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Interannual Changes in Arctic Ice-edge Blooms: Impact on Ecosystem and CO2 Drawdown

Explore the interannual variations in Arctic ice-edge blooms and their implications on ecosystem vitality, fish stock, and CO2 drawdown. Learn about the impact of reduced ice coverage on productivity models and bloom characteristics in regions like Chukchi Sea. Discover the importance of timing and intensity in ice-edge blooms for total productivity.

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Interannual Changes in Arctic Ice-edge Blooms: Impact on Ecosystem and CO2 Drawdown

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  1. Interannual Changes in Arctic Ice-edge Blooms Graham Quartly1 & Mahé Perrette2 1 – National Oceanography Centre (NOC), UK 2 – Potsdam Institute for Climate Impact Research (PIK), Germany

  2. Arctic Ocean: Region of change Concern about effect of reduced ice coverage ?? Impact on vitality of ecosystem ?? Effect on fish stock ?? Importance for CO2 drawdown [from Wassmann et al. (2011)

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

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

  5. Schematic of bloom development [From Sakshaug and Skjoldal (1989) ] Ice conc. too high Algae underneath the ice 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 Westward 3 km / day mg m-3 20 days 60 km 3 months Time (year day) 10% 50% Hovmöller diagram : transect perpendicular to the ice edge 300 km Longitude (65°W – 54°W)

  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 ) VGPM Marra et al. Carr [from Perrette et al. (2011)} ]

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

  11. Ratio VGPM Carr Marra et al

  12. Bloom occurrence & timing (2007) • Most observations in June – August • 90% of adequately observed pixels experience chl > 0.5 mg.m-3, and 70% > 1 mg.m-3 • Blooms take place later as the season advances (and as the MIZ moves futher North) • overall 50 % of blooms > 0.5 mg.m-3 are over within 30 days Observations > 20 Peak 0 - 20 < 0 > 30 Termination < 15 March Apr. May June July Aug.

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

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

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

  16. Implications • Large changes in melt date affects intensity of ice-edge bloom • Ecosystem may lose dual-bloom nature • Highly variable effects on other trophic levels • ?? Effects on total productivity and CO2 drawdown

  17. Summary • Ice-edge bloom is an important ecological niche (bloom within 20 days of ice-melt occurs in ~90% of seasonal ice zone) • Growth and productivty dependent upon timing (likely different response for different regions) • Early ice-melt may affect other trophic levels Perrette, M. et al. (2011), Near-ubiquity of ice-edge blooms in the Arctic, Biogeosciences, 8, 515–524.

  18. Changes in ice melt

  19. Data consistency SSM/I Combining SeaWiFS, MERIS, MODIS, need to allow for: chlorophyll calibration data flagging swath width sampling time

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