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Ecology of Aquatic Environments > Freshwater Wetlands > Flashcards

Freshwater Wetlands Flashcards

1
Q

What two factors are wetlands dependent on?

A

-Source of water (hydrology)
-Location in the landscape (geomorphology)

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2
Q

What are two distinguishing features of wetlands?

A

-Hydric soils
-Macrophytes

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3
Q

What three things do all wetlands have?

A
  1. Shallow water / saturated soils
  2. Accumulate organic plant material that decomposes slowly
  3. Supports a variety of specialist plants and animals adapted to the saturated conditions
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4
Q

What three characteristics can be used to described wetlands?

A
  1. Hydrology (Flow, frequency )
  2. Physiochemical environment (Sediments, soil chemistry)
  3. Biota (Vegetations, animals)
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5
Q

What is the single most important determinant of wetlands?

A

Hydrology
-So important for establishment and maintenance of specific wetland types and wetland processes

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6
Q

What does hydrology include?

A

-Hydroperiod
-Water depth
-Flow patterns
-Duration and frequency of flooding
-Anaerobic soil
-Nutrients
-Macrophytes

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7
Q

What is hydroperiod?

A

Is the seasonal pattern of the water levels within a wetland and characterises wetland types

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8
Q

What influences hydroperiods?

A

-Local landscape
-Proximity of other wetlands
-Climate and basin geomorphology

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9
Q

How does hydrology modify and change the physico-chemical environment?

A

-Dissolved oxygen availability
-Nutrient availability - P
-pH
-Toxicity of soils

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10
Q

How does outflows regulate wetland environments?

A

By removing excess toxins, sediments and detritus

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11
Q

How can sediment build up modify hydrology?

A

By changing basin geomorphology

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12
Q

What are key features of wetlands in cool, wet climates that are flat or gently sloping?

A

Climate and Basin geomorphology
-Less evapotranspiration and excess rainfall

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13
Q

How does hydrology affect unique vegetation?

A

-Selects for water tolerant plants
-Can limit or enhance species richness depending on the hydroperiod
-Species richness increases as flow increases = renews minerals
-Creates anaerobic conditions

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14
Q

How does hydrology affect primary production?

A

-Enhanced by slow flowing conditions and episodic hydroperiods
-Depressed by stagnant or deep-water conditions

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15
Q

How does hydrology affect organic accumulations?

A

-Increased PP and decreased decomposition = export of OM
-Catchments draining wetlands export OM and retain more nutrients than catchments without wetlands

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16
Q

How does hydrology affect nutrient cycling?

A

-Controlled by rainfall, river flooding, surface and groundwater flows
-Important determinants of wetland productivity and decomposition
-High productivity and decomposition rates = high internal nutrient cycling

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17
Q

What does the physicochemical environment have a direct effect on?

A

Biota

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18
Q

What is a wetland’s biogeochemistry?

A

-Transport and transformation of chemicals within the wetland ecosystem

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19
Q

Describe hydric soils

A

-Water saturated
-Anaerobic
-Where chemical transformations take place resulting in characteristic colours and physical structure of the soil
-Primary storage of available nutrients for most wetland plants

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20
Q

What are the two types of hydric soils?

A

Mineral (<20-30% OM)
Organic

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21
Q

Describe mineral soils

A

-Soil < 20-35% organic matter (OM)
-Low porosity (45-55%)
-Low water holding capacity
-High nutrient availability
-Low cat ion exchange capacity
-High bulk density
-pH circum-neutral
-eg. Fen marsh

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22
Q

Describe organic soils

A

-High porosity (80%)
-High water holding capacity
-Nutrient poor soils
-Low nutrient availability
-High cat ion exchange capacity (H+)
-Low bulk density
-pH acidic
-Eg. Bog

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23
Q

What is the present at the soil-water interface?

A

-A thin oxidised soil layer is present

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24
Q

What is oxidation?

A

Removal of H+ electron in the presence of O2

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25
Q

What is reduction?

A

Gaining of H+ electron in the absence of O2

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26
Q

What elements make brown-reddish soil?

A

Fe3+
Mn4+
No-3
S04

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27
Q

What elements make bluish-grey to greenish-grey?

A

Fe2+
Manganous
Ammonia
Sulphides

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28
Q

What happens when mineral soils are flooded?

A

Mineral soils show redoximorphic features that are mediated by microbial processes

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29
Q

Describe gleying

A

Development of black-grey soil resulting from a chemical reduction in Fe

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30
Q

Describe oxidised rhizosphere

A

Macrophytes transfer O2 from stems and leaves to roots
-Excess O2 is diffused to the surrounding soil matrix forming deposits of oxidised Fe

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31
Q

Describe mottles

A

Found in seasonally flooded soils which develop spots of highly oxidised reddish material (Fe or Mn) in the grey soil matrix

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32
Q

What are histosols?

A

Are soils consisting primarily of organic materials
-Is remains of plants in various stages of decomposition that accumulate as a result of anaerobic conditions created by standing water or poorly drained conditions (peat)

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33
Q

What plants make up histosols?

A

Composed of remains of plants like:
-Sphagnum
-Phragmites
-Carex spp.
-Cladium
-Typha
-Betula
-Pinus

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34
Q

What colours are histosol? (organic soils)

A

Dark in colour, ranging from dark brown to black

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35
Q

How does Iron affect chemical reactions in hydric soils?

A

Iron affects mobility of other elements

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36
Q

What is the chemical reaction of iron in relation to soils?

A

4Fe2+ + O2 + 4H+ = 4Fe3+ + 2H2O
(grey/black-green) (brown-reddish)

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37
Q

What does Ferrous (Fe2+) iron form in the presence of O2?

A

Forms ferric (Fe3+) iron

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38
Q

What are chemosynthetic bacteria?

A

Are a group of autotrophic bacteria that use chemical energy to produce their own food

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39
Q

What is Fe2+ do in wetlands?

A

Toxic in wetlands, creates anoxic conditions
-Is washed out in minerals soils (gleying)
-Forms iron pans in blanket bogs

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40
Q

What is H2S?

A

Hydrogen sulphide

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41
Q

What is the sulphur chemical reaction?

A

4H2 + SO4 = H2S + 2H2O + 2OH-

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42
Q

What happens to Sulphates (SO4) in anaerobic conditions and under low Fe concentrations?

A

Releases hydrogen sulphide (H2S)

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43
Q

What happens when wetland sediments are disturbed?

A

Smells like rotten eggs

44
Q

What is H2S toxic to?

A

Rooted macrophytes and microbes

45
Q

What is the chemical formula for carbon in relation to wetlands?

A

CO2 + 8e- + 8H+ = CH4 + 5H2O

46
Q

What is methanogenesis?

A

Methanogenesis is the biological production of methane mediated by anaerobic microorganisms from the domain Archaea

47
Q

Who carries out methanogenesis?

A

Methanogens

48
Q

How is methane released into the atmosphere?

A

When wetland sediments are disturbed (marsh gas) bubbles in the water column

49
Q

What factors influence methane emission?

A

Depends on:
-Soil temperature
-Hydroperiod
-Degree of flooding
-Presence or absence of vegetation

50
Q

What impacts does seasonal flooding have on methane emissions?

A

-Clear seasonal patterns minimise CH4 emission
-Greater fluxes are released from permanently flooded wetlands

51
Q

What is a limited nutrient in flooded soils?

A

Nitrogen (N)

52
Q

Describe ammonium (NH4+)

A

Is the primary form of mineralised N in acidic, anoxic flooded soils

53
Q

What is nitrogen important for?

A

Important in the oxidation of organic matter in wetlands

54
Q

What is a major nutrient in intact bogs and marshes?

A

Phosphorus

55
Q

Describe phosphorus (p) in wetland environments

A

-Phosphorus retention is one of the most important features of natural and constructed wetlands
-Phosphorus tied up as organic matter in mineral soil wetlands and as peat in organic soil wetlands (sink)

56
Q

How is phosphorus rendered unavailable to plants?

A

-Precipitation with iron and aluminum in acid soils and calcium and magnesium in alkaline soils under aerobic conditions (sink)
-Adsorption onto clay particles, organic peat, and ferric and aluminum hydroxides and oxides (sink)

57
Q

Where is phosphorus most bioavailable?

A

Phosphorus is most available at slightly acidic to neutral soils

58
Q

What do wetlands do regards to chemicals?

A

Serve as sources, sinks or transformers of chemicals

59
Q

What are the reasons that in temperature climates that there is higher retention of nutrients in the summer?

A
  1. Higher microbial activity in the water column and sediments
  2. Greater macrophyte productivity
60
Q

What can happen to wetlands over time?

A

Chemical loading, they become saturated with nutrients

61
Q

How does upstream ecosystems affect wetlands?

A

Are sources of chemicals to wetlands

62
Q

How do downstream aquatic systems benefit from wetlands?

A

They benefit from the ability of wetlands to retain certain chemicals or from the export of OM

63
Q

Comment on highly productive ecosystems in regards to nutrients

A

Are rich in nutrients by also have low productivity caused by scare supply of nutrients

64
Q

What are two ecosystem engineers?

A

-Microbes
-Macrophytes

65
Q

What do microbes do?

A

-Catalyse the chemical reactions within hydric soils
-Controlling nutrients and primary productivity

66
Q

How do macrophytes affect the ecosystem?

A

-Influences hydrological conditions and physico-chemical environment
-Peat accumulation
-Sediment trapping / erosion
-Nutrient retention / source
-Water shading
-Transpiration

67
Q

What are major stressors to wetland biota?

A

-Anoxia
-Water fluctuations

68
Q

What adaptions to organisms have to anaerobic conditions?

A

-Ability to respire anaerobically
-To detoxify end products of anaerobic metabolism
-To use reduced organic compounds in the sediments as energy sources

69
Q

What role do microbiota play in wetlands?

A

-Wetland primary and secondary production
-Food chains
-Mineral cycling

70
Q

What are the three key microorganisms in wetlands?

A
  1. Bacteria
  2. Aquatic fungi
  3. Algae
71
Q

What does bacterial flora reflect?

A

Reflects water chemistry, temperature, 02 levels and Organic matter content

72
Q

Where can bacteria be found in wetlands?

A

Free floating in the water column
Growing on plants
Litter and soil surfaces

73
Q

What are the key types of bacteria?

A

-Denitrifying bacteria
-Manganese-reducing bacteria
-Iron-reducing bacteria
-Sulphate-reducing bacteria
-Methanogenic bacteria
Heterotrophs and autotrophs

74
Q

What four processes do bacteria carry out?

A

-Fermentation
-Aerobic respiration
-Anaerobic respiration
-Methanogenesis
all are linked to hydric soil chemical processes

74
Q

Describe aquatic fungi

A

-Obligate aquatic spp. semi-aquatic fungi and terrestrial fungi
-All heterotrophs
-Aerobic respiration
-Found attached to substrates
-Role in plant and animal litter decomposition
-Mycorrhizae

75
Q

Describe algae

A

-Composition depends on water chemistry, light conditions, temperature
-Plankton (phtyo and zoo) -free floating organisms

76
Q

What are periphyton?

A

Algae, fungi, bacteria and invertebrates
-Organisms growing on or attached to any kind of substrate

77
Q

What are metaphyton?

A

Mats of filamentous algae

78
Q

What are macrophytes?

A

-Major primary producers
-Alter the environmental conditions
-Creates microhabitats that differ in water velocity, light levels, diurnal temperatures and oxygen concentrations
-Animals utilise various microhabitats depending on their requirements for food, oxygen, nesting sites and absences of predators

79
Q

What are the morphological adaptations for macrophytes?

A

-Aerenchyma cells
-Adventitious roots
-Stem hypertrophy
-Root adaptations
-Lenticels
-Heterophylly

80
Q

What are the three adaptations that macrophytes have for wetland environments?

A

-Morphological
-Physiological
-Life History

81
Q

What physiological adaptations do macrophytes?

A

-Pressurised flow gas- increased O2 supply to roots
-Rhizosphere oxygenation- reduced toxic effects of ions
-Lower water table
-Altered nutrient adsorption
-Sulphide avoidance
-Anaerobic respiration

82
Q

How is macrophyte life history adapted to wetland environments?

A

-Seeds produced in dry season
-Seeds are buoyant
-Seeds germinate while the fruit is attached to the tree
-Produce large, persistent seed banks
-Produce tubers, roots and seeds that can survive long periods of submergence

83
Q

What determines invertebrate communities?

A

Dependent on:
pH
Temperature
Water depth and fluctuations
O2 levels

84
Q

Describe diptera

A

-Live in sediment, rotting vegetation, mud or on emergent vegetation
-Diversity often very high
(Ephemeroptera, Plecoptera, Trichoptera (EPT)

85
Q

What diptera are found in acidic, cold nutrient poor wetlands?

A

Higher diversity of:
-Odonata
-Hemiptera
-Coleoptera

86
Q

What diptera are found in wetlands with fluctuating water levels?

A

Higher diversity of:
-Hemiptera
-Coleoptera
-Trichoptera
-Odonata

87
Q

What morphological adaptations do invertebrates have?

A

-Flattening of limbs to oar-like structures
-Fringes or setae on legs to increase surface area
-Elongation of larvae to allow wormlike-wriggling movement
-Strong claws to aid in crawling
-Water jets from the rectum

88
Q

What feeding strategies do invertebrates have?

A

-Shredders
-Collectors/gathers/scrapers
-Filter feeders
-Piercers
-Predators

89
Q

What adaptations do invertebrates have for aerobic respiration?

A

-Surface breathers that remain permanently in contact with the air via a mini snorkel (eg. diptera)
-Periodically come to the surface (Hemiptera)
-Carry a bubble or air with them as they dive (dytiscid beetles, water spiders)

90
Q

What organisms obtain oxygen through their cuticle directly from the water?

A

Chironomids

91
Q

Describe chironomids

A

-Membrane growths act as gills improving oxygen uptake
-Contain haemoglobin to improve their oxygen uptake efficiency
-Chironomids are best adapted to low oxygen levels in wetland

92
Q

What do large, diverse wetlands have?

A

-Fish
-Reptiles
-Birds
-Mammals

93
Q

What adaptations do vertebrates have for temperate wetlands?

A

Show no adaptations, fish avoid anoxic areas

94
Q

What adaptations do vertebrates have for anoxic conditions in tropical areas?

A

-Move to an area with oxygen
-Aquatic surface respiration- ventilate their gills in the oxygenated water layer at the surface of the water
-Breathe air- gulp air at the surface of the water

94
Q

What adaptations do vertebrates have for anoxic conditions in tropical areas?

A

-Move to an area with oxygen
-Aquatic surface respiration- ventilate their gills in the oxygenated water layer at the surface of the water
-Breathe air- gulp air at the surface of the water

95
Q

Describe vertebrates that breathe air?

A

-Amphibious air breathers- only breath air when they are stranded on land
-Aquatic air breathers - gulp air regularly
-In dry season, air breathing fish survive in mud in a hypometabolic, estivating state

96
Q

What are common birds species found in wetlands?

A

Divers, grebes, waterfowl, waders, shorebirds, cranes, pelicans, flamingos, passerines, blackbirds, gulls, kingfishers, raptors

97
Q

What are feeding strategies for birds?

A

-Surface swimmers
-Divers
-Flight feeders
-Stationary spear fishers
-Plunge and perch divers
-Course hunters

98
Q

Describe surface swimmers

A

Strain food with their beaks or grab food on or in the water column (ducks)

99
Q

Describe divers

A

Grab or spear fish (mergansers) strain, dig or root food out of the soil (ducks)

100
Q

Describe flight feeders

A

Catch insects

101
Q

What are stationary spear fishers?

A

Heron

102
Q

Plunge and perch divers?

A

Kingfishers

103
Q

Describe course hunters?

A

Seize prey with their feet (eagle)

104
Q

What adaptations do birds have for wetland environments? (feet)

A

-Swimming
-Diving
-Walking on mud or floating plants
-Wading in shallow water
-Grabbing prey

Waterproof feathers

Ecology of Aquatic Environments (14 decks)

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