Toxicity of mercury and copper to marine phytoplankton, Dunaliella salina, Tetraselmis sp. and Chaetoceros calcitrans

Static 96-hour phytoplankton growth tests were carried out to measure the toxicity of mercury (Hg) and copper (Cu) on growth (cell density) and chlorophyll a content of three marine phytoplankton species: Dunaliella salina, Tetraselmis sp. and Chaetoceros calcitrans. The experiments were carried out at a temperature of 27±1ºC, using natural seawater (salinity 30 psu) filtered with a 0.4 μ polycarbonate membrane, under continuous illumination of 3800±200 lux and they were repeated three times for each metal. Resultsshowed that C. calcitrans was the most sensitive species to Hg and Cu, followed by Tetraselmis sp. and D. salina, respectively. In addition, Hg was found to be more toxic to the three species than Cu. The mean IC50 values of Hg on growth of D. salina, Tetraselmis sp. and C. calcitrans were 0.277, 0.144 and 0.043 mg L-1, respectively, while those of Cu were 1.132, 0.270 and 0.090 mg L-1, respectively