Human-Mediated Prehistoric Marine Extinction in the Tropical Pacific? Understanding the Presence of 'Hippopus hippopus' (Linn. 1758) in Ancient Shell Middens on the Rove Peninsula, Southwest Viti Levu Island, Fiji

Abstract

At the Lapita-era (1100-550 B.C.) settlements (Bourewa and Qoqo) along the Rove Peninsula in Fiji, valves of the reef-surface-dwelling giant clam 'Hippopus hippopus' (long extirpated in Fiji) occur in shell midden. Valve size/weight increase with depth, suggesting that human predation contributed to its local disappearance. The timing of this event is constrained by (a) the confinement of 'H. hippopus' remains to the lower part of the midden, (b) their likely association with only the stilt-platform occupation phase at both Bourewa and Qoqo (approximately 1100-900 B.C.), and (c) radiocarbon ages. All these suggest that 'H. hippopus' disappeared from reefs here about 750 B.C. Yet human predation is not considered to be a significant cause of extirpation of 'H. hippopus' in the entire Fiji group. More plausible is that (climate-driven) sea-level fall (55 cm) during Lapita times in Fiji (approximately 1100-550 B.C.) forced changes to coral-reef ecology that saw this sensitive species extirpated throughout the Fiji archipelago. It is also considered possible that the Lapita colonizers introduced bivalve predators or diseases to Fiji that spread independently of humans throughout these islands.