Monthly stable isotope records in an Australian coral and their correspondence with environmental variables

Monthly skeletal stable isotope measurements of a Porites australiensis coral from Abraham Reef, Australia, spanning the period from 1981 to 1991, are compared with monthly averaged SST (sea surface temperature) from satellite collected AVHRR (Advanced Very High Resolution Radiometer) and monthly downward surface short‐wave insolation (SSI) measurements. We found that the δ 18 O values varied as a function of the change in seawater temperature. There were anomalously high δ 18 O values in coral that grew during the summer season of the three El Niño events 1982–83, 1987, and 1991. Advection of seawater with higher salinity (and higher δ 18 O values) to our site or discrepancies between ocean skin temperature and mixed layer SST are likely reasons for the reduced resolution of δ 18 O‐based SST. Increased coral δ 13 C values occurred simultaneously with increases in SSI. During most El Niño events the maximum and minimum δ 13 C values were lower than during normal years.