Evaluating Potential of Traditional and Newer Periphytic Diatom Metrices for Deciphering The Impact of Organic Pollution on Residing Aquatic Biofilms

Abstract

The present study examined impacts of organic contamination on periphytic biofilms at different sites near rivers using various traditional and newer diatom-based metrics, which is rarely tested under organic contamination. All examined sites were dominated by diatoms rather than green algae, which often dominate nutrient-rich sites. Biodiversity indices were higher at riverine and mass bathing sites than the kitchen waste site. Newer diatom metrics showed more promising results in terms identifying possible differences among sites. The three examined waste sites showed the dominance of motile forms, high percentages of unhealthy cells and enlarged lipid bodies in the community, indicating the contamination of nutrients and organic matter. A remarkable higher percentage of tube-dwelling forms at kitchen waste sites likely indicates the presence of organic contamination in the water. The percentage of deformed diatom frustules was low at all sites, indicating that organic contamination did not affect the morphology of diatom cells, but the occurrence of both cell shape and striae deformations at the RWS site might indicate slight metal contamination. Finally, we conclude that the combination of both traditional and newer diatom metrics in biomonitoring improves our understanding on the effects organic contamination in aquatic ecosystems.