Macroalgal distribution at Lee Stocking Island, Bahamas

Abstract

The preservation of coral reef communities has become a major concern to scientists and environmentalists due to the increase in coral diseases and reef degradation on a worldwide basis. As a result of coral mortality and the removal of herbivores from the reef community, macroalgae have been increasing in abundance on the reefs surrounding Lee Stocking Island (LSI), Bahamas. Macroalgal patches prevent coral recruitment and growth, thereby restructuring the reef. In such cases, coral and algal monitoring programs would assist in determining the condition of the reef community. In order to aid such programs at LSI, an assessment of macroalgal assemblage was initiated. This was accomplished by collecting data at four study sites around LSI, during six different sampling periods. Video transacts were taken at each site during each sampling period. Using computer analysis, macroalgae were identified and their area of coverage was measured. These measurements were converted into values of abundance, dominance, frequency, diversity, and evenness, and were statistically analyzed. Results showed that total abundance, dominance, diversity, and evenness differed significantly between sites and sampling periods, as did individual algal abundance and dominance. Possible causes of differences between sampling periods included seasonal changes in water temperatures and light intensity. Possible explanations for locational variations included differences in the amount of air and light exposure, in the amount of wave and current erosion, and differences in substrate configuration at each site. The existence of seasonal and locational differences in macroalgal distribution demonstrates the need for additional data collection and continuous monitoring of reef conditions at Lee Stocking Island, Bahamas.