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SUMMARY:Using tagged seals to evaluate the MODIS record: can perturbations
  to the base of the Southern Ocean food web be detected in 12 years of dat
 a? - Lauren Biermann\, CEFAS
DTSTART:20160519T120000Z
DTEND:20160519T130000Z
UID:TALK66259@talks.cam.ac.uk
CONTACT:Claire Waluda
DESCRIPTION:The Southern Ocean maintains a complex marine food web based o
 n its stock of photosynthesizing phytoplankton. For the same reason\, it i
 s our most significant sink of carbon\, vital to the functioning of our gl
 obal atmospheric systems. However\, this key polar ocean is also responsiv
 e to atmospheric variability dominated by the Southern Annular Mode (SAM).
  In response to ozone depletion\, the SAM has exhibited a significant tren
 d to its positive phase since the 1970s. Consequently\, the westerlies dri
 ving circulation have strengthened and contracted poleward\, changing mixi
 ng regimes and shifting fronts further south. Inevitably\, these changes m
 ust impact on phytoplankton patterns\, with ramifications for the Antarcti
 c marine food web. Based on satellite measures of [Chl-a] and light attenu
 ation (Zeu) which were first validated by fluorescence and light data coll
 ected by tagged southern elephant seals\, this talk addresses the possibil
 ity that changes to summer phytoplankton patterns in the Southern Ocean ca
 n already be measured in the 12-year MODIS record. Trends suggest overall 
 declines and shifts in the timing of blooms. In some regions\, changes als
 o appear to be associated with the SAM. However\, declines in surface [Chl
 -a] may point to increases in deep chlorophyll maxima rather than net loss
 es to biomass\, and\, ultimately\, it is the vertical distribution of phyt
 oplankton that structures marine food webs. Southern elephant seals are te
 rtiary consumers\, yet their foraging patterns do not appear to be indepen
 dent of vertically-integrated phytoplankton abundance. This suggests that 
 perturbations to the base of the marine food web will persist through to t
 he top.\n\n\n
LOCATION:British Antarctic Survey\, Room 307
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