Bermuda's north shore reef
Assessing Long Term Change in Bermuda’s Coral Reef Ecosystems

Loren McClenachan

The goal of this research was to assess long -term change to Bermuda’s coral reef ecosystems. This goal was achieved by conducting a series of SCUBA supported surveys around the island and conducting interviews with marine resource managers, historians, anthropologists, and long-time residents of Bermuda. I conducted this research during the week of June 29, 2008. Dr. Thad Murdoch, a marine ecologist who has completed extensive quantitative surveys of coral cover, coral diversity, reef fish diversity, and reef fish community structure on Bermuda’s coral reefs, selected several dive sites that demonstrated a range of environmental conditions and anthropogenic influences along Bermuda’s North Shore. These included patch reefs located on the outer lagoon, the middle lagoon and near the North Shore of the island. Along with conducting daily dives in Bermuda’s reefs, I interviewed local experts about their observations of long-term ecological change. I visited the Coney Island Fisheries Facility and met with Fisheries Wardens and Resource managers, interviewed Phillipe Rouja, a marine historian and anthropologist, as well as several long-time island residents, including Teddy Tucker, a legendary shipwreck diver and retired director of the Bermuda Maritime Museum. Finally, I toured Nonsuch Island, part of the St. George’s World Heritage Site, visited the Walsingham Nature Reserve, which contains mangrove and seagrass habitats and visited Castle Harbour, which contains a highly degraded marine site.

Bermuda’s unique position in the mid-Atlantic confers unique properties to its coral reef communities. On the North Shore, I observed changes in the species composition of the corals and fish across these reefs that reflected environmental and anthropogenic conditions. At the offshore sites, large mounding corals (e.g., Diploria spp.) dominated and herbivores were most abundant. Nearshore, more delicate branching corals (e.g., Madracis mirabilis) were abundant, while omnivorous and carnivorous fish increased in numbers, though fish densities were low at all sites. Compared with other sites in the Caribbean, coral cover in Bermuda was high and few corals showed signs of bleaching or disease. This is likely due to cooler water, which seldom reaches temperatures high enough to cause bleaching events. However, the cooler water and distance from other coral reefs supports lower species diversity, and less resilience to overfishing than in areas with greater population connectivity. Such overfishing was evident in the low fish density observed, and confirmed by interviews with fisheries managers.

Bermuda has a wide spectrum of environmental conditions, ranging from recently restored to highly degraded. Nonsuch Island is widely considered to be the first global example of an island restoration project. In 1930 it served as a base for William Beebe and Otis Barton's landmark bathysphere dive. Now a National Park, the Island boasts the successful restoration of near- pre-colonial conditions, and has recently become the site of a translocation project for the endemic sea petrel, the Cahow, which was believed to be extinct for over 300 years. Castle Harbour demonstrated the opposite end of the development spectrum; substantially dredged during the 1940s during a land reclamation scheme which allowed the development of the airport, a heavy materials dump is still operates for landfill, which has had a negative impact on the surrounding marine habitat. Overall, Bermuda’s marine environment is well protected, but it suffers the effects of a long history of exploitation. Reduced connectivity in Bermuda for fish populations makes it essential to avoid overfishing, but historical fishing has greatly reduced many fish populations.  

 Despite instituting some of the strongest fishing restrictions in the Caribbean over the last two decades, Bermuda’s reef fish populations have not recovered from long-term overfishing, and some species, such as the green turtle, which historically nested in great abundance on Bermuda, have been extirpated. Such long term declines and lack of resilience make active restoration projects such are being undertaken by the Nonsuch National Park, particularly important.

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This material is based upon work supported by the National Science Foundation under Grant No. 0333444. 

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation