French Frigate Shoals - Geology and Ecology

Geology and Ecology

La Perouse Pinnacle, a rock outcrop in the center of the atoll, is the oldest and most remote volcanic rock in the Hawaiian chain. La Perouse Pinnacle stands 120 ft (37 m) tall and is surrounded by spectacular coral reefs. Because of its distinct shape, the pinnacle is often mistaken for a ship from a distance.

Whale-Skate Island is a submerged island in the French Frigate Shoals. These islands suffered considerably from erosion starting in the 1960s, and by the late 1990s, Whale-Skate Island was completely washed over.

The reef system at French Frigate Shoals supports 41 species of stony corals, including several species that are not found in the main Hawaiian Island chain. More than 600 species of marine invertebrates, many of which are endemic, are found here as well.

More than 150 species of algae live among the reefs. Especially diverse algal communities are found immediately adjacent to La Perouse Pinnacle. This has led to speculation that an influx of additional nutrients – in the form of guano – is responsible for the diversity and productivity of algae in this environment. The reef waters support large numbers of fish. The masked angelfish (Genicanthus personatus), endemic to the Hawaiian Islands, is relatively common here. Most of Hawaii's honu (Green Sea Turtles) travel to the shoals to nest. The small islets of French Frigate Shoals provide refuge to the largest surviving population of ʻīlioholoikauaua (Hawaiian monk seals), the second most endangered pinniped in the world.

The islands are also an important seabird colony. 18 species of seabird, the Black-footed Albatross, Laysan Albatross, Bonin Petrel, Bulwer's Petrel, Wedge-tailed Shearwater, Christmas Shearwater, Tristram's Storm-petrel, Red-tailed Tropicbird, Masked Booby, Red-footed Booby, Brown Booby, Great Frigatebird, Spectacled Tern, Sooty Tern, Blue-gray Noddy, Brown Noddy, Black Noddy and White Tern nest on the islands, most of them (16) on Tern Island. Two species, the Blue-gray Noddy and the Brown Booby, nest only on La Perouse Pinnacle. The island also is the wintering ground for several species of shorebird.

A three-week research mission in October 2006 by the National Oceanic & Atmospheric Administration (NOAA) led to the discovery of 100 species never seen in the area before, including many that are totally new to science. The research findings will be used to establish what species live in the area. Further studies will also determine how well the shoals' ecosystem is being managed and the threats it faces. The French Frigate Shoals project is part of the Census of Coral Reef Ecosystems of the International Census of Marine Life.