Test Organisms used for Biomonitoring

     The species which are used in biomonitoring tests depends on the requirements of the regulatory agency. Some of the freshwater species commonly used in freshwater tests include the fathead minnow (Pimephales promelas) and cladocerans (also called water fleas).  Two important cladoceran species are Ceriodaphnia dubia and Daphnia pulex.   Marine species commonly used in marine and estuarine tests include the sheepshead minnow, Cyprinodon variegatus, and the mysid shrimp, Mysidopsis bahia.

     These species have been chosen because they are: (1) easily cultured in the laboratory; (2) considered to be good indicators in that they tend to be sensitive to a wide variety of pollutants; and (3) small enough to be easily tested in groups in relatively small containers (ie. typically 500 ml or less)

     In a given test, all test organisms should be of approximately the same age and from the same source.  Because young organisms are often more sensitive to toxicants than adults, the use of juvenile or larval organisms is usually required in NPDES biomonitoring tests.