Abstract (eng)
Thermal springs are unique biotopes and biodiversity hotspots, which often provide habitats for endemic species because of stable conditions. In this study we focused on the benthic algae community of a low thermal spring “Urspungsquelle” and six sites at its downstream water network, to reveal its changes through the seasons. In addition, several environmental parameters, such as temperature, solar radiation, major ions and trophic values were analyzed.
Multivariate statistics shows that no seasonal differences occur in the phytobenthos at the well, while with distance to it, seasonal patterns are revealed. Canonical correspondence analyses also showed that the spring site and the most distant sampling point have completely different algae species, while the other sites cluster into two major groups. The responsible parameters for this species distribution were total organic carbon, total phosphorous, pH, oxygen, calcium, sulphate, sky openness, and the water temperature.
Diatoms showed the highest proportion of taxa in all locations, followed by Chlorophyta and Cyanobacteria. Rhodophyta and Chrysophyceae were found in low abundances. The taxa number increases with distance to the spring site due to more disturbances and stressors as well as more resources. With higher levels of disturbances and stressors at the downstream sites a tipping point is reached and taxa number again decreases.