Comparative study on sensitivity of higher plants and fish to heavy fuel oil.

Laboratory tests were conducted on higher plants [garden cress (Lepidium sativum), great duckweed (Spirodela polyrrhiza), and Tradescantia clone BNL 02] and fish [rainbow trout (Oncorhynchus mykiss) at all stages of development: eggs, larvae and adults] to estimate their sensitivity to heavy fuel oil (HFO). A number of biological indices (survival, growth, and physiological and morphological parameters) as well as the genotoxic impact (Tradescantia) of HFO was evaluated by acute and chronic toxicity tests. Fish were found to be more sensitive to the toxic effect of HFO than were higher plants. EC(50) values obtained for higher plants ranged from 8.7 g/L (L. sativum) to 19.8 g/L (Tradescantia), and maximum-acceptable-toxicant concentration (MATC) values ranged from 0.1 to 1.0 g/L of total HFO for L. sativum and Tradescantia, respectively. The 96-h LC(50) values ranged from 0.33 g/L, for larvae, to 2.97 g/L, for adult fish, and the MATC value for fish was found to be equal to 0.0042 g/L of total HFO. To evaluate and predict the ecological risk of the overall effects of oil spills, studies should be performed using a set of acute and chronic bioassays that include test species of different phylogenetic levels with the most sensitive morphological, physiological, and genotoxic indices.