Assessment of the impacts of Hurricane Lenny (1999) and status of the reef 2000

Bythell, John; Hillis-Starr, Zandy; Philips, Brendalee; Burnett, William; Larcombe, Juliet; Bythell, Mary

Two vital characteristics of the ecology of coral reefs are firstly that they are in a continual state of change and secondly that they are patchy. The natural change on reefs is brought about by mortality from various forms of disturbance. This promotes high species diversity by preventing one or a few species from becoming dominant and by opening up space for more species to colonise. The patchy nature of reef communities ensures that not all the reef system is at the same state at any one time. We have previously shown that the sites that were most impacted by Hurricane Hugo increased in biodiversity, while sites that were not significantly impacted did not increased in diversity. The natural patchiness and state of flux of coral reefs means that it is extremely difficult to judge the status or 'health' of the reef system. We have seen that each of the three permanent transect sites that were established in 1988 have changed in very different ways over the past 12 years, but the overall community structure has remained virtually the same. That is, the differences between these different 'patches' is greater than the changes we have seen over time. During the 2000 field survey, additional monitoring sites were established so that we can develop a more representative idea of how the whole system is functioning. However, it is clear that the system has not so far been fundamentally altered by the recent hurricane impacts. There are three main issues of concern, however: 1. With coral cover reduced, it is vital that space is available for coral recruitment and that macroalgae is kept in check by grazing fishes and sea urchins. There have been dramatic shifts to macroalgal overgrowth in many areas of the Caribbean due to overfishing, particularly after reductions on coral cover from hurricanes. Prevention of illegal fishing at Buck Island is critical to maintaining the health of the coral reef and promoting recovery from the recent hurricanes. 2. There are some areas at Buck Island where elkhorn coral Acropora pa/mata has successfully recruited. Following the devastation of populations of this important reef framework species since the 1970s due to white band disease, these areas may become important seed areas for other parts of the system. During the 2000 surveys, two A. pa/mata monitoring stations were established to determine whether the recovery can be sustained. Buck Island Reef Post-Hurricane Lenny Coral Reef Assessment 3. There was a significant coral bleaching event in 1998 that mainly caused mortality to star coral, Montastraea annular is populations. This robust species has been largely resilient to the recent hurricane impacts at Buck Island. There is world-wide concern over the potential for increased frequency and severity of coral bleaching events due to Global Climate Change and it will be important to continue the seawater temperature monitoring programme over the next decade and establish whether there is a local warming trend that may threaten the system. In summary, the current status of parts of the reef system at Buck Island is poor, but not unexpected given the recent hurricane activity. Given a period of recovery without major disturbances, it is likely that the system will recover and may ultimately benefit from these impacts. This capacity for recovery is dependent on fishing pressure being kept to a minimum or prevented. Importantly, it is clear that the measures in place to control the impacts of the substantial visitor pressure to the island have been successful in preventing significant damage to the reef system.

Assessment of the impacts of Hurricane Lenny (1999) and status of the reef 2000

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