Journal article
Stable carbonate isotopes in giant clam shells
Abstracts with programs - Geological Society of America, Vol.49(6)
Geological Society of America, 2017 annual meeting & exposition (2017)
2017
Abstract
Giant clams (Cardiidae: Tridacninae) are excellent bioarchives of their local low latitude reef ecosystems because they are sedentary, grow rapidly and have longevity. Stable oxygen isotopes from shell carbonate are in equilibrium with seawater, thus useful archives. However, stable carbon isotopes are often measured simultaneously but disregarded as they have not been well-associated with environmental or vital factors. Stable isotope ratios from the internal layer of the aragonitic shells have previously been measured in fourteen modern and ten fossil individuals. This study presents a thorough literature review of all published stable isotope profiles of Tridacna to compare species, localities, and changes through time as well as present original isotope profiles from a modern Palauan T. derasa. Results suggest that delta (super 18) O is sensitive to very local conditions, thus cannot be accurately compared on an oceanic scale. However, median delta (super 13) C values have become depleted in giant clam shells since the early 1960's, the oldest modern measurement, additionally supported by delta (super 13) C of T. derasa collected from Palau in 2016. This trend is similar to that of delta (super 13) C of atmospheric CO (sub 2) , which has been becoming depleted in (super 13) C due to the anthropogenic burning of fossil fuels which are isotopically light. Since the evolution of C (sub 4) plants (isotopically heavy) in the Miocene, atmospheric CO (sub 2) has become heavier, thus as fossil fuels burn, they are introducing isotopically light CO (sub 2) from C (sub 3) sourced fossil fuels. Atmospheric CO (sub 2) is mixed relatively quickly and incorporated into seawater. Subsequently it is included in the shell aragonite. Although there are other influences on carbon in giant clam shells, it appears that delta (super 13) C values can be a useful analogy to delta (super 13) C from atmospheric CO (sub 2) .
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Details
- Title
- Stable carbonate isotopes in giant clam shells
- Creators
- Michelle Gannon - Drexel UniversityDavid VelinskyAnonymous
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.49(6)
- Conference
- Geological Society of America, 2017 annual meeting & exposition (2017)
- Publisher
- Geological Society of America (GSA)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Environmental Biogeochemistry; Biodiversity, Earth, and Environmental Science (BEES)
- Identifiers
- 991020836610604721