Site History and Resources
Overview
Fagatele Bay is the smallest and most remote of the national marine sanctuaries, but its coral reefs may have the highest marine-life diversity in the sanctuary system. The bay's habitats are home to a variety of tropical fish, invertebrates and algae. Fagatele Bay sanctuary was designated as a national marine sanctuary in 1986 because it serves as an extraordinary example of a tropical marine environment and coral reef ecosystem of exceptional productivity. The sanctuary is co-administered by the National Oceanic and Atmospheric Administration (NOAA), within the U.S. Department of Commerce, and the American Samoa Department of Commerce.
Located in the South Pacific Ocean along the southern coast of American Samoa's main island of Tutuila, Fagatele Bay sanctuary protects a one-quarter square mile (163 acre) marine area. With water visibility normally around 20 - 30 meters (65-98 feet), the small bay is a partially drowned crater of an extinct volcano and is bordered by a ridge 60 - 120 meters (200 - 400 feet) high with vertical cliffs and steep slopes. These slopes are covered with dense, lush vegetation composing one of America's few tropical rainforests. The steepness of the ridges surrounding Fagatele Bay has helped ensure that most of the watershed has remained free of introduced vegetation, maintaining a relatively unspoiled refuge for American Samoa's native plants and wildlife.
Fagatele Bay sanctuary's marine environment is typical of the fringing coral reef ecosystems associated with high islands of volcanic origin, many of which lie in the warm waters of the Pacific Ocean. Coral reefs are key coastal marine ecosystems in the tropical Pacific and provide vital coastal protection and marine resource utilization by the people who live in the region. Fagatele Bay National Marine Sanctuary was designated as a way to help preserve American Samoa's coastal resources and to contribute to coral reef conservation efforts throughout the Pacific.
Due to the need to protect the natural resources represented by Fagatele Bay and to enhance public awareness of marine resource protection and marine ecosystem research, the governor of American Samoa proposed Fagatele Bay to NOAA as a candidate for marine sanctuary designation in 1982. After a lengthy period of public hearings, consultation and review, a management plan was approved, culminating in the designation of the sanctuary on April 29, 1986 by an act of Congress. Fagatele Bay sanctuary is part of American Samoa's conservation strategy, which includes the National Park of American Samoa and a community-based marine protected area program coordinated by the Department of Marine and Wildlife Resources.
Location
Fagatele Bay lies along the southernmost shore of Tutuila, the largest and most populated of the seven islands comprising the U.S. Territory of American Samoa. As American Samoa's largest island, Tutuila is the center of all administrative and economic activity, and home to over 90 percent of American Samoa's population of 65,500. Annual population growth is currently high at around 2 percent and the population is predicted to exceed 76,000 people by 2020. Located approximately 1,600 kilometers south of the equator, American Samoa constitutes the eastern portion of the Samoan archipelago. The islands of Savai'i and Upolu to the west form the independent nation of Samoa. American Samoa is the only U.S. Territory south of the equator and comprises five volcanic islands (Tutuila, Aunuu, Ofu, Olosega, and Tau) and two small remote coral atolls (Rose Atoll and Swains Island).
Geology
Tutuila Island is composed of Pliocene or early Pleistocene volcanics extruded approximately 1.5 million years ago by a series of volcanic eruptions. The island consists primarily of basaltic rocks, with the bulk of the island being made up of lava flows. Because of rapid submergence during the last period of Pleistocene sea level rise, the fringing reefs around Tutuila are discontinuous and have their foundation on bedded calcareous sand and silt as well as coral reef limestone deposited over the last 10,000 years.
Tutuila lies on the Pacific Plate, which moves in a westward direction at about 7 centimeters (3 inches) per year. Approximately 160 kilometers south of the island, the Pacific Plate collides with the Australian Plate, causing the Pacific Plate to slowly break into two parts. As the northern section of the plate continues to move westward, the southern section slides beneath the Australian Plate, forming the 10 kilometers deep Tongan Trench. The Samoan archipelago rides on this northern section of the Pacific Plate. The islands formed as the plate traveled over a "hot spot" of volcanic activity. As a consequence, the islands of American Samoa are geologically younger than Savai'i and Upolou, the islands of Independent Samoa to the west. The "hot spot" is presently located 50 kilometers east of Ta'u Island where ongoing volcanic eruptions on the seafloor are building a new island (Vailulu'u) that has yet to rise above the sea surface.
Human Settlement
Archeological evidence suggests the islands of Samoa have been inhabited since at least 1300 B.C. While trade and social interactions with Tonga and the other islands of the Pacific occurred over the subsequent 2,000 years, a distinctly Samoan society existed in the islands by the time of European arrival. Jacob Roggeveen first documented the islands in 1722, but Louis de Bougainville's 1772 name for the archipelago, "The Navigator Islands," was used until the end of the 19th century. La Peruse was the first European to set foot on Tutuila in 1787. The Wilkes Expedition from the U.S. in 1837 provided the first systematic natural history and cultural surveys of Samoa. This expedition and the arrival of Christian missionaries established the Western influence over Samoan society that continues today. Although the shore of Fagatele Bay was the site of a village from prehistoric times to the 1950s, at present no settlement exists in the sanctuary other than a simple structure housing two temporary agricultural workers.
Commerce
In 1878, the U.S. Navy established a lease of land on the shore of the deep harbor at Pago Pago at Tutuila for a coaling station. The subsequent relationship between American Samoa and the United States has brought dramatic changes to the territory's economy. Despite significant social, economic and religious change, Samoan cultural traditions remain strong in American Samoa society, governance and land tenure. Today, tuna processing and the territorial government are the largest employers and the mainstay of the territory's economy. Two large U.S. tuna canneries form the basis of an industry that employs more than 3,000 Samoan and foreign workers. International fishing fleets supply catches to the canneries for export while small-scale artisanal fisheries supply the local market for fish. Tuna canned in South America, which is allowed into the U.S. duty-free under the Andean Trade Preferences Act, threatens the future viability of the tuna industry in American Samoa.
Retail trade and services dominate the rest of the territory's economy. Agriculture on the islands of American Samoa mainly supplies local markets. The most important crops include taro, coconuts, bananas, oranges, pineapples, papayas, breadfruit, and yams. Tourism is not well developed in American Samoa, but short visits by cruise ships are a periodic addition to the economy.
Climate and Water Quality
Yearly air temperatures in American Samoa range from 21 - 32°C (70 to 90°F), with an average humidity of 80 percent. The average yearly rainfall is about 5 meters (200 inches), with the heaviest rains occurring during summer months, from December through March. As summer progresses, the temperature of the ocean’s surface waters also increases by about 3°C (6°F). Warmer ocean temperatures, in turn, help provide the energy to start tropical cyclones. Thus, the chance of a cyclone is greatest between November and April. The mean annual water temperature of Fagatele Bay fluctuates around 28°C (82°F).
Habitat
Fagatele Bay formed when the seaward side of the Fagatele volcanic crater was breached by the ocean and flooded sometime in the Pleistocene.
The resulting geography is a well-protected marine environment recessed into the adjoining land and surrounded by steep-sided ridges. Seumalo Ridge rises over 120 meters (400 feet) high along the western and northern sides of Fagatele Bay, while the eastern side of the bay is bounded by Manautuloa Ridge at over 60 meters (200 feet) high. Although foot trails exist to lead hikers from the mountain ridge to the shore, the steepness of the slope makes access to the bay from land difficult.
The prevalent feature of Fagatele Bay sanctuary is its extensive coral reef ecosystem. Shallow-water coral reefs and reef-building organisms are confined to the upper euphotic zone, with the majority of reef production occurring in less than 10 meters (33 feet) of water.
Fagatele Bay's coral reef consists of a near-shore inner reef flat that slopes to a deeper water reef (reef slope) farther offshore. The reef crest, between the inner reef flat and outer reef slope, lies in extremely shallow water and is exposed during the lowest tides.
Waves commonly break on the reef crest. The fringing reefs found in Fagatele Bay, and their geographic orientation relative to prevailing winds, moderates shoreline erosion from ocean waves.
Living Resources
The coral reefs of Fagatele Bay provide habitat for at least 271 species of fishes. Abundant groups include adult and juvenile damselfish, surgeonfish, wrasse, butterflyfish, and parrotfish. Surveys have also identified 200 species of coral living on the reefs in the sanctuary. Corals play a particularly important role in coral reef ecosystems because they provide shelter and habitat for the abundant varieties of marine life that make coral reefs their home. Many species on coral reefs depend on one another in various ways. For example, some damselfish and corals have a symbiotic relationship. The corals' branches provide the fish with protection from predators, and the fish excrete nitrogen in the form of ammonia, which the corals use for growth. Throughout the reef ecosystem, close, complex relationships like this exist between very different types of organisms, creating an extremely diverse and highly productive biological community. Sponge, mollusk, echinoderm, crustacean, annelid, bryozoan, and tunicate fauna are integral components of the overall biodiversity. Taxonomic surveys have identified at least 1,400 species of algae and invertebrates (other than coral) living on Tutuila's coral reefs and likely to be found in Fagatele Bay.
In addition to fishes and invertebrate coral reef organisms, several species of dolphin (e.g., Pacific bottlenose and spinner dolphin) are found in the vicinity of the Fagatele Bay sanctuary. Hawksbill and green sea turtles are also frequently seen swimming in the bay.
The migratory paths of humpback whales in the southern hemisphere intersect with American Samoa. Each year, from July through October, humpbacks use the waters around American Samoa for breeding and calving. Occasionally, sperm whales venture into the waters surrounding American Samoa and may be seen seaward of Fagatele Bay. Birds are the most conspicuous wildlife in American Samoa. 60 species have been documented by the U.S. Fish and Wildlife Service, 24 are seabirds and 36 are waterfowl. Eight of these species are introduced (in comparison, at least 142 species of birds, from six continents, have been introduced since 1850 to the Hawaiian Islands (Moulton et al. 2001)).
Birds use the shore, rocky cliffs and the surrounding heavily forested ridges for nesting and feeding. The area around the bay provides sea and shorebirds with comparatively remote, favorable physical environments for nesting, as well as ready access to rich foraging areas that are necessary during the breeding season. In addition to birds, large colonies of fruit bats, also known as flying foxes, reside in the forest surrounding Fagatele Bay. These bat colonies are infrequently encountered in other locations on Tutuila and are susceptible to human disturbance. The Fagatele Bay colonies are therefore important because of their relative isolation.
Maritime Archaeological Resources
Imagery and documentation of Fagatele Bay suggests that the sanctuary contains no large submerged archaeological artifacts. However, the site of at least one pre-historic village has been identified and mapped along its shore. This village site is presumed to be a long-occupied fishing village, which exploited the rich resources of the bay. The site consists of foundations of structures and pathways. The site is overgrown by thick forest vegetation and has not been excavated.