Macrofaunal polychaete densities across a fine‐sand intertidal flat in Pauatahanui Inlet, North Island, New Zealand, were examined seasonally from a pair of adjacent transects. Density patterns had shore‐normal trends, despite weak tidal‐cycle environmental gradients. Abundances frequently corresponded between transects separated by 15 m.Capitellasp.,Nicon aestuariensis,andScolecolepides benhamideclined in density downshore, whereasHeteromastus filiformisincreased.Microspio maoriandAxiothella serratalacked strong trends.Boccardia acus’density was affected by the size and number of the bivalveChione stutchburyi,its substratum. Basic zonation patterns of each species persisted over a 2 year period. Within the density concentrations seasonal cycles were apparent, with some population redistribution attributable to differential mortality (H.filiformis),to recruitment (M. maori, A. serrata),or to migration (N. aestuariensis, S. benhami).