Assembly rules of fish communities in Tuamotu archipelago atoll lagoons: The case of Fangatau, a lagoon dominated by giant clam habitats

Abstract

Assembly rules of fish communities in Tuamotu Archipelago lagoons have been previously investigated but without considering lagoons where shallow habitats are dominated by giant clam populations. We tested if assembly rules for 14 atolls were challenged by such an atoll (Fangatau), and in doing so investigated the robustness of inter-island population patterns to specialized habitats. Fangatau had significantly higher proportions of Pomacentridae and Scaridae, but lower proportions of Labridae, Acanthuridae, Balistidae and Serranidae. Functionally, herbivores, omnivores, species <7 cm or between 50 and 80 cm, and species forming schools were found in higher proportions, while sessile invertebrate feeders, medium-size species (30–50 cm) and solitary species were lower. These differences were rather related to Fangatau isolation, as no other physical or ecological feature could explain them. Total richness, functional richness, and functional redundancy remained correlated mainly to atoll size, without outliers related to high clam abundance and presence of peculiar habitats.