Cold-water corals may hold valuable records of oceanographic variation. This study evaluates Dendrophyllia cornigera and Dendrophyllia ramea as geochemical archives for reconstructing seawater temperature and nutrient concentrations, with two hypotheses:
H1: Li/Mg ratios in Dendrophyllia reflect local seawater temperature.
H2: Ba/Ca ratios in Dendrophyllia reflect ambient nutrient concentrations.
Samples collected off Sagres, Portugal, were analysed for Li/Mg and Ba/Ca and compared with World Ocean Atlas data. Li/Mg showed an exponential relationship with temperature. High explanatory power was achieved with a temperature-averaged model (R² = 0.764, p = 0.000202), while reasonable power was found for a genus-specific model (R² = 0.407, p = 2e-04). Reconstructed temperatures closely followed climatological values (down to ± 0.03°C). Incorporating these data into a global model improved its former performance (R² = 0.86, p = 3.5e-07), validating H1.
Ba/Ca ratios were weakly correlated with phosphate (R² = 0.176, p = 0.0484) and nitrate (R² = 0.158, p = 0.0593), failing to support H2. Cleaning methods were effective, and structural subsampling had little impact on results.
While no conclusions can be made for Ba/Ca, these results confirm Li/Mg as a robust paleotemperature proxy, also when applied to Dendropyllia corals.
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