The effect of algal symbionts on the accuracy of Sr/Ca paleotemperatures from coral.
The strontium-to-calcium ratio (Sr/Ca) of reef coral skeleton is commonly used as a paleothermometer to estimate sea surface temperatures (SSTs) at crucial times in Earth's climate history. However, these estimates are disputed, because uptake of Sr into coral skeleton is thought to be affected by algal symbionts (zooxanthellae) living in the host tissue. Here, we show that significant distortion of the Sr/Ca temperature record in coral skeleton occurs in the presence of algal symbionts. Seasonally resolved Sr/Ca in coral without symbionts reflects local SSTs with a temperature sensitivity equivalent to that of laboratory aragonite precipitated at equilibrium and the nighttime skeletal deposits of symbiotic reef corals. However, up to 65% of the Sr/Ca variability in symbiotic skeleton is related to symbiont activity and does not reflect water temperature.
Cohen
Anne L
AL
Department of Geology and Geophysics, Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA 02543, USA. acohen@whoi.edu
Owens
Kathryn E
KE
Layne
Graham D
GD
Shimizu
Nobumichi
N
D000818:Animals; D001267:Atlantic Ocean; D002118:Calcium / Q000032:analysis; D002119:Calcium Carbonate / Q000737:chemistry*; D002980:Climate; D003063:Cnidaria / Q000737:chemistry* / Q000254:growth & development / Q000502:physiology; D056890:Eukaryota / Q000502:physiology*; D010788:Photosynthesis; D012621:Seasons; D012623:Seawater; D013324:Strontium / Q000032:analysis; D013559:Symbiosis; D013696:Temperature; D013995:Time
D002119:Calcium Carbonate; D002118:Calcium; D013324:Strontium