European Diatom Database-East African Dataset

The European Diatom Database (EDDI) is a web-based information system designed
to enhance the application of diatom analysis to problems of surface water
acidification, eutrophication and climate change.

The East African training set includes samples from 98 sites situated between
19N and 14S in latitude, 27N and 43E in longitude. They range from afro-alpine
bogs at altitude of up to 4000 m to hypersaline lakes lying below sea-level.
The conductivity ranges from 40 to 50,000 S cm-1 and the pH from 5 to 10.9. The
chemical facies is of the alkaline earths/bicarbonate type for freshwaters, to
the Na/carbonate or Na/chloride type for highly concentrated waters. The
training set consists of 187 samples. Most samples have been collected by F.
Gasse (98) from 1970, P. Kilham (19), J.-F. Talling (14) and R.B. Wood (14).
Other collaborators in collecting diatom samples have been C. Barton, R.M.
Baxter, J. Green, J. Kalff, ad J. L. Richardson. All diatom samples were
counted by F. Gasse. Detailed descriptions of the diatom samples and chemical
analyses were published by Gasse et al. (1983). This paper also provides a
numerical classification of the diatom assemblages. A total of 579 taxa was
identified in the data set, the taxonomy and ecology of which are discussed and
illustrated by Gasse (1986a). This data set was used to develop transfer
functions for estimating pH (Gasse and Tekaia, 1983) and conductivity (Gasse
and Tekaia, unpublished) and the model has subsequently been applied to diatom
sequences to reconstruct lake pH and salinity histories and related changes in
the water balance (e.g. Gasse, 1986b ; Barker, 1990 ; Barker et al., 1991).