BIOSTRATINOMY OF RUGOSE CORAL EPIBIONTS.

*Hageman, S.A., B.L. Hoffman, J.R. Sawyer and J.D. Price.

Department of Natural and Physical Sciences, Park University

Examination of 300 solitary rugose corals (Caninia torquia) from the Beil Limestone Member (Upper Pennsylvanian) reveals three major epibionts: worm tubes (47%), bryozoans (25.7%), and algae (22.5%).  Epibionts were recorded for four upper and four lower quadrants.  A chi-square test on the results confirms that algae and bryozoans are strongly distributed into preferred quadrants.  Worm tubes encrust all surfaces including broken surfaces.  Algal epibionts are 34.6% and bryozoans (Fistulipora) 25.8% more likely on the bottom surface.  Growth into a muddy substrate seems unlikely, and a detailed analysis of bryozoan distributions revealed that 67% of the bryozoans on the lower surface were located on the half closer to the polyp.  This may be partially a function of increased surface area but an analysis reveals a strong correlation to bryozoans preferring the exposed surfaces near the substrate.  The theca locations that were 3x more likely to possess bryozoans were commonly juxtaposed to the substrate and near the polyp.  These locations would create protection from predation and are positioned to receive nutrients “crumbs” not utilized by the coral.  The distribution of the epibionts further suggests a depositional setting in the photic zone with calm waters allowing for filter feeding organisms to function on a muddy substrate.  Periodic storm events appear to have overturned corals as indicated by their reoriented growth and the positioning of epibionts.