2009 Volume 11 Issue 1 Pages 91-107
Reef building corals in temperate region could be a powerful tool for reconstructing climatic/environmental changes such as global warming and ocean acidification. To demonstrate the possibility of high latitude corals for reconstruction of paleoenvironments, we analyzed oxygen and carbon isotopes in core specimens of living massive colony, Porites lutea, taken from Tatsukushi Bay, Kochi prefecture, Japan. Isotopic variations were compared with the coral skeletology deduced from X-ray photographs and luminescence bands. Comparing with observed sea surface temperature (SST), oxygen isotope profile showed the lack of geochemical records during low temperature. This result was corresponding with the occurrences of high density bands, low skeletal extension rate, and low calcification rate in winter. Annual averages of carbon isotopes increased from 2001 toward 2008 and coral luminescence bands observed in the period from 2001 to 2005. These results suggested that the calcification significantly decrease or cease in low temperature. Coral in this study recorded the local history of marine environments at Tatsukushi Bay caused by terrestrial inputs due to heavy rainfall event occurred in 2001. Coral isotopic compositions and skeletal structure were sensitive to response on SST changes. Future analysis using the full length of coral cores could be expected to capture both global environmental changes and local history at Tatsukushi Bay.