Invertebrate drift in a large, braided New Zealand river

1. The spatio-temporal patterns of drifting macroinvertebrates in a large, braided New Zealand river were determined by sampling with drift nets, seasonally, for 1 year. 2. Drift densities were greatest in autumn, and at night in all seasons except winter. A greater proportion of larger animals drifted at night than during the day in all seasons. Mean annual drift densities were ninety-six animals 100m^?3 and 47 mg dry weight 100 m^?3. 3. There were relatively few taxa in the drift, and the mayfly Deleatidium spp. comprised more than 85% of the drifting aquatic invertebrates in all seasons except autumn. Chironomidae and terrestrial forms were the only other groups to occur at densities of more than one animal 100 m^?3 in all seasons. 4. Drift density was positively correlated with benthic density, which in turn was adversely affected by floods, particularly during spring and summer.