When assessing biological responses to chemical exposure it is important to know the sensitivity of the species used. Therefore, we adopted an standardized guideline described in the Draft ISO Guideline ISO/DIS 14669, ISO/TC 147/SC5 "Water quality - Determination of acute lethal toxicity to marine copepods (Copepoda, Crustacea)" 1997. Some adjustments had to be made because the ISO standard test is described for a smaller copepod; Acartia tonsa. The exposure media volume was increased from 25 ml to 500 ml, while the length of exposure was increased from 48 to 96 hours, and finally the temperature used was decreased from 20°C to 10°C. The endpoint in this test is lethality, and the concentration by which 50% of the copepods died (LC50) is calculated.

This acute toxicity test has been used to determine acute toxicity to C. finmarchicus for a range of single chemicals (organic and inorganic) and on water soluble fraction (WSF) of petrogenic oils. These LC50-concentrations may be used as input into models (e.g. OSCAR, DREAM) for determination of influence areas for e.g. oil spills.