Spatial heterogeneity and ecology of algal communities in an ephemeral sandstone stream in the Bohemian Switzerland National Park, Czech Republic

Abstract

Spatial patterns and biodiversity of algae assemblages, and the effect of environmental factors on species composition were studied in an ephemeral pristine stream. Samples were taken along a longitudinal stream transect beginning at the source. At each sampling site, different types of substrates were collected and water chemistry investigated. A total of 109 infrageneric algal taxa were identified with diatoms being the most diverse group (85 taxa). Characteristic diatom species included: Chamaepinnularia soehrensis, Diadesmis laevissima, D. paracontenta, Eunotia exigua agg., E. incisa, E. ursamaioris, Fragilariforma virescens, Microcostatus krasskei, Pinnularia silvatica agg., and P. subcapitata agg. In addition, green algae of the Chlococcaceae agg., and Klebsormidium flaccidum were also abundant. Composition of algal assemblages were primarily influenced by the type of substratum (20.5% variance explained, p = 0.001) and by the spatial distance from the stream origin (3.0%, p < 0.05). Variation in species composition explained by conductivity, pH, temperature and nitrogen was relatively low (10.1%).