Excellent work, Zoe!
Pratte ZA, Longo GO, Burns AS, Hay ME, Stewart FJ. 2017. Contact with turf algae alters the coral microbiome: contact versus systemic impacts. Coral Reefs. In press.
Coral reefs are degrading to algal-dominated reefs worldwide, with alterations of coral microbiomes commonly co-occurring with reef demise. The severe thermal anomaly during the 2016 El Nino event in the South Pacific killed many corals and stressed others. Here, we examined the microbiome of turf algae and of the coral Porites sp. in contact with turf during this thermal event, allowing for the in situ examination of algal turf effects on the coral microbiome during a period of environmental stress. Whereas the microbial composition affiliated with turf did not differ between coral-contacted and non-contacted turfs, microbiomes of corals in direct contact with turf were similar to those of the turf microbiome and differed significantly from coral portions 5 cm from the point of turf/coral contact and from portions of the coral that looked most healthy, regardless of location. Although the majority of significant differences occurred in coral samples at the point of contact, a small subset of microbial taxa were enriched in coral tissues taken 5 cm from turf contact compared to all other sample types, including samples from areas of the coral that appeared most healthy. These results suggest that the coral microbiome is susceptible to colonization by microbes from turf, but not vice versa. Results also suggest that algal contact elicits a subtle shift in the coral microbiome just beyond the contact site. The combination of turf microbiome stability and coral microbiome vulnerability at areas of contact may contribute to the continued decline in coral cover and increase in algal cover associated with coral-algal phase shifts.