Cryoalgotox: Use of cryopreserved alga in a semistatic microplate test

Use of cryopreserved alga Selenastrum capricornutum has been evaluated as a simple and cost‐efficient procedure in a new semistatic algal ecotoxicity test. Experiments have been conducted to compare performance criteria of this method, named Cryoalgotox, versus the classic microplate test using fresh algae. Cryoalgotox 72‐h 50% effective concentrations (EC50s) determined with Cd 2+ , Cu 2+ , Cr 6+ , and atrazine were more sensitive, repeatable (low coefficients of variation), and reproducible (low time effect) than the results obtained with the classical microplate tests. The effect of storage time at −80°C on the sensitivity of the algae was assessed using cadmium as a toxic reference; it was shown that algae stored at −80°C over a 3‐month period gave comparable toxicity results to those found with fresh algae.