Physiological effects of copper on the freshwater alga Closterium ehrenbergii Meneghini (Conjugatophyceae) and its potential use in toxicity assessments

Physiological effects of copper on the freshwater alga Closterium ehrenbergii Meneghini (Conjugatophyceae) and its potential use in toxicity assessments

Although green algae of the genus Closterium are considered ideal models for testing toxicity in aquatic ecosystems,little data about the effects of toxicity on these algal species is currently available. Here, Closterium ehrenbergii was usedto assess the acute toxicity of copper (Cu). The median effective concentration (EC50) of copper sulfate based on a dose responsecurve was 0.202 mg L-1, and reductions in photosynthetic efficiency (Fv / Fm ratio) of cells were observed in culturesexposed to Cu for 6 h, with efficiency significantly reduced after 48 h (p < 0.01). In addition, production of reactive oxygenspecies significantly increased over time (p < 0.01), leading to damage to intracellular organelles. Our results indicate thatCu induces oxidative stress in cellular metabolic processes and causes severe physiological damage within C. ehrenbergiicells, and even cell death; moreover, they clearly suggest that C. ehrenbergii represents a potentially powerful test modelfor use in aquatic toxicity assessments.

Although green algae of the genus Closterium are considered ideal models for testing toxicity in aquatic ecosystems,little data about the effects of toxicity on these algal species is currently available. Here, Closterium ehrenbergii was usedto assess the acute toxicity of copper (Cu). The median effective concentration (EC50) of copper sulfate based on a dose responsecurve was 0.202 mg L-1, and reductions in photosynthetic efficiency (Fv / Fm ratio) of cells were observed in culturesexposed to Cu for 6 h, with efficiency significantly reduced after 48 h (p < 0.01). In addition, production of reactive oxygenspecies significantly increased over time (p < 0.01), leading to damage to intracellular organelles. Our results indicate thatCu induces oxidative stress in cellular metabolic processes and causes severe physiological damage within C. ehrenbergiicells, and even cell death; moreover, they clearly suggest that C. ehrenbergii represents a potentially powerful test modelfor use in aquatic toxicity assessments.