The intellectual merit of the research is to extend our understanding of the biology and ecology of marine picophytoplankton, a group of microbes that are responsible for a large proportion of the total photosynthetic carbon fixation that occurs in the world's oceans. The importance of picophytoplankton as the dominant primary producers in open-ocean ecosystems is well-established. However, the factors that regulate the distribution and abundance of these populations remain poorly understood. The investigators will explore the dynamics of top-down (grazer-mediated) regulation of picophytoplankton populations in a specific context: the maintenance of summertime subsurface maxima in the pico-cyanobacterium Prochlorococcus (but not Synechococcus) in the Sargasso Sea. This phenomenon represents a relatively simple and predictable model system within which to test hypotheses about the regulation of oceanic picophytoplankton in general.
Recent results suggest that despite their abundance, Prochlorococcus in the subsurface maxi-mum are growing (and being grazed) rather slowly, as compared to the smaller population at the surface. In order to understand the factors responsible for this apparent paradox, this project will use a combination of field and laboratory studies to characterize and compare the interactions between Prochorococcus and its protozoan grazers at these two contrasting depths, and in relation to Synechococcus, which forms no such sub-surface maximum.
The broader impacts include training for graduate and undergraduate students. In addition, given the significance of picophytoplankton as primary producers at the base of oceanic microbial food webs, the results of this project should inform efforts to describe and model the broader oceanic ecosystem, and ultimately to understand its role in the global carbon cycle.
Dataset | Latest Version Date | Current State |
---|---|---|
Prochlorococcus in situ growth rates from cell cycle analysis from RV Cape Hatteras cruises CH0409 and CH0510 in the Western Sargasso Sea in 2009 and 2010. | 2017-10-12 | Final no updates expected |
Diel series of pico-cyanobacteria concentration and cell properties from the RV Cape Hatteras cruises CH0409 and CH0510 in the Western Sargasso Sea in 2009 and 2010. | 2017-10-12 | Final no updates expected |
Prochlorococcus in situ cell cycle phases fractions from RV Cape Hatteras cruises CH0409 and CH0510 in the Western Sargasso Sea in 2009 and 2010. | 2017-10-12 | Final no updates expected |
Prochlorococcus and Synechococcus cell counts in dilution experiment treatments from samples collected on RV Cape Hatteras cruises CH0409 and CH0510 in 2009 and 2010. | 2017-10-12 | Final no updates expected |
Principal Investigator: Dr Brian Binder
University of Georgia (UGA)
Contact: Dr Brian Binder
University of Georgia (UGA)