On the effect of tile size and surface texture on recruitment pattern and density of the barnacle,Semibalanus balanoides

The aim of this work was to analyse the stratigraphic recruitment pattern of S. balanoides on smooth and textured surfaces, determine the effect of varying tile area on recruitment density and relate the results to larval behaviour, and identify other factors affecting within‐tile variation in recruitment, including panel size and frame design. A set of polyester tiles was manufactured in four textures, viz. smooth, fine, medium and coarse. In addition, a set of smooth polyester tiles of 5 different sizes was also made. Both sets of tiles were deployed intertidally in the Clyde Sea, UK. The smooth tiles of the textured array showed a significant systematic decline in the number of recruits from top to bottom in 1 cm vertical strata. For the tiles of varying size, recruit density ranked 20 × 20 cm tiles > 10 × 10 cm > 5 × 5 cm >2 × 2 cm > 1 × 1cm. A consistent strati‐graphic pattern was found on the 20 × 20 cm tiles. It is suggested that on substrata lacking significant surface texture, a positive phototaxis by cyprids during exploratory behaviour leads to a net vertical movement, causing an increased number of recruits towards the top of the tile; this contrasts with the behaviour of cyprids on textured surfaces. It is recommended that settlement panels should be at least 10 × 10 cm to permit exploratory behaviour of cyprids on relatively texture‐free surfaces and that the means of attachment of tiles or panels and frame design need to be carefully considered.