ECOLOGICAL AND BIOGEOGRAPHICAL ASPECTS OF DIATOM DISTRIBUTION IN PYRENEAN SPRINGS

The distributions of many diatom taxa in the Pyrenean springs show remarkable affinities with other areas. Soft water springs have many species of boreoalpine distribution, while diatom communities inhabiting the calcareous springs possess noticeable similarities with temperate calcareous areas. Water mineral content emerges as a key factor in modelling diatom distribution. When compared with other environments (e.g. streams, subaerial rocks), springs in the Pyrenees show a higher number of taxa with poorly-known distribution. Slow-moving springs have more characteristic communities, possibly because conditions of flow allow colonization of more habitats. © Taylor & Francis Group.