The Crown of Thorns starfish Acanthaster planci (COTS) has contributed greatly to declines in coral cover on Australia’s Great Barrier Reef, and remains one of the major acute disturbances on Indo-Pacific coral reefs.
I hadn’t seen them much around Guam for the first couple of years that we were here. I saw my first one at Dadi Beach on the Navy base. I ran into two at Fish Eye Marine Park, and so on.
However, I had heard that they could sometimes breed like crazy and take over an area. Last weekend, I finally saw that happen.
We were swimming from Gun Beach towards Tumon Bay. As we passed the Beach Bar and the stage where they have traditional dances, we began to see Crown of Thorns star fish. First just one, then another, then another, then another…
By the time we were even with the wedding chapel just past the beach area, we were in the midst of a huge bloom of Crown of Thorns, at depths of 10 feet to 30 feet all along the coral.
It is always discouraging to come upon these very poisonous and very evil star fish who gobble up healthy coral and leave barren wastelands. However, it is even worse at Gun Beach, where last year’s bleaching had already taken so much of the coral. Now what little is left is being gobbled up!
For anyone who snorkels or dives regularly, remember that it can make a huge difference if you report these Crown of Thorns blooms right away to whomever handles such things in your area. Here on Guam, it’s up to NOAA, who do reef monitoring, and who are piloting a program to begin killing Crown of Thorns star fish.
It’s harder than one would imagine to kill a Crown of Thrones. I always figured it would be a good idea to just grab them from the water and let them dry out and die on land. However, it turns out that they spawn when they feel threatened.
If you scare or upset a Crown of Thorns, it will essentially spray babies out. Therefore, it is up to the professionals to strap on a dive tank, and carefully inject each arm of the Crown of Thorns with poison.
This way they are killed without being jostled or moved, and so they don’t know it is happening. (They are only star fish after all, so it’s not like they have brains.)
So the takeaway here is: These evil star fish are killing what coral we have left. If you see something, say something. Don’t try to kill them yourself, or you could make a bad situation worse. And avoid contact because they are very poisonous.