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Yvette H. Spitz Oregon State University, CEOAS

Western Arctic Ocean Primary Productivity Changes over the Last Three Decades and in the Future: not a Simple Story. Yvette H. Spitz Oregon State University, CEOAS Carin J. Ashjian (1) , Robert G. Campbell (2) , Michael Steele (3) and Jinlun Zhang (3).

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Yvette H. Spitz Oregon State University, CEOAS

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  1. Western Arctic Ocean Primary Productivity Changes over the Last Three Decades and in the Future: not a Simple Story. Yvette H. Spitz Oregon State University, CEOAS CarinJ. Ashjian(1), Robert G. Campbell(2), Michael Steele(3)and Jinlun Zhang(3) (1) Woods Hole Oceanographic Institution (2) University of Rhode Island, GSO (3) University of Washington Applied Physics Laboratory http://psc.apl.washington.edu/zhang/BIOMAS/index.html

  2. Ice Extent (Sept 1979) Ice Extent (Sept 2011)

  3. Open Water Days in the Beaufort Sea , 1980 to 2009 NSIDC Courtesy Irina Overseem, University of Colorado Boulder.

  4. Salinity Depth of 33.1 salinity Deepening of the nutricline and chlorophyll maximum in the Canada Basin interior, 2003–2009 (Fiona A. McLaughlin and Eddy C. Carmack)

  5. How will this large scale ice melting and changes of water properties (light, temperature, mixing, etc) affect the ecosystem?

  6. BIOMAS’ Circulation Model and Grid • Parallel ocean and sea ice model (Zhang/Rothrock 2003). => Multi-category thickness and enthalpy distribution sea ice model. => POP (parallel ocean program) ocean model (Smith et al. 1992). physical open boundary conditions imposed from a global model run

  7. Schematic of BIOMAS’ Pelagic Ecosystem Model NH4 NH4 NO3 DOM Si(OH)4 Sinking Vertical Migration Diatoms (PD) Flagellates (PF) Predators (ZP) Copepods (ZL) Small Zoo (ZS) opal Detritus DOM Zhang et al. (2010) – based on Nemuro

  8. Changes in PP and planktonin the Arctic Ocean Satellite derived PP values are from Pabi et al. 2008 and Arrigo et al. 2008 Is the trend the same for all the Seas? Is that due to a longer growing season? If not, then why?

  9. Arctic Regions for Analysis Purpose

  10. Start and End of Growing Season (10% above Phytoplankton Winter Value) Beaufort Sea Day 1988 2010 Year Chukchi Sea Diatom Flagellate Chlorophyll

  11. Integrated PP (mg C m-2 d-1 ) April – June, 1988-2000 Change in Spring Mean Primary Productivity PP and its increase over the years are small in the spring (07-11) – (88-00) (01-06) – (88-00)

  12. PAR (W m-2) – April-June. 1988-2000 Spring Mean PAR Change of mean PAR (%) at the water surface (07-11) – (88-00) (01-06) – (88-00)

  13. Trend of Yearly Maximum (day (black), magnitude (red))for the Beaufort Sea

  14. Maximum of Biomass and Primary Productivity, and Minimum of Nitrate – Change in Day from 1988 to 2010 Change in timing of max. PP is the largest in the Chukchi Sea and the largest change in timing of phytoplankton happens in the Beaufort Sea Change in timing of the secondary producer biomass is largest in deep basin, especially for the predatory zooplankton Nitrate minimum happens earlier at the surface but later at depth in the Beaufort Sea and Deep Basin

  15. Maximum of Biomass and Primary Productivity, and Minimum of Nitrate – Change in value from 1988 to 2010 Change in flagellate biomass and PP is the largest in the deep basin. Decrease of diatom biomass in Beaufort and Deep Basin Change in the secondary producer biomass is the largest in deep basin Nitrate is decreasing at the surface (except in the Chukchi Sea) and over the first 100m

  16. Integrated PP (mg C m-2 d-1 ) July – September, 1988-2000 Summer Mean Int. Primary Productivity (100m or bottom) • Increase on the shelves (almost double on the western Chukchi Sea shelf • Decrease significantly in the Beaufort Gyre (07-11) – (88-00) (01-06) – (88-00)

  17. PAR (W m-2) – July-September. 1988-2000 Summer Mean PAR Change of mean PAR (%) at the water surface Significant especially in the Beaufort Sea (07-11) – (88-00) (01-06) – (88-00)

  18. Int. Total Nitrogen (mmol N m-3) July – September, 1988-2000 Summer Mean Int. Total Nitrogen (100m or bottom) • Increase on the shelves (almost triple on the western Chukchi Sea shelf • Decrease significantly in the Beaufort Gyre (close to be depleted at the center of the Gyre) (07-11) – (88-00) (01-06) – (88-00)

  19. Int. Chlorophyll (mg Chl m-3) July – September, 1988-2000 Summer Mean Int. Chlorophyll (100m or bottom) • Increase on the shelves (almost double on the western Chukchi Sea shelf • Decrease significantly in the Beaufort Gyre (almost zero at the center (01-06) – (88-00) (07-11) – (88-00)

  20. Int. Zooplankton (mmol N m-3) July – September, 1988-2000 Summer Mean Int. Zooplankton (100m or bottom) • Increase on the shelves, especially on shelf break/slope • Decrease in the Beaufort Gyre (07-11) – (88-00) (01-06) – (88-00)

  21. Int. Kinetic Energy (cm2 s-2) July – September, 1988-2000 Summer Mean Int. Kinetic Energy (100m or bottom) • Acceleration of the Beaufort Gyre • Reduction of KE on the shelves • Note the change at the Bering Strait (07-11) – (88-00) (01-06) – (88-00)

  22. Conclusions and future research • While we found that the maximum of productivity occurs earlier and reaches higher values in general, we did not find a significant trend in the start and end of the growing season. But • The timing, magnitude and pattern of cycles are changing differently from region to region. Flagellate increase is larger than diatom increase in general. Grazer increase is larger in the Deep Basin. • There is increase of primary productivity and total nitrogen over the shelves (especially Western Chukchi Sea) and shelfbreak but decrease at the center of the Beaufort Gyre. This decrease of nitrate is accompanied of a reduction of primary productivity. On the edge of the gyre, there seems to be an increase of plankton biomass and primary prodiuctivity. • While trends can be found, the complex nature of the Arctic Seas call for cautions when analyzing observations. High resolution models are needed to resolve the present and future changes in the Western Arctic

  23. Surface Chlorophyll-a (mg Chl m-3) – July 04 - ICESCAPE Constant Chl:N 2003 2011 Chl:N from ICESCAPE regression of Chl and PON

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