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From Organisms to Ecosystems - Lectures > Lecture 34. Freshwater Ecosystems: Rivers and Lakes > Flashcards

Lecture 34. Freshwater Ecosystems: Rivers and Lakes Flashcards

1
Q

What percentage of worlds fish species live in rivers ?

A

40%

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2
Q

How long does it take for a river to renew its self ?

A

5-20 days

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3
Q

What is the function of rivers ?

A

Link ground water and lakes by estuaries to sea

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4
Q

How are rivers formed ?

A
  1. Springs
  2. Snow fed rivers
  3. Glacial rivers
  4. Bog fed rivers
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5
Q

What is the river continum concept ?

A

Calssifys rivers by size, substrate, abiotic factors and biota

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6
Q

What are the classifications of rivers ?

A
  1. Headwater (1st to 3rd order)
  2. Mid reaches (4th to 6th order)
  3. Large rivers (6+ order)
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7
Q

What happens to flow speed as river order increases ?

A

FLow speed decreases

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8
Q

How would you describe the light penetration of rivers as river order increases ?

A

Positive curve ie. n-shaped

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9
Q

What can effect light penetration ?

A
  1. Overshadowed by trees

3. High turbulence

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10
Q

How would you describe temperature as river order increases ?

A

Positive curve - n-shaped (steeper slope)

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11
Q

What are some abiotic factors affecting the river continum concept ?

A
  1. Flow speed
  2. Light penetration
  3. Temperature fluctuation
  4. Nutrients
  5. Organic matter
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12
Q

What is periphyton ?

A

Organic matter produced in river itself

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13
Q

What are the different types of organic matter in rivers ?

A
  1. Terrestrial coarse detritus
  2. Periphyton
  3. Macrophytes
  4. Phytoplankton
  5. Fine detritus particles
  6. Upstream accrual
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14
Q

What sort of animals live in each area of the river ?

A
  1. Shredders
  2. Fine particle collectors
  3. Periphyton grazers
  4. Benthic filter feeders
  5. Sediment burrowers
  6. Water column filter feeders
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15
Q

Where is biodiversity highest in rivers ?

A

Middle reaches

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16
Q

Why is the biodiversity in rivers highest in middle regions ?

A
  1. Temperature fluctuations
  2. Energy source
  3. Most light available
17
Q

What are shredders ?

A

Large organic matter into smaller pieces

18
Q

What are collectors ?

A

Small dead organic matter

19
Q

What are grazers ?

A

Scraping algae or filtering

20
Q

What are threats to river systems ?

A
  1. Dams block migration routes and disrupt habitat
  2. Overexploitation
  3. Global warming, floods, pollution and drought
  4. Eutrophication from agricultural and urban areas
  5. Water withdrawal for human use
  6. Invasion of exotic species can harm native animals and plants
21
Q

What are some stressors to rivers in farming ?

A
  1. Dissolved nutrients like nitrogen and phosphorous increase
  2. Deposition of fine sediments increase - disturbed by cattle
  3. Water temperature increases due to loss of shading
  4. Water input decreases - as water extracted for irrigation
  5. Chemical pollutants increases - pesticides and herbicides
22
Q

When does the macroinvertebrate decrease ?

A
  1. Increasing nutrient addition

2. Increasing presence of fine sediment

23
Q

What does the decrease in macroinvertebrate result in ?

A

Reduce in stream health

24
Q

Which is more influential fine sediments or nutrients ?

A

Sediments

25
Q

What is fine sediment bad for ?

A

Detrimental to itself and makes other stressors wworse

26
Q

What may increase the complexity of interaciton between stressors ?

A

Global warming

27
Q

What is expected with rising temperatures ?

A

Ecological surprises

28
Q

Where is zebra mussel native to ?

A

Caspian and black sea region

29
Q

How is zebra mussel spread ?

A

Boat movement

30
Q

What are zebra mussels very efficient at ?

A

Filtering water - filter feeder

31
Q

What does the zebra mussel cause as a result of filter feeding ?

A
  1. Extinction of native mussel
  2. Remove food for fish
  3. Increased water transparency
  4. Macrophyte growth, visually hunting predators
32
Q

What do invasive species escape from ?

A

Parasites and diseases

33
Q

What is the Japanese eel ?

A

Nematode infecting the swim bladder of eels co-introduced

34
Q

What may invaders bring with them ?

A

Their parasites which local species are not adapted to

35
Q

What determines the success of invasive parasites ?

A
  1. Specificity

2. Life cycle

36
Q

What is meant by high specificity ?

A

Only infecting few genotypes within one species meaning they are less likely to switch hosts

37
Q

What is meant by generalist ?

A

Infects many different host species which means it is likely to successfully establish in new hosts

From Organisms to Ecosystems - Lectures (37 decks)

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