Total biovolume of major diatom species in the periphytic community subjected to various nutrient enrichments in March and June 2014. Abbreviations for various treatments have been explained in Figure 2. Data are presented for day 10 and day 20 only. Data bearing different letters for different time periods are significantly different from each other (p < 0.05, Tukey's HSD test). The uppercase letters have been used for March, while lowercase for June.