Ecotoxicity test with the marine rotifer Brachionus plicatilis

(UNE 77106: 2014 Standard)

Standard UNE 77106: 2014 establishes a test method for the determination of the ecotoxicity of dispersants by studying acute toxicity using juvenile individuals of the marine rotifer Brachionus plicatilis. This standard applies to all types of dispersants that can be used in the marine environment to combat accidental contamination with hydrocarbons.

In order to carry out this test, juvenile individuals obtained by stimulating the eruption of rotifer cysts should be used. After a period of acclimatization in standard seawater, groups of 5 to 10 rotifers are transferred to the wells of a test plate where they are exposed to the dispersant solution solutions under evaluation, including negative controls and positive controls of a toxic reference product prepared in standard seawater. Six replicates of five concentrations of the dispersant product in geometric series should be analyzed, as well as six replicates of five concentrations of a toxic reference. The exposure plates are incubated in the dark at 25°C for 24 hours. After the exposure period, live and dead rotifers are counted under microscopic observation and the mean lethal concentration of the dispersant is determined, causing a 50% mortality (LC50).

The result of the bioassay of ecotoxicity of the dispersant is considered negative (non-ecotoxic) when the LC50 at 24 hours is higher than 100 mg/L, otherwise, the result is considered positive (ecotoxic).