Estimating the growth rates of Prochlorococcus and Synechococcus in the sea from diel cell cycle ana...

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" Estimating the growth rates of Prochlorococcus and Synechococcus in the sea from diel cell cycle analysis "
H. Liu L. L. Campbell, Michael

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1113216
Doc. No	:	TLpq304343126
Main Entry	:	H. Liu
	:	L. L. Campbell, Michael
Title & Author	:	Estimating the growth rates of Prochlorococcus and Synechococcus in the sea from diel cell cycle analysis\ H. LiuL. L. Campbell, Michael
College	:	University of Hawai'i at Manoa
Date	:	1997
student score	:	1997
Degree	:	Ph.D.
Page No	:	252
Abstract	:	Photosynthetic bacteria--Prochlorococcus and Synechococcus--are important components of phytoplankton biomass and primary production in the most warm open ocean. To determine the relative importance of Prochlorococcus and Synechococcus to primary production in various oceanic ecosystems, appropriate growth rate methods were required to permit species-specific estimates. Cell cycle analysis has been proven a reliable tool for estimating growth rates of Prochlorococcus spp. Applying a modified model to Prochlorococcus in the equatorial and subtropical North Pacific Ocean revealed that Prochlorococcus grew equally well in oligotrophic and mesotrophic conditions at about one doubling per day in the surface mixed layer. However, the contribution by Prochlorococcus to primary production was significantly higher in the oligotrophic subtropical North Pacific than in the mesotrophic central equatorial Pacific. Attempts to estimate the growth rate of Synechococcus from cell cycle analyses were negatively impacted by preliminary results which showed that natural Synechococcus populations are less tightly synchronized to the daily photocycle and some populations possess irregular cell cycle patterns. Applying the relationship between usd\rm t\sb{S+G2}usd and chemostat growth rate of Synechococcus WH7803 to field samples collected from the Arabian Sea provided unrealistic results. Therefore, an alternative method was developed in which Synechococcus growth rate could be calculated from diel variations in population abundances based on the fact that Synechococcus cell division occurred mostly during daytime. Using this approach for Synechococcus and the diel cell cycle analysis for Prochlorococcus, I estimated their growth and mortality rates and productions in Arabian Sea during SW and NE Monsoons. Overall, I have demonstrated that an inverse relationship between the importance of Prochlorococcus and Synechococcus to primary production exist. This relationship holds among all studied oceanic regions with nutrient conditions ranging from oligotrophic open ocean to nutrient-rich coastal upwelling water.
Subject	:	Arabian Sea
	:	Biological sciences
	:	cell cycle
	:	Microbiology
	:	Oceanography
	:	Pacific Ocean