Interpretation of benthic foraminiferal stable isotopes in subtidal estuarine environments
Diz, P.; Jorissen, F.J.; Reichart, G.-J.; Poulain, C.; Dehairs, F.; Leorri, E.; Paulet, Y.-M. (2009). Interpretation of benthic foraminiferal stable isotopes in subtidal estuarine environments. Biogeosciences 6(11): 2549-2560. http://dx.doi.org/10.5194/bg-6-2549-2009
In: Gattuso, J.P.; Kesselmeier, J. (Ed.) Biogeosciences. Copernicus Publications: Göttingen. ISSN 1726-4170; e-ISSN 1726-4189, more
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| Keywords |
Biochemical phenomena > Calcification
Chemical compounds > Nitrogen compounds > Ammonia
Environmental effects > Salinity effects
Isotopes
Oxygen
Properties > Water properties > Temperature > Water temperature
Water bodies > Coastal waters > Coastal landforms > Coastal inlets > Estuaries
Water bodies > Inland waters > Rivers
Ammonia tepida (Cushman, 1926) [WoRMS]; Foraminifera [WoRMS]; Haynesina germanica (Ehrenberg, 1840) [WoRMS]
Marine/Coastal; Brackish water |
| Authors | | Top |
- Diz, P.
- Jorissen, F.J.
- Reichart, G.-J.
- Poulain, C.
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- Dehairs, F., more
- Leorri, E.
- Paulet, Y.-M.
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| Abstract |
Here we present a novel approach for the interpretation of stable isotope signatures recorded in benthic foraminifera from subtidal estuarine environments. The stable isotopic composition (d18O and d13C) of living Ammonia tepida and Haynesina germanica is examined at four stations in the Auray River estuary (Gulf of Morbihan, France) sampled in two contrasting seasons, spring 2006 and winter 2007. Comparing benthic foraminiferal d18O measurements with theoretical oxygen isotopic equilibrium values, calculated on the basis of water temperature and salinity measurements in the upper and lower estuary, i.e., T-S-d18Oeq. diagrams, strongly suggests that foraminiferal faunas sampled at the four stations calcified during different periods of the year. This interpretation can be refined by using the benthic foraminiferal d13C, which is mainly determined by the mixing of sea and river water. In the upper estuary foraminifera mainly calcified in early spring and winter, whereas in the lower estuary calcification mainly took place in spring, summer and autumn. This new method provides insight into the complexity of estuarine benthic foraminiferal stable isotope records. In addition, it can also be used to obtain new information on preferred calcification periods of benthic foraminiferal taxa in different parts of the estuary |
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