Endolithic algae and cyanobacteria from cliffs of the Niagara Escarpment, Ontario, Canada

A comprehensive survey for endolithic organisms was undertaken to evaluate the distribution of endolithic algae and cyanobacteria in the structure of ancient cliff ecosystems of the Niagara Escarpment. Rocks were collected at 12 sites along the escarpment. Three rock samples were collected from each of five transects for a total of 180 rock samples. Cryptoendolithic or cha smoendolithic organisms were extracted from freshly cleaved faces under lab oratory conditions, and attempts were made to culture, grow, and identify t hese organisms. Cultures of cryptoendolithic organisms were successfully ob tained from between 6.7 and 40% of the culture plates from any one site, wh ereas chasmoendolithic organisms were obtained from 98% of the attempts. Tw enty-two taxa were found, including some Cyanophyta that were present at mo st sites (Chlorogloea) and others that were found rarely (Schizothrix). Cya nophytes were more common at northern sites than southern sites. Among the Chlorophyta, Stichococcus bacillaris was ubiquitous, but Stichococcus exigu us was restricted to one site. The chlorophytes were evenly found along the Escarpment. No geographical trends were obvious among the Xanthophyceae, b ut some taxa such as Chloridella neglecta were common and others such as El lipsoidion stichococcoides were not. These results suggest that endolithic organisms within the rocky limestone cliffs of the Niagara Escarpment are n ot uniform in abundance or species composition. Consequently, management pl ans intended to maintain microbial species diversity in the face of differe nt patterns of land use and environmental pollution may have to be location -specific along the escarpment.