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Navassa Island

Introduction

Navassa Island
Location of Navassa Island in the Caribbean Sea.

Navassa is a small (5.2 km2; 1,344 acres), uninhabited, and isolated oceanic island located in the Windward Passage approximately 55 km west of the southwestern tip of Haiti (180 25’ N; 750 02’ W). The United States claims the island as an unincorporated unorganized territory that is administered by the U.S. Fish and Wildlife Service as a U.S. National Wildlife Refuge. The refuge includes a 12 mile radius of marine habitat around the island.  Navassa is also claimed by Haiti and by a private U.S. citizen. Because of its remote location and uninhabited status, the surrounding marine ecosystem is relatively healthy. Although there are no permanent residents on Navassa, transient Haitian subsistence fishers regularly visit the island. While quantitative catch data are not available, they seem to have had some effect on the size structure of fish populations. Miller et al. (2003) suggested that the community composition had changed from observations made during a 2000 cruise because of serial overfishing, i.e., a progression of depletion in which the largest and most vulnerable species are removed first, followed by a series of shifts to smaller, less-desirable targets as each is depleted.

Wildfires have destroyed some habitats for nesting seabirds and migratory song birds. These fires, in part, may have been caused by squatters seeking to clear land in order to plant food crops. Because of the island's remoteness, existing protective regulations are not enforced. Navassa lacks beaches and mangrove forests. The island rises abruptly from deep water as a raised dolomite plateau (maximum elevation 77 meters) ringed by tall (9-15 meters) vertical cliffs. The depth at the shoreline is about 24 meters and then gradually slopes downward. Coral cover is most extensive in shallow waters (about 30 meters) in limited areas around the northwestern part of the island and in Lulu Bay. The benthic habitats comprise large areas of live bottom (soft and hard corals, sponges and algae), huge boulders which have broken away from the limestone cliffs, rubble, corals growing on cliff walls, scattered patch reefs and hard bottom areas.

The surface of Navassa is forested with brush undergrowth, scattered cacti, and with some grassy areas. About 120 plant species occur, dominated by four species of tropical-subtropical trees. An abandoned 162-foot lighthouse and cistern are located midway along the western shore. Prominent land animals are large colonies of seabirds, migrating songbirds, snails, four endemic species of lizard, 650 species of invertebrates, including over 500 new insect species, 30 percent of which may be endemic. Over 100 non-insect arthropods, mostly spiders, make up the rest. The only mammals on the island are introduced rats, dogs, cats, and goats.

Special thanks to Gregory Andrew Piniak, Ph.D.(NOAA Center for Coastal Fisheries and Habitat Research) and Andrew Gude (U.S. Fish and Wildlife Service) for reviewing and offering expert advice on the original essay manuscript, and to Margaret W. Miller, Ph.D. (NOAA Southeast Fisheries Science Center) and Keith Pamper (Shedd Aquarium, Chicago) for providing photographs used to illustrate the essay.

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