Cladocerans are used extensively internationally for aquatic toxicity testing and have been found to adapt well to laboratory conditions (Environment Canada 1992; USEPA 1993; Hall and Golding 1998). The functional role of cladocerans in a freshwater community favours them as test animals. They have an important role in converting phytoplankton and bacteria into nutritionally valuable food for species higher up the food chain.

Acute and chronic test methodologies have been developed (e.g. Environment Canada 1992; ASTM 1997) and applied to both pure chemical and industrial wastewater discharges (USEPA 1985). The chronic three-brood test method was introduced for use in effluent and ambient water evaluations, and is one of several methods used by the USEPA and Environment Canada for regulatory monitoring programs.

Ceriodaphnia dubia

Paracalliope fluviatalis

The freshwater amphipod Paracalliope fluviatilis is potentially one of the most useful indigenous freshwater species for toxicity testing. It is common throughout New Zealand and usually found in flowing waters, inhabiting sediment and weed beds along the edges of streams. Previous studies have found them to be sensitive to a wide range of contaminants (e.g Burnett 1972; Hunt 1974; Hickey and Vickers 1994; Hall and Golding 1998) and their relative sensitivity suggests that P. fluviatilis may be one of the most vulnerable species to contaminants.