The overall objective of the proposed research is to develop, calibrate and verify three independent salinity proxies which will be used in climate reconstruction and modeling. Project aims and objectives Most proxy calibrations are based on empirical relationships based on observations in recent systems that cover only part of the total variability through time. Ideally, proxy relationships should be based on an understanding of the mechanisms (biological, chemical, physical) by which proxies are linked to their environmental target parameters. Such a mechanistic understanding includes a detailed knowledge of the actual shell formation process (how are proxies incorporated?) and of the ecological niche of the organism (when and where are proxies incorporated?). Paleosalt methodology 1) A mechanistic study of Mg incorporation during biomineralisation 2) a. Develop an independent salinity proxy based on the ?D of organic compounds b. Develop an independent salinity proxy based on the difference in ?D and 18O 3) Develop an independent salinity proxy based on trace element ratios