Classification of Danube Delta lakes based on aquatic vegetation and turbidity

The aquatic vegetation present in lakes in the delta of the River Danube wa s studied using field survey data and satellite image. Based on the spectra l information from satellite images, three categories of lakes were disting uished: clear / macrophyte-dominated, intermediate and turbid / poorly vege tated. The satellite-based classification was consistent with vegetation co ver and water transparency measured in the field. Cluster analysis of veget ation data from 235 releves made in 22 lakes (1996-1998, each year in June) identified ten submerged vegetation types. The lakes were characterised by the frequency of occurrence of each vegetation type and ordinated, using P rincipal Components Analysis (PCA). A strong relationship appeared between the composition and density of aquatic vegetation and water transparency. I solated lakes within the extensive beds of floating reed (plaur lakes) form ed a separate group. Based on the ordination analysis, connectivity of lake s in the Danube Delta was concluded to be a major factor for the developmen t of dense macrophyte vegetation.