TOXICITY OF COPPER AND ZINC TO 2 STRAINS OF SCENEDESMUS-ACUTUS HAVINGDIFFERENT SENSITIVITY TO CHROMIUM

A Cr-tolerant strain of Scenedesmus acutus (Chlorophyceae) was culture d in the presence of different Cu2+ or Zn2+ concentrations to evaluate if it was also tolerant to these metals and consequently maintained u naltered its nutritional value for consumer organisms. The evaluation of tolerance was based on culture growth and recovery rates which were compared with those of the wild type. The evaluation of the nutrition al value was based on quantitative determinations of dry mass and carb ohydrate and protein content. In the presence of Cu concentrations tha t were toxic to the wild type, the Cr-tolerant strain grew better and, when transferred to metal-fret culture medium, resumed growth more qu ickly. It also maintained fluorescence and unchanged protein levels. T his suggests that the Cr-tolerant strain is also less sensitive to cop per. However, no evidence of a lower sensitivity to zinc was found. (C ) 1998 Elsevier Science B.V. All rights reserved.