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Kam W. Tang  Amy R. Shields  Walker O. Smith, Jr. Virginia Institute of Marine Science

ESCAP Ecology of Solitary and Colonial Antarctic Phaeocystis. David Elliott Maureen Lynch Jennifer Gaydos Britt Anderson Eva Bailey Heidi Geisz Adriana Veloza Emily Yam. Dark and cold survival of Phaeocystis antarctica.

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Kam W. Tang  Amy R. Shields  Walker O. Smith, Jr. Virginia Institute of Marine Science

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  1. ESCAP Ecology of Solitary and Colonial Antarctic Phaeocystis David Elliott Maureen Lynch Jennifer Gaydos Britt Anderson Eva Bailey Heidi Geisz Adriana Veloza Emily Yam Dark and cold survival of Phaeocystis antarctica Kam W. Tang  Amy R. Shields  Walker O. Smith, Jr. Virginia Institute of Marine Science Gloucester Point, Virginia, USA 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 freezing and darkness in winter

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

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

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

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

  8. Dark treatment Light treatment

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

  10. Pbmax = 0.4mgC mgChla-1 h-1 Pbmax = 0.26mgC mgChla-1 h-1 Pbmax in culture: 0.19 - 4.10 (Schoemann et al. 2005)

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

  12. 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.

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