Eric N. Powell, Rutgers University
Sally E. Walker, University of Georgia
Carlton E. Brett, Univeristy of Cincinnati
Anne Raymond, Texas A&M University
George M. Staff, Austin Community College
W. Russell Callender, NOAA
Richard Krause, Virginia Tech
Kathryn Ashton-Alcox, Rutgers University
The SSETI team began a long-term study of the fate of skeletal material on the sea floor in 1993. The purpose was to better understand what happens to organisms' remains after death and what the potential for fossilization is in a wide variety of marine environments. The death of an organism usually begins the decay and recycling process that completely removes that organism from any chance of becoming a fossil, but we do have a record of organisms over time and the fossils record various stages of decay and various preservation styles.
Our hypothesis is that fossils formed in different post-mortem environments will exhibit characteristic preservation styles. Therefore we placed experiments at depths from 15m to 600m across the shelf to slope break in the Bahamas and the Gulf of Mexico.
The Shelf and Slope Experimental Taphonomy Initiative (SSETI)
The Flower Garden Banks National Marine Sanctuary provides SSETI with several unique and important settings with great potential for fossilization. The deep carbonate reef, the brine pool, and the interface between the brine and normal seawater are all included in the SSETI experimental design. Experiments consist of mesh bags containing five species of shelled mollusk, the blue crab Calinectes sapidus, six wood species, and two species of sea urchin (a spiny urchin and a pencil urchin).
Results from the East Flower Garden Banks brine seep have been most exciting. They collected samples from within the brine (which is at 200ppt compared to 32ppt for normal sea water). The brine lacks oxygen and also has high levels of sulfur. These conditions are so noxious that everything that falls into the brine becomes pickled. Living things die and are preserved extremely well, including soft parts. The crabs that they placed in the brine returned after two years and eight years with muscle tissue still intact.
Brines like this have been cited as possible environments of exceptional fossil preservation, such as the famous Burgess Shale fossils of western Canada and the Solnhofen Limestone in Germany that preserves the important Jurassic bird Archaeopteryx. By studying the preservation process in the East Flower Garden brine seep, we can learn more about the geochemical conditions of preservation in such brines and begin to understand rates of decay in such unusual environments.
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