Home • Phaeocystis globosa Pg-G v2.3
Photo of Phaeocystis globosa Pg-G v2.3
Species tree for Phaeocystis globosa with other Haptophyta and species from Cryptophyta, Chlorophyta, and Chlorarachniophyta

Photosynthetic marine microalgae, particularly the relatively few species that form massive blooms, are responsible for half of total global carbon fixation, on the order of 45-50 billion tons of production annually. The chlorophyll c-containing haptophyte alga genus Phaeocystis is distributed globally and forms massive blooms that structure planktonic ecosystems, export significant amounts of materials to the sea floor, and produce prodigious amounts of the important climate gas dimethylsulfoniopropionate (DMSP). Phaeocystis exhibits life-cycle alternations between solitary cells and gelatinous colonies. These transitions caused by systems stresses, whether abiotic or biotic, restructure entire food webs and prompt adjustment of a variety of ecosystem characteristics, ranging from nutrient utilization to trophic energy transfer to vertical export of salient elements. Because Phaeocystis can account for as much as 85% of total production, transitions into the colonial morphotype provoke substantial alterations in the flow of energy and nutrients away from food webs supporting fisheries to those fueling more regenerative detrital pathways.

In addition to ecological considerations, Phaeocystis occupies a supremely interesting and poorly understood position within the tree of life. It is now well accepted that chlorophyll c-containing algae share a common ancestry due to an ancient evolutionary event that resulted in the domestication of red algal cells into what are now called secondary plastids. The subsequent diversification of this lineage has yielded an astounding diversity of ecologically dominant phytoplankton that manage pivotal roles in major geochemical scenarios (e.g. coastal upwelling, new production, and particle flux). Ultimately, a comparative genomics context will enhance understanding of the fundamental processes that drive the relative success of "red lineage" or Chromist phytoplankton.

Phaeocystis globosa is by far the most well represented member of its genus in phytoplankton culture collections, and the physiology, ecology, life history, and life cycle of certain strains have been thoroughly investigated. This species also offers an opportunity to study differences in gene expression between colonies and solitary cells (both of which are typically found in P. globosa cultures).