Buck Island Reef National Monument lies just north of the island of St. Croix in the U.S. Virgin Islands. When it was established in 1961, the park encompassed 176-acre (71 ha) Buck Island and 704 acres (285 ha) of marine habitat surrounding it. The park proclamation describes the monument and its “adjoining shoals, rocks, and undersea coral reef formations” as “one of the finest marine gardens in the Caribbean Sea,” which are of “great scientific interest and educational value to students of the sea and to the public.” Multiple use was prescribed in the original park purpose, allowing fishing in some areas but protecting others. In 2001 the relatively small national monument was expanded to 19,015 acres (7,695 ha), and all forms of resource extraction were completely prohibited (fig. 1).

In a tropical marine ecosystem, coral reef communities live in a fragile, interdependent relationship and include essential, interconnected habitats. The 2001 expansion of Buck Island Reef National Monument added coral reefs, sea grass beds, and sand communities, as well as algal plains, shelf edge, deep and dimly lit reefs, and deep oceanic habitats not originally within the monument boundary. These additional habitats preserve ecological links that help sustain the monument and its resources. Another important part of the boundary expansion was placing a vast reef shelf area of elkhorn coral (Acropora palmata), a major reef-building species, under management of the National Park Service (see fig. 1).