Heron, S. F., Pressey, R. L., Skirving, W. J., Rauenzahn, J. L., Parker, B.-A. A., Eakin, C. M.

Identifying oceanic thermal anomalies in the Coral Triangle region

2012

Cairns, Australia

Proceedings of the 12th International Coral Reef Symposium. 17D Managing Bleached Coral Reefs

5

"Mass coral bleaching has historically been linked to episodes of thermal stress. While locationspecific time-series data have been examined, the oceanic thermal anomalies that underlie broad-scale thermal stress events are apparently unstudied quantitatively in terms of their spatial extent, temporal development, and intensity. Knowledge of the spatial and temporal parameters that characterise anomalies can be useful in understanding how bleaching-level stress develops, providing context for and a basis for modelling of future events. Here we examine historical satellite sea-surface temperature (SST) data with the goal of identifying and characterising oceanic anomalies in the Coral Triangle region. This region is of interest because it is influenced by the Indian and Pacific Oceans and is the centre of coral ecosystem diversity and significant coral reef conservation efforts. Oceanic anomalies are defined here using the HotSpot metric, which is the positive variation in temperature above the maximum of the monthly mean climatology values. This metric describes thermal stress that has been linked to coral bleaching episodes. It is proposed that the method for identifying oceanic anomalies described here be applied to datasets of varying spatial resolutions to evaluate if, and how, the characterisations are resolution-dependent. If these anomalies can be comparably identified and characterised at a coarser spatial resolution, this could open the way to examining the likely impact of oceanic thermal anomalies further back in time using historical datasets or in the future using climate models, both of which are available only at lower spatial and temporal resolutions."

oceanic thermal anomaly; coral bleaching; sea surface temperature