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Age and Growth Program

Stable Oxygen Isotopes

Tom Helser at the ion microprobe at the University of Wisconsin Read the full article here (PDF)

The Age and Growth Program is collaborating with colleagues at the University of Wisconsin, Department of Geosciences to analyze Pacific cod otoliths for stable oxygen isotopes. The Ion Microprobe-Secondary Ion Mass Spectrometer (SIMS) is a $6M instrument funded by the National Science Foundation that is used to explore new applications of in situ analysis to stable isotope goechemistry. Research in many disciplines can benefit by using the IMS-1280 ion microprobe, the latest version of CAMECA large radius magnetic sector SIMS. The dramatic reductions of sample size and analysis spot sizes from 1 to 10 micrometers offer many exciting, potentially revolutionary, research opportunities. In this study, researchers were able to obtain nearly one hundred oxygen isotope spot samplesacross a traverse of a thin sectioned age-6 Pacific cod otolith that was tagged with an electronic data logger. Detailed analysis of oxygen isotopes and in situ temperatures of over a half dozen otoliths from archived tagged cod provides new innovative tools for age validation and understanding biogeography.

 

 

Tom Helser at the ion microprobe at the University of Wisconsin

Ion microprobe spot samples and measured sequence of secondary ion mass spectrometry stable oxygen isotopes in a traverse section of a six year old Pacific cod. Measured peaks in the oxygen isotope signature correspond to seasonal temperature lows in the Bering Sea and help researchers elucidate the age of fish (oxygen isotopes and temperature are inversely related-below).

 

 

 

 

 

 

Tom Helser at the ion microprobe at the University of Wisconsin

Sequence of ion microprobe spot samples measuring stable oxygen isotopes from a traverse sectioned Pacific cod tagged with an electronic data logger (temperature and depth) and at liberty for two years illustrates the strong inverse relationship between oxygen isotopes and in situ temperatures. Oxygen isotope signatures in otoliths allows researchers to reconstruct the thermography of a fish’s life history uncovering questions of the study of biogeography.


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