Last week, I was served Giant Clam. How did an endangered species find its way to my lunch table?! This particular clam was one of many marine casualties from a recent boat grounding. I was called in to conduct the damage report after a large tugboat ran aground inside of a protected fish sanctuary, and left a large hole where there was once reef.
Assisted by three Filipino free divers, we surveyed the area taking underwater measurements with a large 50m transect line of the damage area. Secondly, I took many photos with my underwater camera to document the destruction. Finally, I conducted a visual survey of damaged species including displaced fish species, sea stars, corals, sponges and most notably the Giant Clam.
The Giant Clam can live to be over 100 years old, reaching sizes of up to 4 feet and more than 440lbs. Luckily, the clam damaged in our boat grounding was only about the size of a basketball, but that is still much larger than any clam I had ever seen in the Atlantic Ocean! Giant Clams attain such impressive sizes through a symbiotic relationship with zooxanthellae, an algae that lives inside of its tissues, giving the clam its color. This is the same algae found inside the stony corals which build coral reefs. Zooxanthellae captures light energy and produces food for the clam through photosynthesis, while the clam provides a home for this algae. Did you know that no two Giant Clams have the same color pattern?!
The Crown-of-Thorns (CoT) sea star (Acanthaster planci) can pose serious threat to Pacific coral reefs. The CoT varies from traditional sea stars in that it may have anywhere from 7 to 23 limbs and possesses numerous, long, sharp, toxic spines. In normal quantities this invertebrate is an appropriate part of the Pacific reef ecosystem. However, recent, increased, massive outbreaks of CoTs are highly problematic because the CoT is a corallivore, meaning it feeds on coral. Thus, outbreaks have the potential to destroy entire reefs. The CoT eats the fleshy polyps of a stony coral colony leaving behind white scars of the remaining dead calcium carbonate coral skeleton. In a balanced ecosystem CoTs feed on fast-growing Acroporid coral species, however when CoT numbers are abundant they begin feeding on slow growing coral colonies like Porites, which can devastate reefs for many years into the future.
Natural predators of the adult CoT include titon triggerfish (Balistoides viridescens), white-spotted pufferfish (Arothron hispidus), napoleon wrasse, humphead wrasse (Cheilinus undulates), giant triton snails (Charonia tritonis) and painted shrimp (Hymenocera picta). Overfishing of these predators, particularly the Giant Triton, valued for its large, beautiful shell, may have led to increased CoT outbreaks. Furthermore, it is possible that our wastewater and fertilizer have also contributed to these outbreaks. Scientists theorize that nutrient-rich runoff into the ocean from human activities has enabled more CoT larvae to survive, because CoT larvae feed on planktonic algae and an increase in nutrients favors excessive algal growth. Thus more nutrients –> more algal –> more CoTs –> greater damage to coral reefs.
Methods of CoT control:
Collect CoTs, handling them with large serving tongs. Bring them to land and bury them.
When stressed CoTs will attempt to spawn, therefore it is essential to remove them from the water as quickly as possible.
Cutting up and Crushing in situ
Tying in bags in water
Poison Injection (acetic acid or sodium bisulfate)
Injection causes the CoT to disintegrate
Using dead CoTs as material for compost has been practiced in Fiji
Currently, we are exploring these methods at my site and will be developing a removal program in the future!
The Philippines gets hit with an average of 20+ typhoons every year. Glenda which hit earlier this week was my first with promise of several more throughout my time here. Following such storms brown outs (loss of electricity) are common due to down power lines. With the loss of power comes the loss of water. Currently, at our training center we have regained power but are still operating without running water meaning we collect rain water, take bucket showers, and conserve as much as possible. Fresh drinking water is brought in in jugs. This typhoon hit metro Manila, the capital of the Philippines, especially hard. I heard rumors of incredible traffic due to traffic light outages. The roads at our training center were completely covered with debris and we had numerous trees down. The photos below were taken during the calm period of the typhoon eye, thus imagine double the debris picture at the end. To help clean up we used sticks and branches as brooms/shovels to push leaves and sticks of the road. The larger trees had to be tackled with saws and teamwork.
Here is a link with some nationwide photos of the effects: http://www.gmanetwork.com/news/story/370527/news/specialreports/in-pictures-typhoon-glenda-whips-through-luzon
SJ Byce as a Peace Corps Volunteer in the Philippines. And Intern at CIEE Bonaire '17