The Ecological Consequences of Upwelling in the Southeast ...

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The Ecological Consequences of Upwelling in the Southeast ...

The Ecological Consequences of Upwelling in theSoutheast Beaufort SeaJean-Éric Tremblay 1 , Simon Bélanger 2 , David Barber, 3 Yves Gratton 4 , LouisFortier 1 & Bruno Lansard 51Université Laval, Québec, Canada2UQAR, Rimouski, Canada3University of Manitoba, Winnipeg, Canada4INRS-ETE, Québec, Canada5McGill UniversityState of the Arctic, Miami, 16 March 20102003-2004 2007-2008UNIVERSITÉLAVAL


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The Canadian Beaufort Shelf


Resilient stratificationNitrate (µM)Overwintering in landfast ice1510Nitrate (µM)N (x10 -3 s -1 )50806040200Depth (m)squares = CFLcircles = CASESWinter maximumEddies (transit)Upwelling (shelf-break)Tremblay et al., 2008, JGR 113


Atmospheric forcing (late 2007 & 2008)hPaWang et al. 2009, Geophysical Research Letters 36, L05706


Wind, ice and upwelling+


Surface signature during October 2007Salinity3433NO 3-(µM)1815+3212319306293280Chl a (µg l -1 )86DIC (mmol kg-1 )2.252.202.1542.102.0522.001.9501.90• Late-fall new production = previous annual estimate for the shelf• Production of ice diatoms doubled in spring 2008


Upwelling and primary production in 2008Site A20042008Site B


Response of Calanus glacialis on the middle shelfAbundance (x 1000 ind m -2 )Fall(16 October ± 2 days)Summer(5 July ± 5 days)


Collateral damage?! - aragoniteDepth (m)Offshore (Amundsen Gulf)Outer shelf (mild upwelling)Outer shelf (strong upwelling)Middle shelf (strong upwelling)


ConclusionsWinter(Beaufort)Eddies Winter(Beaufort) (Barents)Upwelling(Beaufort)Winter(Bering Sea)1 x 1.3 – 2 x 2.1 x 3 x6 xNitrate inventory in upper 50 m (mmol m -2 )! The notion that pelagic food webs depend on a single burst ofphytoplankton production is unsupported.! Expectactions of ice-algal demise and trophic mismatch in coastalregions are based on overly simplistic scenarios.! Upwelling stimulates productivity in the short term, but could havenegative effects in the long run (pH, contaminants, denitrification)

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