1. Replication of a coral
strontium/calcium-based
Medieval ocean temperature
record from the Caribbean
Jessalyn Kohn, REU Fellow
Crop, Soil, and Environmental Sciences, University of Arkansas
Dr. Hali Kilbourne, Research Assistant Professor
Chesapeake Biological Laboratory, University of Maryland Center for Environmental
Sciences

2. Extension of Instrumental
Climate Records
Tierney et al 2015
• Instrumental climate data only extend
back to the mid-19th century.
• Understanding past climate enables
better predictions of future climate
change.
• Climate conditions in the tropics impact
climate around the world.
Xu 2014

3. Corals Can Be Used To
Reconstruct Past Sea
Surface Temperatures
(SST)
• Long-lived - centuries
• Can be dated (U-series)
• Monthly to seasonal
resolution
• Sr/Ca in coral skeleton is
indicative of SST

4. Research Project
• Sampled a coral (13AN6) from Anegada, British
Virgin Islands.
• Generated a Sr/Ca record of variability from 1304-
1341.
• Compared results to a coral (13AN13) record from
1281-1347 to verify reliability of both records.
CC BY-SA 3.0
Uploaded by Louiswray
Created: November 6, 2011
Xu 2014

5. These corals were killed and washed
ashore in a tsunami during the 1400s, so
we aren’t sure exactly where on the reef
they came from…
Did growth habitat affect their
ability to accurately record
environmental signals?

6. Methods
Giry 2010
Determined sampling line along
thecal wall of coral skeleton.
Collected coral
powder from thecal
wall by drilling
along sampling line.
Analyzed Sr/Ca using ICP-OES.

7. Data Analysis:
Convert to Time and Compare Datasets
1. Convert depth to time
– Counting annual density
bands
– Matching seasonal cycles of
Sr/Ca to modern SST
2. Resampled time series to
even monthly intervals
3. Correlation analysis on
monthly basis with 13AN13

8. Seasonal Cycles Have Similar
Amplitude
9.10
9.15
9.20
9.25
9.30
9.35
9.40
9.45
9.50
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar
Sr/Ca(mmol/mol)
month
13AN13 13AN6
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar
ΔSST(°C)
month
13AN13 13AN6

9. Similar Cycles, But Different
Mean Sr/Ca
Interannual variability in 13AN6 may impact correlation:
• Box 1 (1310.79 – 1319.54): anomalously high Sr/Ca values
• Box 2 (1323.04 – 1326.04): anomalously low Sr/Ca values
• Box 3 (1335.79 – 1336.79): very little variation in Sr/Ca values
9.0
9.1
9.2
9.3
9.4
9.5
9.6
9.7
1300 1305 1310 1315 1320 1325 1330 1335 1340 1345
Sr/Ca(mmol/mol)
year
13AN13 13AN6
321

10. y = 0.4334x + 5.3706
R² = 0.1163
9.0
9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7
13AN6Sr/Ca(mmol/mol)
13AN13 Sr/Ca (mmol/mol)
y = 0.5517x + 4.2548
R² = 0.3119
9.0
9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7
13AN6Sr/Ca(mmol/mol)
13AN13 Sr/Ca (mmol/mol)
Correlation Improved When Sections
With Anomalously High or Low
Interannual Variability Were Removed

11. Need to Consider
Location

12. Environmental
Conditions at
Growth Site Likely
Affected Sr/Ca
Uptake

13. Conclusions
• Environmental conditions at the growth site
affected the results of our study.
• Since seasonal cycles were still robust, 13AN6
may be usable for exploring past seasonal
changes in Anegada.
• Checking the reproducibility of environmental
signals in corals that grew during the same time
period can help reduce errors in paleoclimate
reconstructions.
© Matthew Meier 2010.858-504-0469.matt@matthewmeierphoto.com.All Rights Reserved

14. Dr. Hali Kilbourne
National Science Foundation
Maryland Sea Grant REU
University of Maryland Center
for Environmental Sciences
Chesapeake Biological Laboratory
University of Arkansas
Katie Hoffman
Dr. Mike Allen and Fellow REUs
Acknowledgements

15. Questions?