Relationships between macrophyte species, their life forms and environmental factors in floodplain water bodies from the Bulgarian Danube River Basin

The composition and structure of macrophyte assemblages in different water bodies from Bulgarian Danube River catchment area for a period of three years were studied. Main environmental variables: water depth and transparency, substrate type, nutrients (ammonium, nitrate, nitrite and total nitrogen, phosphate and total phosphorus) were simultaneously measured. Our aim was to investigate the spatial and temporal variability of macrophyte composition on the taxonomical (species) and functional (life forms) level in relation to environmental factors by means of multivariate analyses (PCA, CCA and RDA). The Bray-Curtis index was also used to investigate species similarities within and between different kinds of water bodies. Hydromorphology and connectivity were the main factors explaining the spatial variations of both species and life forms. The phosphate phosphorus, total nitrogen and temperature were the variables explaining temporal variation of species.