2.3. Assessment of sediment toxicity with H. incongruens
The 6-day solid phase microbiotest with H. incongruens was performed in accordance with the Standard Operational Procedure of the OstracodtoxkitF™ ( Janssen and Persoone, 2010). It was performed in a multiwell test plate using neonates of the benthic ostracod crustacean H. incongruens hatched from cysts at 25 °C for 52 h, under continuous illumination (60–80 mol/m2s). Three wells were filled with reference sediment and the other three wells were filled with the sediment sample in each multiwell plate. The percentage of mortality and growth of the crustaceans (e.g. length increment) was determined after 6 days of direct-contact exposure to the sediment and compared to the results obtained with the (non-toxic) reference sediment. The validity of the tests was assessed according to the criteria previously published elsewhere (Janssen and Persoone, 2010).