Sedimentation is a significant potential threat to the reefs of American Samoa. The islands are very steep and rainfall is often heavy. Currently, steep slopes are almost completely covered by dense native vegetation except in areas cleared for agriculture and quarry operation during prehistoric settlement (Clark and Herdrich, 1993). If a significant amount of vegetation were to be removed, sediment runoff in nearshore areas would likely increase, especially near river mouths, in bays and in other low-flushing areas.



Tutuila, where almost all of American Samoa’s estimated population of 66,900 people live (American Samoa Department of Commerce, 2007), has only about 26 km2 (10 mi²) of flat land, almost all coastal. The high and increasing population density and associated construction activities place great strains on shoreline resources. The potential impact of sedimentation on nearshore resources led the Department of Marine and Wildlife Resources (DMWR) Key Reef Species Program to conduct a quantitative assessment of the sedimentation rates along the south shore of Tutuila and determine its effect on sport fish populations. Nine sediment traps were deployed and retrieved monthly at the reef slopes of 12 monitoring sites from January 2006 to February 2007. Six sites were located in embayment areas while six were at topographic points to account for habitat variability. Two additional sites at the mouth of streams (Fagaalu and Fagatogo) were included to determine the amount of sediment delivered by the stream compared to direct terrestrial inputs. The dry weight of sediment was used to estimate sedimentation rates in grams per cm² per day. Results showed that sedimentation rates in bays averaged 12.1 g/cm²/day, which was significantly higher than at point sites, which averaged 1.4 g/cm²/day (Figure 10.12). Sedimentation rates from stream sites, however, were drastically higher than both bay and point sites at 84.7 g/cm²/day. Such high sediment loads were considered detrimental to coral reefs while rates at the bays and points were considered to have moderate and slight effects, respectively (Pastorok and Bilyard, 1985). There were also some noticeable temporal variations as higher sedimentation rates occurred between January and June, a difference that was more evident at embayment sites than point sites. However, this does not correlate with rainfall or with trends in wave action (expressed in significant wave height in meters) that can resuspend sediments.



High sediment output from stream sites seemed to be dispersed within nearshore areas since only a small amount was detected on reef slopes. Qualitative observation by DMWR biologists suggests that sediments from streams are deposited on reef flats, but no quantitative data has been collected to date. The DMWR Key Reef Species Program will continue to investigate sediment dispersal rates and patterns on reef and possible impacts on juvenile sport fish habitat.

Currently there are seven National Pollutant Discharge Elimination System permitted discharges in American Samoa. The permitted discharges include treated wastewater from Tutuila’s two wastewater treatment plants, effluent from the two tuna canneries, and other point source discharges that could contain minor amounts of oil and other toxic or biological materials. The point sources are not considered major contributors to poor water quality.



Nonpoint source pollution is now considered the primary pollution source for coastal areas in American Samoa. The American Samoa Environmental Protection Agency (ASEPA) developed a Coastal Nonpoint Source Monitoring Strategy as part of the American Samoa Coastal Nonpoint Pollution Control Program in order to evaluate the effectiveness of best management practices for achieving water quality objectives through tracking trends in water quality.



Pago Pago Harbor is seriously polluted with contaminated sediments and fish processing wastes, which contribute to high bacterial levels that peak during and after heavy rains. Sources of bacterial contamination include piggeries, septic tanks, sewage and animal wastes. ASEPA has issued a general advisory against consumption of fish caught in the inner harbor due to the presence of arsenic, mercury and polychlorinated biphenyls (PCBs). Fish toxicity is attributed to contaminated sediments since the water quality in the harbor meets or exceeds applicable U.S. Environmental Protection Agency (USEPA) water quality standards.



Uncontrolled effluent from piggeries contaminates local watersheds and has resulted in impaired water quality in some coastal waters. Approximately 1,006 piggeries with about 9,000 pigs currently operate in the territory, and the effluent from 82% of them are channeled into deficient cesspools and septic systems or discharge directly into streams or wetlands. Although piggeries are required to have land use permits, 97% are out of compliance (Buchan et al., 2006). ASEPA has been given authority to write citations for piggeries that are out of compliance and has moved forward with a strong enforcement program.

There continues to be relatively little tourism in American Samoa. Only two flights a week operate between Honolulu, HI and Pago Pago International Airport for most of the year. There are several flights daily between American Samoa and neighboring independent Samoa and limited service to a few other destinations. It is estimated that American Samoa received 7,762 tourists in 2006 and 7,027 tourists in 2005 (ASDOC, 2007). Approximately 82% of tourists to American Samoa are citizens of the U.S. (52%) or New Zealand (30%).



The Ecotourism Plan for American Samoa, released in June 2005, states that ecotourism is the preferred means of promoting tourism and the economy in the territory (Liu et al., 2005). The objectives of the Ecotourism Plan are: to incorporate ecotourism into the territory’s policies and goals for environmental protection; to promote the conservation of American Samoa’s natural resources through ecotourism; and to determine the desirable growth rates and limits for the ecotourism industry in the territory.

There is no trade in coral and live reef species at this time.

As reported in Craig et al. (2005), nine foreign-flagged longliners were grounded on reefs in Pago Pago Harbor during Hurricane Val in 1991. They were removed in 2000 by building a causeway for machinery to reach each longliner for removal. During preparations in 1999, approximately 1,000 corals were removed from areas planned for the causeways. Although a storm damaged most of the removed corals, over 300 colonies were transplanted into the footprint of one of the vessels at Onesosopo near the mouth of the harbor. The survival, growth, and live tissue status of 354 transplanted corals were evaluated in 2001 when 91-92% had survived and 2005 when 60-78% had survived. Massive Porites species and Pocillopora eydouxi had significantly higher survival rates than small and mid-sized Pocillopora species. Transplanted corals fared as well as controls in terms of survival, growth and change in live tissue cover (Kolinski, 2006). One of the nine longliners was removed whole and scuttled outside the harbor. It was sighted in early 2007 resting intact on a sand patch near the outer reef at Taema Banks in water depths of about 30 m. Some corals had begun to grow on it.

A limited amount of marine debris washes in from offshore and is deposited on American Samoa’s coral reefs. The bulk of marine debris in the territory originates from land-based activities. Local resource management agencies and community groups organize occasional beach cleanups. NOAA’s Office of Response and Restoration is providing technical assistance in planning for the removal of two additional derelict vessels and vessel debris. The vessels in question are deteriorating and scattering debris in nearshore areas, which harms corals and limits human uses of the areas due to concerns about the presence of sharp metal in the intertidal and nearshore subtidal zones. The development of removal plans is expected to assist the territory in seeking funding opportunities for vessel removal.

Security training activities are not considered a major threat to coral reef ecosystems in American Samoa.

No oil and gas exploration occurs in American Samoa.

Coral reefs in Pago Pago harbor were severely damaged by massive human impacts from the 1950s to 1990s including dredging, infilling, sediment runoff, and the discharge of tuna cannery wastes. A transect started in 1917 on the reef flat at Aua is one of the oldest coral reef monitoring projects in the Pacific and showed steady declines in coral cover and predominant cover of dead rubble. Small areas of reef flat communities near the mouth of the harbor have high cover of healthy corals along the reef crest. Introduced species, ship groundings, tourism, marine debris, and collection for trade are all minor threats. All future human threats will be exacerbated by rapid and unsustainable population growth, which has grown from fewer than 10,000 residents in 1910 to an estimated present population of 69,000; projections are that this population will double within 40 years. As the entire territory is a coastal zone with limited habitable space, these population pressures will undoubtedly increase in the years ahead and are currently being addressed by a multi-agency local action strategy.

Most of the population of American Samoa resides on Tutuila. However, only approximately one-third of the land area has a slope of less than 30%. As a result, the population density of the island is 1,350 people per km2, which surpasses the population density of Manhattan in New York City, even though the island is semi-rural and the tallest structures are two stories high. This density has placed considerable demands on American Samoa’s coastal areas. Though all of the Territory’s lands are within the coastal zone, most of the land favorable for development lies immediately adjacent to the coast (Figure 11.5). Several hundred landuse permit applications are received per year, a majority of which are approved with conditions.