Abstract
Species diversity and cover of aquatic macrophytes were investigated in the River Salaca in 2007. In total 24 different taxa were found. Schoenoplectus lacustris was the dominant species, Sagittaria sagittifolia, Nuphar lutea, Nymphaea candida, Butomus umbellatus and different Potamogeton species were frequent. Cover of macrophytes varied in the river between 10-90%, maximum in-stream cover reached in rapidly flowing sites. Comparison of total cover of macrophytes in 1986 and 2002 surveys of several stretches was done. Causes for the changes are discussed. The increasing growth of aquatic vegetation in the River Salaca have been related to climatic factors—higher mean annual air temperatures, earlier springs and decrease in the period of ice cover in winter.