The effects of probiotics and stony coral tissue loss disease exposure on coral recruits

Florida and Caribbean coral reefs have been in decline for decades due to pollution, overfishing, climate change and disease. In 2014, stony coral tissue loss disease (SCTLD) emerged in Florida and has since spread throughout much of the Caribbean. SCTLD triggers rapid tissue loss and mortality across > 20 coral species, dramatically impacting ecosystem function. Little is known about how SCTLD impacts early life stage corals and whether interventions can aid recruits. Therefore, the goals of this study were to (1) assess if exposure to SCTLD impacts newly settled Montastraea cavernosa and Dendrogyra cylindrus recruits and (2) determine if probiotic treatment could enhance recruit survival. Our results show that M. cavernosa recruits exposed to disease experienced lower survivorship. D. cylindrus recruits were not significantly impacted by disease, but disease severity of donor corals, as assessed by lesion progression, was minimal in the D. cylindrus experiment, which could explain the results. Treatment of recruits with the probiotic Pseudoalteromonas sp. McH1-7 did not have a significant effect on recruit survivorship for either species, although this could be due to interactions with the settlement inducer tetrabromopyrrole, which we used to induce larval settlement, but can also have antibiotic properties. Given the myriad of challenges coral reefs are facing, understanding how SCTLD impacts early life stages and developing methods to enhance recruit survival would be invaluable.