Beschreibung:
Abstract. We measured the 14C age of pre-bombsuspension-feeding bivalves of known age from coastal West Africa across alatitudinal transect extending from 33∘ N to 15∘ S. Thespecimens are from collections belonging to the Muséum Nationald'Histoire Naturelle (Paris, France). They were carefully chosen to ensurethat the specimens were collected alive or that they died not long before collection.From the 14C dating of the known-age bivalves, we calculated the marinereservoir age (as ΔR and R values) for each specimen. ΔRvalues were calculated relative to the Marine20 calibration curve, and the Rvalues were calculated relative to Intcal20 or SHcal20 calibration curves. Except for fiveoutliers, the ΔR and R values were generally homogenous withweighted mean values of −72 ± 42 14C years (1 SD, n=24) and 406 ± 56 14C years (1 SD, n=24) respectively. These values aretypical of low-latitude marine reservoir age values. Five suspension-feedingspecies living in five different ecological habitats were studied. Forlocalities where several species were available, the results yielded similarresults whatever the species considered, suggesting that, in these locations,the habitat has only a limited impact on marine reservoir agereconstruction. We show that our measured marine reservoir ages follow thedeclining trend of the global marine reservoir age starting ca. 1900 CE,suggesting that the marine reservoir age of coastal West Africa is driven,at least to the first order, by the atmospheric CO2 14C ageing due tofossil fuel burning rather than by local effects. Each outlier wasdiscussed. Local upwelling conditions or sub-fossil specimens may explainthe older 14C age and thus the larger marine reservoir ages for thesesamples. Bucardium ringens might not be the best choice for marine reservoir agereconstructions.