Grantee Research Project Results
Does Iron Limit the Cell Division Rate of the Marine Cyanobacteria Prochlorococcus in the Equatorial Pacific?
EPA Grant Number: U914963Title: Does Iron Limit the Cell Division Rate of the Marine Cyanobacteria Prochlorococcus in the Equatorial Pacific?
Investigators: Mann, Elizabeth L.
Institution: Woods Hole Oceanographic Institution
EPA Project Officer: Lee, Sonja
Project Period: January 1, 1996 through January 1, 1999
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Fellowship - Marine Biology , Academic Fellowships , Biology/Life Sciences
Objective:
The objective of this research project is to determine if iron limits cyanobacteria productivity in the equatorial Pacific by computing the cell division rates of the marine cyanobacteria Prochlorococcus before and after an in situ fertilization with iron.
Approach:
The chlorophyll per cell and the forward -angle light scatter (related to cell size) of Prochlorococcus increased inside the iron fertilized patch, but the population size did not. This could result if: (1) iron fertilization had no effect on the cell division rate of Prochlorococcus,; or (2) iron increased the cell division rate, but the grazing rate increased fast enough to keep the population in check. To distinguish between these two possibilities, the cell division rate was determined using the cell cycle analysis method of Carpenter and Chang (Marine Ecology Progress Series 1988,; 43, :105-111). Samples for DNA histograms were taken both before and after the iron fertilization,; cell cycle analysis indicates that Prochlorococcus were dividing almost once a day before the iron was added, and that the cell division rate doubled inside the iron fertilized patch.