Environmental and Ecological Regulation of Differences and Interactions between Solitary and Colonial forms of Phaeocystis antarctica

PIs: Dr. Kam W. Tang (kamtang@vims.edu) and Dr. Walker Smith (wos@vims.edu) Project nickname: ESCAP - Ecology of Solitary and Colonial Antarctic Phaeocystis Funding: NSF-OPP Research site: McMurdo Station, Antarctica Deployment dates: late-November 2006 to mid-February 2007 (Year 2) Deploying Team Members: Kam Tang Walker Smith Amy Shields David Elliott Maureen Lynch Britt Anderson Eva Bailey Jennifer Gaydos

Click here to see our Antarctic journey slide show (in powerpoint; takes a few seconds to load)

Conference presentation: Workshop on Phaeocystis blooms: causes and consequences, 29-30 January, 2007 Boulogne-sur-Mer, France. [Abstract] [Powerpoint presentation] (Data are not to be cited without permission from the authors)

Research Objectives:

Phaeocystis antarctica (Prymnesiophyceae) is widely distributed in the Southern Ocean and plays important roles in polar ecology and biogeochemistry. It is a dominant primary producer, a main component of organic matter vertical fluxes, and the principal producer of volatile organic sulfur in the region. Yet P. antarctica is also one of the lesser known species in terms of its physiology, life history and trophic relationships with other organisms. P. antarctica occurs mainly as two morphotypes: solitary cells and mucilaginous colonies, which differ significantly in size, architecture and chemical composition. Relative dominance between solitary cells and colonies determines not only the size spectrum of the population, but also its carbon dynamics, nutrient uptake and utilization. However, what regulates the differences between solitary and colonial forms of P. antarctica is not certain. The research objective of this proposal is therefore to address these over-arching questions:

• Do P. antarctica solitary cells and colonies differ in growth, composition and photosynthetic rates?
• How do nutrients and grazers affect colony development and size distribution of P. antarctica?
• How do nutrients and grazers act synergistically to affect the long-term population dynamics of P. antarctica?

Experiments will be conducted in the McMurdo station with natural P. antarctica assemblages and co-occurring grazers. Laboratory experiments will be conducted to study size-specific growth and photosynthetic rates of P. antarctica, size-specific grazing mortality due to microzooplankton and mesozooplankton, the effects of macronutrients and micronutrients on the relative dominance of solitary cells and colonies, and the effects of grazing-related chemical signals on P. antarctica colony development. We will also be developing educational materials to bring polar science to K-12 students and the general public.