Caribbean Marine Research Center, Lee Stocking Island,
Bahamas

National Undersea Research Programme
Rutgers University

The Shelf and Slope Experimental Taphonomy Initiative (SSETI) programme was established to measure taphonomic rates in a range of continental shelf and slope environments of deposition (EODs) over an extended period of time. Taphonomy is the subdiscipline of Paleontology concerned with the processes responsible for any organism becoming part of the fossil record and how these processes influence information in the fossil record, from causes such as changes in rainfall, availability of food, etc. Understanding the ways in which living organisms become fossilized leads to improved interpretations of fossil records, as well as a more accurate reconstruction of past ecologicaland evolutionary states.

The locations were chosen based on the assumption that the process of burial and the influence of depth and sediment type play major roles in determining differences among EODs in the taphonomic process. Eighteen distinctive EODs, at depths ranging from 15metres to 530metres, were studied in two areas. Experiments were deployed on the forereef slope off Lee Stocking Island, Bahamas for six years and the continental shelf and slope of the Gulf of Mexico for two years. By recovering experiments that had been deployed for six years, the Shelf and Slope Environmental Taphonomy Initiative (SSETI) is considered the longest running taphonomic experiment in the scientific community.

Coastal and marine resources (Chapter IV of the Barbados Programme of Action)

SSETI is the first large-scale taphonomy experiment that has demonstrated the ability to deploy and successfully recover long-term experiments in a diversity of EODs above and below storm wave base, for it surpassed the length of a previous experiment by a single three-year deployment at a petroleum seep in the Gulf of Mexico by Callender.

The findings of the experiment include the following:
• Taphonomic alteration was greater on hardgrounds and in brine-exposed sites than on terrigenous muds.
• Dissolution was less effective at sites where burial was greatest.
• Discoloration occurred most rapidly at shallower sites and on hardgrounds.
• Discoloration was by far the dominant process over the two-year deployment period, with dissolution a close second.
• Periostracum breakdown was less noticeable, as was the loss of shell weight, chipping and breakage.
• Water depth was the least influential. The limited influence of water depth is probably due to the presence of shallow sites that, for one reason or another, were protected from certain taphonomic processes and deeper sites that were characterized by unusually strong aphonomic signals.
• EOD-specific edaphic factors often overrode the influence of geographic-scale environmental gradients.
• Overall, a large quantity of shells deployed at most sites ex-perienced relatively minor changes in shell condition. Most sites, however, showed similar taphonomic signatures.

• After two years, taphonomic alteration was not particularly intense in any EOD, and no species stood out as particularly susceptible or resistant to the taphonomic process. A few sites experienced one or more of the following: high rates of oxidation of reduced compounds; presence in the photic zone; and significant burial and exhumation events. Consequently,taphonomic signatures clearly distinguishable from the central group were produced.
• The taphonomic process evidences an unexpected degree of complexity. Factors such as location, transect, water depth, and degree of exposure had significant effects. On the average, shallow sites were significantly altered from the controls more frequently than deeper sites. However, the number of significant interaction terms between time and the other main effects indicates a complex interaction between the taphonomic process and the local environment, which, over the short term, defies any attempt at delineating taphofacies that cover a broader spatial area than a single deployment site.
• Some locations may attain the same taphonomic signature in different ways. Deeper-water sites and shallow buried sites may yield similar taphonomic signatures because shells are in the aphotic zone in both cases, and this limits the rate and range of taphonomic interactions. Consequently, the same taphonomic signature can be acquired in a distinct way, which makes simple distinctions among taphonomic rules difficult.
• The taphonomic process was strongly non-linear in time. This was true for all taphonomic attributes in all species and all EODs. Non linearity in the taphonomic process prevents the ready extrapolation of two-year trends into the future forany species or EOD.

Contacts PI:
Dr. Eric Powell
Rutgers University
Haskin Shellfish Research Laboratory
6959 Miller Avenue
Port Norris, NJ 08349-3167

CMRC Contact:
Dr. John Marr
Perry Institute for Marine Science
Caribbean Marine Research Institute
250 Tequesta Drive
Tequesta, FL 33469
Tel.: (561) 741-0192