Fluorescence microscopic images of <i>Acropora tenuis</i> polyps associated with clade C1 or D <i>Symbiodinium</i> algae, and aposymbiotic polyps 20, 58, and 80 days after inoculation.

<p>Bright green fluorescence can be seen in the body walls and tentacles of polyps associated with clade C1 algae. On day 20, polyps associated with clade D algae show little green fluorescence, and aposymbiotic polyps have a pale fluorescence. Red fluorescence dots indicate the chlorophyll fluorescence of <i>Symbiodinium</i> algae. Polyps with clade C1 algae contain few <i>Symbiodinium</i> cells, although many cells are aggregated around the polyps on days 20 and 58 (Fig. 3), thought to be <i>Symbiodinium</i> algae released from the corals. Scale bar = 0.5 mm.