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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
What is reduction?
Gaining of H+ electron in the absence of O2
26
What elements make brown-reddish soil?
Fe3+ Mn4+ No-3 S04
27
What elements make bluish-grey to greenish-grey?
Fe2+ Manganous Ammonia Sulphides
28
What happens when mineral soils are flooded?
Mineral soils show redoximorphic features that are mediated by microbial processes
29
Describe gleying
Development of black-grey soil resulting from a chemical reduction in Fe
30
Describe oxidised rhizosphere
Macrophytes transfer O2 from stems and leaves to roots -Excess O2 is diffused to the surrounding soil matrix forming deposits of oxidised Fe
31
Describe mottles
Found in seasonally flooded soils which develop spots of highly oxidised reddish material (Fe or Mn) in the grey soil matrix
32
What are histosols?
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)
33
What plants make up histosols?
Composed of remains of plants like: -Sphagnum -Phragmites -Carex spp. -Cladium -Typha -Betula -Pinus
34
What colours are histosol? (organic soils)
Dark in colour, ranging from dark brown to black
35
How does Iron affect chemical reactions in hydric soils?
Iron affects mobility of other elements
36
What is the chemical reaction of iron in relation to soils?
4Fe2+ + O2 + 4H+ = 4Fe3+ + 2H2O (grey/black-green) (brown-reddish)
37
What does Ferrous (Fe2+) iron form in the presence of O2?
Forms ferric (Fe3+) iron
38
What are chemosynthetic bacteria?
Are a group of autotrophic bacteria that use chemical energy to produce their own food
39
What is Fe2+ do in wetlands?
Toxic in wetlands, creates anoxic conditions -Is washed out in minerals soils (gleying) -Forms iron pans in blanket bogs
40
What is H2S?
Hydrogen sulphide
41
What is the sulphur chemical reaction?
4H2 + SO4 = H2S + 2H2O + 2OH-
42
What happens to Sulphates (SO4) in anaerobic conditions and under low Fe concentrations?
Releases hydrogen sulphide (H2S)
43
What happens when wetland sediments are disturbed?
Smells like rotten eggs
44
What is H2S toxic to?
Rooted macrophytes and microbes
45
What is the chemical formula for carbon in relation to wetlands?
CO2 + 8e- + 8H+ = CH4 + 5H2O
46
What is methanogenesis?
Methanogenesis is the biological production of methane mediated by anaerobic microorganisms from the domain Archaea
47
Who carries out methanogenesis?
Methanogens
48
How is methane released into the atmosphere?
When wetland sediments are disturbed (marsh gas) bubbles in the water column
49
What factors influence methane emission?
Depends on: -Soil temperature -Hydroperiod -Degree of flooding -Presence or absence of vegetation
50
What impacts does seasonal flooding have on methane emissions?
-Clear seasonal patterns minimise CH4 emission -Greater fluxes are released from permanently flooded wetlands
51
What is a limited nutrient in flooded soils?
Nitrogen (N)
52
Describe ammonium (NH4+)
Is the primary form of mineralised N in acidic, anoxic flooded soils
53
What is nitrogen important for?
Important in the oxidation of organic matter in wetlands
54
What is a major nutrient in intact bogs and marshes?
Phosphorus
55
Describe phosphorus (p) in wetland environments
-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
How is phosphorus rendered unavailable to plants?
-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
Where is phosphorus most bioavailable?
Phosphorus is most available at slightly acidic to neutral soils
58
What do wetlands do regards to chemicals?
Serve as sources, sinks or transformers of chemicals
59
What are the reasons that in temperature climates that there is higher retention of nutrients in the summer?
1. Higher microbial activity in the water column and sediments 2. Greater macrophyte productivity
60
What can happen to wetlands over time?
Chemical loading, they become saturated with nutrients
61
How does upstream ecosystems affect wetlands?
Are sources of chemicals to wetlands
62
How do downstream aquatic systems benefit from wetlands?
They benefit from the ability of wetlands to retain certain chemicals or from the export of OM
63
Comment on highly productive ecosystems in regards to nutrients
Are rich in nutrients by also have low productivity caused by scare supply of nutrients
64
What are two ecosystem engineers?
-Microbes -Macrophytes
65
What do microbes do?
-Catalyse the chemical reactions within hydric soils -Controlling nutrients and primary productivity
66
How do macrophytes affect the ecosystem?
-Influences hydrological conditions and physico-chemical environment -Peat accumulation -Sediment trapping / erosion -Nutrient retention / source -Water shading -Transpiration
67
What are major stressors to wetland biota?
-Anoxia -Water fluctuations
68
What adaptions to organisms have to anaerobic conditions?
-Ability to respire anaerobically -To detoxify end products of anaerobic metabolism -To use reduced organic compounds in the sediments as energy sources
69
What role do microbiota play in wetlands?
-Wetland primary and secondary production -Food chains -Mineral cycling
70
What are the three key microorganisms in wetlands?
1. Bacteria 2. Aquatic fungi 3. Algae
71
What does bacterial flora reflect?
Reflects water chemistry, temperature, 02 levels and Organic matter content
72
Where can bacteria be found in wetlands?
Free floating in the water column Growing on plants Litter and soil surfaces
73
What are the key types of bacteria?
-Denitrifying bacteria -Manganese-reducing bacteria -Iron-reducing bacteria -Sulphate-reducing bacteria -Methanogenic bacteria Heterotrophs and autotrophs
74
What four processes do bacteria carry out?
-Fermentation -Aerobic respiration -Anaerobic respiration -Methanogenesis all are linked to hydric soil chemical processes
74
Describe aquatic fungi
-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
Describe algae
-Composition depends on water chemistry, light conditions, temperature -Plankton (phtyo and zoo) -free floating organisms
76
What are periphyton?
Algae, fungi, bacteria and invertebrates -Organisms growing on or attached to any kind of substrate
77
What are metaphyton?
Mats of filamentous algae
78
What are macrophytes?
-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
What are the morphological adaptations for macrophytes?
-Aerenchyma cells -Adventitious roots -Stem hypertrophy -Root adaptations -Lenticels -Heterophylly
80
What are the three adaptations that macrophytes have for wetland environments?
-Morphological -Physiological -Life History
81
What physiological adaptations do macrophytes?
-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
How is macrophyte life history adapted to wetland environments?
-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
What determines invertebrate communities?
Dependent on: pH Temperature Water depth and fluctuations O2 levels
84
Describe diptera
-Live in sediment, rotting vegetation, mud or on emergent vegetation -Diversity often very high (Ephemeroptera, Plecoptera, Trichoptera (EPT)
85
What diptera are found in acidic, cold nutrient poor wetlands?
Higher diversity of: -Odonata -Hemiptera -Coleoptera
86
What diptera are found in wetlands with fluctuating water levels?
Higher diversity of: -Hemiptera -Coleoptera -Trichoptera -Odonata
87
What morphological adaptations do invertebrates have?
-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
What feeding strategies do invertebrates have?
-Shredders -Collectors/gathers/scrapers -Filter feeders -Piercers -Predators
89
What adaptations do invertebrates have for aerobic respiration?
-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
What organisms obtain oxygen through their cuticle directly from the water?
Chironomids
91
Describe chironomids
-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
What do large, diverse wetlands have?
-Fish -Reptiles -Birds -Mammals
93
What adaptations do vertebrates have for temperate wetlands?
Show no adaptations, fish avoid anoxic areas
94
What adaptations do vertebrates have for anoxic conditions in tropical areas?
-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
What adaptations do vertebrates have for anoxic conditions in tropical areas?
-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
Describe vertebrates that breathe air?
-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
What are common birds species found in wetlands?
Divers, grebes, waterfowl, waders, shorebirds, cranes, pelicans, flamingos, passerines, blackbirds, gulls, kingfishers, raptors
97
What are feeding strategies for birds?
-Surface swimmers -Divers -Flight feeders -Stationary spear fishers -Plunge and perch divers -Course hunters
98
Describe surface swimmers
Strain food with their beaks or grab food on or in the water column (ducks)
99
Describe divers
Grab or spear fish (mergansers) strain, dig or root food out of the soil (ducks)
100
Describe flight feeders
Catch insects
101
What are stationary spear fishers?
Heron
102
Plunge and perch divers?
Kingfishers
103
Describe course hunters?
Seize prey with their feet (eagle)
104
What adaptations do birds have for wetland environments? (feet)
-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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