The average marine protected area (MPA) has an area of
approximately 16 km2 (Kelleher, Bleakley, & Wells, 1995).
Thus, IKONOS data may be an effective tool for monitoring
the spatial dynamics of habitats in many MPAs which are
small enough for habitat identification to take place in thefield. An example would be monitoring the recovery of
dense seagrass beds from propeller damage which is currently
achieved using airborne methods (Anonymous,
1998). Where field survey is restricted (e.g., when mapping
large areas), satellite data may be confined to measuring
large structural disturbances, such as those caused by
tropical storms (Done, 1992) with impacts on scales of
hundreds of metres. However, satellite data are unlikely to
be effective for assessing other large-scale impacts on reef
ecosystems. Many large-scale deleterious processes on reefs
such as coral bleaching (Brown, 1997) and overfishing
(Hughes, 1994) result in a decline of living coral and
increase in macroalgae (McCook, 1999).