Conclusion

The investigation of six wetlands of Coimbatore records 27 dominant species such as Cyclotella meneghiniana, Nitzschia sp., Sellaphora pupula, Gomphonema parvulum and Navicula sp.which are cosmopolitan in its distribution. Singanallur wetland and Noyyal river stretches are characterised by pollution tolerant species with low diatom diversity. Diatom assemblages indicate that Vedapatti, Perur and Sundakamuthur wetlands are moderately polluted, while Pallapalayam, Noyyal River and Singanallur wetlands are heavily polluted. In these wetlands distribution of Cyclotella sp. was determined by high electrolyte conductivity and Gomphonema sp. and Nitzschia sp. were distributed in all pH and conductivity ranges, where Fragilaria sp. is restricted to neutral alkaline pH and moderate electrolytic waters. CCA plot also marks that Pallapalayam, Singanallur and Noyal river sites are associated with largest amount of variation in the data set. High pH and electric conductivity values accounted for most of the variability in the diatom assemblages. With respect to habitat preference epiphytic, epilithic and episammic habitats contained 50%, 10.4%, and 7.2% of taxa unique to that habitat. Diatoms indices reveal that water quality of the sampled wetlands are moderate (mesotrophic) to heavily polluted (eutrophic). Current study conveys that diatom indices can be used in gaining support and recognition for diatom based approaches to water quality monitoring. This study can further be adopted in the formulation of diatom metrics for dissemination of simplified monitoring method as useful information to resource managers and government authorities for wetland management.