IMPORTANCE OF THE ASSOCIATION BETWEEN CRUSTOSE CORALLINE ALGAE AND CORALS TO REEF BUILDING IN THE FOSSIL RECORD

In modern oceans, crustose coralline algae (CCA) play a vital role in coral reef health by providing structural stability and inducing the settlement of reef building coral larvae. It has been suggested that CCA played a similar role in ancient reefs as far back as the Cretaceous. However, there has been no definitive analysis of their importance in deep time. The goal of this project is to quantitatively assess the importance of CCA on ancient coral reefs (Jurassic through Pleistocene) using the Paleobiology Database and the PaleoReefs Database. If the relationship between corals and CCA in fossil reefs was similar to the modern association, coral reefs with higher abundances of CCA are expected to have greater relief and overall carbonate production. It is also predicted that coral reefs with greater amounts of CCA will have greater taxonomic diversity. The parameters used in this project are reef thickness and volume as well as reef diversity to assess carbonate production and ecological health, respectively. Additional factors taken into consideration are paleolatitude, reef type, and percent of CCA on the reef. The parameters are either listed or can be calculated from the aforementioned databases. As calcifying organisms, modern CCA are particularly sensitive to changes in ocean chemistry (e.g. acidification and anoxia). Thus, special attention is paid to the Paleocene-Eocene Thermal Maximum, a time of probable ocean acidification. The response of the CCA-coral association at the Paleocene-Eocene is one possible example of how the role of CCA on coral reefs is affected by ocean acidification and warming.