This study describes the toxic effects of different prominent aquatic pollutants?heavy metals (Cd & Pb), pesticides (alphamethrin and deltamethrin) and salt (NaCl)?on the intracellular proline content in the cyanobacterium, Westiellopsis prolifica?Janet strain?NCCU331. Despite a reduction in growth (measured as chlorophyll a content), the intracellular proline content increased in the presence of heavy metals, pesticides and high salt concentration. The intracellular cyanobacterial proline accumulation was more pronounced under salt stress than in the presence of pesticides and heavy metals. We have also compared whether or not anionic components influence heavy metal toxicity. It was found that the chlorides of Cd and Pb were more [...]