Day 5


Today we set out to finish our research projects. As I mentioned on one of my prior blogs, we had to modify our initial blue tang behavior project. Now, our project focuses on what generally defines a shallow reef as healthy or unhealthy. For this project, we came up with three criteria: herbivore population, algae coverage, and coral bleaching coverage. We decided healthy reefs would have a moderate to high herbivore population with populations over six. They would also have a moderate amount of algae that fish would feed on. Coral bleaching percentages would be below half the entire reef. In contrast, unhealthy reefs would have low herbivore populations (#<6), algae coverage that was too high or too low where fish would not feed, and coral bleaching percentages over fifty percent. Heading out to the boat, we decided to do two dives: one healthy and one unhealthy. In the reef, we set up a 20×20 foot parameter using lionfish markers to make a border. Next, we started a ten minute timer, had two people counting herbivores, two people filming and taking pictures (me being one of them), and one person noting the algae and coral bleaching coverage. We followed this procedure at both a healthy and unhealthy reef. During the healthy reef dive, we noticed everything we predicted; however, during the unhealthy reef dive, we noticed plenty of fish and low coral bleaching, meaning only our algae prediction of it being high was correct. Following our dives, we ate lunch on the boat and snorkeled to a beach where we traveled on foot to a natural salt pond. Unfortunately, Virgin Gorda is currently experiencing a drought so we did not see the pond in its full glory. Fortunately, what we did see was still interesting because we were basically walking on a dried marsh where we could see crab remains and places where marsh grasses had stood before drying out. Additionally, I learned that the salt pond acted as a natural filter between the sediment of the rocks and the beach below, meaning the debris from construction could not pass through the salt pond and pollute the ocean. The salt itself is formed when water escapes the area with the sediment and has no way to return. Following the salt pond trip, we headed back to Guavaberry where we prepared our presentation for our research project. Because our data differed from our hypothesis, we came up with new conclusions on healthy and unhealthy reefs. One new conclusion was that sea urchins played a key role in recognizing a healthy reef. Our data showed that no sea urchins were present on an unhealthy reef, so we concluded that their number would be a strong gauge people could use to generally determine a reef’s health. I feel that our project went well despite its ups and downs and I am proud of what my group was able to accomplish. Ending the day, we ate pizza on the beach. So far, our trip has been everything I have expected and more. I am looking forward to my last day tomorrow and the final experiences I gain in the Jesuit Marine Biology program.