Progression of the Coral-Algal Phase Shift in the Caribbean: A Case Study in Bonaire, Dutch Caribbean

Abstract

Coral reefs around the globe are subject to environmental and anthropogenic stressors that are causing habitat degradation and a decline in reef resilience. Past studies of Caribbean reefs document a decrease in coral cover with a simultaneous increase in algal cover after significant stress, disturbance, or coral mortality. The long-term shift from coral-dominated reefs to algae-dominated reefs is known as a coral-algal phase shift. This study assessed the progression of a coral-algal phase shift at a fringing reef around Bonaire, Dutch Caribbean, by comparing current coral and algal benthic cover to historical data, from 1997 to 2008, at a site nearby. Research was conducted over a 5-w period from September to October 2012. Twenty 10-m transects were filmed and analyzed through Coral Point Count with Excel extensions software to determine percent live coral and algal cover. Mean coral cover at the study site was 14.3%, and algal cover was 72.4%. In comparison to historical data, a significant increase in the algae-coral ratio indicated a progression of a coral-algal phase shift in Bonaire. This study contributes to the scientific knowledge of coral-algal phase shifts in the Bonaire reef ecosystem and the broader scientific reef conservation.