Using Corals for Proxy Temperature and Salinity Why we can use corals for paleo-proxies
Deposit annual high density/ low density bands which providestimescale (like tree rings) High density = winter Low density = summer Corals are very sensitive to changes in temperature, salinity, nutrients, These changes are reflected in the make-up of the corals skeleton Decreased/increased growth Changes in stable isotope ratios Nutrients trapped within coral skeleton Basic coral anatomy Zooxanthellae CaCO3 Ca2+ Coral Calcification Coral Drilling Pneumatic hand drill Larger pneumatic drills
Coral Drilling Larger pneumatic drills Porites astreoides Diploria strigosa : 3 = ( 2 ) Proxy SST Ca2+ How to use isotopic ratios for proxy SST
Obtain annual CaCO3 samples Lazer ablation Digestions of annual CaCO3 deposits. Inductively coupled plasma mass spectrometry (ICPMS) Mg2+/Ca2+, Ba2+/ Ca2+, Sr2+/ Ca2+ Multiple linear regression SST = (X2+/Ca2+)m + b Proxy SSS Ca2+ How 18O reflects SSS P E Two major oxygen isotopes: 18O and 16O
Controlled by evaporation (E) and precipitation (P) 18O 18O 16O 16O 18O 16O P E 16O 18O 16O 18O 16O 16O 18O 18O 18O 18O 18O 18O Bleaching recorded in coral skeletons
Nutrients recorded in coral skeletons Thank you!