Understudied and Overlooked: Shedding Light on the Underrepresentation and Benthic Community Trends of Gorgonian Octocorals in Caribbean Reef Ecosystems

Abstract

It is estimated that Caribbean reefs have experienced drastic declines in coral cover over the last century. In addressing these trends, reef health research has focused almost exclusively on phase shifts from states of hard coral dominance to macroalgal dominance. Despite their noted abundance on Caribbean reefs, octocorals (specifically gorgonians) have been hugely understudied and overlooked. When researchers do study octocorals, they generally employ line transect methods that were designed to examine hard coral cover. This thesis aims to shed light on the underrepresentation of gorgonian octocorals and the role of gorgonians in traditional notions about reef phase shifts using field data collected in Ùtila, Honduras. It is determined that the overall space occupation of gorgonian corals is underrepresented by line transect methods because of the separation between their encrusting bases and their upwards-growing branches. Furthermore, it is shown that base size is an accurate predictor of 3-D surface area, offering a method by which the full scope of gorgonian space occupation can be effectively and efficiently determined. Using combined data from line transects and belt transects, it is also illustrated that gorgonian octocorals are independent from traditional hard coral-macroalgae phase shift processes. Specifically, while hard coral cover increases across reef sites with respect to decreasing macroalgal cover, gorgonians exhibit a significant stability. Given changing climate patterns, it is imperative that we begin to eradicate transect biases, account for total gorgonian surface area, and evaluate the role of gorgonians in damaged reef ecosystems.