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Limnology > Part I > Flashcards

Part I Flashcards

1
Q

What does limnology mean? Who is one important limnologist?

A

The study of inland waters.

Stephen Forbes. Forel defined Limnology (lentic systems)

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2
Q

Describe African poisonous gas. What causes them?

A

AKA Cameroon explosions. Sudden releases of CO2 gas. Originates magma. Accumulates in deep stratified lakes.

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3
Q

What is significant about African poisonous lakes?

A

Populous.
10% rise in CO2 and 15-20% increase in methane
Energy can be extracted.

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4
Q

Who was Tommy Edmondson?

A

UW professor studied algal blooms. Resulted in action to stop nutrient (P) pollutions. Lake WA

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5
Q

Types of study designs specific to limnology

A

1) Comparative
2) Whole lake manipulation
3) meso/microcosm
4) Paleolimnology
5) Mathematically
6) statistically

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6
Q

What is paleolimnology?

A

study of temporal limnology. Study cores from the benthic region. Can identify events based on core composition.

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7
Q

What types of lentic water bodies are there? (6)

A

1) Lakes
2) Ponds
3) Reservoirs
4) Wetland
5) Rock pools
6) bog

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8
Q

What does lotic mean? ex. ? (4)

A

river or stream, means moving water.

1) spring
2) canal
3) backwater
4) estuary

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9
Q

Mechanisms that cause lakes to form? (9)

A

1) Glaciation
2) oxbow
3) sinkholes
4) rock pools
5) frost
6) tectonic activity
7) volcanic activity
8) meteorites
9) biological activity

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10
Q

Types of glacially formed lakes

A

alpine (tarns form at base of a steep cliff) , kettle (glacial till and blocks of ice) , moraine (damming sediments), plunge basins (dry falls), Alluvial dams (sediment caused dams), Glacial scour (gouges bedrock)

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11
Q

What were the Missoula Floods?

A

Massive floods that resulted b/c of ice dams breaking in Glacial lake missoula and glacial lake columbia. Swept from Spokane to astoria.

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12
Q

How do oxbows form?

A

River side channel slowly is cut off from main flow due to sediment inputs from the river (fluvial).

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13
Q

How do sinkholes form lakes?

A

Form in regions with limestone (karst regions). Limestone is weak. Streams and precip can form caverns–>collapse form lakes. Shallow and round.

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14
Q

Rockpools?

A

Form in depressions along rock cliffs, usually sandstone of granite.

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15
Q

frost polygons?

A

when permafrost melts in summer small lakes form.

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16
Q

Tectonic activity and lake formations?

A

One plate moves downward relative to other, deep rift or fault forms. Lake Tanganyika

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17
Q

How do volcanoes form lakes?

A

Goldwater lake and crater lake

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18
Q

How do meteorites form lakes?

A

Impacts from falling rock i.e. Lake Manicouagan, Quebec. Rare

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19
Q

What biological activity forms lakes?

A

Beaver ponds, wallows, or human created. Alvord Desert playa

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20
Q

Who were some early contributors to limnology?

A

Forbes, Birge, Juday, Hasler, Hutchinson, and Edmondson

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21
Q

What is and where is the littoral zone located?

A

Located along the shoreline, shallow and photosynthesis usually occurs. Provides refuge for fish.

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22
Q

What is the limnetic zone

A

AKA the pelagic zone. Known as the center of the lake. Free swimming fish, zoo plankton, and phytoplankton exist here.

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23
Q

What is the euphotic zone?

A

Depths where > 1% of light penetrates the water which is necessary for photosynthesis.
about 3x secchi depth

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24
Q

What is the aphotic zone?

A

Region below the euphotic zone.

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25
Q

Benthos?

A

Bottom of the lake. Sediments

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26
Q

How does shape and size influence lake physical properties?

A 
depth-->light penetration
chemical composition-->mixing outside influences
Ratio of limnetic to littoral
Deeper lakes >stratification
Temporal mixing
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27
Q

What is Zmax?

A

Maximum depth

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28
Q

Average depth?

A

Volume/Surface area

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29
Q

What does L signify?

A

perimeter or shoreline lenght

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30
Q

What is the index of shoreline development?

A

DL

ratio of the length of shoreline to circumference of a perfect circle of area equal to that of the lake= L/2SQRT(pieSA)

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31
Q

Average depth: max depth?

A

Tells us about the shape of the lake. A perfect cone is 0.33. Shallower average depth results in small ration.

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32
Q

What is the global distribution of lake size?

A

Most lakes are small. There are very few very large lakes.
Largest lake by area (salt) caspian sea
Freshwater (largest) Superior
Largest by volume (saltwater) Baikal

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33
Q

What is a watershed?

A

the area of landscape that contributes to the water supply of a lake or stream. (catchment)

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34
Q

Describe some properties of water?

A

Polar (sticky to other polar), dissolves variety of polar solutes (acids, bases, sugar, salt, alcohol). Surface tension formed from weak hydrogen bonds. Density changes with temperature

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35
Q

How does water density change with water?

A

Max density @ 3.98C. Water is more dense that ice which is why ice floats.

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36
Q

Discuss oxygen solubility

A

Air is 21% oxygen. Oxygen is more soluble that nitrogen, more O2 dissolved in water than N2. Solubility changes with temperature, salinity, and pressure.

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37
Q

How does O2 solubility change with pressure?

A

Less soluble as pressure decreases

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38
Q

How does O2 solubility change with temp?

A

Less soluble at high temperature

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39
Q

How does O2 solubility change with salinity

A

Less soluble in high salinity water

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40
Q

If temp and salinity are constant, what happens to oxygen in a high elevation lake?

A

Oxygen solubility decreases because pressure decreases.

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41
Q

What is specific heat?

A

amount of heat (calories) required to raise the temp 1C of 1g of a substance. (water=1)

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42
Q

What is the latent heat of fusion and melting?

A

water–>ice (Fusion)
ice–> water (melting)
79.7 cal/g

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43
Q

What is the latent heat of evaporation?

A

water–>steam (540 cal/g

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44
Q

Why is the specific heat of lakes so important?

A

b/c it takes so much energy to change the temperature, lakes tend to be much more thermally stable.

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45
Q

What is a thermocline?

A

Thermocline is depth where temperature is changing the fastest, steepest plane of change in temp.

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46
Q

What is the epilimnion?

A

Top most layer of the lake generally stable. Uniformly warm, well mixed (

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47
Q

What is the metalimnion?

A

Region of steep thermal gradients (thermal discontinuity) (>1C/m)

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48
Q

What is the hypolimnion?

A

Deepest level of the lake and generally the coldest temperature. More stable than the metalimnion
Cold and relatives undisturbed (

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49
Q

What is lake stratification?

A

A pattern that results from the relationship of water temperature and density.

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50
Q

What causes isothermal conditions?

A

Constant mixing of the lake causes the same temperatures throughout the lake

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51
Q

What is relative thermal resistance?

A

The amount of thermal energy required to mix water of two different temperatures. Where RTR is greatest is generally where the thermocline is located.

52
Q

What happens in the Spring to stratification?

A

Temperate lakes may be ice covered. Temperatures are isothermal and cold. Wind mixes water from top to bottom, called Spring turnover.

53
Q

What happens in the late Spring to stratification?

A

Surface water warms and becomes less dense, floating on cooler water. RTR increases. Epilimnion forms and mixes w/itself.

54
Q

What happens in early summer to stratification?

A

Stratification into 3 layers. Persist through summer. Highly resistant to mixing.

55
Q

What happens in late summer to stratification?

A

Epilimnion temperature increases. Thermocline drops in depth. Hypolimnion will warm slightly.

56
Q

What is stability?

A

Amount of work required to mix the entire volume to a uniform temperature. How resistant a system is to wind.

57
Q

What happens in Autumn to lake stratification?

A

Surface water cools in the fall. Cooler surface water is dense and sinks. Eventually epilimnion and hypolimnion temperatures equalize.

58
Q

What happens in the winter to stratification?

A

Lakes cools back to 4C and ice forms. Inverse stratification occurs, cooler water over warmer water can occur.

59
Q

What does dimictic mean?

A

circulate and stratify twice a year (summer and winter)

60
Q

Monomictic

A

circulate and stratify once a year.

61
Q

Amictic

A

perennially ice covered. No mixing, but can stratify

62
Q

polymicitc

A

frequent mixing, shallow and often tropical

63
Q

oligomictic

A

stratified much of the year, has regular circulation events. No ice.

64
Q

Meromictic

A

deep layer of dense saline water that does not mix with rest of the lake (soap lake)

65
Q

Heat budgets, what are they?

A

Powerful indicators of temperature patterns in lakes.

66
Q

Summer heat income?

A

amount of heat to raise the temperature from 4C to the maximum heat content

67
Q

Winter heat income?

A

amount of heat to raise the temperature to 4C from the minimum heat content

68
Q

Annual heat budget?

A

amount of heat to raise the temperature from the minimum of winter to the max of summer

69
Q

What is a proxy measurement of salinity? Why?

A

conductivity because it measures the conductance of the water which is highly associated with salt ions.

70
Q

What is the chemocline

A

where conductivity changes the fastest or the steepest slope.

71
Q

what has an effect on winter and summer heat incomes?

A

Temperature and depth

72
Q

What influences water motion in a lake?

A

wind, thermal and chemical gradients, rive inputs, etc.

73
Q

what are standing waves and who coined the term?

A

Forel in Lake Geneva. Known as surface seiche. Rocking of water in a bathtub. Waves reflect back off basin edges.

74
Q

Wavelength=? Amplitude?

A

L (lambda); amplitude=1/2 wave height

75
Q

What is the difference btw a surface and internal seiche?

A

a wave occurring inside the lake rather than on the surface. Tend to have greater amplitude and longer periods than surface seiche.

76
Q

How does wind affect temperature in lakes?

A

Downwind and upwind locations have been observed to have differences in temperature. Which can greatly effect metabolic rates of fish i.e. growth rates. Also forms wave

77
Q

What influences wave height?

A

Wind
topography
lake shape and size (fetch)

78
Q

Explain difference of fetch and effective fetch.

A 
Fetch= distance over which the wind has blown uninterrupted by land. 
Effective= takes into account prevailing wind direction.
79
Q

What is the maximum theoretical height of a wave?

A

h (cm)=0.15sqrt(x)

x=fectch (cm)

80
Q

What are foam streaks and how are they formed?

A

combo of organic, water, air

form by combo of wind, upwelling and wave action. (See slide diagram)

81
Q

What is the reynolds number?

A

the ratio between two forces: viscosity and inertia.
R=Ud/v
U=speed of object in water
d=characteristic size of an object moving through water
v=kinematic viscosity of water (0.01 cm2/s @20C)

82
Q

what causes turbulence in water/lakes?

A

unstable stratification
in and out flows
upwelling
temperature

83
Q

What does light do in water? Why is water blue?

A

Scatter=changes direction
Reflect=light changes direction at surface
absorbed=dissapates
B/c blue light scatters more readily in water than red.

84
Q

How is light measured?

A

secchi disk. euphoric zone 2-3x secchi.

85
Q

Oxygen profiles temporal in eutrophic lake

A

early spring and late fall are relatively isothermal

Summer and winter temperature and oxygen become stratified. Oxygen used up by respiration

86
Q

What is metalimnetic O2 maxima?

A

In low productivity lakes light can penetrate the metalimnion allowing for photosynthesis. Results in a peak of O2 in the metalimnion.

87
Q

What are seepage lakes?

A

no inflow or outflow. Gains and losses solely through groundwater, evaporation, and precip

88
Q

What are drainage lakes?

A

usually have an inflow and outflow

89
Q

What is a water budget

A

Creates measures that allow for comparisons between lakes.

90
Q

What is residence time?

A

How long it would take to replace all the water in the lake.
residence time=lake volume(m3)/discharge rate (m3/yr)

91
Q

Forms of C present in Lakes?

A

CO2
DIC
DOC
POC

92
Q

What are some types of DIC?

A

carbonic acid, bicarbonate, carbon dioxide, and carbonate

93
Q

What is the carbon equilibrium?

A

balance between DOC, DIC, POC, and CO2. When one increases or decreases the others will fluctuate in correlation to the increase or decrease. When CO2 is removed via photosynthesis another DIC will dissociate removing H+ thereby increasing pH.

94
Q

What is redox potential?

A

Used to evaluate potential chemical reactions that typically occur under low oxygen environments. Measured as electron activity (Eh) in units voltage. Negative log scale (like H)->pE(=-log[e-])

95
Q

What is biomagnification?

A

Accumulation of toxins ad chemicals at the highest trophic levels. Typically lipophilic chemicals.

96
Q

Describe the relationship between benthic & phytoplankton productivity?

A

As one increases the other likely decreases. Vadeboncoeur et al 2002 graph. Linear relationship is not seen. When benthic PP was high Phyto was low. Phyto can block out the sunlight limiting benthic PP. Benthic is better equipped to absorb nutrients.

97
Q

Why are biomass pyramids inverse for aquatic systems?

A

In an oligotrophic lake often times macrophytes and other pp are not present and the phyto that are present are very small. When phyto becomes more dominant they often become less edible therefore resulting in more biomass.

98
Q

How can carbon isotopes inform food web interactions?

A

isotopes occur variably throughout the different areas of lakes such as the pelagic and littoral zones because of varying levels of pp. An increasingly negative value indicates more profundal origin and less negative moves into the pelagic to the littoral zones. Each system is different so must measure each system individually to determine what isotopes occur where.

99
Q

What are the three main sources of acid deposition? How has its distribution change over the last three years?

A

1) Carbonic( H2CO3)
2) Nitric (HNO3) combustion engines.
3) Sulfuric (H2SO4) coal burning/smelting.

Decreased since the 80’s.

100
Q

What is acid buffering and how does it differ in lakes?

A

Water bodies are able to absorb additional hydrogen ions added to the system differently based on many physical differences. Buffering is the acid neutralizing capacity of water to buffer acids (aka alkalinity). Inorganic carbon is major source of buffering ability. Sodium bicarbonate.

101
Q

What is the Sudbury story?

A

Nickel producers->sulfur dioxide. nearby lakes biodiversity dropped and species physically suffered. Regional variation of acidity due to geologic differences. Legislation passed to decrease sulfur dioxide. Most lakes recovered well, some did not.. Likely geology or other land use trends.

102
Q

how important are chemical and nutrients in lakes?

A

may ultimately determine who is present and who is not. Effect all biota

103
Q

what roles does phosphorous play in metabolism?

A

Used in DNA and ATP

104
Q

Explain Liebig’s law of the minimum

A

growth is controlled not by the total amount of resources available, but by the scarcest resource. The barrel example.

105
Q

Where does phosphorous come from?

A

mostly from geologic origins like rocks. Small amount from atmosphere.

106
Q

What are the key forms of phosphorous?

A

1) soluble reactive=inorganic and organic dissolved in water and available to plants (DIP=ortho PO4^3-)
2) Particulate organic= living or dead organisms dead leaves.
3) particulate inorganic=ortho attached to particles thro electrostatic attraction (Ca, Mg, Fe)
4) total phos=sum of all forms.

107
Q

What is trophic status?

A

overall measure of lake productivity. Total phosphorous influences this classification.

108
Q

What is TSI?

A

Trophic state index. Rating system to determine trophic class (i.e. oligo, meso, eu, or hypereu.)

109
Q

Main factor that influences P arrival into a lake?

A

Land use. Tahoe vs. Vancouver lake.

110
Q

What is luxury consumption?

A

excess uptake or P in order to store for future generations.

111
Q

What is sediment loading and why is it important to P cycles?

A

P cycles between the sediment and overlaying water. The return of P to water from sediment is called sediment loading. Sedimentation occurs w/ auto and allochthonous.

112
Q

How does oxygen affect P cycle?

A

when O is low inorganic compounds like Fe become soluble in water and releases a phosphate into the water column and is biologically available.

113
Q

What is the mass balance model?

A 
DeltaM/Deltat=I-O-(Sgross-R)
M/t=storage or loss in lake
I=external load
O=outglow
Sgross=loss to the sediment
R=internal load
(Gross-R)=net sedimentation
114
Q

What are the major culprits of eutrophication?

A

Anthropogenic–>detergents, fertilizers, livestock, sewage.

115
Q

Name some lakes that experienced rampant algal blooms in the 60’s and 70’s and hypoxia? why sig?

A

Lake Erie and Lake Washington. Agal blooms formed and persisted through summer. Algae dies and falls to the bottom, causes hypoxia conditions.

116
Q

Who identified culprit for algal blooms and hypoxia in the 70’s?

A

Schindler 1974. Full lake manipulation. One without PN the other side with.

117
Q

How does nutrient cycling differ in streams and rivers?

A

Rivers and streams, because they are lotic systems, have a spiraling effect on nutrients. nutrient losses in lakes are greater because more are stored in lakes. Increased P doesn’t have same affect in rivers as in streams because of spiraling effect.

118
Q

If nitrogen is mostly in the atmosphere how is it used by organisms?

A

Specialized bacteria known as cyanobacteria can fix nitrogen to a usable state such as ammonia (NHx) or nitrogen oxide (NOx)

119
Q

Where does nitrogen come from?

A

cyanobacteria, atmospheric deposition, combustion, urban runoff, fertilizers, industry

120
Q

What is the red field ratio?

A

ratio of C:N:P.
106:16:1
Determined that growth of algae maintained the ratio. All are limiting, if one is low environmentally, the others will be taken up at lower rates.

121
Q

What does the redfield ratio tell us?

A

helps determine which nutrient is limiting. Some are N limited but most are P. Nitrogen limited lakes will be dominated by cyanobacteria.

122
Q

How do plants and animals differ in nutrient recycling?

A

plants can store excess nutrients animals generally need to maintain elemental homeostasis. As one nutrient becomes limiting, animals will excrete non limiting nutrient which further exacerbates the limiting nutrients effects.

123
Q

Name some dissolved ions in lakes. how are they measured?

A

Ca, Mg, bicarbonate, K, Na, sulfate, chloride, nitrate, phosphate, silicate. Salinity measurement (ppt/ppm) or specific conductance (microsiemens) which increases ~2%/C.

124
Q

how do ions enter a system?

A

weathering of rock and soil

125
Q

Where are saline lakes common?

A

seepage basins where outflow is absent or restricted. When evaporation > inflow.

Limnology (2 decks)

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