National Wildlife Refuge
|717 nautical miles west-southwest of
Honolulu, HI 96850 - 5167
Phone Number: 808-792-9560
|Visit the Refuge's Web Site:
Continued . . . Today Johnston Atoll is a broad, shallow platform of about 50 square miles with four islands--Johnston, Sand, North (Akau), and East (Hikina)--and a 9-mile-long emergent reef on its northwest side. North and East Islands were built by dredging and filling in early 1960s. Johnston and Sand Islands were modified and enlarged the same way. The massive dredging and filling destroyed many reefs to expand the size of the main islands and to build an airport, deep draft port, and entrance channel.
In contrast to shallow coral reefs rich in marine life, the upper layer of the open ocean surrounding atolls is a biological desert. In these warm tropical waters, few nutrients rise to the surface, so microscopic plant life at the base of the food chain is sparse. As the only shallow water and dry land area in hundreds of thousands of square miles of ocean, Johnston Atoll is an oasis for reef and bird life. Corals are true animals, but many species contain microscopic algae (zooxanthellae), which capture the sun's energy as plants on land do and, through photosynthesis, provide their coral hosts with organic carbon as a source of food. There are 33 known species of coral at Johnston Atoll; most of these species contain zooanthellae.
Slightly more than 300 species of fish have been recorded from the reefs and near shorewaters of Johnston Atoll. Three species are protected under the Endangered Species Act: the green turtle, the Hawaiian monk seal, and the humpback whale.
Seabirds are the most noticeable form of wildlife on Johnston Island Refuge and are among the longest-lived birds in the world; life spans in excess of 30 years are common for some species. Shearwaters and petrels belong to a highly distinctive group of marine birds that are readily identified by their hooked bills and also by their nostrils, which are sheathed in horny tubes arising near the base of the bill.
Tropicbirds, frigatebirds, and boobies are medium-sized to large birds, distantly related to pelicans. All have webbing between all four toes, instead of three as in most other seabirds. Terns are small to medium-sized with narrow, graceful wings and thin, sharp bills. They feed by plunging or snatching prey from the surface of the water. The common term noddy comes from the stereotyped head-nodding courtship displays between adults.
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