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Limnology > Exam Questions > Flashcards

Exam Questions Flashcards

1
Q

How is coarse particle organic matter broken down?

A

Shredders break down CPOM (eg leaves,twigs,macrophytes) feeding on bacteria and aquatic fungi.

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2
Q

Give examples of shredders that break down CPOM.

A

Gammatids

Plecoptera

Trichoptera

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3
Q

How big are COPM?

A

Greater than 1mm in size.

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4
Q

Where do CPOM collect and gather?

A

In front of boulders with small woody debris or settle in pools.

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5
Q

What is CPOM dominated by?

A

CPOM is dominated by macro invertebrate shredders and collectors.

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6
Q

How do shredders break down the CPOM?

A

They chew large organic matter and assimilate 40% and pass 60% as faeces (Fine particulate organic matter) (FPOM)

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7
Q

What factors determine changes in functional feeding groups (macro invertebrate communities) ?

A

Amount and type of organic matter entering the river (CPOM)

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8
Q

What percentage of organic input does CPOM contribute to the River Continuum concept (RCC)?

A

Upwards of 90%

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9
Q

Headwaters include what organic matter?

A

CPOM and FPOM

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10
Q

Provide a detailed account of seasonal thermal stratification in temperate lakes.

Spring-

A
  • Incoming light energy is converted directly in to heat.
  • Ice cover decreases in thickness and breaks up.
  • Temperatures in spring rise and water temperature increases.
  • Little resistance to mixing.
  • A process driven by wind energy and convection.
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11
Q

Provide a detailed account of seasonal thermal stratification in temperate lakes.

Summer-

A
  • Intensity of solar radiation increases = water temperature increases = density decreases.
  • Wind and surface generated currents distribute this heat vertically within the lake but only to a limited depth.
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12
Q

What are the three layers in stratification?

A
  • Epilimnion
  • Thermocline
  • Hypolimnion
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13
Q

Is there free mixing and temperature variation within the layers?

A
  • Within each of the three layers there is free mixing and little temperature variation

however

  • Between layers there is little mixing and clear temperature differences.
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14
Q

What causes a thermocline in freshwater lakes?

A

The significant difference in density between the warmer surface layer (Epilimnion) and the colder bottom layer (Hypolimnion) results in stratification causing a thermocline.

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15
Q

What causes stratification to occur in freshwater lakes?

A

The significant difference in density between the warmer surface layer and the colder bottom layer results in stratification.

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16
Q

What kind of water is Lentic?

A

Standing water

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17
Q

What kind of water is Lotic?

A

Running water

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18
Q

What does Abiotic mean?

A

Non living

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19
Q

Key physical abiotic factors

A
  • Water levels/depth
  • Temperature and light
  • Flow/Velocity of current
  • Turbidity
  • Water Colour
  • River width and wetted width
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20
Q

Key physical abiotic factors pt 2

A
  • Substrate size and type
  • Geology and soil type
  • Catchment land-uses and management practices
  • Rainwater composition
21
Q

Key chemical abiotic factors

A
  • pH
  • Dissolved oxygen (mg/l)
  • Conductivity
  • Alkalinity
  • Hardness
  • Nutrients (nitrate, phosphate, total phosphorous)
  • Organic matter
22
Q

What does Biotic/Biota mean?

A

Living

23
Q

What are the key biotic factors?

A
  • Micro organisms : bacteria/fungi
  • Phytoplankton
  • Macrophytes, trees, mosses
  • Invertebrates: sponges, worms, snails, insects
  • Birds
  • Fish
  • Mammals
24
Q

What are Trophic interactions?

A

The classification of organisms based on their feeding habits and relationships.

25
Q

Give an example of Freshwater food web

A

1- Fish - territory consumer / predators

2- Macroinvertebrates- secondary consumers/ predators

3- Microscopic zooplankton - primary consumers/ herbivores

4- Microscopic phytoplankton - primary producers

26
Q

What is a Biogeochemical cycle?

A

It is the cyclic path nutrients take within an ecosystem to flow between the non-living, the living, and back to the non living components.

27
Q

Describe the biogeochemical cycle

A

Output from one ecosystem is the input of another.

Nutrients are exported from terrestrial to freshwater ecosystems, and from freshwater to marine ecosystems

28
Q

Name the three components to every biogeochemical cycle.

A
  • Inputs
  • Internal cycling
  • Outputs
29
Q

What do the inputs, internal cycling and outputs act as?

A

Sources of nutrients

30
Q

What are the stages in the biogeochemical cycle diagram?

A

(1. Net primary productivity
2. Internal cycling )

-Litterfall
-Dead organic matter (output)
-Decomposition
-Soil nutrients(output)
(Input-from the weathering of rocks and minerals)
- Plant uptake
-Incorporation into plant tissues

31
Q

What are the key processes involved in internal cycling of nutrients (biogeochemical cycle)

A

Net primary productivity and decomposition

32
Q

What are the two basic types of biogeochemical cycling?

A
  • Gaseous

- Sedimentary

33
Q

Describe the gaseous cycle

A

-The atmosphere and the oceans are the primary sources of nutrients e.g. Nitrogen, Oxygen, Carbon

34
Q

Describe the sedimentary cycle (biogeochemical)

A
  • The dominant sources are rocks, soils and minerals eg Phosphorus.
  • Based on the primary source of nutrient input to the ecosystem.
  • Driven by the flow of energy in the ecosystem.
  • Tied to the water cycle.
35
Q

What water is lotic?

A

River and stream

36
Q

What are the characteristics of lotic systems?

A
  • Unidirectional flow with variable velocity(speed)
  • Linear form with changing gradients
  • Erosion and deposition
  • Complex variable channel
  • High stream variability
37
Q

How are lotic systems classified?

A

The Strahler classification method

38
Q

Describe the Strahler Classification method.

A

1st order- single, Unbranched headwater channels

2nd order- when two 1st order streams meet

3rd Oder - when two 2nd order streams meet

39
Q

What are the dominant physical factors that determine the nature of rivers ?

A

Flow and Substrate

40
Q

How is the physical habitat of the lotic ecosystem channel size determined?

A

Flow

  • the volume of the water
  • the velocity(speed of the water)
  • flow and weather
  • flood flows
41
Q

How is substrate determined in the nature of rivers?

A
  • Inorganic substrates e.g. sand and boulders

- Organic eg leaves , fallen trees, aquatic plants

42
Q

What are wetlands?

A

They are Lentic standing waters that are defined as areas of land whose characteristics are determined by the presence of water, either permanent water logging or through seasonal flooding.

43
Q

What are the benefits of wetlands?

A
  • Support specialised plant communities where soil conditions remain saturated for most or all of the year.
  • Supports a diverse community of invertebrates.
  • Fish in these wetlands are a good base for birds
  • Amphibians and reptiles inhibit the emergent growth , soft mud and open waters of marshes and swamps
44
Q

What are the three freshwater wetlands ecosystems?

A
  • Riverine eg oxbow lakes
  • Lacustrine eg slow flowing rivers
  • Palustrine eg Peatlands
45
Q

Describe the characteristics of Riverine wetlands.

A
  • linked with river systems only
  • connected only during high water
  • hydrologically separated from the parent water body
  • rely on the input of sediments and water during floods for nutrients
    E.G. - river Shannon Callows
46
Q

Describe the characteristics of Lacustrine wetlands

A
  • Continuous hydrological connection with parent water body
  • Exchange nutrients with open water body
  • Supports communities which are detritus lead (OM)

EG- River Corrib at Corrib village

47
Q

Describe the characteristics of Palustrine wetlands

A

-develop in shallow lake basins
-independent hydrology=rainwater
-accumulation of partially decayed organic matter
-water table always at the top or near soil surface
-constantly water logged
EG- Abbeyleix bog Co Laois

48
Q

What causes a clear decrease in CPOM?

A

Increasing stream order

49
Q

What are the four wetland characteristics?

A

Geomorphology
Hydrology
Hydric soils
Aquatic plants

Limnology (2 decks)

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