PARENT SESSION
26 - Metal Pollution: From Exposure to Ecological Effects (1)
8:30 AM to 12:20 PM, Tuesday, 14 May 2002
Session Chair: Janssen, Colin ¹, Gerhardt, Almut ¹, ¹ .
Strauss C

(26-05) Detection of Copper toxicity in cultures of microalgae using the potential photochemical efficiency of PSII.

Pérez, Patricia^*,1, Beiras, Ricardo¹, Fernández, Emilio, ¹ Departamento de Ecoloxía e Bioloxía Animal. Facultade de Ciencias. Universidade de Vigo. Lagoas-Marcosende, Vigo, Spain

ABSTRACT- The toxic effect of pollutants is reflected on inhibition of photosynthesis and growth in microalgae, as well as other closely related variables. In this study we attempt to prove the usefulness of the fluorescence parameter: potential photochemical efficiency of the open reaction centres of PSII ( _po), as an indicator of the degree of pollution by Copper in cultures of two marine microalgae: Isochrysis galbana and Skeletonema costatum. The two microalgae were exposed to Copper concentrations of 0, 45, 90, 180g/L. The parameters daily assayed were cell density and _po. Rates of exponential growth of both species studied were significantly lower at concentrations of Cu above 90 g/L in comparison with the control (ANCOVA, p<0.05). A similar pattern was observed with regard to _po. As a general rule, higher values of _po appear to be related to greater photosynthetic efficiency. This correspondence is shown during the exponential growth of the cultures. _po measured in the control (0.530) and [Cu]=180g/L cultures (0.450) were significantly different (GLM Analysis of repeated measurements, Bonferroni test, p<0.05). Both variables show a good inverse linear correlation with [Cu] (R²>0.82). The good relationship found between [Cu] and _po, will guide our design of further research, based on the measurement of _po by using the Fast Repetition Rate Fluorometer, which can measure _po in continuous. The development of this technique will be potentially valuable as a fast, non-destructive way of detecting populations of microalgae under high-polluted conditions.

Key words: Copper, photochemical efficiency, toxicity, microalgae