Sea bottom temperature (SBT) Modeling
The objective of this study was to illustrate that coral bleaching models could be improved through the addition of sea bottom temperature data. Sea bottom temperature (SBT) is believed to be a more realistic predictor of temperature-induced coral bleaching than sea surface temperature (SST). Typically, spatial predictions of coral bleaching use satellite derived SST, but corals, living on the seafloor, are presumably more vulnerable to SBT than SST. In circumstances where a reef tract experiences an inverted thermocline, as in the Florida Keys, SBT can be warmer than SST. In these situations, corals may be more likely to experience temperature-induced bleaching than surface temperature would predict.
A Generalized Additive Model was created to predict SBT from satellite-derived SST. In general, SST data predicted more areas prone to bleaching stress than SBT data, indicating that under typical thermal conditions a simple SST model may overestimate bleaching risk in nearly half of the Florida Keys reef tract. However, when bottom temperature exceeds surface temperature, as experienced during an inverted thermocline event, results suggest that a model using SST data alone may, in fact, underestimate true bleaching risk. Therefore, research using SST as the single predictor of coral bleaching may be over or under estimating bleaching depending on the respective thermoclines within the area of interest.
Temperature data collected by FWRI and our partners can be viewed on the Unified Reef Map Viewer.