Abstract
The assemblage organisation and macrohabitat segregation patterns of an intertidal assemblage of hermit crabs was studied at the Quirimba Archipelago in northern Mozambique. The assemblage exhibits a strong tidal zonation pattern, with different species dominating the studied tidal zones. Superimposed onto this, is a macrohabitat segregation pattern. Coastal features such as presence/absence of sandy beaches or mangroves explained the presence/absence of certain species, e.g. Coenobita rugosus H. Milne Edwards 1837 and C. cavipes Stimpson 1858. Smaller islands with less heterogeneous shores (mostly reef) were dominated by Clibanarius virescens (Krauss 1843). Larger islands with a range of macrohabitats (mangrove, sand, reef, seagrass, rock) had more complex patterns. Within each tidal zone, at least two distinct assemblage groups are recognised, due to differential species presence/absence patterns and differences in abundance of the constituent species. Superimposed onto these two patterns, is a further pattern of island size, with in the majority of cases, the within-zone habitat segregation pattern corresponding to a dichotomous split between larger and smaller or medium sized islands. These patterns in macrohabitat use illustrate the importance of habitat segregation patterns in alleviating inter-specific competition for available resources.