1. Kam W. Tang  Amy R. Shields  Walker O. Smith, Jr. Virginia Institute of Marine Science Gloucester Point, Virginia, USA Dark and cold survival of Phaeocystis antarctica David Elliott Maureen Lynch Jennifer Gaydos Britt Anderson Eva Bailey Heidi Geisz Adriana Veloza Emily Yam ESCAP Ecology of Solitary and Colonial Antarctic Phaeocystis Acknowledgements: U.S. NSF ANT-0440478 RPSC, McMurdo Station, Crary Lab

2. Rousseau et al. (1994) P. globosa P. pouchetii P. antarctica

3. ESCAP – Ecology of Solitary and Colonial Antarctic Phaeocystis - Survival of grazing - Survival of grazing - Survival of freezing and darkness in winter - Survival of freezing and darkness in winter

4. Chlorophyll-size-fraction-specific grazing by microzooplankton in McMurdo Sound as determined by dilution technique >>> Limacina Clione Calanus acutus Oithona Microcalanus Calanoides Paraeuchaeta Copepod nauplii Stephos Polychaete larvae Ctenophore P. antarctica single cells and small colonies are consumed by (small) grazers, which subsequently support the higher trophic levels.

5. P. antarctica Grazers + Food Dialysis bag Does grazing affect colony formation? (sensu Jakobsen & Tang 2002)

6. Consistent with previous studies on P. globosa (Jakobsen & Tang 2002; Tang 2003) Grazer No grazer P. antarctica exposed to “grazing signal” had significantly larger colonies * * *

7. Can P. antarctica survive austral winter? Physiological response to long period of darkness. Physiological response to freeze-thaw treatment.

8. Light treatment Dark treatment

9. >0.7  m “Single cells + Colonies” >5  m “Small+ Large colonies” >20  m “Large colonies” Chlorophyll (  g l -1 ) Significant decrease Significant increase

11. P b max in culture: 0.19 - 4.10 (Schoemann et al. 2005) P b max = 0.4 mgC mgChla -1 h -1 P b max = 0.26 mgC mgChla -1 h -1

12. Freeze for 15 days Recovery for up to 21 days

15.  Grazing signal led to larger colonies --- potential defense mechanism against small grazers  P. antarctica may survive long darkness and freezing in ice during austral winter, and subsequently seed the water column population in the spring.