, Volume 10, Issue 2, pp 145-151

Photosynthetic and population growth response of the test alga Selenastrum capricornutum Printz to zinc, cadmium and suspended sediment elutriates

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Abstract

Short-term 14C-fixation (4 h) Selenastrum capricornutum algal toxicity tests were conducted with Cd (n=8), Zn (n=9) and suspended sediment aqueous elutriates (n=28) and the results were compared to those obtained in a 48 h population growth test. In order to provide more realistic experimental conditions, toxicity tests were carried out in prefiltered nutrient-spiked Lake Geneva water. The population growth inhibition test was significantly more sensitive than the14 C-fixation test for Cd (median EC50-4h and EC50-48h values of 600 and 118 µg L-1, respectively) whereas no significant difference was measured for Zn toxicity (median EC50-4h and EC50-48h values of 97 and 96 µg L-1, respectively). With suspended sediment aqueous elutriates, the relative sensitivity of the two different end points is sample dependent, with ratios of the EC25 for the14 C-fixation: population growth test ranging from <0.26 to >53.3. Elutriate toxicity shows no apparent relationship between the acute and chronic test, indicating that population growth inhibition cannot be derived directly or predicted from14 C-fixation. Both tests with their specific advantages and limitations provide valuable complementary information to measure the impact of single toxicants or complex mixtures on aquatic plants.

This revised version was published online in June 2006 with corrections to the Cover Date.