Response of the marine microalga Dunaliella tertiolecta (Chlorophyceae) to copper toxicity in short time experiments.

Heavy metals are introduced into aquatic ecosystems from industrial wastes, agricultural runoff and mining activities. The toxicity of heavy metal ions in solution to microalgae is well known. The essentiality and toxicity of heavy metals has been a subject of extensive research (Stokes 1983). From a biological point of view, heavy metals can be divided into two categories: essential and non-essential. However, essential heavy metals also have been reported to be toxic at high concentrations. Many of these metals have a direct influence on various physiological and biochemical processes including reduction in growth, photosynthesis, and chlorophyll content or inhibition of enzyme activities (Reddy and Prasad 1990).