Mayotte coral reveals hydrological changes in the western Indian Ocean between 1881 and 1994

Abstract

We reconstruct the hydrologic history of the tropical western Indian Ocean by calculating the δ 18 O seawater from coupled coral Sr/Ca and δ 18 O measurements in a massive Porites coral from Mayotte (Comoros) between 1881 and 1994. We found that the precipitation‐evaporation balance varies naturally on time scales of 5–6 years and 18–25 years. High (low) SSTs are associated with positive (negative) δ 18 O seawater implying that atmospheric variability is linked with remote climate modes in the Indian Ocean and the tropical/extratropical Pacific Ocean. Warm El Niño‐Southern Oscillation events are associated with a negative freshwater balance at Mayotte. This case study demonstrates that a much denser network of δ 18 O seawater reconstructions is crucial for understanding the spatial patterns of hydrological conditions.