Alternative stable states of macrophytes versus phytoplankton in two interconnected impoundments of the New Danube (Vienna, Austria)
Dokulil, M.T.; Janauer, G. A.
Natural dynamic processes leading to a shift from algal to macrophyte domination in the two impoundments of the New Danube flood-relief channel are associated with and explained by a theory of bi-stable states. Changes are largely caused by alterations of water level and hence the retention times of the impoundments. Implications for water quality evaluation are discussed using the concept of potential water column concentrations of phosphorus. Calculations indicate the importance of macrophytes as structures that can buffer nutrient concentrations, via uptake and storage in plant tissues. Results are contrasted with similar but anthropogenically-induced forward and reverse shifts in the nearby Old Danube seepage lake, and implications for lake management are discussed.