Temperature regime in a braided river system : an indicator for morphological heterogeneity and ecological potential

Water temperature is one of the most important abiotic variables in streams and strongly influences the distribution and abundance of freshwater organisms. It might be assumed that in natural streams home to heterogenous habitats also a wide range of thermal habitats exist, whereas in altered and channelized streams variability in water temperatures will be less pronounced. In order to test this hypothesis a case study at river Sense in Switzerland was carried out. At five river reaches characterized by different morphological patterns variability of water temperature was analysed. Temporal variability could be investigated by means of temperature loggers, whereas detailed temperature measurements in each water body along predefined transects served to elaborate spatial variability. As a key result if could be shown that there is an evident correlation between morphological characteristics and spatial variability of water temperatures.