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Biogeosciences An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
07 Mar 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Biogeosciences (BG) and is expected to appear here in due course.
Also tropical freshwater ostracods show a seasonal life cycle
Juliane Meyer1, Claudia Wrozyna1, Albrecht Leis2, and Werner Piller1 1University of Graz, Institute of Earth Sciences, NAWI Graz Geocenter, Heinrichstrasse 26, 8010 Graz, Austria
2JR-AquaConSol GmbH, Steyrergasse 21, 8010 Graz, Austria
Abstract. Isotopic signatures of ostracod shells became common proxies for the reconstruction of paleo-environmental conditions. Their isotopic composition is the result of the composition of their host water and the phenology and ecology of the target species. The sum of spatial and temporal variations from environmental factors in the species habitat defines the maximum isotopic variation of a population during the time of their shell formation. Here we present isotopic signatures (δ18O, δ13C) of living Cytheridella ilosvayi (Ostracoda) and chemical and isotopic compositions of 14 simultaneously sampled freshwater habitats in South Florida and instrumental data of the region. The chemical and isotopic compositions of the selected sites characterize the different habitats and show the influence of the source water, biological activity and the duration of exposure to the surface. Isotopic signatures of C. ilosvayi shells correlate well with the isotopic composition of their host waters. Within-sample variability of repeated isotopic measurements of ostracod shells reflect habitat dependent ranges and indicate temperature and the δ18O composition of precipitation (δ18Oprec) as regional environmental factors responsible for the population variation. Instrumental data of water temperature and δ18Oprec were used to calculate the monthly variation of a theoretical calcite in rivers of Florida showing distinct seasonal variations in values and ranges. Different configurations of the theoretical calcite were compared to the within-sample variability to identify possible calcification periods of C. ilosvayi. For a plausible calcification period the ostracod isotopic range has to correlate with mean values of the theoretical calcite with a slight positive offset (vital effect) and the extension of the theoretical calcite range. The tested model suggests a seasonal calcification period of C. ilosvayi in early spring. The surprising seasonality of a tropical ostracod life cycle is probably coupled to the hydrologic cycle of Florida. The results of this study contribute to the application of ostracod isotopes in modern calibration studies and their potential use in paleontology.

Citation: Meyer, J., Wrozyna, C., Leis, A., and Piller, W.: Also tropical freshwater ostracods show a seasonal life cycle, Biogeosciences Discuss.,, in review, 2017.
Juliane Meyer et al.
Juliane Meyer et al.


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Short summary
Isotopic signatures of ostracods from Florida correlate with their host water implying a regional influence of temperature and precipitation. Calculated monthly configurations of a theoretical calcite formed in rivers were compared to ostracod isotope composition. The data suggest a seasonal shell formation during early spring that is coupled to the hydrological cycle of the region. The surprising seasonality of tropical ostracods is of importance for paleontological interpretations.
Isotopic signatures of ostracods from Florida correlate with their host water implying a...