European Diatom Database-Svalbard pH dataset

This training set is comprised of water chemistry and surface sediment diatom assemblages from 23 lakes on Svalbard (Jones & Birks in press). The top 0.5 cm of short sequences taken by gravity corer were analysed for diatoms, 500 diatoms per sample were counted for these surface sediment samples. Over 180 taxa were found but generally samples are taxon poor, with the majority of sites dominated by benthic genera such as Fragilaria, Navicula and Achnanthes. Planktonic Cyclotella species occur at only 3 sites. Current relationships between diatom abundance and water chemistry and other environmental variables were explored numerically and a preliminary transfer function for pH was constructed. Lakes fall into three groups on the basis of their diatom assemblages from (1) high pH, high cation, high conductivity sites characterised by Amphora libyca, (2) shallow sites with relatively high nutrient values characterised by Fragilaria species and (3) more acid and dilute sites with higher snow cover in the catchments characterised by small Achnanthes species and Navicula digitulus. Jones & Birks also apply the training set to the diatom assemblages of five sediment cores that represent the recent past. Further details of water chemistry methods, site locations and descriptions are given in Birks et al. (2001) and Wathne et al. (1997).