Low-lying, small reef islands on Pacific atolls are vulnerable to coastal erosion and flooding, mainly due to rises in sea level, as well as local stresses associated with overpopulation. Because reef island sediments on Pacific atolls are composed mostly of shells of large benthic foraminifers (LBFs), their future stability depends on understanding foraminiferal shell sources and their production rates around the islands. Here, we report on the distribution and population density of LBFs around Fongafale Island, the main populated island of Tuvalu in the South Pacific, where coastal erosion and inundation have occurred.