Lunar and semi-lunar reproductive cycles in some spinose planktonic foraminifers

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Abstract
Reproductive cycles of spinose planktonic foraminfera appear to be related to distinct phases of the moon. Based on a time series of plankton-net tows, a synodic lunar reproductive cycle is demonstrated in Globigerinoides sacculifer (Brady). The reproductive cycles of Globigerinoides ruber (d''Orbigny) and probably Globigerinella siphonifera (d''Orbigny) are characterized by a semi-lunar periodicity. Samples collected during scientific cruises into the Red Sea and the northwest Atlantic Ocean and many blue water SCUBA dives in the Caribbean Sea support these observations. Inter-species differences in the lifespan result in a different empty shell output. As a consequence, the sediment does not reflect the situation in the water column. The relative abundances that are preserved in the sediments are not primarily indicative of variations in the reproduction-potential between species, but must fundamentally be interpreted as discrepancies between reproductive cycles. These results yield consequences for the interpretation of sediment analyses and implications for paleoceanography. Reproduction is often preceded by the formation of an atypical final chamber. Time and frequency correlations demonstrate that these morphotypes are associated with the reproductive process but are not a prerequisite for gametogenesis.