Marine Microbial Processes Flashcards

1
Q

What is Oligotrophic?

A

Pelagic environment (water column) that has low plant nutrient concentrations. Subtropical gyres are oligotrophic.

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2
Q

What is Eutrophic?

A

Pelagic environment (water column) has high plant nutrient concentrations. Coastal upwelling zones are eutrophic.

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3
Q

What is the preferred prey size?

A

1/10 of consumer size

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4
Q

Why is size an important factor in an organism’s role in pelagic environment?

A
  1. It determines who it will eat (all organisms 1/10 its own size).
  2. It determines who will eat it (all organisms 10 times bigger than it).
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5
Q

What is the general rule for optimal prey size?

A

1/10 or 1:10 of pelagic animals for smallest pelagic organisms (protozoans and bacteria).

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6
Q

What is the Traditional Food Chain Concept?

A

Organisms are in a given Trophic Level depending on whether they produce chlorophyll or not (Autotrophs vs. Heterotrophs) and on the organism’s size.

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7
Q

What is the New View of Marine Food Webs?

A

High bacterial abundance and large fraction of heterotrophic nanoflagellates.

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8
Q

What is the source of carbon and energy for heterotrophic bacterial growth?

A

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.

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9
Q

What is “Microbial Loop”?

A

The role that microbes play in the marine ecosystem carbon cycle.

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10
Q

What is the difference between early 1970’s and early 1980’s?

A

The autotrophs in the early 1980’s undergo microbial loop to make dissolved organic matter.

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11
Q

What is the name of this important new autotroph?

A

Prochlorococcus

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12
Q

What is the importance of the Flow Cytometry Optics?

A

It allowed us to discover Prochlorococcus.

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13
Q

What is Prochlorococcus Abundance?

A
  1. Prochlorococcus abundance in the oligotrophic open-ocean is similar to the abundance of heterotrophic bacteria.
  2. 1/3 of bacteria in the oligotrophic open-ocean is autotrophic Prochlorococcus.
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14
Q

What is the New View (1990’s) of Marine Food Webs?

A

It recognizes the importance of Prochlorococcus.

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15
Q

Recall: What does low nutrient concentration do?

A

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.

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16
Q

What does Prochlorococcus mainly contribute to?

A

Primary production in open-ocean environments. The remainder is contributed by other phytoplankton groups.

17
Q

What should we know about heterotrophic bacteria?

A

Heterotrophic bacteria are highly abundant in all ocean environments.
Heterotrophic bacteria consumes dissolved organic carbon from large phytoplankton cells. Protozoans and heterotrophic bacteria cause the organic carbon to respire back to carbon dioxide.

18
Q

What should we know about Prochlorococcus?

A

Prochlorococcus is an autotrophic bacterium, which contains chlorophyll and is the smallest type of phytoplankton.

  1. Main primary producer in oligotrophic (low nutrient) environments.
  2. Responsible for more than a quarter of global ocean primary production.
19
Q

What forms are most of the biomass in the open-ocean?

A

Heterotrophic bacteria and Prochlorococcus

20
Q

Recall: What is the importance of the global ocean primary production?

A

It is the component of the global ocean cycle.

21
Q

What happens to the pathway when nutrient concentration varies?

A

The pathway also varies because the carbon from CO2 (gas) particulates organic carbon (through photosynthesis) into particulate organic carbon of higher trophic levels.

22
Q

What is an efficient biological carbon pump?

A

Large dominant phytoplankton cells have large dominant grazers, which means large fecal material sinks to the deep ocean with organic carbon.

23
Q

What is an inefficient biological pump?

A

Small dominant phytoplankton cells have small dominant grazers, which means small fecal material cannot sink and the particulate organic carbon is respired back to CO2.

24
Q

What is the expected efficiency of the Biological Carbon Pump for Coastal Upwelling Zones?

A

The carbon pump is very efficient in coastal upwelling zones.

25
Q

What happens to carbon when small phytoplankton cells are found at low nutrient concentrations?

A

Carbon is not efficiently pumped into the deep ocean.

26
Q

What happens to carbon when large phytoplankton cells are found at high nutrient concentrations?

A

Carbon is efficiently pumped into the deep ocean.

27
Q

What happens to growth advantage when nutrient concentration is reduced?

A

The growth advantage shifts to small phytoplankton cells.

28
Q

Recall: A complex ecosystem can be simplified by grouping organisms based on?

A
  1. Presence of chlorophyll

2. Body size

29
Q

What is the simplified pelagic food chain conceptualization?

A

From bottom to top

  1. Primary Producers (Phytoplankton)
  2. 1st Consumers
  3. 2nd Consumers
  4. 3rd Consumers
  5. 4th Consumers