Location: Brewer’s Bay (18.34403, -64.98435), St. Thomas, The U.S. Virgin Islands
Disease prevalence was recorded as the percentage of individuals infected by the end of the seven-day study. Disease prevalence among species was compared using a Fisher’s Exact Test in R. A photograph and timestamp was captured upon appearance of lesions and then immediately before each fragment was culled around 30% tissue loss. Disease severity was measured by calculating the rate of lesion progression across the coral fragment as the amount of tissue lost between the appearance of the lesion to the time it was culled divided by that time period. Time to infection was measured by the number of days it took for each coral fragment to show lesions throughout the seven-day study and visualized with a survival plot through a Kaplan-Meier estimate of the survivorship by using the survfit function in the R package survival (Therneau, 2020). The relative risk of each species was also calculated as: “Relative risk (RR) = Risk in exposed / Risk in non-exposed” where the risk in exposed individuals was calculated as the prevalence (diseased/total population) of those exposed to disease and risk in non-exposed individuals was calculated as the prevalence (diseased/total population) of those not exposed to disease.
Disease transmission and phenotypic sampling matched the methods from this published study “Species-specific susceptibility to white plague disease in three common Caribbean corals” Williams et al. (2020). Dr. Marilyn Brandt was the lead PI in that investigation and a CO-PI in the investigation being submitted.
Instruments:
Band Saw to fragment colonies. Camera and ruler to take photographs. Hammer and chisel to take samples of culled coral. Samples flash frozen in liquid nitrogen, stored in -80˚C until shipped via dry shipper to The University of Texas at Arlington for molecular work.
