National Park of American Samoa

History

The National Park of American Samoa was established on October 31, 1988 by Public Law 100-571 but the NPS could not buy the land because of traditional communal land system. This was resolved on September 9, 1993, when the National Park Service entered into a 50-year lease for the park land from the Samoan village councils. In 2002, Congress approved a thirty percent expansion on Olosega and Ofu islands.

In 2009 an earthquake and tsunami produced several large waves, resulting in 34 confirmed deaths, more than a hundred injuries and the destruction of about 200 homes and businesses. The park encountered major damage. The visitor center and main office were destroyed but there was only one reported injury among the NPS staff and volunteers.

Tutuila

The Tutuila unit of the park is on the north end of the island near Pago Pago. It is separated by Mount Alava (1,610 feet (490 m)) and the Maugaloa Ridge and includes the Amalau Valley, Craggy Point, Tafeu Cove, and the islands of Pola and Manofa. It is the only part of the park accessible by car and attracts the vast majority of visitors to the area. The park lands include a trail to the top of Mount Alava and historic World War II gun emplacement sites at Breakers Point and Blunt's Point. The trail runs along the ridge in dense forest, north of which the land slopes steeply away to the ocean.

Ofu Unit

Ofu island is only accessible via small fisherman boats from Ta'u island. Accommodations are available on Ofu.

Ta‘ū Unit

Ta‘ū island can be reached by a flight from Tutuila to Fiti‘uta village on Ta‘ū. Accommodations are available on Ta‘ū. A trail runs from Saua around Si’u Point to the southern coastline and stairs to the 3,170-foot (970 m) summit of Lata Mountain.

Biodiversity

Because of its remote location, diversity among the terrestrial species is low. Approximately 30% of the plants and one bird species (the Samoan starling) are endemic to the archipelago.

Fauna

Three species of bat are the only native mammals: two large fruit bats (Samoa flying fox and white-naped flying fox) and a small insectivore, the Pacific sheath-tailed bat. They serve an important role in pollinating the island's plants. The sheath-tailed bat was nearly eliminated by Cyclone Val in 1991. Native reptiles include the pelagic gecko, Polynesian gecko, mourning gecko, stump-toed gecko, Pacific boa and seven skink species. A major role for the park is to control and eradicate invasive plant and animal species such as feral pigs, which threaten the park's ecosystem. There are several bird species, the most predominant being the wattled honeyeater, Samoan starling, and Pacific pigeon. Other unusual birds include the Tahiti petrel, the spotless crake, and the rare (in this locality) many-coloured fruit dove.

Flora

The islands are mostly covered by tropical rainforest, including cloud forest on Ta'u and lowland ridge forest on Tutuila. Most plants arrived by chance from Southeast Asia. There are 343 flowering plants, 135 ferns and about 30% are endemic plant species.

Marine

The surrounding waters are filled with a diversity of marine life, including sea turtles, humpback whales, over 950 species of fish, and over 250 coral species. Some of the largest living coral colonies (Porites) in the world are at Ta'u island.

Geologic history

The volcanic islands of Samoa that dominate the acreage of the national park are composed of shield volcanoes which developed from a hot spot on the Pacific Plate, emerging sequentially from west to east. Tutulia, the largest and oldest island, probably dates from the Pliocene Epoch, approximately 1.24 to 1.4 million years ago, while the smaller islands are most likely Holocene in age.

The islands are not made up of individual volcanoes, but are rather composed of overlapping and superimposed shield volcanoes built by basalt lava flows. Much of the lava that erupted has since broken into angular fragments known as breccia. The volcanoes emerged from the intrusion of basaltic dikes from a rift zone on the ocean floor during the Pliocene Epoch, and were heavily eroded during the Pliocene and early Pleistocene Epochs, leaving behind trachyte plugs and exposed outcrops of volcanic tuff throughout the park. Ta'u island, the youngest of the islands included within the national park, is all that remains from the collapse of a shield volcano during Holocene time. This collapse produced sea cliffs over 3,000 feet high on the north side of the island, some of the highest such escarpments in the world.

While the Samoan islands have not shown evidence of volcanism for many years, the hot spot beneath the islands continues to give indications of activity, with a submarine eruption detected just east of American Samoa in 1973. The Vailulu'u Seamount, located east of Ta'u, is a future Samoan island developing from submarine lava flows, continuing the eastward progress of volcanic development from the hotspot below the islands. The lava flows forming the seamount have been dated by radiometric methods to between 5 and 50 years, during which time the seamount has risen 14,764 feet from the ocean floor.

Evidence exists of past submarine and surface landslides as a result of weathering and other forms of erosion of the rocks and soil making up the islands. On Ta'u island, an inland escarpment known as Liu Bench (a feature of mass wasting) threatens to slump into the nearby ocean, an event which could produce a tsunami strong enough to devastate the island of Fiji to the southeast.

Threats

The coral reefs are under significant threat due to rising ocean temperatures and carbon dioxide concentration, as well as sea level rise. As a result of these and other stresses, the corals that form the reefs are projected to be lost by mid-century if carbon dioxide concentrations continue to rise at their current rate.