Department of Commerce National Oceanic and Atmospheric Administration Department of Commerce
National Oceanic and Atmospheric Administration

U. S. Virgin Islands

The biologically rich coral reef ecosystems in the U.S. Virgin Islands (USVI) consist of a mosaic of benthic habitats, principally hard coral and other hard bottom areas, seagrass meadows, and mangrove forests that are home to a great diversity of organisms. These coral reef ecosystems provide, inter alia, shoreline protection and support valuable socio- economic activities. The USVI consists of three large main islands, east of Puerto Rico and several smaller islands. St. Croix is the largest island, St. Thomas is the second largest, and St. John is the third largest. Coral reefs in the USVI and reefs elsewhere in the Caribbean face similar environmental stresses which include climate change, diseases, storms, coastal development and runoff, coastal pollution, tourism and recreation, fishing, and vessel groundings.

 


 

 

Introduction

If you leave Playa de Fajardo, on the east coast of Puerto Rico, sail into the Caribbean Sea on a heading of 89 degrees and travel for approximately 40 nautical miles along this heading, you will enter an archipelago of small, mountainous islands. These are the islands which Christopher Columbus discovered on his second voyage (ca. 1493) and named “Los Once Mil Virgenes” (the Eleven Thousand Virgins, in honor of the feast day of St. Ursula and 11,000 virgins, who were said to have been martyred with her) or, in modern usage, the U.S. Virgin Islands.  The United States purchased what is now the United States Virgin Islands (USVI) from Denmark in 1917.  The non-U.S. Virgin Islands are British.

The U.S. Virgin Islands are to the left of the dotted line.
The U.S. Virgin Islands are to the left of the dotted line.
 Map of the Caribbean  showing the location of the U.S. Virgin Islands.
Map of the Caribbean showing the location of the U.S. Virgin Islands.

The principal islands of the U. S. Virgin Islands are St. Croix, St. John, and St. Thomas.  There are, in addition, a number of small islands and cays, 82 of which are named (some with colorful names such as Cockroach Island, Cow Rock, Watermelon Cay, and Whistling Cay).  Water Island (considered the fourth major island by some geographers) lies in the Charlotte Amalie Harbor (St. Thomas) and for historic ecological reasons, is one of the more interesting of the smaller islands.  The name “Water Island” is based on the historic occurrence of many fresh-water ponds on the island.  These ponds were so numerous that seafarers used them to replenish their supplies of fresh water.  Unfortunately the kinds of fresh-water plants and animals which might have lived in this unique environment appear to be unknown. The ponds were ultimately lost to cattle grazing and the development of cotton plantations.

 

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