Double Keyhole Carbonate Experiment

We visited Double Keyhole Spring located on the west coast of Florida. The Spring discharges into the Gulf and we have published several papers describing how this spring creates an "invisible" estuary that is a sensitive ecosystem supporting juvenile fish. Vicki is running a carbonate dissolution experiment begun by former student Rachel (now graduated). It is a long term measurement of how fast carbonate dissolves in a variety of conditions. This experiment is in its third year. Carbonate dissolution is what enlarges conduits and creates sinkholes and other karst features over time.

We drove to Aripeka, put the boat in the water and motored several miles to Double Keyhole Spring. Bobby and Dr. Garey made the dive with Vicki there to help with the boat and handle the samples we collected. The experiment is set up in a shallow conduit that is about 8 feet in diameter back in about 200 ft at a depth of 25 ft. We collected one set of microcosms (pvc tubes with sorted limestone gravel) and also collected biofilm from rock surface and from the pvc frame that holds the microcosms. Finally, we collected sediment and water samples. It was a lot of samples and we did it in two 45 minute dives. Then back to the boat, back to the dock, and back to USF and another long night of sample analyses with all the lab members pitching in.

Bobby sorting through our sample bag making sure we have all the samples.

Bobby sorting through our sample bag making sure we have all the samples.

The PVC rack with the tubes containing limestone gravel. There are 15 tubes in each set under three conditions. We collected the lower left hand set this dive. Note the thick biofilm covering all the surfaces.

The PVC rack with the tubes containing limestone gravel. There are 15 tubes in each set under three conditions. We collected the lower left hand set this dive. Note the thick biofilm covering all the surfaces.