Coral Ecosystem Connectivity 2015: From Pulley Ridge to the Florida Keys

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This is the fourth year of a five-year study to investigate the role that the mesophotic coral ecosystems of Pulley Ridge (off the southwest coast of Florida) may play in replenishing key fish species, such as grouper and snapper, and other organisms in the downstream reefs of the Florida Keys and Dry Tortugas (Figure 1).

Mesophotic reefs are coral reef environments found at depths ranging from 30-40 meters to greater than 100 meters in the Gulf of Mexico where sufficient light enables certain reef-building corals (i.e., corals with symbiotic algae growing in them) to survive. Mesophotic reefs support a diversity of populations of algae, sponges, corals, other invertebrates, and fishes.

In the summer of 2015, we are conducting our fourth and final year of fieldwork, using two separate vessels. The first cruise took place on the M/V Spree (a charter dive vessel operated out of Key West, Florida) from June 20-29. The second cruise will occur on the R/V F.G. Walton Smith (owned and operated by the University of Miami/Rosenstiel School of Marine and Atmospheric Science) from August 22-September 4 (Figure 2). A total of six science divers and one technician were on the Spree, while 9 scientists and technicians will be on the Walton Smith. Each vessel addresses a different facet of the project.

M/V Spree Cruise

On the Spree, the science divers focused on collecting specimens of target taxa for population genetic analyses in the laboratory. We made these collections in areas that have been shown to support higher-than-average densities of the target species.

All specimens will be used for genetic studies and age and growth information for the fish species. Additionally, the divers recovered, for the final time, the instruments that track oceanographic currents.

R/V F.G. Walton Smith

On the Walton Smith, the science team will focus on:

• Characterizing the benthic (bottom) and fish communities using a surface-driven remotely operated vehicle (ROV). A high-definition still frame camera mounted on the Mowhawk remotely operated vehicle (ROV) and pointed downwards will record the abundance and distribution of benthic organisms and bottom type (e.g., sand, broken coral rubble, and live bottom). A video camera pointed forward will record fish species present and their abundance in front of the ROV as it moves along the bottom. By simultaneously recording the GPS position of the ROV, we can estimate the area of the bottom actually covered and equate the abundance of the various organisms to density estimates.
• Collecting Organisms for Identification. Sometimes we are unable to identify organisms captured by the ROV on video or still camera. In cases, like these, the only way to properly identify them requires a specimen in hand. Luckily for us, this year, the ROV has been fitted with a sample tool sled, which will allow us to collect organisms using either the manipulator arm or a suction hose. Once we get the samples back in the lab, we will then be able to identify them to species.
• Recovering Oceanographic Moorings. In June, the Spree removed all of the oceanographic instruments measuring currents from the three moorings, one in Pulley Ridge and two in the Dry Tortugas. We will be recovering the mooring weights, which requires a heavy-duty winch, as they weigh over 700 pounds each.