OECD 202: Daphnia sp., Acute Immobilisation Test

Water flees are important grazers feeding on phytoplancton. Therefore they are part of risk assessments for several kinds of substances like plant protection products, industrial chemicals, biocides and medicinal products for human and veterinary use. Additionally, they are easy to rear and sensitive to water pollution.

Study Design

Test organism

The water flea Daphnia magna belongs to the Crustacea, subclass Phyllopoda. Young daphnids not older than 24 hours are tested from a synchronous laboratory culture.

Course of the acute immobilisation test

The acute toxicity test determines immobility during an exposure period of 48 hours. Immobilisation and abnormal behaviour is recorded at 24 and 48 hours and compared with control values. The test item is mixed into reconstituted water. 20 Daphnia are divided in four replicates per control and test item concentration. Most usually a dose-response study with a geometric series of five test item concentrations is tested. For the test, a static semi-static or flow-through design can be used.

Exposure takes place in a controlled environment room with defined temperature and light regime. Dissolved oxygen, pH and water temperature are measured regularly. The test item concentrations
are checked by analytical dose verification.

Alternative species testing

In order to determine a species sensitivity distribution (SSD), additional species can be tested in adapted test designs on request e.g. Chironomus riparius, Ceriodaphnia dubia, Tetrahymena thermophile, Brachionus calyciflorus or Thamnocephalus platyurus.


LOEC, NOEC, EC50 (EC20, EC10) for immobility of the daphnids are determined.

Guidelines and Literature

  • OECD 202: Daphnia sp., acute immobilsation test
  • Council Regulation (EC) No 440/2008, C.2. Daphnia sp., Acute Immobilisation Test
  • EPA Ecological Effects Test Guideline OPPTS 850.1010 Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids