Photo-induced toxicity of anthracene to the green alga,Selenastrum capricornutum

The photo-induced toxicity of the polycyclic aromatic hydrocarbon (PAH), anthracene, to the green alga, Selenastrum capricornutum, was characterized. The dose-response relationships among anthracene concentration, ultraviolet (UV) radiation intensity, and algal growth rate and ¹⁴C-bicarbonate incorporation were determined. The 22 h EC₅₀ for specific growth rate was inversely related to UV-A radiation intensity and ranged from 37.4 to 3.9 g/L anthracene. For ¹⁴C-bicarbonate incorporation on a volume basis (primary production), the 24 h EC₅₀ ranged from 24.0 to 3.3 g/L anthracene depending on the UV-A intensity. The incorporation of ¹⁴C-bicarbonate on a per cell basis (cellular photosynthesis) was more resistant than cell growth or primary production. The threshold for photo-induced toxicity of anthracene was 1.5–3 g/L anthracene, however, no UV-A radiation threshold was evident for many of the measurements of toxicity studied. Algae appeared to be slightly more resistant to photo-induced toxicity of anthracene than fishes and invertebrates. An environmental hazard assessment suggests that some aquatic systems are sufficiently contaminated by PAH that a hazard to natural algal communities due to photo-induced toxicity of PAH may be present.