Open AccessProchlorococcus growth rates in the central equatorial Pacific: An application of the ƒ max approach
Author(s) -
Liu Hongbin,
Landry Michael R.,
Vaulot Daniel,
Campbell Lisa
Publication year - 1999
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1998jc900011
Subject(s) - prochlorococcus , upwelling , equator , transect , oceanography , growth rate , phytoplankton , subtropics , biomass (ecology) , nitrate , environmental science , biology , nutrient , latitude , ecology , geology , cyanobacteria , synechococcus , genetics , geometry , mathematics , geodesy , bacteria
Minimum daily growth rates of Prochlorococcus were estimated for the central equatorial Pacific (12°S–12°N, 140°W) during El Niño (February‐March 1992) and normal upwelling (August‐September 1992) conditions. Growth rate estimates were based on the percentages of cells in the S and G 2 division phases at dawn (∼0700 LT) and dusk (∼1800 LT) as approximate values for ƒ min and ƒ max , respectively. During both environmental conditions, depth‐integrated growth rates of Prochlorococcus were higher in oligotrophic waters at the northern end of the transect (0.36–0.52 d −1 ) and decreased to a minimum at the equator. The lowest growth rates were found at the equator during El Niño and at 2°N during normal upwelling, where a large biomass of buoyant diatoms had accumulated in the vicinity of a convergent front. Prochlorococcus growth rate reached a high of 0.64 d −1 at 1°S and maintained a moderate rate (0.36–0.49 d −1 ) throughout the southern end of the transect. An inverse relationship was found between the contribution of Prochlorococcus to the total primary production and nitrate concentration as well as total primary production measured by the 14 C method. While Prochlorococcus is a dominant primary producer in tropical and subtropical open‐ocean ecosystems generally, it is relatively more important in oligotrophic waters than in the nutrient rich equatorial upwelling zone.