Organisms used in testing must be grown and then acclimated to our client's test-specific requirements, such as life stage, age, water type, and temperature regime.

NEB routinely maintains large breeding stocks of fathead minnows, Pimephales promelas , to ensure a ready supply of eggs and fry for testing. In-house freshwater invertebrate cultures include the daphnids, Daphnia pulex , Daphnia magna , and Ceriodaphnia dubia. For sediment toxicological investigations, NEB also cultures amphipods, Hyalella azteca , and chironomids, Chironomus tentans. Axenic stocks of the freshwater alga, Selenastrum capricornutum , are maintained as a food source for daphnids and as test organisms in algal growth and inhibition tests.

Saltwater in-house invertebrate cultures include the mysid shrimp ( Americamysis bahia (formerly Mysidopsis ). Facilities and equipment are also available for long-term holding of the sea urchin ( Arbacia punctulata), inland silversides ( Menidia beryllina ), and sheepshead minnows ( Cyprinodon variegatus ).

NEB also maintains cultures of the red worm, Eisenia foetida , for terrestrial soil toxicity tests. Depending on size and environmental needs of the test organisms, cultures are maintained in either temperature and photoperiod controlled rooms or environmental chambers. Temperature-controlled water baths are also used for organisms with special holding requirements.

When demand for test organisms exceeds laboratory production, reputable commercial suppliers are used. When using organisms from an outside source, US EPA guidelines for holding and acclimating organisms are followed. For all organisms used in toxicological investigations, reference toxicant tests [e.g., copper (nitrate & sulfate), sodium dodecyl sulfate, potassium chloride, and sodium chloride] are routinely performed to assess organism health. For in-house cultured organisms, health is verified at least once per month. For organisms obtained from commercial suppliers, reference toxicant tests are performed to assess organism health. NEB maintains internally-generated cumulative-summation control charts for both cultured and purchased test organisms.