Chamaesiphon species in soft-water streams in Germany: occurrence, ecology and use for bioindication

We analyzed the records of several species of Chamaesiphon A. Braun ex Grunow 1865 collected by the water management authorities of the German federal states North RhineWestphalia (NRW) and Saxony (SN). In total, 579 sampling events from 429 different sampling sites at soft water streams and rivers of the Central German Uplands (types 5, 5.1 and 9 of the German typology for running waters) were included. Samples were collected between 2006 and 2012. Sites ranged from unimpaired, nutrient-poor to nutrient-rich sites. Twelve different species of Chamaesiphon were recorded. The epiphytic species C. confervicolus and C. incrustans and the epilithic species C. fuscus, C. polymorphus and C. starmachii were most common in both federal states. Uni- and multivariate methods were employed to describe autecological preferences of these taxa. C. fuscus and C. starmachii occur at significantly lower nutrient levels and therefore are characteristic for unimpaired sites, whereas C. confervicolus, C. incrustans and C. polymorphus prefer nutrient-rich sites. C. confervicolus and C. incrustans are different in respect of the morphological features of the sampling sites like stream width, depth and substrate. C. polonicus which occurs in the medium range regarding nutrients and geochemical properties is known to be a tolerant species. The use of Chamaesiphon species for assessment and especially their classification within the PHYLIB tool is discussed.