This International Standard specifies an early-life stage test procedure for determination of the toxic effects of a chemical substance, effluent, or water sample on a cold-water marine and brackish water copepod species under semi-static conditions. The biological endpoints include survival and development of the early-life stages. The exposure starts with eggs and is continued until emergence of juvenile stages. Copepods occur widely in marine, brackish, and fresh water ecosystems. They represent important prey items for the larvae of many fish and larger invertebrates and are increasingly used as a live food source in aquaculture. They feed on phytoplankton and, thus, are an ecologically important energy-transfer link between primary producers and higher trophic levels.