Stable carbon and oxygen isotop of freshwater mollusk for seasonal and climate change’s indicator

Fossil shells use to tell what the climate might have been like in the past. Stable isotope value of biogenic carbonate material including mollusk shell has become an important tool to evaluate environmental variable such as temperature, δ18 O and δ 13C. These biologic archives are particularly interesting because shell or skeletal carbonate is often deposited continually over the lifetime of the organism and isotopic compositions recorded in the carbonate can potentially be used to reconstruct past conditions. This information is important and useful to predict seasonal changes in the future. Carbonate samples took from Adult and Embryo Gastropod (Pachychilidae : Tylomelania) and Bivalve (Unionidae). Inner layer shell gastropod was drilled by hand-drill along the ribs. Sections of bivalve shell were mounted on glass slides. Using a computer assisted MERCHANTEK EO – Micromill, sequential samples were milled parallel to growth banding from the shell.Oxygen and carbon isotope was measured using Finnigan Delta mass spectrometer connected with GasBench II and equipped with CTC Combi PAL Autosampler device. The Unionidae oxygen isotopes vary on the range -8,34‰ to -5,59‰ More maximum values among the oxygen isotope exhibit the isotopic composition closer to dry conditions. It can define at least 10 maximum peaks for δ18O Unionidae. It worse assumed that the Unionidae pass 10 dry seasons equal with 10 years along their life. δ18O values of adult Tylomelania range from -6,88‰ to - 6,21‰ and δ13C values range for -8,82‰ to -7,65‰. Whereas, embryo δ18O vary between -7,71‰ to - 6,52‰ and δ13C is about -15,05‰ to -8,49‰. Unfortunately, the δ18O and δ13C data from both adult and embryo of Tylomelania were not quite significant. More carbonate sample along their growth line complete with the information regarding their life cycle, nursing care period, and also ecological data was needed to explain δ18O and δ13C composition record of the embryo.