Still Cruisin!

Hi everyone! Where are all your comments??? Sorry it has taken me a day or so to post again. The internet connection has been slow because the ship has been carving back and forth across the ocean using sonar to map the bathymetry around the NOAA undersea habitat called aquarius - very cool!

Here is what has been going on over the last few days....and a little more about my research. Sorry if it's a little long, skip around and pick out the good stuff! :)

We are still cruisin the western Florida Keys and outer bank reefs. Wednesday afternoon we dove ‘The Pulaski’ – a reef located adjacent to a tower equipped with oceanographic and atmospheric equipment that can monitor the weather as it passes through the western keys into the Gulf of Mexico. The current was ripping, but I got some great photos of moon jellies in the water column with their commensal fish hitchhikers. We spent the evening touring Fort Jefferson until the rain forced us back to the ship. There are some idyllic views that span 360o from the upper battlements.

Today (Thursday) we descended about 75 feet onto deeper reefs in the Tortugas Banks. There was an ominous darkness that enveloped us as we sunk deeper through the water column – this is because red and yellow (warm colored) wavelengths can not travel as deep as the blue and green spectrum. As we settled down to the bottom we could immediately recognize a difference in benthic diversity compared with the shallow reefs we surveyed over the past few days. Here there were far fewer gorgonians (e.g. sea fans) and soft corals. There were also several coral species that were more common at this deeper depth (e.g. Montastrea franksi, Mycetophyllia sp. and Dendrogyra).

Though I was most intrigued by the macroalgal differences – at depth there were very few Halimeda, a calcareous green alga. Halimeda are generally a primary component of shallow reef communities and contribute a significant portion of calcium carbonate which is then incorporated back into the system. These deeper reefs were dominated by several species of Dictyota, which are brown algae (also prevalently found on shallow reefs), but thrown into the mix were short bushy clumps of Hypnea and encrusting Lobophora.

As a Ph.D student at Auburn University my research interests generally include how these foliose macroalgae associate with one another and with corals through competitive and facilitative interactions. Many algae are strongly chemically defended, producing secondary metabolites known to deter herbivory. Secondary metabolites (which means, not used for primary metabolic processes) also can be active antimicrobials and may influence the natural microbial flora on and within adjacent organisms. Organisms, such as humans, have natural microbial assemblages that serve to protect us from disease and assist in boosting our immune system. Because corals do not have complex immune systems, microbes are proving to be a critical protective mechanism against disease. When these bacteria are disrupted the overall physiology of the coral may be compromised leading to increased disease susceptibility. Tomorrow I will collect samples of coral mucus and associated macroalgae during our dives off Summerland Key at Looe Reef. Hopefully these data will help me determine whether macroalgae play a role in the prevalence of coral disease along the Florida Keys reef tract.