Contrasting endolithic habitats for cyanobacteria in spring calcites of the European Alps.

It is often difficult to decide which cyanobacteria found in endolithic habitats of calcite spring-tufa deposits are present as ephemeral components of the biota or are persistent, structural elements. To answer this question, we repeatedly studied two microhabitats of contrasting calcareous tufa springs in the European Alps. Pigment extracts, fluorescence probe measurements of samples and traditional microscopy confirmed the dominance of cyanobacteria over eukaryotic algae and their viability in both microhabitats.