DISARTICULATION AND DISSOLUTION OF CALLINECTES ACROSS TIME AND DEPTH GRADIENTS IN THE BAHAMAS

The fields of Paleontology and Paleoecology would not be complete without taphonomy, the study of the processes affecting organisms between death and fossilization. Taphonomy is important because it allows us to make more complete conjectures about prehistoric organisms and environments, and makes us aware of possible holes and biases in the fossil record due to highly destructive processes or the loss of delicate, non-resistant organisms. Studies on the processes affecting modern organisms have contributed greatly to the understanding of ancient processes; however, most of these studies are near-shore and short-term. What is lacking is information on the effects of these factors over long periods of time, and to depths below 50 meters. To gain more information about these long-term effects, the Shelf and Slope Experimental Taphonomy Initiative (SSETI) has deployed sets of crabs, mollusks, urchins, and wood at depths from 15 to 300 meters, and on different substrates in the Bahamas. Sample groups have been collected every few years for the last six years, and are compared to control sets.

My preliminary research focuses specifically on the crabs, species Callinectes sapidus, from experimental sites in the Bahamas. The crab remains display a wide range of dissolution and disarticulation, varying with time and depth. In particular, the size, dry weight, and surface condition of each of the specimens is being documented and analyzed statistically to determine the effects of depth and environment through time. Scanning Electron Microscope analysis of exoskeletal surfaces is being conducted to determine the degree of dissolution of each specimen. Preliminary results show that crabs are reduced to disarticulated chelipeds and distal leg fragments within one year in most environments. The outer surfaces of the remains show complete loss of pigmentation and loss of the outer layer of exoskeleton. Taphonomic condition of the crabs varies greatly with depth, degree of burial, and time along the two Bahamas transects. Thus crab taphonomy may prove to be a useful paleoenvironmental key to reconstructing ancient environments.