The seasonal mean weighted average optima (Table 3) of conductivity
range from 297 lS/cm (Nitzschia obtusa) to 494 lS/
cm (C. placentula). Four diatom species satisfied the indicator
selection criteria for conductivity as Nitzschia gracilis (488 lS/
cm), Navicula cryptocephala (458 lS/cm), Fragilaria sp.
(453 lS/cm), and S. acus (455 lS/cm). For BOD optima, the
seasonal mean ranged from 7.9 mg/L (Cyclotella kuetzingiana)
to 2.2 mg/L (F. acus). Diatom species as Amphora perpu