Settlement of a Tropical Marine Epibenthic Assemblage on Artificial Panels: Influence of Substratum Heterogeneity and Complexity Scales

The influence of substratum topographic heterogeneity and complexity on the settlement of a tropical epibenthic subtidal assemblage was examined using artificial substrata offering a combination of different heterogeneity scales. A 4 week experiment was carried out in March 1999 using eight types of dark grey polyvinylchloride (PVC) panels immersed at middle depth (2 m) in the water column and arranged in the field according to a Latin square design (n=64). Four heterogeneity scales (0, 1, 10, 100 mm) and complexity (the hierarchical combination of those scales: 0+1+10, 0+1+100, 0+10+100, 0+1+10+100 mm) were used. Results show that total abundance of settlers was significantly influenced by the heterogeneity (P<0·01) and complexity (P<0·01) of substratum. Abundance was higher on panels with intermediate orders of complexity (2nd and 3rd), combining 0 and 1 mm, and 0, 1 and 10 mm scales of heterogeneity. Larvae settled more on protected (grooves) than on exposed surfaces. The choice made by larvae for particular scales of heterogeneity and orders of complexity are discussed in the light of available evidence from similar field and laboratory experiments conducted in subarctic and temperate environments.