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Flashcards in Lecture 6 - DA Deck (110)
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1
Q

Between aquatic and terrestrial environments, which has more phyla?

A

Aquatic, therefore more diverse.

2
Q

What kinds of terrestrial environments have huge diversity?

A

Forests, rainforests, mainly from insects.

3
Q

What are two differences between aquatic and terrestrial environments that had an impact on how they evolved?

A

Movement - the need to move through water vs air.

Water - absorbs light, creating a gradient.

4
Q

What effect do currents have on aquatic systems? How does it affect distribution versus a terrestrial environment?

A

Currents allow easier movement and distribution of organisms compared to a terrestrial one. Therefore, aquatic organisms are more distributed than terrestrial ones.

5
Q

What is the dominant primary producer in aquatic environments and terrestrial ones?

A

Aquatic - phytoplankton

Terrestrial - large plants

6
Q

The dominant primary producers are different in aquatic and terrestrial environments. How does each affect energy flow to higher trophic levels in each, and why? What does this reflect about the energy flow?

A

Aquatic - Phytoplankton are very small, and fed on by small primary consumers, which are fed on by small fish, which are fed on by larger fish etc. More steps are needed to reach higher trophic levels.
Terrestrial - Large plants can be fed on directly by large primary consumers, and less steps are needed to reach higher trophic levels.
Reflects how much energy can be passed to higher levels.

7
Q

Between aquatic and terrestrial systems, which has more benthic/unmoving organisms, and why?

A

More in aquatic systems, because they can filterfeed, and use water to distribute gametes.
Terrestrial organisms must move around to find food and mates.

8
Q

Between terrestrial and aquatic environments, what are the nutrients present in the dominant medium like (soil vs. water)? What consequence does this have?

A

Nutrients are present in soil at high concentrations, while in water, they are more dilute.
Nutrients are therefore often a limiting factor in aquatic systems, and not so in terrestrial systems.

9
Q

Name 3 storage compartments for water in the hydrologic cycle. Give an example for each if applicable.

A

Atmosphere - clouds
Land - ice/groundwater
Water bodies - inland/marine

10
Q

Name 3 movements between storage compartments in the hydrologic cycle, with an example for each.

A

Atmosphere to land - precipitation
Land to water bodies - surface/groundwater runoff
Water bodies to atmosphere - evaporation

11
Q

Define evapotranspiration. What consequence does this mechanism have?

A

Plants open stomata for gas exchange to uptake CO2 and expel O2, and water is lost in the process.
This drives the uptake of water from the roots of the plant however.

12
Q

What are the contributing factors of water moving from water bodies to the atmosphere?

A

Evaporation from sunlight/heat, but also evapotranspiration, a high contributor, especially in rainforests.

13
Q

What dominates over land, precipitation or evaporation? What happens to the excess?

A

Precipitation > evaporation.

Excess precipitation is carried to oceans by surface/groundwater runoff.

14
Q

Most precipitation over land originates from where?

A

From evaporation of the ocean.

15
Q

What dominates over oceans, evaporation or precipitation?

A

Evaporation > precipitation

16
Q
Order the following by retention time of water, from lowest to highest.
Ground water
Inland bodies
Ocean
Atmosphere
Polar ice
A
Atmosphere
Inland bodies
Groundwater
Ocean
Polar ice
17
Q

Name 5 human activities that can influence water distribution.

A
Damming rivers
Land clearing
Redirecting rivers
Exploiting groundwater
Anthropogenic climate change
18
Q

Define limnology.

A

Study of lakes, rivers, wetlands

19
Q

Define lentic.

A

Standing water systems - lakes, ponds

20
Q

Define wetland.

A

Transition zone between terrestrial and aquatic systems.

21
Q

What is the soil like in wetlands? Are there any rooted aquatic vegetation?

A

Soil is waterlogged at least part of the year.

Have some rooted aquatic vegetation.

22
Q

Define catchment.

A

Area around land drained by a river system - also a watershed/drainage basin.

23
Q

Do lakes have a catchment?

A

Yes.

24
Q

What is the water saturation at the surface of a catchment like? What is this zone called, and what does water movement here dictate?

A

Surface isnt saturated, and the water moves freely, infiltrating down this area. This is the unsaturated zone. Water movement here dictates how water overall moves.

25
Q

What defines the saturated zone of a catchment? What is the surface of this definition called?

A

Is defined by a line below which the water is saturated, the surface is the water table.

26
Q

Can water still move freely into the saturated zone?

A

Yes.

27
Q

Define aquifer.

A

Reserve of water.

28
Q

Does water move freely just below the water table? What kind of aquifer is this area? What about far deeper down?

A

Water can move freely just below the water table, and is an unconfined aquifer.
Deeper down, water is saturated but not moving freely, and is a confined aquifer.

29
Q

Define lag time.

A

Time taken for water to go across the land, into a stream.

30
Q

How does vegetation promote infiltration in water movement?

A

Entrapment under litter and root channels in soil.

31
Q

How does vegetation reduce erosion, and what effect does this have on water movement?

A

Promotes soil stability, reducing erosion, and preventing muddy waters.

32
Q

How does vegetation reduce water runoff?

A

Producing high transpiration rates.

33
Q

What is a consequence of no vegetation after heavy rainfall?

A

Rivers rise more rapidly, and also return to base flow more rapidly as well.

34
Q
Describe the effects of forest clearcutting on the following
Stream velocity
UV light
Temperature
Nutrient levels
Organic matter
A
Stream velocity - increases
UV light - barrier removed, more light
Temperature - increases due to more UV
Nutrients - accelerates loss
Organic matter - accelerates loss
35
Q

Define epilimnion.

A

Epilimnion - surface layer mixed by wind or temperature driven currents.

36
Q

Define metalimnion. Which two layers is it found between?

A

Metalimnion - region of the thermocline, the transition between the epilimnion and hypolimnion.

37
Q

What is the photic zone, what occurs here, and why?

A

Is the epilimnion, where net primary production occurs, as there is enough light.

38
Q

Where is the profundal zone found?

A

The upper metalimnion.

39
Q

Where is the aphotic zone, what occurs here, and why?

A

Is the lower hypolimnion, where net respiration occurs, as there isnt enough light for photosynthesis.

40
Q

What manner of creatures live in the aphotic zone?

A

Benthic.

41
Q

What are two features of the aphotic zone?

A

Stagnant, and no gas exchange with the atmosphere.

42
Q

Define lacustrine.

A

Related to or associated with lakes.

43
Q

What is the littoral region?

A

The shore.

44
Q

What two factors affect water density, and when is freshwater most dense?

A

Temperature and salinity.

Freshwater is densest at 4*C.

45
Q

What happens to water density as the temperature goes below 4*C? Why?

A

Density starts decreasing, because it expands as it freezes, and therefore floats if frozen.

46
Q

The relationship between temperature and water density is not linear. What about with salinity?

A

Is linear.

47
Q

Define stratification.

A

Presence of different layers in a water system.

48
Q

In a stratified water system, is the epilimnion homogeneous? Why/why not?

A

Is homogeneous due to wind mixing.

49
Q

Define the thermocline. What happens to water temperature here?

A

Is the layer below the epilimnion. Temperature changes rapidly with depth - temperature gradient.

50
Q

What is the temperature like below the thermocline, and why?

A

Is cold and constant as no exchange occurs here.

51
Q

Define holomixis.

A

Complete mixing to the bottom of the water system.

52
Q

Define meromixis.

A

Incomplete mixing, doesnt reach the water systems bottom.

53
Q

What causes water mixing, and why (aside from wind)?

A

Changes in density, where warmer temperatures up to 4C are denser, and will therefore sink - ie when ice melts to 4C, it will sink.

54
Q

What happens to a water system during spring? What kind of water column is created?

A

As the ice melts, it initially becomes more dense, and will sink.
Induces mixing, and will create an isothermal water column.
Winds also mix deeply.

55
Q

Is the water column stable in summer? Why/why not?

A

Is stable due to thermal stratification.

56
Q

What happens to a lake water column during autumn?

A

As the surface cools, the summer thermal stratification breaks down as it cools to 4*C, becoming dense and sinking.

57
Q

Are winter water columns stable?

A

Can be stable if the surface cools to under 4*C.

58
Q

How does summer stratification affect nutrients? What about oxygen? Why does this occur?

A

Leads to depleted nutrients in the surface water - this is due to consumption by primary producers.
Also leads to depleted oxygen at low depths - this is due to the domination of respiration and lack of circulation.

59
Q

Define overturn.

A

Breakdown of stratification.

60
Q

What effect does an overturn have on nutrients and oxygen levels in the water?

A

Will inject regenerated nutrients into surface water and oxygen into deep water.

61
Q

What effect does an overturn have on plankton growth and decomposition?

A

Stimulates plankton growth at the surface, and decomposition at depth.

62
Q

How can lakes be classified?

A

By how they mix.

63
Q

Why does clear water appear blue?
What does high productive water look like?
What about those saturated with humic substances?

A

Blue light is scattered and transmitted, the others are absorbed rapidly.
Highly productive water appears green from chlorophyll.
Humic substances makes water look brown.

64
Q

What percentage of water is absorbed by the top 1m of water? What 4 factors affect this?

A

Typically 50%.

Depends on silt, detritus, minerals and dissolved organic matter.

65
Q

What is a secchi disk, and how does it work?

A

Measures water clarity. Drop it into the water using rope, and sink until it just disappears, then measure distance.

66
Q

How is the ocean pH kept stable?

A

Carbonate buffering system.

67
Q

Which is more stable, ocean pH or freshwater pH? Why is this so?

A

Ocean pH is more stable - 6 to 9.
Freshwater is between 4 and 12.
Is because freshwater doesnt have as much carbon dissolved into it.

68
Q

Dissolved oxygen in the epilimnion depends largely on what?

A

Water temperature.

69
Q

Dissolved oxygen in the hypolimnion depends largely on what?

A

Microbial respiration and mixing.

70
Q

What two elements are most important for biological growth?

Which of the two is more limiting in freshwater? What about oceans?

A

Phosphorus and nitrogen.

P is typically limiting in freshwater, while N is limiting in oceans.

71
Q

What is the relationship between P and chlorophyll? What can it be a measure of?

A

Strong correlation between the two, a measure of primary production.

72
Q

Describe the characteristics of oligtrophy lakes.

A

Low production, associated with low P and N.

73
Q

Describe the characteristics of eutrophy lakes.

A

High production, associated with high P and N.

74
Q

Describe the characteristics of acidotrophy lakes.

A

Low production, associated with low P, N, and low pH (<5.5).

75
Q

Describe the characteristics of alkalitrophy lakes.

A

High production, associated with high calcium concentration.

76
Q

Describe the characteristics of argillotrophy lakes.

A

Low production, associated with high clay turbidity.

77
Q

Describe the characteristics of siderotrophy lakes.

A

Low production, associated with high iron concentration.

78
Q

Describe the characteristics of dystrophy lakes.

A

Low production, associated with high humic colour.

79
Q

Define eutrophication.

A

Enrichment of a body of water with nutrients.

80
Q

What can eutrophication lead to (5)?

A

Excessive primary production, high organic matter, hypoxia, eventually anoxia.

81
Q

Where is eutrophication more common?

A

Shallow bodies.

82
Q

What can eutrophication be caused by?

A

Pollutants, input from runoff, sewage etc.

83
Q

Define light pene.

A

Depth to which something is visible by eye.

84
Q

What happens to the light pene as waters become more eutrophic?

A

Light pene decreases.

85
Q

Between rooted vegetation and plankton, which are more affected by eutrophication and why?

A

Rooted plants, because plankton can get nutrients from their surroundings, while rooted plants can only get it from the soil. Runoff will not enter the soil, and plankton will outcompete.

86
Q

Define autochthonous organic matter.

A

Matter produced within the system.

87
Q

Define allochthonous organic matter.

A

Matter produced outside the system.

88
Q

Define periphyton.

A

Plankton growing on the surface of another organism.

89
Q

Define neuston.

A

Microscopic organism in the pleuston.

90
Q

What is the flow like in a lotic system versus a lake?

A

Unidirectional flow, versus variable flow in lakes.

91
Q

Are flow rates constant in lotic systems, or is there a gradient?

A

Flow rate fluctuates.

However, a they have a gradient along the downstream axis, in addition to the vertical exis.

92
Q

Are lotic systems typically deep or shallow?

A

Typically shallow.

93
Q

What is the oxygen content of lotic systems like?

A

High, especially when turbulent.

94
Q

Is the organic matter in lotic systems mostly autochthonous or allochthonous?

A

Allochthonous.

95
Q

What is the temperature of lotic systems like?

A

Fluctuates greatly.

96
Q

Does thermal stratification occur in lotic systems?

A

Rarely.

97
Q

What can influence the solute content of lotic systems?

A

Soil, rocks, the substratum below.

98
Q

What is the dominant cation from limestone rocks?

A

Ca2+.

99
Q

What cation dominates lotic systems in many parts of Australia?

A

Na+

100
Q

What kind of gradient is present for organic matter and nutrient content downstream for lotic systems?

A

Organic matter and nutrient content increase with distance downstream.

101
Q

What does the substratum of lotic systems depend on? Give an example.

A

Substratum depends on flow velocity.
If fast, typically rocky.
If slow, typically muddy.

102
Q

Define the following:
Epipelic
Epilithic
Epiphytic

A

Epipelic - grows on sediment
Epilithic - grows on rock
Epiphytic - grows on plants

103
Q

What 3 factors affect the kind of fauna in a lotic system?

A

Current strength, substratum, and microhabitat.

104
Q

Define stenothermal.

A

Species in torrential regions.

105
Q

Define eurythermal.

A

Species in depositional regions.

106
Q

What concentrations of what cation do shelled animals depend on?

A

Ca2+ at >20ppm

107
Q

How does stream order change with distance downstream and channel width?

A

Stream order increases with distance downstream and increasing channel width.

108
Q

Streams begin with a strong influence from what? What kind of invertebrates and organic matter are present?

A

Begin with a strong terrestrial influence.

Has detritus feeding invertebrates, and allochthonous organic matter.

109
Q

What happens as stream order increases?

A

More autochthonous organic matter, microalgal and macrophyte growth, and literfeeding invertebrates.

110
Q

Describe 2 characteristics of lentic systems, in terms of its gradients and mixing. Contrast with 2 characteristics of lotic systems.

A
Lentic
-Often strong vertical gradients
-Dynamics influenced by vertical mixing
Lotic
-Often strong horizontal gradients
-Dynamics influenced by horizontal flow