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SUMMARY:Southern Ocean coccolithophore biogeography – controlling factor
 s and implications for global biogeochemical cycles - Cara Nissen\, ETH Zu
 rich 
DTSTART:20170626T100000Z
DTEND:20170626T110000Z
UID:TALK72744@talks.cam.ac.uk
CONTACT:Dr Peter Davis
DESCRIPTION:Southern Ocean phytoplankton biogeography is important for the
  biogeochemical cycling of carbon\, silicate\, and the transport of macron
 utrients to lower latitudes. With the discovery of the “Great Calcite Be
 lt” (GBC)\, revealing an unexpectedly high prevalence of calcifying phyt
 oplankton between 40-55°S\, the relative importance of Southern Ocean coc
 colithophores for phytoplankton biomass\, net primary productivity and the
  carbon cycle need to be revisited. \nHere\, I present results from a regi
 onal high-resolution model with an embedded ecosystem module (ROMS-BEC) fo
 r the Southern Ocean (24-78°S). We assess the environmental drivers of So
 uthern Ocean coccolithophore biogeography over the course of the growing s
 eason focusing on biotic interactions and the relative importance of top-d
 own versus bottom-up factors controlling growth and abundance. Furthermore
 \, we perform iron fertilization experiments to assess the effects of chan
 ged nutrient availability on coccolithophore abundance in the GCB. We find
  that top down controls are a major control on the relative abundance of d
 iatoms and coccolithophores in the Southern Ocean and that changes in nutr
 ient stoichiometry significantly alter phytoplankton community composition
 \, the relative contribution of particulate organic and inorganic carbon\,
  as well as opal to export\, and the supply of nutrients to lower latitude
 s. Consequently\, when assessing potential future changes in Southern Ocea
 n coccolithophore abundance and its implications for biogeochemical cycles
 \, both physical (temperature\, light\, nutrient availability) and chemica
 l (ocean acidification) changes\, but also biotic interactions need to be 
 considered.\n
LOCATION:British Antarctic Survey\, Innovation Centre\, Seminar Room 2
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