Relationship between benthic foraminiferal assemblages and environmental factors in atoll lagoons of the central Tuamotu Archipelago (French Polynesia)

Abstract.

Foraminiferal assemblages were studied in ten atoll lagoons in the central Tuamotu Archipelago, French Polynesia, in order to determine which environmental factors influence their distribution. Among geomorphological conditions, the degree of aperture has a major influence on lagoonal communities. Cluster and factor analyses reveal a clear contrast between the foraminiferal associations located in the peripheral and central areas of the lagoons, showing the effect of the vicinity of coral reef, and a limited post-mortem transport of species from the periphery toward the center of the lagoons. The rarity of planktonic species indicates limited penetration of the lagoon by planktonic forms, including planktonic stages of benthic colonizers. Colonization of these remote lagoons, even those with a high degree of aperture, may thus require long periods. Therefore, the Holocene transgression that flooded the deeper lagoons before the shallower ones, allowing a longer colonization period, may have contributed to the higher species richness of foraminifera within them.