Metal and metalloid contamination in the waterbodies and its undesirable effect on the residing diatom communities is a problem of global concern. In the present study, the effect of metals (Fe and Zn) and metalloids (As and Hg) was examined (for 15 days) in the motility and protoplasmic content of different live diatom genera under laboratory conditions. Under Hg treatment, the % motile frustules in the six diatom genera lies between 2–5% after one day of exposure, while under As treatment value lies between 30–80%. In contrast, under Zn treatment % motile frustules in the six diatom genera lie between 60–80% after one day of exposure, while under Fe treatment value lies between 40–80%. However, after 15 days of exposure to Hg, the % motile frustules in the six diatom genera lies between 0–3%, while under As treatment value lies between 5–20%. In contrast, under Zn treatment % of motile frustules in the six diatom genera lies between 10–40% after one day of exposure, while under Fe treatment value lies between 10–20%. Based on the above results, the toxicity trends of metals and metalloids showed the following: Hg > As > Fe > Zn. Based on correlation ship analysis, it is found that % motile frustules in different diatom genera showed an inverse relationship with the % reduction in the protoplasmic content of the live cells i.e., the higher the value of the reduction in protoplasmic content lower will be the % motile frustules in the community. Based on obtained results, we can conclude that motility in live diatoms is the highly sensitive endpoint to assess the impact of metal and metalloid contamination in the water bodies. However, in comparison to metals, diatoms are more sensitive to the metalloid’s exposure, especially for Hg. Finally, we conclude that % motile diatom frustules in the community is a highly sensitive, quick, and easy-to-assess biomonitoring tool for assessing the metal and metalloid contamination in the water bodies.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.