Influence of zinc on productivity and species composition in algal periphyton communities
Atazadeh, Islam; Sharifi, Mozafar
In order to evaluate the influence of zinc on biomass and species composition in algal periphyton communities, indoor artificial streams were used with differing zinc additions (0, 1 and 2 mg L-1). The effects of zinc on community biomass were assessed by measuring dry mass, ash-free dry mass (AFDM), chlorophyll a, species composition, relative abundance, biovolume and bioconcentration factor. In artificial streams with zinc, there was a significant (p < 0.05) reduction of chlorophyll a, dry mass and AFDM. Species diversity and relative abundance of periphyton species changed drastically under the influence of zinc. In an artificial stream containing the higher concentration of added zinc (2 mg L-1), the taxonomic composition of the population shifted from a cyanophyceaen dominated community to a community mainly consisting of Chlorophyceae, while changes among species within the Bacillariophyceae did not show a marked difference under the influence of zinc. Some taxa such as Oocystis crassa and Scenedesmus sp. showed a strong association with the higher concentration of zinc. These observations suggest that biomass and structure of periphyton community could serve as an indicator of zinc pollution.