Lunar cycles and seasonal variations in deposition fluxes of planktic foraminiferal shell carbonate to the deep South Atlantic (central Walvis Ridge)

• Published in: Deep-sea research. Part I, Oceanographic research papers Vol. 52; no. 7; pp. 1178 - 1188
• Main Authors: Lončarić, Neven, Brummer, Geert-Jan A., Kroon, Dick
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2005; Elsevier; Pergamon Press Inc
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Carbonate flux; Fundamental and applied biological sciences. Psychology; Hastigerina pelagica; Lunar reproduction; Marine; Ocean currents; Planktic foraminifera; Plankton; Sea water ecosystems; Seasons; Sediments; Synecology; South Atlantic; Atlantic Ocean; AS, South Atlantic, Walvis Ridge; Hastigerina pelagica; Planktic foraminifera; Carbonate flux; Lunar reproduction; Lunar cycle; Protozoa; Foraminifera; Deep water; Walvis Ridge; Marine environment; Reproduction; Seasonal variation; Shell(anatomy); Carbonates
• ISSN: 0967-0637; 1879-0119
• DOI: 10.1016/j.dsr.2005.02.003

Several authors have argued that lunar reproductive cycling controls the shell fluxes of planktic foraminifera, one of the major carbonate-producing groups in the global pelagic ocean. A time-series sediment trap at 2700 m depth on the central Walvis Ridge below the South Atlantic central gyre demonstrate for the first time that shell deposition fluxes of Hastigerina pelagica are synchronous with lunar periodicity. Spectral analysis of the 6-month time-series with 8-day resolution showed a strong 30-day cyclicity in the flux maxima of H. pelagica arriving at the ocean floor on average 12.5 days after each full moon. Given a shell settling velocity of about 400 m day −1, which implies about 7 days for settling, this coincides with the pronounced endogenous reproduction rhythm of 5±2 days after full moon as originally observed in laboratory-cultured isolates from off Bermuda in the North Atlantic. By contrast, no endogenous or exogenous lunar periodicity was observed in the deposition flux or size distribution of any of the 27 other shell species from austral winter (August 2000) to austral summer (February 2001). Instead, the deposition fluxes of shell species, the bulk carbonate and the total mass were dominated by a seasonal maximum during austral spring, without any periodicity in the 16–90-day domain of this study. Since H. pelagica exhibits low fluxes with a low burial efficiency, and continuous (re)production is shown by the deposition fluxes of other species, lunar reproductive cycling appears not to affect pelagic carbonate productivity and deep ocean sedimentation fluxes.