Premium
Evaluating the efficacy of the mollusc T ridacna crocea for reconstructing ancient sea‐surface temperatures in the Rock Islands of Palau, Micronesia
Author(s) -
JEW NICHOLAS P.,
DODRILL TAYLOR,
FITZPATRICK SCOTT M.
Publication year - 2019
Publication title -
archaeology in oceania
Language(s) - English
Resource type - Journals
eISSN - 1834-4453
pISSN - 0728-4896
DOI - 10.1002/arco.5182
Subject(s) - sea surface temperature , archipelago , intertidal zone , isotopes of oxygen , oceanography , shellfish , geology , stable isotope ratio , subsistence agriculture , δ18o , archaeology , geography , fishery , biology , geochemistry , aquatic animal , fish <actinopterygii> , physics , quantum mechanics , agriculture
Previous stable isotope studies for shellfish collected in waters surrounding the Palauan archipelago (north‐western tropical Pacific) have demonstrated that various local shellfish taxa may be reliable recorders of their ambient water temperatures from modern and archaeological contexts. In this study, we analysed stable oxygen isotope (δ 18 O) signatures of Tridacna crocea from the archaeological site of Metuker ra Bisech (B:IR‐2:24) to reconstruct average nearshore sea‐surface temperatures (SST) from two components dated to c.560 and 120 calBP. Modern shellfish samples and environmental data were collected from intertidal zones on nearby Orrak Island to provide a modern analogue. These shells were tested using X‐ray diffraction to ensure no secondary recrystallisation of the aragonitic structure. Uncontaminated samples were measured for δ 18 O to pair with recorded SST. The most appropriate oxygen isotope‐to‐SST conversion formula was then applied to δ 18 O signatures from archaeological T . crocea to estimate SST averages. The results of this study indicate that T . crocea accurately records ambient SST and is a good proxy for palaeotemperature reconstruction. Our results were compared to previous isotopic studies on Palauan taxa collected to identify regional changes to SST through time, thus allowing for comparisons between human subsistence practices, resource availability and past palaeoenvironments.