Twenty Years of Disturbance and Change in Fagatele Bay National Marine Sanctuary, American Samoa

Fagatele Bay National Marine Sanctuary contains a moderately diverse coral reef community (150 coral species, 259 fish species) that is protected from most human activities. The coral community was devastated by a crown-of-thorns starfish invasion in 1979 and has recently been affected by two major hurricanes (1990 and 1991) and a period of unusually high water temperature (1994). Long-term monitoring of the sanctuary allows for description of the effects of these disturbances in the absence of anthropogenic processes. The crown-of-thorns damaged deeper portions of the coral communities most severely, whereas the hurricanes and warm water affected shallower portions to a greater degree. Soon after these disturbances, corals started recruiting abundantly and the reefs began to recover. This is in contrast to some other areas in American Samoa, where chronic anthropogenic effects seem to have inhibited coral recruitment and reefrecovery. Fish communities were affected by the habitat degradation associated with the crown-of-thorns outbreak, but have remained relatively unchanged ever since. reef ecosystems in the absence of anthropogenic affects (Buddemeier 1992). Fagatele Bay is located on Tutuila Island in American Samoa (14 22' S, 170 40' W [Figure 1]) and was declared a National Marine Sanctuary in 1986 because of its isolation, spectacular beauty, and the pristine nature of its marine resources. The bay is a volcanic crater whose vertical cliffs and rough water conditions discourage access to the area, so both terrestrial and marine ecosystems are relatively protected from anthropogenic processes. The submerged portion of the crater is dominated by a coral reef ecosystem with a terraced structure. In the late 1970s, Fagatele Bay comprised healthy coral reef communities characterized by high coral cover (30-50%: especially table Acropora) and diversity (R.H.R. and C.E.B., pers. obs.). An outbreak of the crown-ofthorns starfish devastated the coral communities in 1979, which led to a dramatic reduction in live coral cover in the bay (Figure 2 [Birkeland et al. 1987]). A long-term monitoring program was established in the sanctuary in 1985. Since then, the area has endured two major hurricanes (Ofa in 1990 and