Sites adjacent to the wreck on San Cristobal were
initially surveyed during the two-day period when the
Jessica was aground but not leaking, and sites on Santa
Fe were surveyed just as oil was reaching the island.
Tidal range for all sites was approximately 1.5 m.
Tidal height of each quadrat could not be accurately
measured due to time constraints; however, an estimate
of height above low water level (chart datum) was made
using estimated height above low water level at the time
of surveying each quadrat, with reference to tide charts
and time of day to determine tidal level