Tag Archives: acanthaster plancii

Underwater Superhero

Want to be an underwater superhero?! That’s what it feels like to participate in crown-of-thorns removal.
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SJ Byce: underwater superhero in action! Be careful not to touch the venomous spines on the back of the seastar. My right thumb recently discovered that it is, in fact, painful.
The crown-of-thorns seastar (Acanthaster planci) is a corallivore, meaning it consumes coral and does so at a rate of roughly 6 square meters per year (more during spawning season, less if immature). Outbreaks of crown-of-thorns (COT) are devastating reefs through the Indo-Pacific region to the point that a single reef might have hundreds or thousands of COTs, which consume coral faster than it can grow back. The COTs leave behind a barren trail of white feeding scars where there was once healthy coral. The origin of such outbreaks is thought to be an overfishing of predators such as Triton snails, Humphead wrasse, and Titan triggorfish as well as an enhanced larval survival perhaps the result of elevated water nutrient levels.
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COTs extrude their stomach to feed so their acidic digestive juices will break down coral polyps to a nutritious slurry of food. When I pulled this guy off the coral you could see his stomach!
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Notice the dead white coral called a feeding scar left behind by COTs. The one who ate this coral colony is currently in my net and trying to climb up the side
COT outbreaks and the corresponding management efforts have been documented since the 1960s in primarily Japan and Australia. Australia recently even developed a robot to target COTs. http://www.gizmag.com/aquatic-robot-autonomous-killer-starfish-barrier-reef/39254/ In small coastal communities COTs wreck comparable havoc, however effective and cost efficient management efforts have not yet thoroughly explored, particularly in the Philippines.
My research project will explore existing COT awareness levels, management efforts, and removal success in small coastal communities throughout the Philippines to help such communities improve their response in the future.
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Local fishermen load COTs into our bamboo boat “banka.” Notice his traditional wooden goggles, underwater he is wearing a single wooden fin.
To complete my research project I often get the opportunity to play the part of underwater superhero. Donning my mask, fins and snorkel and equipped with kitchen tongs and a floating wash basin aside a Filipino fisherman equipped with his own wooden goggles and single large, flat fin tied on with bits of elastic rope we dive down in search of COTs. Scanning the reef for fresh white feeding scars is the giveaway sign that a COT is nearby often hiding under a coral ledge. On some reefs we have barely enough time to breath as we collect COT after COT, scooping them up with our kitchen tongs and filling our floating wash basin. In the past year we have collected over 10,000 COTs amounting to 60,000 square meters of coral reef saved from consumption! After we bring the COTs to shore they are buried on the beach above the high tide line.
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Burying our collection of COTs on the beach above high tide
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Educating locals about COTs