Population dynamics and reproduction strategies of planktonic foraminifera in the open ocean

Abstract. It has long been assumed that the population dynamics of planktonic foraminifera is characterised by synchronous reproduction associated with ontogenetic vertical migration. However, due to contradictory observations, this concept became controversial, and subsequent studies provided evidence both in favour against these phenomena. Here we present new observations from replicated vertically resolved profiles abundance shell size variation four species tropical Atlantic test for presence, pattern, extent synchronised migration oceanic region. Specimens Globigerinita glutinata, Globigerinoides ruber ruber, Globorotalia menardii Orbulina universa were collected over first 700 m at nine depth intervals stations a period 14 d. Dead specimens systematically observed irrespective interval, sampling day size. Conversely, smaller fractions dominated sampled populations all times recorded depths, indicating might have occurred continuously throughout occupied part water column. closer look temporal distribution within each revealed an overrepresentation large depths beginning (shortly after full moon) small individuals surface subsurface end (around moon). These imply disproportionately portion followed canonical reproductive trajectory, which involved descent progressively maturing individuals. This consistent initial Red Sea, on modelled. Our data extend model non-spinose microperforate symbiont-bearing species, but contrary extension other foraminifera, cannot provide ascent during maturation. We also show more than half does not follow helps reconcile existing contrasting observations. results flux empty shells open ocean should be pulsed, amounts being delivered pulses caused reproduction. The presence reproducing outside trajectory implies individual fossil sample will record calcite their range habitat trajectories, emerging statistically substantial background range.