1. Using Corals for Proxy Temperature and Salinity

2. Why we can use corals for paleo-proxies
Deposit annual high density/ low density bands which provides timescale (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 coral’s skeleton
Decreased/increased growth
Changes in stable isotope ratios
Nutrients trapped within coral skeleton

3. Basic coral anatomy
Zooxanthellae
CaCO3

4. Ca2+
Coral Calcification

5. Coral Drilling
Pneumatic hand drill

6. Larger pneumatic drills
Coral Drilling
Larger pneumatic drills

7. Porites astreoides
Diploria strigosa

8. 𝐶𝑎𝑙𝑐𝑖𝑓𝑖𝑐𝑎𝑡𝑖𝑜𝑛 : χ 𝑐𝑚 𝑑 ×𝜌 𝑔 𝑐𝑚 3 =𝐺 ( 𝑔 𝑐𝑚 2 𝑑 )

10. Proxy SST
Ca2+

11. 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

12. Proxy SSS
Ca2+

14. How δ18O 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

16. Bleaching recorded in coral skeletons
Nutrients recorded in coral skeletons

17. Thank you!