Buck Island Reef National Monument

St. Croix, US Virgin Islands

Six thousand feet long and a half mile wide, uninhabited Buck Island rises 328 feet above seal level 1 ½ miles off the northeast side of the island of St. Croix in the US Virgin Islands. Five miles from Christiansted, 19,015-acre Buck Island Reef National Monument includes the 176-acre island and 18,839 acres of submerged land and coral reef system. First protected in 1948, the area was proclaimed a national monument in 1961 and expanded in 2001 to preserve "one of the finest marine gardens in the Caribbean Sea." The park is one of the few fully protected marine areas in the National Park System. Threatened and endangered species living and nesting here include the brown pelican, least tern, and hawksbill, leatherback, and green sea turtles. Buck Island formed from uplifted and tilted volcanic ash originally deposited in the deep sea. Two-thirds of this tropical dry forest island is surrounded by an elkhorn coral barrier reef. The entire Monument is closed to all fishing and collecting activities, and anchoring is only allowed off the deep sand beach. Off the east end of the island a snorkel trail with underwater interpretive signs meanders through coral grottoes out to the forereef. Unique elkhorn coral patch reefs, resembling haystacks, are scattered along the outside of the forereef and rise nearly to the water’s surface from the seabed as much as 40 feet below. Snorkelers encounter colorful parrotfish, French angelfish, and blue tangs. Concessioners offer daily half- and full-day tours to Buck Island from St. Croix for snorkeling and other activities.

Coral Reefs

Coral reefs are complex colonies of individual animals called polyps. These produce carbonate skeletons cemented together by blue-green algae, resulting in massive but surprisingly fragile formations. Polyps are filter feeders eating floating plankton they trap in their tentacles. As polyps die, new ones expand the reef by growing on their remains. Polyps enjoy a mutually beneficial relationship with algae living inside them. This efficient symbiosis makes coral reefs rich with life. Coral reefs support an incredible diversity of animal and plant life. Coral reefs have existed for millions of years and are as ancient as rain forests.

Buck Island’s Barrier Reef

Buck Island Reef’s underwater scene taxes human perception with the abundant variety of shape, pattern, color, texture, and movement. Its barrier reef ranks among the Caribbean’s best. Its thick, branching elkhorn corals push their sheer mass to 30-foot heights. Like fortress walls corals rise off the sea floor and dominate the underwater world. The irregular arc of reef surrounding Buck Island’s northern and eastern shores creates a lagoon between reef and island. Wide and shallow lagoon between waters seldom exceed 12 feet deep, and the protecting reef moderates the wave action. In the calmer waters of the lagoon, brain corals grow larger, nearly reaching the surface. Seaward of the barrier reef, elkhorn and star coral patch reefs occur around the island, except to the southwest.

Protecting Fragile and Endangered Species

Worldwide, coral reefs are fast disappearing. They are slow-growing and vulnerable to pollution, sedimentation, overfishing, warming of the seas, and boat damage. Buck Island’s reef system shows significant impacts from a variety of coral diseases and undetermined environmental factors. These cause corals to reject the algae that help nourish them, bleaching tissues. If severely affected, the corals die. Because corals thrive only in a narrow range of conditions, biologists see their plight as a planetary danger signal.

Buck Island Reef National Monument provides protected habitat for several threatened and endangered species, terrestrial and marine. Brown pelicans feed in the near-shore waters and nest on the island’s north side. Research on hawksbill turtles provides valuable information for their survival in the Caribbean. Human introduction of the mongoose and rat, exotic species, may have eradicated the St. Croix ground lizard.

Endangered hawksbill, leatherback, and green sea turtles are protected by law. Every two to three years they migrate here in the summer to nest in shoreline forests and on beaches. Nesting hawksbills may spend up to 60 minutes ashore, selecting a nest site, digging an egg chamber, laying approximately 140 eggs, and returning to the sea after carefully covering her nest. Two months later hatchlings emerge and crawl to the sea.