Abstract
The role of different taxa of plankton as biological sign of heavy metal pollution in the river Ravi from Lahore Siphon to BalokiHeadworks has been studied. Levels of heavy metals investigated were higher than the permissible standards suggested for drinking water by EPA of USA and Pakistan. Aquatic biota exhibited higher tendency to amass metals in their bodies. The phytoplankton taxa showed direct relationship with the concentrations and amount of metals in river water as these taxa disappeared in extremely polluted sampling sites. The zooplankton taxa were almost absent due to heavy metal pollution. Among 13 zooplanktonic groups investigated, Brachionus and Cyclops were dominating with higher abundance. Present study indicated a strong affinity of plankton for the metal accumulation from the water.