Growth and distribution of endolithic algae in some North Yorkshire streams (UK)

Abstract

A survey of some UK, limestone streams showed that four endolithic algae: Gongrosira incrustans, Hyella fontana, Phormidium favosum and Schizothrix perforans were widely distributed and often abundant. S. perforans colonized limestone substrata within one year and trichomes penetrated 70 μm into the rock. On older surfaces, endoliths penetrated up to 1·3 mm of rock but were rare below 0·5 mm. Large calcite crystals were barely colonized after three years of immersion. All species etched the substratum, showing euendolithic behaviour, but zones of weakness in the limestone fabric were also exploited by Gongrosira and Schizothrix.

Carbon fixation rates of 7–20 mg C m^-2 h^-1 which were obtained for pure growths of S. perforans, were comparable to those of some encrusting algal communities in the stream.