Abstract:

Oyster shells that were potentially exposed to oil from the BP spill were analyzed across ontogeny for stable carbon (δ13C) and oxygen (δ18O) isotopes. It was hoped the profiles could be used to calculate growth rates to better interpret data produced by collaborators in other components of the overall project. The isotope profiles did record evidence of oyster growth, but the data were not determined to be necessary once collaborators found the most of these shells were not contaminated.

Suggested Citation:

Andrus, Fred. 2015. Stable oxygen and carbon isotope profile in oysters shells from the Alabama coast that may have been exposed to oil. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7D798C6

Purpose:

The goal of this project is to measure stable carbon (δ13C) and oxygen (δ18O) isotopes through ontogeny in valves of oysters thought to have been exposed to oil and/or dispersant. It is hoped that the oxygen isotopes will record the time of oyster transplant from the hatchery into the wild as would be expected with a sudden shift in both δ18Owater and temperature. Using this benchmark, growth rates can be calculated and the carbon isotope profile or other biogeochemical parameters could then be analyzed for evidence of oil exposure. If found, these measurements would potentially lead to a new time-series proxy for oil exposure in wild oyster populations.

Data Parameters and Units:

Powdered calcite samples from the oysters (no aragonite sections of the shell were milled) were analyzed for δ13C and δ18O using a Thermo GasBench II coupled with a Thermo Delta plus and/or Thermo Delta V gas-source isotope ratio mass spectrometer in contiguous He flow mode. All results are presented in parts per mil (‰) relative to the Vienna Bee Dee Belemnite (VPDB) standard. Average analytical precision was finer than 0.05‰ for both δ13C and δ18O based on repeated analysis of NBS-19 (n=15/96 analysis run). These standard data were also used to assess and correct for drift and sample-size linearity if needed. Sample naming: F.M. = Samples collected from Fort Morgan OB = Samples collected from Orange Beach

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