The West Antarctic Peninsula (WAP) exhibits strong spatial and temporal oceanographic variability, resulting in highly heterogeneous biological productivity. Calcifying organisms that live in the waters off the WAP respond to temporal and spatial variations in ocean temperature and chemistry. These marine calcifiers are potentially threatened by regional climate change with waters already naturally close to carbonate undersaturation. Future projections of carbonate production in the Southern Ocean are challenging due to the lack of historical data collection and complex, decadal climate variability. Here we present a 6-year-long record of the shell fluxes, morphology and stable isotope variability of the polar planktic foraminifera Neogloboquadrina pachyderma (sensu stricto) from near Palmer Station, Antarctica. This species is fundamental to Southern Ocean planktic carbonate production as it is one of the very few planktic foraminifer species adapted to the marine polar environments. We use these new data to obtain insights into its ecology and to derive a robust assessment of the response of this polar species to environmental change. Morphology and stable isotope composition reveal the presence of different growth stages within this tightly defined species. Inter-and intra-annual variability of foraminiferal flux and size is evident and driven by a combination of environmental forcing parameters, most importantly food availability, temperature and sea ice duration and extent. Foraminiferal growth occurs throughout the austral year and is influenced by environmental change, a large portion of which is driven by the Southern Annular Mode and El Nino-Southern Oscillation. A distinct seasonal production is observed, with the highest shell fluxes during the warmest and most productive months of the year. The sensitivity of calcifying foraminifera to environmental variability in this region, from weeks to decades, has implications both for their response to future climatic change and for their use as palaeoclimate indicators. A longer ice-free season could increase carbonate production in this region at least while carbonate saturation is still high enough to allow for thick tests to grow.
1.Cardiff Univ, Sch Earth & Ocean Sci, Main Bldg, Cardiff CF10 3AT, S Glam, Wales 2.Univ Bristol, Sch Earth Sci, Wills Mem Bldg,Queens Rd, Bristol BS8 1RJ, Avon, England 3.Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands, England 4.British Antarctic Survey, Madingley Rd, Cambridge CB3 0ET, England 5.Vrije Univ Amsterdam, Fac Sci, Dept Earth Sci, De Boelelaan 1085, NL-1081 HV Amsterdam, Netherlands 6.British Geol Survey, NERC Isotope Geosci Facil, Nottingham NG12 5GG, England 7.Univ Nottingham, Sch Biosci, Ctr Environm Geochem, Sutton Bonington Campus, Loughborough LE12 5RD, Leics, England 8.Univ Colorado Boulder, Inst Arctic & Alpine Res, Boulder, CO 80303 USA 9.Columbia Univ, Lamont Doherty Earth Observ, 61 Route 9W, Palisades, NY 10964 USA
Recommended Citation:
Mikis, Anna,Hendry, Katharine R.,Pike, Jennifer,et al. Temporal variability in foraminiferal morphology and geochemistry at the West Antarctic Peninsula: a sediment trap study[J]. BIOGEOSCIENCES,2019-01-01,16(16):3267-3282