Toxicity of copper sulfate to fishes, phytoplankton and bacteria, Aeromonas hydrophila
1990
Panawon Jirawong
Static acute toxicity of copper sulfate was determined for common carp (Cyprinus carpio Linn.) and nile tilapia (Oreochromis niloticus Linn.) in water of various pH and hardness. The 96 hour LC50 values ranged from 0.115 to 1.75 ppm for common carp and 12.5 to 29.5 ppm for nile tilapia. Both pH and hardness had no effect on the toxicity to nile tilapia. At low hardness (46-50 ppm), copper sulfate was more toxic to common carp than at the higher hardness (158-160 ppm and 245-250 ppm). Histopathological changes of common carps that survived from the acute toxicity test were observed. Edema in the epithelial cells of the secondary lamellae and some precipitations of copper particles at the base of gill filaments. Hyperplasia of the epithelial cells of the secondary lamellae were observed in some of the survived fish. Copper sulfate at the concentrations of 1.0 and 2.0 ppm could reduce the amount of phytoplankton, especially, blue-green algae and Chlorella and decreased the total amount of dissolved oxygen but free carbondioxide was increased. Copper sulfate at the concentrations of 0.5, 1.0 ppm killed over 90 percent of the bacteria, Aeromonas hydrophila within 2 hours and 99 percent of the bacteria were killed within 8 and 4 hours, respectively. Copper sulfate at the concentration of 2.0 ppm killed over 99 percent of the bacteria within 2 hours and killed 100 percent within 8 hours.
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