Freshwater Alga and Cyanobacteria: Growth Inhibition Test

ISO8692

Within both freshwater and marine ecosystems, algae provides the nutritional basis that will flow through the aquatic food chain. It is therefore vital to evaluate potential toxic effects on algae growth when assessing plant protection products, biocides, industrial chemicals, and medicinal products intended for human and veterinary use that might enter aquatic environments.

This test determines the effects of a substance on the growth of freshwater microalgae and/or cyanobacteria. Exponentially growing test organisms are exposed to the test substance in batch cultures over a period of normally 72 hours.

The system response is the reduction of growth in a series of algal cultures exposed to, at least, five concentrations of a test substance. Three replicates at each test concentration should be used. The response is evaluated as a function of the exposure concentration in comparison with the average growth of control cultures. The cultures are allowed unrestricted exponential growth under nutrient sufficient conditions (two alternative growth media: the OECD and the AAP) and continuous fluorescent illumination. Growth and growth inhibition are quantified from measurements of the algal biomass as a function of time. The limit test corresponds to one dose level of 100 mg/L. This study includes: the determination, at least daily, of the algal biomass; the measure of the pH (at the beginning and at the end); microscopic observation.

Aquatic Plants, Acute, Chronic, Freshwater.

OECD (2011), Test No. 201: Freshwater Alga and Cyanobacteria, Growth Inhibition Test, OECD Guidelines for the Testing of Chemicals, Section 2, OECD Publishing, Paris, https://doi.org/10.1787/9789264069923-en.