Hierarchical scales of spatial variation in the smaller surface and near-surface macrobenthos of a subtropical intertidal seagrass system in Moreton Bay, Queensland

Abstract

Core samples were taken along a 4 km stretch of intertidal seagrass on North Stradbroke Island, eastern Australia, at nested scales of 1 m (stations), 150 m (sites), and 2 km (localities) to investigate the extent to which abundance, diversity, and assemblage composition of the dominant smaller members ( 10% to the total numbers (the microgastropod Calopia imitata and crab Enigmaplax littoralis, both little known, rarely recorded endemics). On average, a species only occurred at 6% of stations and only four occurred at >25%. Assemblages at the three localities did not vary significantly in gross ecological features (levels of species richness, faunal abundance and species diversity per component site) (ANOVA P ≫ 0.05), but did vary markedly in their composition at all spatial scales (PERMANOVA P < 0.05). Variance partitioning showed that components of total variance were least at the largest spatial scale (locality 15.9%) and greatest at the smallest scale (station 59.3%). The commoner individual species all showed random distributions at small spatial scales but clumped distributions at large spatial scales.