Toxicity of Formalin, Calcium Hypochlorite and Copper Sulfate to Chaetoceros calcitrans

Abstract

The toxicity effects of formalin, calcium hypochlorite and copper sulfate on Chaetoceros calcitrans, a marine diatom, were studied by monitoring changes in its growth in terms of cell population using short term bioassays.  Inhibition of cell growth of Chaetoceros calcitrans was observed at concentrations of 2.27, 2.00 and 0.35 ppm of formalin, calcium hypochlorite and copper sulfate, respectively. Low concentrations of formalin (1.00 ppm) and copper sulfate (0.10 ppm) had no effect on the growth of C. calcitrans. Lethal effect was observed at concentrations of 26.46 and 60.00 ppm of formalin, wherein algal cell number decreased continuously from initial cell concentrations. Total mortality of C. calcitrans was observed at 48 h at 60.00 ppm of formalin. Algal cell concentration also continually decreased at calcium hypochlorite concentrations of 9.10, 15.09, 25.00 and 50.00 ppm. Total mortalities were observed at 48 and 72 h with 50.00 and 25.00 ppm calcium hypochlorite, respectively. Effective Concentration values at 96 hours (96h-EC₅₀) of calcium hypochlorite, copper sulfate and formalin for Chaetoceros calcitrans were 2.60, 4.30 and 8.00 ppm, respectively.