Multiple stress effects on marine planktonic organisms: Influence of temperature on the toxicity of polycyclic aromatic hydrocarbons to Tetraselmis chuii

In the present context of global warming and increasing long-range transport of oil and goods by sea potentially resulting in oil spills, more knowledge on the toxicological interactions between temperature and oil components on marine organisms is urgently needed. Therefore, the effects of temperature increase on the toxicity of three polycyclic aromatic hydrocarbons (PAH; anthracene, phenanthrene and naphthalene) to the marine planktonic algae Tetraselmis chuii were investigated under laboratory conditions. T. chuii cultures were exposed for 96 h to different concentrations of each of the test substances at both 20 and 25 °C. Effect criterion was the inhibition of culture growth assessed at 24 h intervals. All the PAHs significantly reduced T. chuii growth after 96 h of exposure with 20% inhibition concentrations between 0.052 and 1.124 mg L− 1 at 20 °C, and between 0.048 and 0.831 mg L− 1 at 25 °C. At both temperatures, the ranking, in order of decreasing toxicity based on the 50% inhibition concentration, was phenanthrene > naphthalene > anthracene. The increase of temperature by 5 °C significantly increased the toxicity of all the PAHs tested. These findings highlight the importance of considering temperature variation in the ecological risk assessment of oil and other chemical spills in the marine environment, and the need of more research on the toxic effects of multiple stressors on marine organisms.