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SUMMARY:A year in the life of the minutiae in a changing Arctic Ocean - Br
 yan Wilson\, University of Bergen
DTSTART:20170628T120000Z
DTEND:20170628T130000Z
UID:TALK72630@talks.cam.ac.uk
CONTACT:Claire Waluda
DESCRIPTION:Abstract: As the global climate changes\, the higher latitudes
  are seen to be warming significantly faster and it is likely - if not alr
 eady apparent - that the Arctic biome will experience considerable shifts 
 in ice melt season length and permafrost thawing\, leading to changes in p
 hotoirradiance and in the freshwater and terrigenous inputs to the marine 
 environment. The exchange of nutrients between Arctic surface and deep wat
 ers and their biogeochemical cycling throughout the water column is driven
  by the seasonality of some of the most extreme environmental changes on t
 he planet. The impacts\, however\, of the current global climate transitio
 n period on the biodiversity and its continued nutrient cycling within the
  Arctic Ocean are not yet known. To determine seasonal variation in the mi
 crobial flora and fauna of the deep water column\, samples were collected 
 from a 1000m depth profile in the seas around the Western coasts of the Sv
 albard archipelago throughout the polar year. High-throughput sequencing o
 f tag amplicon and shotgun metagenomes were used to monitor microbial dive
 rsity and function in both the epipelagic surface waters (defined by the d
 iametric diurnal conditions of the polar summer and winter) and the relati
 vely invariable and permanently dark mesopelagic depths. \n\nIn epipelagic
  surface waters (<200m depth)\, seasonal diversity varied significantly\, 
 with light and the corresponding annual phytoplankton bloom pattern being 
 the primary drivers of change during the late spring and summer months. In
  the mesopelagic ocean deeps (>200m)\, seasonality subsequently had much l
 ess effect on biodiversity. Interestingly\, species richness consistently 
 increased down through the water column\, with the deepest darkest waters 
 containing the greatest diversity. The phenomenon of the polar phytoplankt
 on blooms\, followed by the successional explosion of heterotrophic bacter
 ial populations\, also seemingly spurs the annual disappearance of the anc
 ient and chemolithoautotrophic marine Archaea from surface waters. During 
 the winter darkness\, these venerable microbes feast upon the summer fruit
 s of the phytoplankton photosynthesis\, replenishing surface waters with n
 utrients which fuel the next spring bloom\, essentially yin to the phytopl
 ankton's yang.  \n\nHowever\, should suggested models of a freshening Arct
 ic be correct\, surface Arctic basin waters in a warming world may become 
 increasingly stratified\, such that the vertical flux of nutrients between
  deeper waters and the epipelagic zone may be much reduced\; primary produ
 ctivity would consequently be lessened and this annual biogeochemical cycl
 e\, so essential for Arctic Ocean productivity\, would inevitably be disru
 pted. Given the significance of the annual phytoplankton bloom pattern on 
 prokaryote diversity in Arctic waters\, any changes to bloom dynamics resu
 lting from accelerated global warming will likely have major impacts on su
 rface marine microbial communities\, those impacts inevitably trickling do
 wn into deeper waters.\n
LOCATION:British Antarctic Survey\, Innovation Centre\, Seminar Room 1
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