Towards an understanding of phosphate δ18O in the bones and scales of small pelagic fish
Oxygen isotope ratios of fish biominerals reflect environmental growth conditions - specifically, the temperature and δ18O values of water. In Holocene ocean sediments, phosphate δ18O (δ18OP) values of small pelagic fish bones and scales can be coupled with abundance data to study connections between past climate and population dynamics. This requires the detection of decadal scale climate variability via precise isotope measurements. To accomplish this, isotope data is best corrected by multiple regression methods that facilitate both instrumental monitoring and correction model optimization. Our measurements of δ18O values from bones, scales, and otoliths indicated that all three materials provide similar information about growth conditions, provided that each material's unique allometry is considered. For sardines cultured at controlled temperatures, δ18OP values of scales were consistent with the fractionation equation proposed by Longinelli and Nuti (1973). These results support the use of δ18OP to investigate the paleoecology of small pelagic fish.