Evaluation of ostracod-based palaeoenvironmental reconstruction with instrumental data from the arid Faiyum Depression, Egypt

• Published in: Journal of paleolimnology Vol. 38; no. 2; pp. 261 - 283
• Main Authors: Keatings, K. W., Hawkes, I., Holmes, J. A., Flower, R. J., Leng, M. J., Abu-Zied, R. H., Lord, A. R.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.08.2007
• Subjects: Aquatic crustaceans; Aridity; Calcium; Carapace; Carbon; Carbon isotopes; Carbonates; Composition; Cyprideis torosa; Euryhalinity; Evaluation; Fossil assemblages; Fossils; Inland waters; Isotope ratios; Juveniles; Lake deposits; Lake sediments; Lakes; Ostracoda; Qualitative analysis; Ratios; Reconstruction; Salinity; Salinity effects; Sediments; Solutes; Species; Water levels; Water salinity; Wave energy; Wave power; Egypt; Egypt, Arab Rep., El Faiyum, Qarun L; Egypt, Arab Rep; Egypt, Arab Rep., Faiyum
• ISSN: 0921-2728; 1573-0417
• DOI: 10.1007/s10933-006-9074-x

The utility of ostracod-based palaeoenvironmental reconstruction was evaluated using instrumental data for Lake Qarun, Egypt. The euryhaline ostracod Cyprideis torosa was the only species found in the lake’s recent sediment record. This species is known to tolerate salinity levels and water solute compositions that may prevent colonisation by other species. Oxygen and carbon isotope ratios of ostracod carbonate from lake sediments covary with changes in instrumental values for lake level and salinity for the period 1890–1974. δ13C-values correlate negatively with lake water salinity (r2 = 0.87) and δ18O-values correlate negatively with measured lake level changes (r2 = 0.41). Other ostracod proxy data provide qualitative information on lake level trends. Fossil assemblage data (juvenile/adult and valve/carapace ratios and valve preservation) provide information on wave energy. Ecophenotypic variation of C. torosa valves provided some useful palaeolimnological information. Sr/Ca and Mg/Ca ratios in ostracods were not found to reflect water composition, due to the uncoupling of these ratios with salinity in Lake Qarun. Overall, our results highlight the need to calibrate ostracod proxy data in modern systems prior to their use for palaeoenvironmental reconstruction.