ASSESSING SR/CA PALEOTEMPERATURE CALIBRATION TECHNIQUES FOR SUBTROPICAL WESTERN ATLANTIC CORALS USING PSEUDODIPLORIA STRIGOSA

Coral strontium-to-calcium ratios (Sr/Ca) are commonly used to reconstruct past sea surface temperatures (SSTs), extending climate records beyond the temporal extent of instrumental observations. However, in subtropical regions where the seasonal range of SSTs is relatively high, quantification of a clear relationship between Sr/Ca and SST can be potentially problematic, due to reduction in calcification. To address this issue, we present a comparison of Sr/Ca—SST calibrations from two Pseudodiploria strigosa coral colonies with varying skeletal extension rates collected from shallow-water sites (3.0 and 4.5 m depths) on the nearshore ridge complex (NRC) offshore Broward County, Florida. Three regression techniques including ordinary least squares (OLS), reduced major axis (RMA), and weighted least squares (WLS) were used to calibrate SST, and a bootstrap method of each was implemented to assess the influence of minimum and maximum temperature extremes on the resulting calibration slopes. The resulting calibration slopes were also compared with other P. strigosa records from the Caribbean and western Atlantic regions to assess proxy fidelity. The results of this study provide valuable insight into the relationship between Sr/Ca and SST in P. strigosa corals and can be used to improve the precision of future coral-based paleoclimate studies in subtropical regions such as southeast Florida.