Our current sampling design will assess four depth zones. At each of our three sites (Raph’s Wall, South Reef, and Tobacco Reef) we have back reef sites (~30 fsw), reef crest sites (~60 fsw), intermediate sites (~90 fsw), and mesophotic sites (~130 fsw). We are sampling 15 M. cavernosa colonies at back reef, reef crest, and intermediate depths at each of our reef sites (n=45 per reef, n=135 total). Small fragments (~5 polyps) of M. cavernosa are broken off from a colony with a hammer and masonry chisel. Before and after sampling colony photos are taken with 15cm parallel lasers to quantify colony size and qualitative record any visual differences. M. cavernosa fragments are preserved in TRIzol and frozen until we return to Harbor Branch and Ryan can extract DNA from the samples. Ryan will compare microsatellite markers among M. cavernosa samples to compare how genotypes may vary along the depth gradient of the reefs. Along with looking at M. cavernosa genotypes, Ryan will attempt to determine what clade types of algal symbiont zooxanthellae (Symbiodinium spp.) are found in M. cavernosa at the different depth zones. Zooxanthellae are endosymbiotic microbes and are what give color to M. cavernosa tissue. We have noticed many different color morphs of M. cavernosa along our reef sites in Belize, but whether or not these harbor variable zooxanthellae assemblages is an open question.
After three days and eight SCUBA dives we've successfully collected all 135 samples across three depth zones at our main three reef sites. Because we have been so productive and efficient with our sampling, we had extra time to conduct additional surveys on our sites. We tested out (with mixed results) photo transects to make photo mosaic transects to analyze for relative abundance of coral species. Michael and Josh have also been used our lab drone to successfully produce a georeferenced aerial map of Carrie Bow Cay and the surrounding reef.
Check out our Flickr album to view images from the trip.
Post written by Ryan Eckert.