crown of Thorns every day or so and there are thousands of starfish during an infestation. But the critics forget the normal population of Crown of Thorns starfish is just one or two individuals per kilometer of reef. Tritons could easily be a major factor in controlling the starfish in normal conditions. Plus during spawning, the Crown of Thorns assemble and spawn together. This attracts any tritons in the vicinity and when a triton attacks a Crown of Thorns any nearby starfish take off at high speed (they can almost outrun a Triton). This would have a major impact on the spawning success of the starfish. Of course other stresses and a variety of conditions (plankton, water temperature) that favor the survival of Acanthaster larvae are equally likely to be involved in some cases but let's focus on Tritons because the timing of the demise of tritons happens to be symmetrically balanced with the escalation of starfish numbers.

The biggest tritons make the most eggs.

Big ones are quite rare now. I interviewed older divers in many islands of the Pacific and they all agreed the triton population has gone down to practically nothing. Having dived on coral reefs throughout the Pacific Islands for over 50 years I also know the tritons are now few and far between. 

You can still find them in shell shops and in markets, getting fewer, smaller and more expensive each year.

The reason I think the triton is especially important in this whole crown of thorns problem is because the triton/starfish relationship is easy to understand, easy to sympathize with, and - in theory - easy to do something about.

After all, nobody NEEDS to kill tritons.

The only reason we kill them is because they are beautiful and we like to have their shells for decorations. On the other hand, they are key species and killing them endangers the whole coral reef ecosystem.

The people who live on the islands rely on the coral reef ecosystem for fish and other protein. The small amount of money a few individuals might make selling a triton they found will in no way compensate for the loss of protein for the whole community following a crown of thorns attack. American Samoa spent nearly half a million dollars just fighting the starfish. Every sale of every triton ever collected from their reefs did not total that much money.

So, logically, you would think it would be easy enough to do something about this aspect of the problem.

You would think the island governments would leap to the rescue of the triton, banning collection and sales.

In Australia, the government did just that. But it still permits importation of tritons from other countries, like the Pacific islands, and there are plenty of tritons in gift shops just inland of the Great Barrier Reef. There is no way to know if they came from the Great Barrier Reef or Fiji, is there?

New Caledonia is the only country in the South Pacific where tritons are a protected species and killing, transporting, handling, disturbing, buying or selling Tritons - alive or dead - is forbidden. And I've seen them in gift shops in Noumea.

Tonga will not protect its tritons because, "People like them. It's tradition." Nobody would enforce a ban anyway.

CITES.

Biologist Ann Paulson and I managed to get Australia to propose listing Tritons on the Convention against International  Traffic of Endangered Species (CITES). Japan objected; Australia withdrew it's suggestion.

Scientists have spent millions of dollars investigating the Crown of Thorns.

The vast amount of scientific research on the crown of thorns since 1968 has been very interesting. Scientists are currently spending more millions investigating coral bleaching, and a host of coral diseases that flourish in the wake of human abuse of the coral reefs.

As science learns more about the control systems regulating the population explosions of the crown of thorns, the consensus is finally showing, human abuse of the coral reef ecosystem is behind the problem. Or at least making it worse. Basically the same conclusion I reached in 1968.

In 1962 the Queensland government did it's best to sand bag the whole problem. I suspect the politicians realized something right away. Something marine biologists still have not thought of, even though it's pretty obvious.

The dysfunctional control system is larger than the control web in the oceans.

The Triton/Acanthaster dysfunction is the society that collects the triton, killing them because people adore their beauty.

Focus on that. How do you reconfigure that control system?

Going back to the cancer analogy, we know smoking contributes to human stress. We know it results in cancer as well as a host of other diseases. Nobody NEEDS to smoke. But people like it, and young kids do it even if it is against the law. 

See the parallel? Here is the problem to solve. Here is the control system out of wack. Scientists can study the details of coral reef demise for the next 30 years, spending millions to confirm and reconfirm the obvious. 

So? How will that solve the problem?

It won't. 

Starfish as cancers of the reef are going to continue.

So what do we do about it?

Option 1. Nothing. Some people are suggesting we just let it happen. It's nature, they say. Just like any cancer they happen naturally, kill the organism or ecosystem. Eventually, they believe, the reefs will recover. But maybe they won't recover because humanity is going to continue to stress the reefs and as the populations of these cancerous reef creatures increase the chances of the coral reefs ever reaching their former magnificence diminishes.

Option 2. Remove the cancers when they are discovered. Medical doctors don't study the progress and demise of their cancer patients. They remove the cancer and improve the health of their patient to prevent the cancer from happening again. Doctors don't ascribe to the "let nature take it's course" especially when nature's course has been diverted by bad behavior.

It's easy enough to remove the cancerous starfish from the reef. I developed the technique with my volunteer control team in Guam back in 1968. It has been improved by discovering vinegar will kill the starfish without causing any collateral damage.

Get some multiple shot veterinary syringes (like the Automatic Drenching Vaccination Dose Gun Syringe 20mL Livestock Veterinary syringe on Amazon $25) and some enema bag kits with silicon hoses (about $10 on Amazon). Attach the silicone hose to the syringe, fill the bag with white cleaning vinegar, and inject the starfish twice on the disk at the base of the arms with 20cc (two shots). Takes 6 seconds per starfish. In less than 24 hours it will be dead. The vinegar changes the pH of the Acanthaster's body fluid and after it is dead the pickled starfish can decompose or be eaten by crabs or fish without harming them. There is no adverse effects on the surrounding corals. Just the opposite because the corals are still there. One diver can inject about 300 starfish in an hour or two in a major infestation. So with 4 volunteers a large infestation can be eliminated in a day or two. 

That's illogical because when they spawn naturally they choose the right weather, the right time, and assemble to assure a successful spawn. That would, of course, result in a lot more starfish than if they were induced to spawn when they were scattered and being injected. I've watched them spawn and they like to take their time.