Intertidal sand?dwelling Peracarid fauna of Stewart Island

Abstract

The distributions of infaunal Peracarida (Crustacea) and their correlation with sediment type, tidal height, and degree of exposure were studied in winter (June) at five beaches on Stewart Island, New Zealand. The beaches were selected lo cover a range of exposures to wind and wave action and substrate sorting. Substrate and infauna samples were taken at four tidal levels from each, with a 0.0625 m² quadrat. Sieve separation and statistical analysis of the substrate samples indicated predominantly sand‐sized particles from all beaches, with median diameters in the range +1.52 to +2.92 ⊘ (phi) units. Substrates were well sorted throughout the size range: ⊘ quartile deviation ranged from 0.26 to 0.71, skewness from —0.18 to +0.07 ⊘. Peracarid fauna was generally abundant, with a maximum of 29 136 per m²sampled in a more sheltered beach. Cumacea was the most abundant group, followed by Amphipoda, Isopoda, and Tanaidacea; dominance followed a similar sequence, being 78%, 19%, 2% and 1% respectively. Frequency of occurrence at the 19 stations was headed by Amphipoda (100%), with Isopoda 53%, Cumacea 32% and Tanaidacea 11%.