Temporal Variability in the Intertidal Macroinfauna in the Queule River Estuary, South-central Chile

The surface sediments (0-3 cm) of two intertidal areas of the Queule River estuary (c. 39°S) were sampled monthly to study the seasonal variability of the macroinfauna and its relationship with the variability of water and sediment characteristics. One of the areas had sandy sediments; the other had muddy sand. Temperature and water salinity showed a seasonal trend with the lowest values during winter months. No differences were found in the sediment temperatures between areas but the muddy sand area had higher percentages of mud, aggregates, organic matter and water, as well as higher penetrability values. All but one of the macrobenthos species occurred at both areas and the same taxa dominated both assemblages. Population abundances fluctuated seasonally with higher values during summer-autumn and higher variability at the muddy-sand area. Of the variability in the abundances of the most representative species 28-84% was accounted for by the variability in some of the physical variables. Thus, these results show that macrofaunal assemblages occupying different sedimentological facies in the intertidal zone (sand-muddy sand) do not have major differences in their patterns of seasonality, and suggest that sedimentological characteristics have a limited role in determining community structure in the areas studied.