DEVELOPMENT AND PALEOECOLOGY OF HOLOCENE OYSTER REEFS RELATIVE TO CORAL REEFS: AN EQUALLY SIGNIFICANT GAUGE OF GLOBAL ENVIRONMENTAL CHANGE

Paleoecology of Holocene coral reefs have been studied for a variety of earth-system purposes including the tracking of sea level change, demonstrating the impact of anthropogenic and natural forcing of environmental change, and the effect of habitat loss on biodiversity. These purposes have spawned a collection of geoscience investigations concerning subrecent coral reefs. Oyster reef development is more prolific, particularly along the subtropical and temperate coasts of the western Atlantic and Gulf of Mexico, and the paleoecology of these structures is of comparable value to the same problems of environmental management. We have undertaken a long-term study of the paleoecology of Holocene oyster reefs in Southwest Florida, with particular emphasis on the effect sea level rise (SLR) has had on coastal geomorphology and estuarine evolution and the implications this has for management and restoration. The results are compelling and provide valuable lessons for oyster reef-based estuaries elsewhere. Additionally, the work has revealed a remarkable similarity with the paleoecologic study of coral reefs within the tropics.

The sedimentation and accretion rate of oyster reefs is high enough to exceed SLR rate under ~15 cm / 100 years, a rate that is somewhat lower than found in most coral reefs, and this has contributed to the progradation of the coast and the development of a protected estuarine environment since 3500 ybp. Oyster sedimentation brings the substrate into upper intertidal depths and this then becomes a habitat for mangrove recruitment. Like coral reefs, modern oyster reefs are valued ecosystem components and support a great deal of secondary biodiversity. Oyster reef health is consequently used to gauge estuarine conditions and to monitor the effectiveness of Everglades' restoration efforts. The paleoecology of pre-anthropogenic reefs is used to establish restoration targets. Finally, Holocene oyster reefs exhibit both auto- and allogenic successional patterns, like coral reefs, demonstrating that their existence can both affect and be affected by environmental change. Comparative taphonomy, paleontologic analysis, and stable isotope geochemistry are being used to document paleoenvironmental changes, and these results are used to develop predictive conceptual models.