PAGE, Samantha – 2011
The Effects of Coral Morphology and Rugosity on Small-Scale Reef Sediment Dynamics: A Study from Coral View Reef, Utila, Honduras
As threats to coral reefs around the world are increasing in breadth and intensity, it is becoming increasingly important to develop a comprehensive understanding or coral reef dynamics. The purpose of this study was to examine the effects of coral morphology and rugosity on small-scale reef sediment dynamics. To achieve this, obscuration ratio, rugosity and sediment deposition data were collective for three treatments: one dominated by sand, one by leaf/branching morphology and predominantly consisting of the coral species Acropora cervicornis, Agaricia tenuifolia and Porites porites, and one by fan morphology dominated by the coral Gorgonia ventalina,on Coral View Reef, Utila, Honduras from July 8th – August 2nd, 2010. The obscuration ratio was determined using a new underwater field technique adapted from Möller, (2006), the rugosity was determined using the chain and tape method described by McCormik (1994) and the sediment data was determined using sediment deposition measurements from sediment traps.
It was found that Gorgonia ventalina had the highest obscuration ratio (26.8%) followed by Agaricia tenuifolia, Porites porites and Acropora cervicornis with obscuration ratios of 21.4%, 16.4%, and 5.4% respectively. The fan treatment, associated with Gorgonia ventalina, had the highest average rugosity (2.1), followed by the leaf/branching treatment (1.6) and the sand treatment (1). From this data, an obscuration ration measurement matrix was developed for each dominant coral species that can be used to determine the obscuration ratio (in 1.0m2 of water) of any of the four dominant coral species around the world, given width and height measurements. It was also found that the sediment deposition between treatments was not significantly different (at the 95% confidence level) except in the sand sites during the sampling period T4, which coincided with two large storm events causing sediment resuspension in the bare sand areas. Consequently, it can be suggested that storms are the most important drive of sediment transport and deposition in coral reefs.