Coral Reefs, Present and Past, on the West Florida Shelf and Platform Margin

Abstract

In spite of the subtle, low-relief contours seen on bathymetric maps of Florida’s Gulf of Mexico (west Florida) shelf and slope (Fig. 4.1), this rim-toramp carbonate platform has and continues to support a surprisingly wide variety of coral reefs as compared to much better-known morphologically complex areas such the Great Barrier Reef. From the mid-shelf to the upper slope, light-dependent, hermatypic coral reefs have formed as a result of hard substrate availability, ideal oceanographic conditions, and sea-level fluctuations. Indeed, the west Florida slope even supports living lightindependent, ahermatypic coral reefs in ~550m water depth (Newton et al. 1987). This paper summarizes the geomorphic variability of these different reef types, their geologic setting, and the present coral-reef biological community. The paper is organized along a virtual depth transect by presenting different reef settings and types starting from the shallower mid-shelf or mid-ramp setting, moving to the shelf edge, and then to the deeper upper slope.