Yvette - PowerPoint Presentation

Slide1

Yvette H. SpitzOregon State University, CEOASCarin J. 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

Western Arctic Ocean Primary Productivity Changes over the Last Three Decades and in the Future: not a Simple Story.Slide2

Ice Extent (Sept 1979)Ice Extent (Sept 2011)Slide3

NSIDC Courtesy Irina Overseem, University of Colorado Boulder.Open Water Days in the Beaufort Sea , 1980 to 2009Slide4

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

Depth of 33.1 salinitySlide5
Slide6

How will this large scale ice melting and changes of water properties (light, temperature, mixing, etc) affect the ecosystem?Slide7

BIOMAS’ Circulation Model and Gridphysical open boundary conditions imposed from a global model run

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).Slide8

DOM

Small Zoo

(ZS)

Copepods (ZL)

Detritus

Flagellates (PF)

Diatoms (PD)

NO

3

NH

4

DOM

NH4

Sinking

Vertical Migration

Predators (ZP)

Si(OH)

4

opal

Schematic

of BIOMAS’ Pelagic Ecosystem Model

Zhang et al. (2010) – based on

NemuroSlide9

Changes in PP and planktonin the Arctic OceanSatellite 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?Slide10

Arctic Regions for Analysis PurposeSlide11

Start and End of Growing Season (10% above Phytoplankton Winter Value)

Beaufort Sea

Chukchi Sea

Diatom

Flagellate

Chlorophyll

Year

1988

2010

DaySlide12

Change in Spring Mean Primary Productivity (01-06) – (88-00)

(07-11) – (88-00)

Integrated PP (mg C m-2 d-1 ) April – June, 1988-2000

PP and its increase over the years are small in the springSlide13

Change of mean PAR (%) at the water surface(01-06) – (88-00) (07-11) – (88-00)

PAR (W m

-2) – April-June. 1988-2000Spring Mean PARSlide14

Trend of Yearly Maximum (day (black), magnitude (red)) for the Beaufort SeaSlide15

Maximum of Biomass and Primary Productivity, and Minimum of Nitrate – Change in Day from 1988 to 2010 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

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 SeaSlide16

Maximum of Biomass and Primary Productivity, and Minimum of Nitrate – Change in value from 1988 to 2010 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

Change in flagellate biomass and PP is the largest in the deep basin. Decrease of diatom biomass in Beaufort and Deep Basin Slide17

Summer Mean Int. Primary Productivity (100m or bottom)

(01-06) – (88-00)(07-11) – (88-00)

Integrated PP (mg C m-2 d-1

) July – September, 1988-2000

Decrease significantly in the Beaufort Gyre

Increase on the shelves (almost double on the western Chukchi Sea shelfSlide18

Change of mean PAR (%) at the water surface(01-06) – (88-00)(07-11) – (88-00)PAR (W m-2) – July-September. 1988-2000

Summer Mean PAR

Significant especially in the Beaufort SeaSlide19

Summer Mean Int. Total Nitrogen (100m or bottom) (01-06) – (88-00)(07-11) – (88-00)Int. Total Nitrogen (

mmol N m-3) July – September, 1988-2000

Decrease significantly in the Beaufort Gyre (close to be depleted at the center of the Gyre)

Increase on the shelves (almost triple on the western Chukchi Sea shelfSlide20

Summer Mean Int. Chlorophyll (100m or bottom) (01-06) – (88-00)

(07-11) – (88-00)

Int. Chlorophyll (mg Chl m-3) July – September, 1988-2000

Decrease significantly in the Beaufort Gyre (almost zero at the center

Increase on the shelves (almost double on the western Chukchi Sea shelfSlide21

Summer Mean Int. Zooplankton (100m or bottom) (01-06) – (88-00)

(07-11) – (88-00)

Int. Zooplankton (mmol N m-3) July – September, 1988-2000

Decrease in the Beaufort Gyre

Increase on the shelves, especially on shelf break/slopeSlide22

Summer Mean Int. Kinetic Energy (100m or bottom) (01-06) – (88-00)

(07-11) – (88-00)

Int. Kinetic Energy (cm2 s-2) July – September, 1988-2000

Reduction of KE on the shelves

Acceleration of the Beaufort Gyre

Note the change at the Bering Strait Slide23

Conclusions and future researchWhile 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.ButThe 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 ArcticSlide24

Surface Chlorophyll-a (mg Chl m-3) – July 04 - ICESCAPE

2003

2011Constant Chl:N

Chl:N from ICESCAPE regression of Chl and PONSlide25
Slide26