Test 2.1 Freshwater Ecosystems Flashcards

1
Q

Key 8 physical and chemical properties of freshwater ecosystems include:

A
  • Density, viscosity
  • Flow, velocity and depth
  • Light
  • Temperature
  • Dissolved Oxygen
  • Carbon dioxide
  • pH
  • Nutrients
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

% Proportion of ocean water of all water

A

around 97%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

% Proportion of freshwater of all water

A

around 3%

2.15% of which is glaciers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

6 physical challenges of living in freshwaters?

A
Physical medium of water
Buoyancy
Density
Viscosity
Temperature
Salinity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is viscosity?

A

The resistance of a fluid to shear stress - ‘thickness’ or ‘drag’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Reynold’s number?

A

Ratio of inertial forces (opposing current forces) to viscous forces ‘roughness’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What increases roughness/ Reynold’s number?

A

Size and velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Water properties important for large objects?

A

Pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Water properties important for medium objects?

A

Pressure and drag

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Water properties important for small objects?

A

Drag and viscosity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Increase in discharge and flow down the hydrological system due to?

Why are the proportions important?

A
Greater amount of inputs:
Direct runoff
Ice melt
Groundwater
etc.

Temperature and nutrient levels are due to where its from- affects organisms present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are Lotic systems?

A

Flowing systems - rivers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are Lentic systems?

A

Standing systems - Lakes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why is flow important in freshwater ecosystems?

A

Organisms are adapted to velocity and shear stress

Provides nutrients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

List hydraulic variables

A

Velocity
Shear stress
Water depth- more important in lakes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is depth more important in lakes?

A

Temperature- Deep lakes with limited flow proceed strong patterns, effects nutrients

Light- source of energy for organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What determines the temperature of water? (6 reasons)

A

Origin & inputs- groundwater, glacier e.g.
Air temperature
Season
Time of day
Water depth and discharge
Substrate and amount of turbulence (mixing)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Hyporheic zone meaning

A

Below the river bed zone containing water

Exchange of groundwater to surface water- affects temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why is water temperature less variable than air temperature?

A

Due to water’s high specific heat capacity

20
Q

What are the two forms of ice found in rivers?

A

Frazil ice- mobile first particles that form on the surface of the water

Anchor ice- Ice frozen in solid connection with the banks, spreads across the rest of the river surface

21
Q

What is the coolest source in order:
Surface run off
Glacial
Karstic - what is it?

A

Average coolest temperature:

  1. Glacial
  2. Karstic (high proportion from groundwater & most stable)
  3. Surface run off snow melt (most variable)
22
Q

How does variability and average water temperature vary downstream?

A

Average temp increases as you go downstream

Variability is greatest in smaller streams

Larger rivers are more stable due to greater size and buffering capacity

23
Q

How does topography and vegetation affect water temperature?

A

Cooling effect due to shading and evapotranspiration

24
Q

What is the long term trend of average temperature in large rivers (Mississippi; Trent)

What are the causes?

A

Increased even though air temperature recorded was 2.2 degrees cooler.

Mississippi: Warming due to industrial warm effluents.

Trent: Cooling due to closed coal power stations no longer produce water effluent for cooling

25
How does temperature effect Salmon?
Salmon develop in warmer conditions. Very warm conditions can be damaging.
26
How does temperature effect Mayflies?
Speed of development and timing of hatching is temperature dependent. Fast summer generation, slow winter generation
27
Definition of Univoltine & bivoltine?
Univoltine: Single generation period per year Bivoltine: 2 generations per year Often in tropical rivers there are more multivoltine species
28
What effects dissolved oxygen in river water?
Increase: Photosynthesis Turbulence Decrease: Respiration (decomposers - microorganism's)
29
How does temperature affect oxygen levels?
High temperature results in lower oxygen
30
How does altitude affect oxygen level?
Water at sea levels can hold more oxygen than at altitude
31
What is the ecological significance of dissolved oxygen in salmon, trout and tench?
Salmon and trout need high levels of oxygen Tench more tolerant of lower oxygen levels
32
What concentration of oxygen is required for salmon eggs to survive and develop?
5mg/L
33
How are invertebrate species adapted to low oxygen levels?
Gills on body High haemoglobin content Caddis have gills along body, can create current to bring o2 to gills
34
How does pollution affect dissolved oxygen?
Organic sewage broken down using respiration & therefore oxygen.
35
Hows does carbon dioxide affect water quality?
Dissolves to form carbonic acid - disassociation reduces to produce hydrogen ions - raises pH
36
How does temperature affect CO2 levels?
Higher temperature means higher CO2 levels
37
How does limestone & chalk affect buffering capacity?
Rich in natural carbonates and bicarbonates, buffered against acidity due to high pH
38
How many microequivalents per litre are required for a residual buffering capacity?
120me/L and above
39
What are the changes of alkalinity in a diurnal pattern?
Low natural alkalinity with vegetation present tend to find pH rises in afternoon with increase in photosynthesis
40
List essential nutrients for plant growth
Main: Nitrogen Phosphorus ``` Other: Calcium Iron Manganese Magnesium Potassium Silica Sodium ```
41
Where does nitrogen come from in a river?
Atmospheric nitrogen fixed by nitrogen fixing microorganisms into ammonium Decomposition of organisms. Ammonium then through nitrification to nitrite to nitrate
42
Where does phosphorus come from in a river?
Taken up in plants, consumed by animals, broken down and released by bacteria into inorganic phosphorus. Closed cyclic system
43
Name the globally most important limiting element
Phosphorus Sometimes silica
44
What is the natural ratio of N:P?
N:P 16:1
45
What its the effect of nitrogen and phosphorus pollution?
Pollution raising nitrogen no significant effect Pollution raising phosphorus where there is abundant nitrogen has significant effects