Since last summer, the reefs around Koh Chang are slowly recovering from the coral bleaching due to the increased global sea temperature yet they’re facing a new challenge for survival. The crown-of thorns starfish, the world’s second largest sea star, is on the hunt and it’s favourite meal consists out of coral polyps .
The sharp, venomous spines on the sides of the starfish’s limbs resemble thorns and create a crown-like shape, giving the creature its name. The thorns are very sharp and are capable of piercing through standard wetsuits and other clothing, resulting in a serious wound with a sharp stinging pain that can last for hours. Proper first aid is needed to treat these wounds.
The Crown-of-thorns starfish crawls over reef structures, and squeezes its stomach onto the coral. By doing this, it releases a digestive enzyme that allows the starfish to absorb nutrients from the liquefied coral tissue, leaving the white coral skeleton behind.
Normally there aren’t many of these starfish on a reef and their presence might even play a significant role in the natural reproduction and evolution of coral reefs. So why do we see so many of them lately and should we be concerned?
Studies have shown that the crown-of thorns starfish are attracted to coral reefs that are stressed. Several factors such as dynamite fishing, (diving)tourism, climate change and many more contribute to stress the reefs. We know that the reefs around Koh Chang suffered from severe coral bleaching due to an above average water temperature, so this could be a cause for their abundant presence.
The overfishing of one of the few natural predators – the triton shell – isn’t helping either. Many people find triton shells attractive as a design object, and so they are collected and sold as part of the international shell trade. In recent years this has contributed to the animals’ scarcity.
Regulating collecting these shells could help, in an environmentally friendly and above all a natural way, controlling the escalation of the crown-of- thorns starfish numbers amongst our reefs.
When under stress the crown-of-thorns can create outbreaks and, if dismembered, can regenerate from each severed or damaged limb, creating more sea stars. Therefore, controlling the crown-of-thorns is difficult and much care is required.
Divers often give nature a helping hand by removing the starfish from the water or by injecting them with sodium bi-sulphate which is deadly to them, but it does not harm the surrounding reef and oceanic ecosystems.
In the end we have to realise that somehow, perhaps in many collaborative combinations, human abuse of the coral reef ecosystem is behind the problem. Or at least making it worse. Time to take action and look at the other, more human, population which is running out of control.
Happy Bubbles
Enjoy!!
