Marine Microbial Processes Flashcards
What is Oligotrophic?
Pelagic environment (water column) that has low plant nutrient concentrations. Subtropical gyres are oligotrophic.
What is Eutrophic?
Pelagic environment (water column) has high plant nutrient concentrations. Coastal upwelling zones are eutrophic.
What is the preferred prey size?
1/10 of consumer size
Why is size an important factor in an organism’s role in pelagic environment?
- It determines who it will eat (all organisms 1/10 its own size).
- It determines who will eat it (all organisms 10 times bigger than it).
What is the general rule for optimal prey size?
1/10 or 1:10 of pelagic animals for smallest pelagic organisms (protozoans and bacteria).
What is the Traditional Food Chain Concept?
Organisms are in a given Trophic Level depending on whether they produce chlorophyll or not (Autotrophs vs. Heterotrophs) and on the organism’s size.
What is the New View of Marine Food Webs?
High bacterial abundance and large fraction of heterotrophic nanoflagellates.
What is the source of carbon and energy for heterotrophic bacterial growth?
Heterotrophic bacteria grow on dissolved organic matter released from phytoplankton by steady leakage. It could also be released from cell senescence or sloppy feeding by zooplankton.
What is “Microbial Loop”?
The role that microbes play in the marine ecosystem carbon cycle.
What is the difference between early 1970’s and early 1980’s?
The autotrophs in the early 1980’s undergo microbial loop to make dissolved organic matter.
What is the name of this important new autotroph?
Prochlorococcus
What is the importance of the Flow Cytometry Optics?
It allowed us to discover Prochlorococcus.
What is Prochlorococcus Abundance?
- Prochlorococcus abundance in the oligotrophic open-ocean is similar to the abundance of heterotrophic bacteria.
- 1/3 of bacteria in the oligotrophic open-ocean is autotrophic Prochlorococcus.
What is the New View (1990’s) of Marine Food Webs?
It recognizes the importance of Prochlorococcus.
Recall: What does low nutrient concentration do?
It shifts the growth advantage to small phytoplankton cells (mainly Prochlorococcus).
The growth advantage in oligotrophic (low nutrient) open-ocean environments shifts to the smallest phytoplankton cells, which are Prochlorococcus.