The document discusses interannual changes in ice-edge blooms in the Arctic region. It summarizes that ice-edge blooms are an important ecological niche that typically occur within 20 days of ice melt in around 90% of the seasonal ice zone. The timing of ice melt can have varying effects on the intensity and productivity of ice-edge blooms between different regions. Specifically, early ice melt may result in a weaker bloom peak and could affect other trophic levels in the ecosystem. Consistent satellite data is needed to accurately analyze interannual variability in Arctic ice melt and ice-edge blooms.

1. Interannual Changes in Arctic Ice-edge Blooms Graham Quartly 1 & Mahé Perrette 2 1 – National Oceanography Centre (NOC), UK 2 – Potsdam Institute for Climate Impact Research (PIK), Germany

2. Arctic Ocean: Region of change [from Wassmann et al. (2011) C oncern about effect of reduced ice coverage ?? Impact on vitality of ecosystem ?? Effect on fish stock ?? Importance for CO 2 drawdown

3. Arctic: A mix of different ecosystems Three distinct marine environments: Open water year round Permanent ice cover Seasonal ice cover Seasonal ice cover in 2007 Chukchi Sea Baffin Bay Barents Sea

4. Outline of talk Development of ice-edge blooms Productivity models Interannual variations

5. Schematic of bloom development [From Sakshaug and Skjoldal (1989) ] Algae underneath the ice Ice conc. too high Ice-edge bloom Bloom fini-shed Stratification may develop, and then open-water bloom

6. Example from Baffin Bay Ice data from NSIDC or OSISAF (uses SSM/I) Chl data from NASA Goddard (SeaWiFS)

7. Bloom characteristics 50% Time (year day) Longitude (65°W – 54°W) 10% 20 days Westward 3 km / day 60 km 300 km 3 months mg m -3 Hovmöller diagram : transect perpendicular to the ice edge

8. Marginal Ice Zone MIZ period = any time up to 20 days after ice < 10%

9. Primary Productivity PP = f ( Chl, SST, day length, PAR ) [from Perrette et al. (2011)} ] VGPM Carr Marra et al.

10. Ice vs. Spring Intensity, longevity, total contribution

11. Ratio VGPM Carr Marra et al

13. Interannual variability I Year day chlorophyll (mg.m -3 ) First ice-free day Bloom peak Baffin Bay: Late melt => Weak peak (also 2004, 2008) 2005 2006 2007 Mar. April May June July Aug.

14. Interannual Variability II Early melt mismatch ? Year day chlorophyll (mg.m -3 ) Sep. First ice-free day Bloom peak Barents Sea: Early melt => Weak peak 1998 2001 2006 Mar. April May June July Aug.

15. Changes in timing Histogram of first ice-free day Histogram of peak lag after ice-retreat Late blooms Early ice retreat MIZ period Open water Barents Sea Mar. May July Sep.

18. Changes in ice melt

20. Data consistency SSM/I Combining SeaWiFS, MERIS, MODIS, need to allow for: chlorophyll calibration data flagging swath width sampling time 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Pixel SEAWIFS 9 km MERGED 9 km MODIS 9 km NSIDC 25 km OSISAF 10 km