Pre- and post-hurricane images of the shallow backreef on the south side of Buck Island showing the creation of a new rubble berm during Hurricane Hugo (1989). Other areas showed less drastic impacts.

Recently funded by the Natural Environmental Research Council and the US National Park Service, this long-term study investigates coral colony, population and community structure dynamics at Buck Island Reef National Monument, a protected marine reserve on St Croix, US Virgin Islands. The last decade has been a period of unusually intense hurricane activity for this area, with major hurricanes in 1989, 1995 and 1999 following the previous direct hit in 1928! This has allowed us to test some fundamental ideas of coral community dynamics and the role of disturbance in an area relatively free of anthropogenic impacts.

In the absence of significant human impacts such as overfishing and pollution, coral reef community structure has remained remarkably stable over a ten-year period within this small protected marine area. Local community dynamics have been highly variable, however. Sites that were destroyed by disease in the 1970's are showing no recovery, while sites less than a kilometre apart that were devastated by hurricane Hugo in 1989 are recovering well. The strongest recovery has occurred in areas that showed the greatest hurricane impacts and these areas are now more species rich than in 1988, although coral cover has not reached pre-hurricane levels. Coral colony survivorship has been high throughout most of the island. Although partial mortality rates were elevated for several years following Hurricane Hugo, significant whole coral head mortality only occurred during the hurricane periods. We cannot tell from a single study whether the local variations in community dynamics have fortuitously led to a stable island-wide structure, or whether the nature of the natural disturbances at this site differ to those seen elsewhere due to the added effects of human impacts. However, the main conclusion is that this small protected area has been effective at conserving coral community structure at the island scale.

Whatever the mechanisms it is clear that within this protected area where fishing pressure has been light enough to maintain an adequate algal grazer community, it is the regional effects of White Band Disease (Gladfelter 1982) rather than the Diadema mass mortality that has resulted in the most significant long-term change to local coral community structure. While hurricanes are an important part of the disturbance regime, the high variability in effects over space and time means that even frequent hurricane disturbance may be 'intermediate' in its effects.

The long-term assessment of marine protected areas relatively free of local human impacts is critical to our assessment and understanding of the impacts of regional and global environmental change.