The response of ostracod shell chemistry to seasonal change in a Mediterranean freshwater spring environment

We established the relationships between water chemistry changes in a pool fed by a permanent spring and seasonal variations in trace-element contents (Sr & Mg) in the shells of the ostracod species Herpetocypris intermedia, based on monthly collections of ostracod and water samples. The water chemi stry of the investigated pool (Maiques, Valencia, Spain) was dominated by c alcium and bicarbonate, and showed marked seasonal variation in alkalinity, Ca2+ content, Sr/Ca and Mg/Ca ratios. Although the variability in the wate r chemistry was relatively low (similar to 10% relative standard deviation over the entire period), the trace-clement contents: in the ostracod shells tracked the seasonal change in the water chemistry of Maiques pool. Moreov er, due to the rapid renewal of H. intermedia population, this species is a ble to record in its shells the evolution of the water chemistry at a month ly time scale. Our results also showed that, in the Maiques pool system, os tracod Sr/Ca and Mg/Ca ratios increased with the decrease in water salinity . To our knowledge, this is the first geochemical study of ostracods dwelling in spring environments. The results of this study may be applied to paleoh ydrological reconstruction using ostracods preserved in sediments deposited around springs (i.e., travertine and tufa deposits).