Microbial Ecology Flashcards

1
Q

When do lakes stratify?

A

During summer months from increased solar radiation, with weak summer wind unable to mix the dense cold water beneath.

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2
Q

When does wind mixing occur?

A

Fall turnover

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3
Q

Why does spring and summer support algal blooms?

A

As deep-layer nutrients are brought up from the mixing period in the winter and early spring.

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4
Q

Algal importance in ecosystems?

A

Photosynthetic primary producers, consumed by protozoa, crustaceans, consumed by consumers.

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5
Q

Oligotrophs

A

The ability for micro-organisms to grow when oxygen levels are low, being slow growing.

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6
Q

Eutrophic

A

Enrichment of nutrients increasing plant/algal growht in coastal winter and estuaries.

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7
Q

When do eutrophs exist?

A

Not in winter due to low nutrient concentrations

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8
Q

Microbial Loop

A

Models aquatic ecosystems comprising bacteria, dinoflagellates, ciliates and other zooplankton.

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9
Q

Phagotrophic

A

This is feeding by engulfing good cell or particles and ingesting it in phagocytic vacuoles.

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10
Q

How is organic matter assimilated?

A

By bacteria

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11
Q

What are the domainant primary producers in marine envrionments?

A

Planktonic algae.

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12
Q

Redfield Ratio

A

Describes C ; N ; P ratio nearly constant at 106 ; 16 ; 1.

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13
Q

What sunlight do lakes recieve?

A

Shortwave solar and reflected longwave.

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14
Q

What is downward lake movement mediated by?

A

Mechanical energy

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15
Q

How is stratfication ecologically important?

A

When stratified, the metalimnion prevents water-column mixing, thus isolating hypolimnion from atmospheric gas exchange

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16
Q

When might the hypolimnion recieve light for photosynthesis?

A

Clearer lakes allow deeper penetration

17
Q

When does stratifcaition occur summer?

A

Temperate lakes

18
Q

How might deep water temperature increase?

A

Humic substance oxygenation produces heat, and sediment heat release.

19
Q

Effects on Diurnal variations?

A

Solar radiation increases with cloudless days incerasing stratification

20
Q

Types of lake based on stratification?

A

Dimictic
Monomictic
Oligomictic
Polymictic
Amictic
Meromictic

21
Q

Dimictic

A

Typical of temperate climates where stratification occurs twice a year.

22
Q

Monomictic

A

Experience turnover only once a year, thic can be cold or warm.

23
Q

When do monomicitc lakes occur?

A

Cold below 4C or subtropics never below 4C

24
Q

Oligomictic

A

Do not stratify every year, found say in low humid and high wind equatorial regions, with little seasonal changes

25
Q

Polymictic

A

Stratify and mix throughout ice-free periods in lakes to shallow to thermally stratify.

26
Q

Amictic

A

Permanently stratified

27
Q

Example of amictic lake?

A

Antartica where permanent ice cover, lakes never turnover.

28
Q

Meromictic

A

Contain eplimnion and metalimnion vertical mixing that does not extend to the hypolimnion.