1. Phenology of sea ice and ocean algal blooms in the Arctic Rubao Ji 1, Meibing Jin 2, Øystein Varpe 3 1. Woods Hole Oceanographic Institution 2. University of Alaska – Fairbanks 3. Norwegian Polar Institute OS 072

2. Phenology of ice algae and phytoplankton blooms in the Arctic Rubao Ji 1, Meibing Jin 2, Øystein Varpe 3 1. Woods Hole Oceanographic Institution 2. University of Alaska – Fairbanks 3. Norwegian Polar Institute OS 072

3. Background Minimum Sea Ice Extent 1978 2011 Extent (Million km 2 ) NSIDC

4. Conceptual model Derived from: Wassman 2011 Søreide et al. 2010 Leu et al., 2011

5. Implications for zooplankton Calanus hyperboreus ClimatologyStart 2-weeks earlier Ji et al., PiO 2011 Individuals can reach overwinter stage within growth season

6. Methods Modeling analysis Satellite data analysis: Ocean color (SeaWiFS) Ice (SMMR& SSM/I) Snow (SMMR& SSM/I) Melt onset: Drobot & Anderson. 2001 Western transect Eastern transect POP CICE Pelagic food web Ice-algae module LANL/NCAR Model run: 1992-2007 (Jin et al., 2011)

7. Observation: W. transect Snow-melt Ice-melt SeaWiFS Chl-a

8. Observation: E. transect Snow-meltIce-melt SeaWiFS Chl-a

9. Observation vs model Ice-melt (obs.)Ice-melt (model) Phyto peak (obs.) Phyto peak (model) Taylor diagram -Model capture basic timing pattern -Model skill similar among years -Model phyto peak earlier than obs. Phyto peak Ice melt

10. Modeled timing B T phyto-peak Lag: B-A A T ice-algae-peak

11. Timing correlation corr(T ice-melt, T phyto-peak ) (model) r (all)r (p<0.05) 0 1.0

12. Timing correlation corr(T ice-melt, T ice-algae-peak ) (model) r (all)r (p<0.05) 0 1.0

13. Timing correlation corr(T ice-melt, Lag) (model) r (all) 0 1.0 r (p<0.05)

14. Model results: W. transect

15. Summary Earlier ice-melt Earlier ice-melt Earlier phytoplankton bloom Earlier ice-algae bloom Shrinking lag between phyto. & ice-algae blooms only in E. Arctic  Potential henological match/mismatch between algae blooms and zooplankton  Need for further study (model development and validation; more phenology analysis).

16. Acknowledgement NSF Shelf-Basin Interaction (SBI) project WHOI Arctic Research Initiative IARC, University of Alaska DOE EPSCoR Program Centre for Ice, Climate and Ecosystems (ICE), Norwegian Polar Institute