CROWN OF THORNS (Acanthaster planci) AND ITS POSSIBLE SPECIES MANAGEMENT PLAN IN ALEGRIA, CEBU: A TABLE PLANNING AND DISCUSSION
By:
TRISTAN C. PAYLADO and LEE. A RICKETTS
Marine Biologist and Dive Instructor
Alegria Dive Resort, Sta. Filomena, Alegria, Cebu
September 12, 2017
INTRODUCTION
By the time you start reading this article, you have probably at least some experience swimming, snorkeling or diving, not just in the shores of Alegria, but maybe in other coastal areas. While on water, you have probably seen this multiple-armed starfish where its body is entirely covered with spiky protrusions and thrives along coral reef areas. If this is the case, then you just have seen a Crown of Thorns Starfish.
Abbreviated as COTs, crown of thorns can grow up to 35 centimeters and can have up to 21 arms that are similar to the ones in a common starfish. Taxonomically, COTs are starfish where they exhibit the typical starfish body that has a central disc with multiple arms that extends outwards and has the ability to regenerate if broken or cut. What sets apart COTs from other types of starfish is that their spiny protrusions are stiff yet it can be flexible especially when it maneuvers in tight spaces.
If you are concerned if the spines of COTs have venom, then you should be aware that their entire body contains saponins. If you accidentally puncture yourself with the spines of COTs, saponins (which is a type of natural toxic steroid) will enter your bloodstream and will cause stinging pain that may last for hours. Nausea and swelling of the punctured skin can also set in minutes after the venom enters your body system. First aid includes soaking the punctured area in luke-warm water. But you have to take note that this will only address the pain. If symptoms persist for hours, do not hesitate to seek medical help and do not attempt to manually remove embedded spines in your skin as they are brittle and can easily break off. Surgery must be done to prevent further skin infection and complications.
But of all the marine species, why are we talking about COTs?
Are we really concerned about their painful stings? I guess the answer is a 10% NO since there are people that are really concerned about what will happen to them in case they got accidentally stung by COTs. But what is really concerning about COTs is their infestation in the reef system.
In the past few years, worldwide outbreak of COTs has been reported and has been partly linked to the loss of its main natural predator, the triton’s trumpet shell (Charonia tritonis). Although it is not discounted that COTs have other predators like pufferfish, triggerfish, parrotfish and other species of fish that have a beaked tooth, their means of predation is not through total consumption (as compared to the predation of a triton shell) and that COTs can possibly survive predation from reef associated fish.
But why get fussy about the loss of its Natural Predator?
If you are concerned about the environment, you should know that the loss of one species can lead to the dominance of the other. This is the case of COTs where their population has grown exponentially. What we really should focus is not about their blooming population, but rather, the effects brought about by their sheer number.
The Effect of a COTs Outbreak
While COTs have a broad range of diet, they prefer to eat coral polyps the lives inside a coral head, making them to be classified as a corallivore. Equipped with hundreds of tube-feets, COTs have the ability to climb and roam around an entire reef system eating all coral polyps that gets on its way. According to Pierre Madl (1998) in his biological study of COTs, a single crown of thorn starfish can consume at least 6 square meters (or 65 square feet) of living coral head leaving behind a white trail of dead corals. He further claimed that the damage of COTs will be higher in tropical areas like the Philippines where COTs are observed to be highly mobile and can even reach a locomotion speed of 35 centimeters/minute.
Now, here’s the thing: we are just talking about a single specimen of crown of thorns starfish and just imagine the destruction it can do if we speak of at least a hundred COTs which is considered the minimal threshold of a simple outbreak.
PROPOSED SPECIES MANAGEMENT PLAN FOR COTs
Disclaimer: Before we proceed, we are not claiming that this is the most effective and applicable method in Alegria against COTs infestation and that further study is needed for a better species management plan.
First and foremost, the objective of this proposed management plan is NOT THE ENTIRE ERADICATION OF COTs in the municipal waters of Alegria Cebu, which is impossible to do. Further, we must remember that COTs are natural marine living organisms and their presence is vital in the concept of a balanced ecosystem.
Instead, what we propose is what we should do in case if there is a COTs outbreak. But first, let us define what is an outbreak. According to Fernandes et al (1999) of the Australian Parks and Wildlife, an outbreak can only be considered when the density of COTs reaches 40 individuals for a single coral mound. But this has been disputed as the size of each coral mound differs from each other. A more detailed figure was brought up by Moran and De’ath suggesting that a density of 0.22 individual per 200 meter x 10 meter area (assessed using manta tow technique) can now be considered an outbreak.
While COTs outbreak studies are still on its way, we proposed that the manual extraction of COTs does not need for an outbreak to happen. As long as there is an observed increased in COTs population, manual extraction could immediately commence.
What is Manual Extraction of COTs?
There are methods in extracting COTs out of their environment but some of them can even bring more damage rather than preventing or minimizing the impacts of an outbreak. This is especially true if the method involves puncturing COTs underwater using metallic object that triggers the release of eggs (when gravid) thereby creating a new generation of COTs.
What we recommend is the use of simple bamboo thongs or improvised clips. Going to a pre-identified area with the greatest concentration of COTs, volunteers and enthusiasts can descend down the reef and start extracting the COTs. We do not mind if the method applied uses SCUBA or skin diving, but not hookah or compressor diving as it is already prohibited by law.
Once a COT is spotted, a volunteer can use the bamboo thong to detach the COT from an infested coral head and will be placed in a collecting bag, like sack or basket. Back on land, all COTs collected should be counted and examined (if necessary for biological reference) and a report for the day’s activity is highly recommended.
Note: First Aid kit is highly advised to be available and easily accessed in case of an accidental COT injury and emergency plan should be established should there be an accident.
Proper Disposal of COTs
If collected COTs are just thrown away at any place, then it will defeat the purpose of this extraction activity. It is highly suggested that a burial site must be designated for all collected COTs. Burning of COTs is not recommended. A simple soil dug-out of at least 1 meter deep (length and width will depend on the total size of the catch) is sufficient enough for COTs to buried and not to cause any harm like emission of foul odor. A wooden sign for each dug-out can also come in handy especially if studies are going to be pursued on the potential of decomposed COTs as organic fertilizers.
WINDING-UP
Before we end this article, you may think that we are just wasting our time doing our research, writing this article and proposing possible management plans. Okay, we will give you the benefit of your doubt, disregard what we are saying and let this article sleep. No worries at all. But just make sure, that when that day comes when your nearby reefs are all colored white, do not blame yourself of not taking preventive measures and be jealous of other reefs that are healthy and thriving.
Signed and Prepared by:
TRISTAN .C PAYLADO
Marine Biologist / CMAS 2Star Instructor
No: PH 041106 M2 000026
Lee .A RICKETS (DBA)
PADI IDC Staff Instructor
No: 287778