Diatoms are an important and often dominant component of periphyton, and their contribution to primary production in aquatic systems has largely been underestimated. Apart from the qualitative and quantitative importance of diatoms in the periphyton, the study of diatoms has the added value that they are excellent environmental indicators, since they are present in almost all aquatic habitats and react with speed and sesitivity to environmental changes. Contents: General Introduction/ Study area (Empordà wetlands/ The salt marshes of the Empordà Wetlands Natural Park)/ Material and Methods/ Factors favouring the predominance of different types of aquatic primary producers (phytoplankton - peiphyton - macrophytes) in lentic waters of Empordà wetlands/ Diatom taxa of the salt marshes of the Empordà wetlands (Check-list/ Diatom taxa of problematic taxonomy/ Plates)/ Factors affecting periphytic diatom communities in the salt marshes of Empordà wetlands/ Morphological variation of Nitzschia frustulum as a response to changes in some environmental variables/ General discussion/ Conclusions/ References/ Appendix I (Taxa acronyms)/ Appendix II (Relative abundance of the species by months and by waterbodies).weiterlesen