Watanabe, T., A. Winter, T. Oba, R. Anzai, and H. Ishioroshi. 2002. Evaluation of the fidelity of isotope records as an environmental proxy in the coral montastraea. Coral Reefs 21 (2) (JUL): 169-78.
Abstract:
Many studies of climate variability in the
Tropical Ocean have used high-resolution chemical
tracer records contained in coral skeletons. The complex
architecture of coral skeletons may lead to the
possibility of biases in coral records and it is therefore
important to access the fidelity of coral geochemical
records as environmental proxies. Coral skeletal records
from the same coral colony, and even the same
corallite, may show large variation due to differing
extension rates, formational timing of the skeletal elements,
colony topography, and sampling resolution. To
assess the robustness of the skeletal record, we present
d13C and d18O data based on different sampling resolutions,
skeletal elements, and coral colonies of Montastraea
faveolata species complex, the primary coral
used for climate reconstruction in the Atlantic. We
show that various skeletal elements produce different
isotopic records. The best sampling rate to resolve the
full annual range of sea surface temperature (SST) is 40
samples per year. This sampling frequency also consistently
recovered SST variability measured at weekly
intervals. A sampling rate of 12 times per year recovered
84% of the annual range recording average
monthly SST changes through the year. Six samples per
year significantly decreased the ability to resolve the
annual SST range. The d18O recorded from two adjacent
colonies were very similar, suggesting that this
isotope can be trusted to record environmental changes.
The d13C, on the other hand, remained highly variable,
perhaps as a result of the activity of symbiotic algae
(zooxanthellae).