Lecture 18- Microbial Processes Flashcards
oligotrophic
- pelagic environment (water column) that has naturally very low plant nutrient concentrations
- vast subtropical gyres
eutrophic
- pelagic environment that has naturally high plant nutrient concentrations
- coastal upwelling zones
traditional food chain concept (1970’s)
- organisms are placed into trophic level based on autotroph verses heterotroph
- organism’s size
traditional bacterial concentrations
were estimated from transmission light microscopy and culture-plate colony counts
use of epifluorescent microscopy and fluorescent DNA stains
- became widespread between 1975 and 1985
- Dramatically increased estimates of bacterial abundance in the ocean
new views of marine food webs recognize the importance of
high bacterial abundance and a large fraction of heterotrophic nanoflagellates (2-20-micron diameter cells) that are consumers of bacteria
prochlorococcus
- new type of small autotroph bacteria found mostly in oligotrophic regions (1/3)
- found using a new technique called analytical flow cytometry
Prochlorococcus abundance in the oligotrophic open-ocean is similar in magnitude to
the abundance of heterotrophic bacteria
importance of prochlorococcus
- in low nutrient open-ocean environments, the growth advantage goes to smallest cells which are no prochlorococcus
- contributes more than 1/4 of the total ocean primary production
what contributes the most to total ocean primary production?
heterotrophic bacteria
what creates efficient biological carbon pump?
when the dominant phytoplankton cells are large, the dominant grazers are large and their large fecal materials easily sinks to the deep ocean taking organic carbon down with it
What is the expected efficiency of the biological carbon pump for coastal upwelling zones?
the carbon pump is VERY EFFICIENT in coastal upwelling zones
