Acute and chronic toxicity of pyrene to the unicellular marine alga Phaeodactylum tricornutum

Polyaromatic hydocarbons (PAHs) are common contaminants in the coastal waters and are known to be bioaccumulated by unicellular algae [ 1; 2]. The influence of microalgae on the fate of PAHs is especially important in the eutrophic areas. The aim of the present study was to determine the toxic effects of pyrene on Phaeodactylum tricornutum using short and medium-term (batch) toxicity tests. The pyrene concentrations were also determined throughout the batch period to check whether there was a decrease in pyrene concentrations in the presence and in the absence of algae. The results of short-term toxicity tests showed that pyrene is acutely toxic to phytoplankton ( EC50 = 68-70 ppb). The dose-response relationship was much less clear in batch growth experiments and disappeared completely when the cultures reached the stationary phase.