A DIATOM-CONDUCTIVITY TRANSFER-FUNCTION FOR SPANISH SALT LAKES

Diatom-salinity transfer functions for interpretation of palaeosalinit y and palaeoclimate change have been developed successfully for parts of North America and North and East Africa, but there is a need for da ta-sets in other saline lake regions of the world. A data-set of 74 mo dem diatom samples and associated water chemistry data is described fr om Spain. The influence of conductivity and other environmental variab les on diatom distribution is explored using canonical correspondence analysis (CCA) and partial CCAs. A transfer function is derived for co nductivity (70 samples) whose apparent predictive ability is high (app arent r(2) = 0.91). Performance under jackknifing is poor due to the h eterogeneous nature of the data-set and poor coverage of the freshwate r end of the salinity gradient. There is a lack of suitable low-salini ty sites in Spain, and the accuracy of estimated salinity optima and t olerance ranges may be improved by merging this data-set with those of other regions. The Spanish transfer function has strong affinities wi th the African data-set and contributes important ecological data for diatom taxa which are absent or poorly represented in the modern flora of African lakes, and for which, in fossil material, there were previ ously no good modern analogues.