Effects of metals and organic contaminants on the recovery of bioluminescence in the marine dinoflagellate Pyrocystis lunula (Dinophyceae)

Pyrocystis lunula Schütt is a unicellular photoautotrophic dinoflagellate, commonly found in marine environments, displaying circadian-controlled bioluminescence. Because of this species' characteristics, effects of pollutants on bioluminescence in P. lunula may make for an easy and simple bioassay that would be valuable for toxicity testing and the protection of coastal resources. This study therefore investigated the short-term effects of metals and organic pollutants on the recovery of the bioluminescent potential in P. lunula. Recovery of bioluminescence was strongly inhibited in a dose-dependent manner by all reference contaminants tested, the system being most sensitive to copper and cadmium (4-h IC50s 0.96 and 1.18 μM, respectively), followed by phenanthrene, lead, SDS, and nickel (4-h IC50s 1.64, 12.8, 15.6, and 73.1 μM, respectively), whereas relatively high concentrations of phenol were needed to elicit a response (4-h IC50 1.64 mM). Except for exposure to lead and nickel, the inhibitory effects of cadmium, copper, and all organic pollutants were reversible, with P. lunula recovering 80%–100% of its bioluminescence potential after a period of 72 h in uncontaminated medium. Our results show that the restoration of bioluminescence in P. lunula is sensitive to the reference contaminants tested and obtains highly reproducible results.