Macrobenthic community composition of six intertidal sandflats in Manukau Harbour, New Zealand

Abstract

Macrobenthic community structure was assessed on intertidal sandflats, apredominant feature of Manukau Harbour. Thirty-six replicate core samples were collected from each of six 9000 m 2 sites, during October 1987. The distribution of individuals amongst taxa was similar at the six sites, but the numerical dominance of the most common taxa changed appreciably from site to site. A shift from polychaete-to bivalve-dominated communities was apparent between sites. Examination of a hypothesised relationship between sediment grain size and trophic structure of the macrobenthos highlights the difficulties in using this relationship to monitor environmental change. Identification of core taxa by DECORANA ordination and TWINSPAN classification is considered a useful mechanism in defining taxa likely to play major roles in influencing community structure and function.

Are soft-sediment communities stable? An example from a windy harbour

“…The sampling design and its justification are presented in detail in Pridmore et al (1990). Hewitt et al (1993) and Thrush et al (1994).…”

“…Extensive intertidal sand-flats are a major feature of the Harbour, comprising about 4 0 % (145 km2) of its area. The macrobenthic infaunal communities of these sand-flats play an important role in the overall ecology of the Harbour (Pridmore et al 1990).…”

“…We specifically assess changes in community structure and stability in relation to both site-specific and harbour-wide variations in weather conditions, as well as to major changes in the abundance of individual species populations. sediment grain size (Pridmore et al 1990). …”

The sandflat habitat: scaling from experiments to conclusions

“…The surface sediments comprise 0-3% gravel (primarily shell hash), 92-97% sand, and 3.5% mud by dry weight. The macrofaunal community is dominated in terms of both abundance and biomass by bivalves (Pridmore et al, 1990).…”

“…Time-series data demonstrate that macrofaunal communities have been remarkably persistent over recent years (Turner et al, 1995). The most relevant descriptions of the Wiroa Island sandflat macrofaunal community are given in Cassie and Michael (1968) and Pridmore et al (1990). Studies of sedimentary processes have shown that sediment entrainment by strong spring tidal currents is restricted to the lower regions of the intertidal sandflat, while episodic wind-waves ( # 0.7 m in height) dominate sediment resuspension in the upper intertidal reaches (Dolphin et al, 1995).…”