Toxic Effects of Aluminium and Fluoride on Planktonic Community of the Microcosms

Aluminium and fluoride were found toxic to phytoplankton, periphyton and zooplankton in the microcosms raised in the greenhouse. The toxicity of aluminium was relatively higher than fluoride, more particularly, during winter season. There were significant reduction in counts of phytoplankton (49-80%), periphyton (algae = 40-68%, zooplankton = 35-75%) and zooplankton (5-77%) in the treatments in comparison to controls. As a result, Reciprocal Simpson index, Equitability index and Shannon- Weiner index decreased. Such changes will affect energy flow in the microcosms.