Seasonal Vertical Distribution of the Intertidal Macroinfauna in an Estuary of South-central Chile

Seasonal sampling of sediments (May 1988–May 1989), carried out at two intertidal areas of the Queule River Estuary, was used to analyse the vertical distribution of the macroinfauna and sedimentological characteristics. In all seasons, the substratum characteristics of both areas showed small differences between 0 and 12 cm depth. The macroinfauna of both areas showed a clear stratification with the highest abundances at the superficial layer of sediment (0–3 cm). No spatial partitioning among the species was evident. It was concluded that the substratum characteristics were not a primary factor in determining the stratification of the macroinfauna. However, some physical factors may well limit the burrowing capabilities of the species (e.g. the discontinuity between the oxidized and reduced sediments), as well as biological factors such as body size (particularly that of the juveniles) and responses against epibenthic predation by burrowing to deeper sediments. Some of these factors would probably better explain the vertical distribution of the intertidal macroinfauna in the Queule River Estuary.