The macroinvertebrates in a sewage-polluted aquifer

Abstract

The macroinvertebrate fauna in a polluted alluvial gravel aquifer downstream of a sewage irrigation area at Templeton, New Zealand, was surveyed using an existing array of unpumped wells. Three crustacean species — Phreatoicus typicus, Phreatogammarus fragilis and Paracrangonyx compactus accounted for 98% of the organisms present. The remainder consisted of turbellarian and oligochaete worms and two further crustacean taxa — Paraleptamphopus subterraneus and a new species of the genus Paracrangonyx. Smaller invertebrates found included juveniles of the macroinvertebrate Crustacea and a new amphipod genus and species. Mean population density and dry weight biomass estimates for the three principal crustacean species in the groundwater underlying the disposal area were, respectively, 192 m−2 and 0.43 g m−2 for P. typicus, 55 m−2 and 0.16 g m−2 for P. fragilis, and 18 m−2 and 0.04 g m−2 for P. compactus.