Trends in Linear Extension Rates for over 100-Year Period in Three Coral Species from Dry Tortugas, Florida

Adis Muslic

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, Department of Environmental Science and Policy, College of Arts and Sciences, University of South Florida St. Petersburg,

Abstract

Study on 3 coral species, Montastraea faveolata, Diploria strigosa, and Siderastrea siderea was done to determine the trends in coral linear extension and the impact of sea-surface temperature (SST) and other environmental parameters on a shallow reef system from Dry Tortugas National Park. The extension rates were species-specific. Montastraea faveolata had the highest average linear extension and variability (0.84±0.14 (n=165)), followed by D. strigosa (0.73±0.06 (n=54)) and S. siderea (0.42±0.06 (n=183)) respectively. Two cores of M. faveolata had significant correlation with each other (r=0.34, df=67, P=0.0043) and similar long-term patterns although one of them had a higher average linear extension than other. There was no significant correlation between the two D. strigosa cores (r=-0.10, df=33, P=0.5676); one of them was affected by hyperplasia tumor. Siderastrea siderea PS-A1 core had an overall increasing trend (r=0.64, df=117, P<0.0001) in the extension rates and M. faveolata PS-B3 had a decreasing trend (r=-0.22, df=117, P=0.0162). None of the other three cores showed any clear overall trend in the extension rates. Siderastrea siderea PS-A1 was correlated significantly with annual SST (r=0.43, df=115, P<0.0001) and warmest month SST (r=0.56, df=115, P<0.0001). Since correlations between the extension rates and SST were positive it suggests that the increase in SST had no negative effect on this species. Siderastrea siderea PS-A1 (r=0.73, df=87, P<0.0001) and M. faveolata PS-C2 (r=0.32, df=64, P=0.0091) had significant correlations with the sea-level anomaly. Siderastrea siderea PS-A1 correlated significantly (r=0.43, df=56, P=0.0008) with Multivariate El vi Nino Southern Oscillation Index. There was no significant correlation of Atlantic Multidecadal Oscillation anomaly with any of the cores.