Figure 1

Diagram depicting the two experimental approaches. (a) Natural dynamics of coral mucus-associated prokaryotes: surface mucus of seven Porites astreoides colonies was regularly sampled in situ over a 2-month period and mucus aging state (‘new mucus’ versus ‘aged mucus’) was visually assessed (following Coffroth, 1991). Insert depicts an in situ impression of the SML for the same P. astreoides colony at two different time points: with new mucus (left side) and with a conspicuous and aged mucus sheet (right side). A selection of new (n=14) and aged mucus (n=6) samples was later used for 16S ribosomal RNA (rRNA) gene amplicon sequencing. (b) Prokaryotic mucus re-colonization after antibiotics disturbance: mucus of 12 P. astreoides colonies exhibiting new mucus was sampled in situ and whole colonies later removed from the reef and brought to the aquaria system of the CARMABI station. Six colonies were incubated in a mix of antibiotics and the other six colonies were incubated as controls. After 8 days in the aquaria, corals were again sampled and thereafter brought back to the reef and installed on a rack (day 0). Over the next 28 days, the health of the colonies was visually assessed and mucus samples were regularly collected. No visual signs of mucus aging were observed throughout the experiment. The 16S rRNA gene was sequenced for all collected mucus samples (n=80) to follow microbial community composition during re-colonization of mucus after antibiotics disturbance.