The effect of metals accumulated in reed (Phragmites australis) on the structure of periphyton

Studies on trace elements in reed stands and limiting effect of the reed substrate on the periphyton structure were performed in various aquatic ecosystems of Greece during the summer and autumn of 2006. The analysed factors were concentrations of chemical elements (cadmium, lead, zinc, chromium, nickel, copper, cobalt, iron, manganese, potassium, sodium, calcium, magnesium) in reed shoots as well as the density of zooperiphyton and phytoperiphyton taxa. The relationships between metal concentrations and periphyton structure were determined with the use of the multivariate methods Canonical Correspondence Analysis (CCA), Detrended Correspondence Analysis (DCA) and RDA (Redundancy Analysis). The results showed that bioaccumulation of lead and cadmium in the reed had the most negative influence on zooperiphyton species, while low concentrations of alkali metals favoured the occurrence of Cyclopoida, Cladocera (Chydorus sp.) and Oligochaeta (Neis sp.). A considerable resistance to toxic heavy metals characterised Cyanophyta representatives and, partly, colonial Bacillariophyta. High concentrations of alkali metals supported the presence of unicellular Bacillariophyta but diminished the densities of colonial Bacillariophyta and Chlorophyta of the genus Scenedesmus.