Boat anchoring contributes to coral reef degradation in the British Virgin Islands

Rebecca Loberg Flynn, University of Rhode Island


Habitat degradation is occurring the world over, threatening species, population dynamics, ecosystem function and valuable ecosystem services. This degradation is in many cases linked to anthropogenic activities, which often reduce a habitat's resilience to other stressors. Coral reef decline, for example, has been linked to climate change, pollution, and overfishing. Few studies have focused on the local-scale physical drivers of coral decline, such as anchoring. As global human population and the popularity of water-based recreation continue to rise, the potential for anchoring to contribute to coastal habitat degradation increases. We sought to determine the potential impact of anchoring to coral reefs by conducting a spatial survey of sites that represent a gradient of anchoring activity in the British Virgin Islands. We collected data on benthic community composition, coral colony size and density, species richness and abundance. We also evaluated reef rugosity and fish population densities. Cover of hard corals and sea fans were both reduced by ~7% at highly anchored sites. Hard corals were ~40% smaller in size and ~60% less dense at sites experiencing high anchoring frequency. In addition, highly anchored sites supported only ~60% of the species richness of little anchored sites. Finally, frequently anchored sites were ~60% as structurally complex and supported only 45% of the fish density as those rarely anchored, with some fish functional groups more affected than others. Anchoring is a major driver of reef community decline, but it is also a relatively tractable management issue. Knowing how local, physical anthropogenic stressors contribute to reef decline can inform management that will promote reef resilience, ecological function, and ecosystem services.

Subject Area

Ecology|Conservation biology|Environmental management

Recommended Citation

Rebecca Loberg Flynn, "Boat anchoring contributes to coral reef degradation in the British Virgin Islands" (2015). Dissertations and Master's Theses (Campus Access). Paper AAI1586534.