Insolation forcing of coccolithophore productivity in the North Atlantic during the Middle Pleistocene. (1st July 2018)

• Record Type: Journal Article
• Authors: Cavaleiro, C.; Voelker, A.H.L.; Stoll, H.; Baumann, K.-H.; Kulhanek, D.K.; Naafs, B.D.A.; Stein, R.; Grützner, J.; Ventura, C.; Kucera, M.
• Is Part Of: Quaternary science reviews. Volume 191(2018)
• Page Start: 318
• Page End: 336
• Publication Date: 2018-07-01
• Subjects: Pleistocene -- North Atlantic -- Coccolithophores -- Paleoproductivity -- Insolation -- Glacials; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2018.05.027
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: Coccolithophores play a key role in the oceanic carbon cycle through the biological and carbonate pumps. Understanding controls on coccolithophore productivity is thus fundamental to quantify oceanic carbon cycling. We investigate changes in coccolithophore productivity over several Pleistocene glacial-interglacial cycles using a high-resolution coccolith Sr/Ca ratio record, which is an indicator of growth rate and thus a proxy for coccolithophore productivity. We use Middle Pleistocene sediments from the North Atlantic Integrated Ocean Drilling Program (IODP) Site U1313 (41.00′ N, 32.58' W) spanning Marine Isotopic Stages 16 to 10 (638–356 kyr). The location of the record allows us to investigate processes affecting productivity in a mid-latitude setting and to unravel the effects of temperature and regional ocean circulation. Coccolithophore productivity shows a dominant glacial-interglacial cyclicity with higher productivity during glacials, which appears to reflect the southward migration of the North Atlantic high productivity zone currently located between 45° and 55° N. Spectral analysis of the productivity record reveals a suborbital variability consistent with forcing by insolation maxima superimposed on the front migration pattern. Similar to today, coccolithophore productivity during interglacials was enhanced when insolation was at its maximum in spring or in autumn, whereas during glacials, productivity was enhanced when summer/autumn insolation was at its maximum. We show that in the studied region, coccolithophore productivity was driven by processes reflecting regional insolation. Applying this information to model experiments is required to assess if coccolithophore productivity played a significant role in past changes of atmospheric CO2 . Highlights: Coccolithophore productivity is higher during glacials. Coccolithophores adjust their phenology in response to insolation forcing. Enhanced productivity occurs when summer/autumn insolation is at its maximum.