Association of the threespot damelsfish (Stegastes planifrons) in ridge mortality of Diploria strigosa in the flower garden banks of the National Marine Sanctuary

Abstract

Ridge mortality is a new coral malady, observed only at the Flower Gardens National Marine Sanctuary and the Florida Keys Sanctuary. Its effects are most dramatically seen on the brain coral (Diploria strigosa). This paper is an attempt to numerically establish, an association between the threespot damselfish, Stegastes planifrons, and D. strigosa affected by ridge mortality. It is known that S. planifrons farm algal patches on open spaces on or around D. strigosa, however it is not known whether or not they farm in higher percentages on corals with ridge mortality. This is the main question this paper addresses. In addition, tests conducted in this project also investigated S. planifrons specific role in ridge mortality. The question is whether the fish initiates the condition by biting coral tissue, or if they take advantage of the open space the condition has made available for farming. Sampling techniques included diver transects, photography and habitat observation. With data collected I have analyzed percent cover of ridge mortality, distribution of S. planifrons , and the correlation between S. planifrons presence and the size of the area infected with ridge mortality. The studies conducted in this research do not give conclusive answers about the cause of ridge mortality, however, they do establish a relationship between S. planifrons and ridge mortality.