Habitat structure in soft-sediment environments and abundance of juvenile snapper Pagrus auratus

Abstract

Small-scale biogenic or physical features, such as depressions, burrows, shells, boulders, cobbles and sand waves, dominate soft-sediment coastal and shelf environments. Such structures may provide refuge from predation and feeding areas for juvenile fish. We investigated the potential for juvenile snapper Pagrus auratus to utilise areas characterised by small-scale structures by sampling soft-sediment habitats that varied in both sediment characteristics and biogenic structure. Juvenile snapper abundance was estimated at each site using opera house traps, while variations in small-scale benthic habitat structure were quantified from video transects of the seafloor. The captured fish had 172 ± 43 mm fork length, indicating that they were 1 to 2 yr old. Statistical modelling revealed that complex habitat structure had a positive influence on the abundance of juvenile snapper, suggesting that these areas are preferentially utilised. This finding highlights the potential for disturbance of such structures (by, for example, trawling or dredging) to affect the abundance of juvenile snapper.