We investigated spatial patterns of stony corals, molluscs and echinoderms
among six habitat types within the lagoons of six atolls in the Tuamotu
Archipelago (French Polynesia). Percent cover (stony corals only), abundance
and richness were recorded within habitat types delineated by specific
geomorphological features. Among six habitat types defined a priori, four
encompassed distinct assemblages of corals and molluscs: (1) pinnacles
possessed maximum richness, abundance and coverage, (2) passes showed
relatively high abundance and coverage, (3) lagoon floors were marked by the
commonness of a few coral genera, and minimum mollusc abundance and
richness, and (4) inner reef flat stations, independent of their location in
front of spillways, motu or rim zones, had low cover, abundance, and
richness. While habitat associations were similar for stony corals and
molluscs, echinoderms were preferentially found on the inner reef flat
facing the rim. Lowest echinoderm abundances and species richness were
recorded on pinnacles and in the vicinity of the pass. Such small-scale
spatial heterogeneity appears to be one of the distinctive characteristics
of coral communities in French Polynesian reefs. These results, along with
those of the TYPATOLL program, demonstrate the importance of both local and
regional factors in determining the diversity and structure of coral
assemblages. Habitat fidelity was weak: many species/genera were poorly
represented among habitats and restricted to a few atolls, while others were
present across all lagoons and habitats. Therefore, marine protected areas
design based solely on representativeness will require the protecting the
vast majority of lagoon habitats.