Persistence of infaunal polychaete zonation patterns on a sheltered, intertidal sand flat

Abstract

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. Capitella sp., Nicon aestuariensis, and Scolecolepides benhami declined in density downshore, whereas Heteromastus filiformis increased. Microspio maori and Axiothella serrata lacked strong trends. Boccardia acus’ density was affected by the size and number of the bivalve Chione 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).

Key words:

• Polychaeta
• infauna
• benthos
• intertidal environment
• ecological zonation
• population density
• seasonal variations
• Pauatahanui Inlet

Notes

Present address: New Zealand Oceanographic Institute, Division of Marine and Freshwater Science, Department of Scientific and Industrial Research, P. O. Box 12–346. Wellington North, New Zealand