Colpophyllia natans From Tobago, a Novel Paleoclimate Archive for Reconstructing Sea Surface Temperature in the Tropical Atlantic

Massive, long-lived Siderastrea and Diploria corals are species commonly used for sea surface temperature (SST) reconstructions in the North Atlantic. However, they are rarely found to exceed 200 years in age. Thus, it is imperative to continuously develop alternative taxa for paleoreconstructions. Colpophyllia natans, a highly populous tropical North Atlantic coral, are known to grow large colonies, potentially containing environmental records spanning several hundreds of years. However, its low density and complicated architecture poses a challenge in extracting climate signals from this coral. This study presents the first monthly-resolved climate calibration of Colpophyllia natans and validates its utility as a new paleoarchive, relative to Siderastrea siderea. Linear regressions of monthly and interannual coral Sr/Ca with instrumental SST reveal robust, significant relationships (p < 0.05), indicating that microsampling along a single thecal wall of C. natans allowed for robust climate reconstructions. Additionally, both corals capture similar SST variations (t-test, p >= 0.05), which allowed for the generation of a single, composite interspecies SST record that correlates with instrumental SST even more strongly (p < 0.0001) than the individual corals. Mean annual and boreal summer interspecies SST correlate significantly with North Atlantic SST indices (p < 0.05), demonstrating the ability to capture regional, long-term SST trends in the North Atlantic. Spatial correlation maps of boreal winter interspecies SST to instrumental SST and geopotential height anomalies reveal coherent spatial patterns linked to the North Atlantic Oscillation. Our findings suggest that Colpophyllia natans has enormous potential as a new paleoclimate archive for reconstructing temporal and spatial SST variability in the tropical Atlantic. \