Exposing partially bleached samples of Stylo-
phora pistillata coral colonies to controlled water-flow treat-
ments revealed differential recovery rates that varied in
accordance with flow rate. Recovery of the number of zoo-
xanthellae per unit area and chlorophyll a concentrations
increased rapidly in moderate-flow treatments (of 20 cm s–1),
after an initial 3 wk of stasis. Colonies in low-flow treatments
(≤3 cm s–1) remained pale for the entire 7 wk experimental
period and showed only slight increases in zooxanthellae per
unit area. In an earlier study, we showed that when corals
were subjected to high temperature and high irradiance,
coral bleaching occurred in low-flow but not in moderate-flow
treatments; the present study shows that recovery from
bleaching is facilitated by flow treatment. In combination,
prevention of and rapid recovery from bleaching by
enhanced water flow suggest that the mechanisms that lead
to dysfunction of the algae-coral symbiosis are driven by
mass-transfer-limited processes.