cf. (dinoflagellate): identification and response to nickel and iron stress revealed through chlorophyll .

Metal toxicity in marine ecosystems is a growing issue owing to terrestrial runoff and anthropogenic pollution. cf. , a newly isolated dinoflagellate from New Caledonia, was cultivated in photobioreactors operating continuously with high concentrations of nickel (1.70 10M) (Ni) and/or iron (1.79 10M) (Fe) and their photosynthetic efficiency was assessed. The photosynthetic measurements indicated that cf. was tolerant to Ni but sensitive to Fe high concentrations. In the presence of Fe, maximum quantum efficiency and maximal relative electron transport rate decreased from 0.62 to 0.47 and from 156 to 102, respectively. The JIP-tests suggested a reduction of the photosynthesis in response to Fe due to a disruption in the electron transport chain rather than a defect in the light absorption and trapping capacity which were on the contrary enhanced by Fe. These results bring new knowledge on the impact of nickel and iron on microalgae photosynthetic pathways.