Test No. 225: Sediment-Water Lumbriculus Toxicity Test Using Spiked Sediment

         This Test Guideline is designed to assess the effects of prolonged exposure to sediment-associated chemicals on the reproduction and the biomass of the endobenthic oligochaete Lumbriculus variegatus (Müller). The method is described for static test conditions.          Worms of similar physiological state are exposed to a series of toxicant concentrations applied to the sediment phase of a sediment-water system (artificial sediment amended with a food source and reconstituted water). Test vessels without the test substance serve as controls. The test animals are exposed to the sediment-water systems for a period of 28 days. The endpoints of this type of study are the ECx for reproduction and biomass. In addition the No Observed Effect Concentration (NOEC), and the Lowest Observed Effect Concentration (LOEC) may be calculated. The purpose of the study, ECx or NOEC derivation, will determine the test design. At least five concentrations and a minimum of three replicates for ECx, or four replicates for NOEC/LOEC, for each concentration should be tested. The test is conducted with at least 10 worms for each replicate. The report should include the total number and the dry weight of the worms, the observations of abnormal behaviour, of mortalities, the water characteristics within the test vessels and the total organic content.       