Resumen

ROMERO, Yollys et al. Efecto tóxico del cadmio sobre microalgas aisladas del nororiente de venezuela. INCI [online]. 2002, vol.27, n.3, pp.104-109. ISSN 0378-1844.

Lethal and sublethal effects of cadmium were studied on two species of microalgae, Chaetoceros sp. (A1) and Tetraselmis sp. (G1), isolated in the northeastern region of Venezuela. In a first experiment, microalgal cultures in logarithmic growth phase were exposed to different concentrations of Cd (0; 0.01; 0.05; 0.1; 5; 10; 50 and 100 mg/l) for 96 hours, determining the toxic effects through cell counts every 12 hours. In another experiment toxic effects were evaluated by microalgae inoculation in media with and without Cd in sublethal concentration of 0.05mg/l for 14 days; cell counts and physiological indicators (cellular volume, biochemical components and pigment concentration) were evaluated in three growth phases of the cultures. The lethal doses (50% of the cultivated population) were 0.63 and 0.56mg/L for Tetraselmis sp. (G1) and Chaetoceros sp. (A1), respectively. Sublethal Cd concentration produced in both algae a decrease in growth and in pigments, and an increase of cell volume. Biochemical components in both species generally remained constant during the growth phases, in contrast with their respective controls, which showed a progressive increase. The study showed that Chaetoceros sp. (A1) was the most affected species physiologically, being the most sensitive one to the contaminant. The results of the study allow us to suggest that Cd has a negative effect on phytoplankton, and to recommend microalgae as model species for ecotoxicological studies in northeastern Venezuela.

Palabras clave : Cadmio ; Microalga ; Xenobiotico ; Contaminación ; Metales Pesados .