Sacha and Mr. M talked with the dive operator this morning and it was still too rough and windy to dive off the back of the reef slope. The weather tomorrow hopefully will get better or we will finish our certification in Cenoto Ponderosa!. Today we will go the lagoon that lies inside the fringe reef, right off the beach at Caribe. The plan for today is for each of us to design a field experiment, collect data, and then share our findings with each other. We will start with a seagrass survey that involves running transect lines through a seagrass bed and collecting sediment samples from the sea floor along the lines. To perform this test, we will lay transect lines using dive weights and rope and use the pythagorean to ensure that the two lines are perpendicular to each other. Students will then measure increments of a meter and a half along the transect lines and collect samples (The area is about 30 meters by 40 meters). We will be testing the hypothesis that seagrass beds stabilize sediments and we predict that we will find finer sediments in the patch of grass. We will then use two ingenious PVC pipe sampling tools (designed by Mr. Mendelow) to collect sediment.
We learned that seagrass beds are important refuges for many larval stages of fish, benthic organisms, and other invertebrates. They also allow organisms to settle from the zooplankton. We saw two species of seagrass in the lagoon, and it seems that the green turtles have heavily grazed the wider bladed Thalassia. When we finish collecting data we will post the results to the blog. Currently, we are sifting the sediments that we collected and are analyzing our data.