Monitoring copper toxicity in natural phytoplankton assemblages: application of Fast Repetition Rate fluorometry

Four experiments were conducted with natural coastal phytoplankton assemblages exposed to [Cu] within the range 5–80 μg L−1. The effect of Cu on several biological variables such as chlorophyll a concentration, particle size distribution, O2-production and fluorescence variables recorded by a Fast Repetition Rate fluorometer was monitored during 72 h. Variable fluorescence (Fv) was the most sensitive and rapid among all the variables tested. This work contributes to reinforce the use of fluorescence endpoints in ecotoxicological studies by proving their ecological relevance through relationships found between fluorescence and population-level responses as growth rate and gross O2 production. The lowest calculated EC10 was 2.65 μg L−1, concentration commonly exceeded in polluted waters.