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Biol 432 Flashcards

1
Q

How to calculate lake distance

A

Distance between 2 furthest points

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2
Q

How to calculate lake width

A

max. distance perpendicular to length

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3
Q

What is fetch and what does it represent

A

Distance over which wind can blow (L, (L+W)/2, surface area)

a) thermocline depth and b) depth to which particles will be resuspended

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4
Q

What is shoreline development

A

D = the ratio of the length of the shore line to the length of the circumference of a circle of area equal to that of the lake

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5
Q

What is indicated on a bathymetric map

A

max depth, volume, mean depth (V/A)

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6
Q

What causes water movement

A

wind, differential heating/cooling of water body, influx of water into lake

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7
Q

What are the two major types of water movement

A 
Waves= exhibit periodicity but have little to no forward flow
Currents= lack periodicity but exhibit unidirectional flow
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8
Q

What defines waves

A

Wavelength (L) = distance between two wave crests Height (H) = vertical distance between wave crest & trough
Amplitude (a) = deviation in vertical axis from mean position
Period = time required for passage of two crests across a fixed point
Frequency = inverse of period

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9
Q

How do waves break on shore

A

vertical movement becomes a horizontal one :

< 0.5 wavelength (L)

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10
Q

Why does the wind cause such a large pile-up in the thermocline and only a small pile-up of surface waters?

A

The larger the density differences (more stability), the smaller the amplitude
Density difference between surface water & air is 1000-fold different whereas as the density difference between the epilimnion & hypolimnion is very smal

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11
Q

What happens when the wind stops blowing?

A

A long wave -aka internal seiche and a surface seiche

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12
Q

importance of internal seiche

A

transport of nutrients, water, and organisms from hypolimnion to epilimnion(and vice-versa)

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13
Q

How does N enter lake water?

A

Gas exchange, direct deposition (acid precipitation) and runoff (fertilizer)

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14
Q

What are the elements in the N-cycle

A

nitrification, denitrification, N-fixation, uptake and excretion & deposition

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15
Q

For algal uptake, what are the fastest and slowest forms?

A

Fastest : NH4

Slowest : N2

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16
Q

What are the reactions inside bacterial or algal cells ?

A

nitrate reduction and N-fixation

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17
Q

Describe n-fixation

A

N2 - NH4+
Anaerobic process
Requires a lot of energy (N N)
Facultative: N fixation only when other sources of N are limiting
N-fixers: Heterotrophic bacteria and Photosynthetic cyanobacteria

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18
Q

Describe n-fixated cyanobacteria

A

have a competitive advantage at low N:P ratios

frequently form mass blooms in late summer

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19
Q

Why are lakes typically P-limited and the oceans typically N-limited?

A
  • Availability of MoO42-(molybdate) probably plays a role.
  • Chemical binding properties of MoO42-are very similar to SO42-(sulfate).
  • SO42-is in high concentrations in marine salt waters but not in freshwater.
  • SO42-competitively inhibits the uptake of Mo which is needed for nitrogen fixation (part of the nitrogenase).
  • input from the atmospheric N pool is lower in marine and other saline systems than in freshwater
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20
Q

Why is DIC important in lakes?

A
  • Source of CO2 for photosynthesis (hence, CO2is the raw material used to build organic matter)
  • However: Carbon is almost never limiting primary production (P and N are)
  • Weak acidic reaction with H2O
  • changes pH in lakesDetermines buffering capacity of lakes
  • Interaction with Ca: Hardness , Buffering
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21
Q

What is the rule of thumb with organic matter?

A

50% is carbon

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22
Q

Where to find elements in carbon cycle

A

CO2 : atmosphere
C : biosphere
POC/DOC : hydro/geo
Fossil fuels and limestone : geosphere

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23
Q

Describe carbon cycle

A 
Respiration
Photosynthesis
Bacterial respiration
Decomposition
Combustion
Fossilization
Erosion
Deposition
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24
Q

Where do very acidic lakes get their acidity?

A

Receiving acid from acid rain, mine drainage,volcanic eruptions, pyrite (iron sulfide) in catchment, etc.(the responsible acid is most often sulfuric acid)
Bogs

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25
Q

Describe calcite precipitation

A

Is often biogenic:
High photosynthesis - high pH - precipitation
Occurs typically in late summer (sometimes every year)
Calcite can remain suspended
lakes looks milky, called a “whiting” event
Calcite can accumulate at lake edges, called “marl”
Calcite can encrust macrophyte

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26
Q

Carbonate is a what?

A

Lakes that have a lot of carbonate can resist changes in pH with the addition of acids
The ability to resist changes in pH with respect to the addition of acid is called
- Alkalinity or(better)
- Acid neutralizing capacity-ANC
Lakes in limestone regions have high buffering capacity and are therefore not as impacted by Acid Rain. Lakes on granite are highly impacted

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27
Q

What are the major ions in lakes?

A

Cations: Ca, Mg, Na, K
Anions: CO3, HCO3, Cl, SO4

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28
Q

How to measure ions?

A
  1. each ion is measured separately (via ion chromatography)
  2. Conductivity of the water sample is measured
  3. Total dissolved solids (TDS) = weight of water sample that has been filtered and then left to evaporate at temperatures ~ 100 oC
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29
Q

When is a lake considered saline?

A

Several categories proposed, one commonly used in Canada by Hammer et al. (1986)
• Freshwater < 3,000 mg/L or < 5, 500 S/cm
• Hyposaline*3 – < 20 g/L or 5.5 – 30 mS/cm
• Mesosaline‡20 – 50 g/L or > 30 – 70 mS/cm
• Hypersaline> 50 g/L or > 70 mS/cm

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30
Q

What factors influence

A

A) Climate & Hydrology – evaporation-driven
B) Weathering of soils and rock
C) Atmospheric precipitation & fallout
D) Human activities

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31
Q

How much does road salt contribute to salinization of surface water

A

51%

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32
Q

Why study light in lakes?

A
  • light provides energy
  • animals use it for vision, orientation
  • heat lake
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33
Q

Light and niche partitioning

A
  • Pigment composition determines competitive outcome
  • Coexistence in white light
  • Partitioning of the light spectrum (“red” and “green” niche
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34
Q

Solar radiation

A

UV = little energy, dangerous
visible light = half of daily energy, PAR
Infrared = half of daily energy, transfer of heat

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35
Q

How do you measure light

A
  1. Photon flux density
  2. Unit based on number of photons per area and time
  3. equivalent to energy flow ( J m-2d-1), but wave length must be known for conversion
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36
Q

What affects light reaching surface of water?

A
  • latitude and season
  • time of day
  • altitude
  • meteo
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37
Q

Movement of light in lake

A
  • solar radiation
  • reflection (albedo)
  • scattering
  • absorption
38
Q

what affects reflection from lake surface

A
  1. angle

2. surface characteristics (waves, snow/ice)

39
Q

describe vertical light attenuation?

A

A constant fraction of light is absorbed(transferred to heat) with each increase in depth, meaning an exponential decay of light with depth
affected by light intensity at surface and depth, depth and wavelength

40
Q

light and the colour of lakes

A
  • Blue light is also most prone to scattering – Rayleigh Rayleigh scattering (of intensity I): blue, clear water
  • Suspended particles in water change these relationships: Blue light is rapidly attenuated - green light is transmitted best
  • In humic or turbid waters: all short wavelengths are absorbed - red, orange dominate
  • The lake water itself may be coloured: Coloured organic material, bacteria, anorganic substances (e.g. iron)
41
Q

what is the euphoric zone?

A

phytoplankton photosynthesis > phytoplankton respiration): 1 % of incident radiation remains

42
Q

Why study the distribution of heat in lakes?

A
  • Biochemical reactions are temperature-dependent
  • growth and reproduction
  • Heat distribution affects the movement of water
  • distribution of nutrients and organism
43
Q

Why is heat not distributed like light?

A
  • density anomaly in water

- wind that moves water masses

44
Q

Difference of heat in lakes in clear lakes

A

The epilimnion of clear lakes (less attenuation per metre) tends to be deeper and colder than that of lakes with lots of particulate matter or coloured lake

45
Q

Impact of climate change on lake tanganika

A
  • Increased temperatures (peak in last 1500 years)
  • sharper density gradient in mixolimnion
  • impedes vertical mixing
  • Reduced nutrient availabilty (stored in the monimolimnion) and reduced oxygenated layer
  • Reduced primary productivity despite larger euphotic zone
  • Reduces higher order productivity (fish yield)
46
Q

What is CA/LA?

A

catchment area/lake area
• CA:LA provides an index of the relative importance of atmospheric vs. watershed loading of allochthonous material
• Lakes with highCA:LA tend to be more nutrient rich
• In CA:LA, one would not include the LA in the CA estimate CA/LA

47
Q

How does the dead zone form?

A

1) Nutrient-rich river inputs promote algal growth in Gulf

2) Algal decomposition occurs in salty zone, mixing of water column prevented b/c of thermal and salinity gradient

48
Q

How large is the hypoxic zone?

A

Size of Lake Ontario

49
Q

What happened to the Aral Sea

A 
4th largest lake, now only 15%
diverted for cotton cultures
Separate bodies now
lost a lot of the biodiversity 
became more saline
not drinking quality
no longer a regional climate regulator
50
Q

What is a lantic and a lotic system?

A 
lantic = standing
lotic = flowing water
51
Q

Differentiate stream and river

A

Streams– tend to be cool, shallow and often have gravel & stony beds- typically contain clear, flowing water- alternating sequences of riffles and pools
Rivers- are warmer, deeper and have silty bed- lack riffle and pools

52
Q

What are the characteristics of streams and rivers?

A
  • Flow is undirectional
  • Dynamic environments:Channel morphology and substrate undergoing constant change
  • Energy flow:Much of the organic matter supporting stream metabolism can be from allochthonous sources
  • High spatial and temporal heterogeneity: Flow (as well as DO and water chemistry) are primary regulators of life in running waters
  • Many lotic organisms have specialized adaptations to live within running waters
53
Q

Where do stream studies take place?

A

Hubbard Brook

54
Q

Findings from Hubbard Brook?

A
  • more acid in rivers than precipitation (from dry deposition and sulfate from watershed)
    • Conducted simultaneous measurements of chemical inputs and outputs, which could then be used to derive mass-balance equations for the watersheds
    1) Undisturbed sites analysed over long-term show:net retention(precip. inputs > stream outputs) of H+, N, Cl, Pnet losses (precip. inputs < stream outputs) of Ca, Mg, Na, K, S, Si, & Al
    2) Experiment deforestation revealed major hydrological effect,and impacts on microbial activity and nutrient cycling, eg.decomposition and nitrification accelerated leading to greater export of H+and NO3
55
Q

Describe stream food web

A
  • Fish are dominant organisms in open water

* Invertebrates dominate stream benthos, greatest densities in riffles

56
Q

Some generalities regarding aquatic insect lifecycles:

A
  • larvae/nymphs usually the most lengthy part of lifecycle

- very few adults have a completely aquatic lifecycle

57
Q

Adaptations of invertebrates to stream life

A
  • In areas of predictable annual flooding, many insects will have evolved such that they emerge just prior to flood
  • Drifting behavior at night allow invertebrates to new habitat without risk of being eaten by visual predators
58
Q

what are shredders?

A

feed on leaf litter and twigs (aka coarse particulate organic matter: CPOM) and associated microbial and fungal community
Family Gammaridae, Subphylum Crustaceae

59
Q

what are collectors?

A

feed on fine particulate organic material (FPOM), which consists of finer plant fragments or suspended plankton
Caddisfly and blackfly

60
Q

what are grazers?

A

feed on periphyton (= attached algae, fungus and bacteria)

water penny and mayfly

61
Q

what are predators?

A

feed on living animal tissue

Giant water bug, dobsonfly

62
Q

Macroinvertebrates role in ecosystems?

A
  • Benthic inverts. process 20 – 73% of leaf litter inputs into headwater streams (Covich et al., ‘99)
  • Benthic inverts. are an important source of foodfor fish residing in streams
  • Benthic inverts. modify nutrient transport in streams and terrestrial environment
63
Q

What is the river continuum concept?

A

model for describing the structure and function of communities along a riversystem

64
Q

What are techniques to assess environmental change?

A
  1. historical records + ancestral knowledge
  2. modeling
  3. Natural archives
65
Q

How do sediments get into lakes?

A

allochtonous: pollen, aerial transported contaminants and soil particles
autochtonous: algae and aquatic insects

66
Q

What is the paleo approach?

A
  1. Select study lake
  2. select coring site and core
  3. Section and date core
  4. sub sample and isolate indicator of interest
  5. Collect indicator data
  6. Analyze data
67
Q

What factors can be addressed using paleolimno?

A
  • Acidification
  • Eutrophication
  • Anoxia and fish habitat
  • Climate change
  • Changes in salinity
  • Fire history
  • History of organic pollutants
  • Etc.
68
Q

How do we collect cores?

A

Gravity Core
Close interval Sectioning
Freeze coring
Livingston piston coring

69
Q

How to date cores?

A 
C or radiocarbon (old)
Pb (150 years)
Cs (nuclear peak in the 1960s)
Tephrachronology (volcano)
Pollen (known veg history)
Varves
episodic events
70
Q

Example indicators:

A
  • Diatoms
  • Cladocera
  • Chironomids
  • Chrysophytes
  • Pollen
  • Isotopes
  • Sedimentary Chla
  • Non‐motile metals
  • Paleo DNA
  • Charcoal
71
Q

What makes a good indicator?

A
  • Preserves well in sediment
  • Abundant
  • Morphologically distinct
  • Reliable indicator of environmental condition
72
Q

Diatoms indicate what?

A

Found all over the world (marine and freshwater species)
•Are often one of the dominant primary producers in freshwaters
•Well defined optima and tolerances for a suite of environmental conditions
•pH, nutrients, salinity •Climate•Habitat ➤periphyton
•Thermal stratification ➤planktonic vs. benthic

73
Q

Chrysophytes indicate what?

A

Also siliceous algae
•2 types of remains•Scale
•Cyst
•> 1000 described species
•Single cells or colonies
•Most have flagella
•Are motile
•Found in the plankton (open water) of lakes
Typically inhabit low nutrient, low temperature, unpredictable climates
•Such as Arctic, Antarctic, and Alpine lakes•Most common in slightly acidic, low nutrient lakes
•Cyst to diatom ratio –coarse indicator of nutrients, ice cover, salinity (cysts)
•Commonly used to track•pH, nutrients, climate

74
Q

What are animal indicators?

A
  • An intermediate or upper trophic position
  • Answer questions that algal indicators can’t
  • Different restrictions on growth
  • Oxygen
  • Predation
  • Macroinutrients, cations
75
Q

Paleolimnological Cladoceran Studies reveal what?

A
  1. Resurrection ecology‐Hatch buried resting eggs ‐Analyze historical populations directly
  2. Trophic interactions‐Multi‐proxy analysis‐Comparison of direct‐monitoring with the sediment record
  3. Ca decline in softwater Ontario lakes‐Cladocera as paleoindicator of lakewater Ca
76
Q

Describe eutrophic

A 
High in nutrients
High primary production
High biomass of primary producers
Low transparency
Low hypolimnetic O2
Hypolimnion dominated by midge Chironomus(Thienemann)
77
Q

Describe oligotrophic

A 
Low in nutrients
Low primary production
Low biomass of primary producers
High transparency
High hypolimnetic O2
Hypolimnion dominated by midge Tanytarsus(Thienemann)
78
Q

Describe primary production and dissolved oxygen method

A

DO(initial) – DO(dark) = Respiration
DO(light) – DO(initial) = Net Photosynthesis
DO(light) - DO(dark) = Gross Photosynthetis

79
Q

What are TP classifications

A 
Ultraoligotrophic<5 ug/l
Oligotrophic5-10 ug/l
Mesotrophic10-30 ug/l
Eutrophic30-100 ug/l
Hypereutrophic> 100 ug/l
80
Q

How are productivity and trophic state are related to basin morphometry.

A

comparing volume of lake and volume of hypolimnion
epi/hypo < 1 means oligo
epi/hypo > 1 means eutro

81
Q

What are reasons for cultural eutrophication?

A
  • Use of fertilizers
  • Increased population density
  • Increase in (untreated) human wasteIncrease in use of detergents (after WW II)
  • Most lakes are P limited. Addition of P led to increased algal growth
  • Both human waste and early synthetic detergents were high in phosphoru
82
Q

how to abate cultural eutrophication?

A
  1. nutrient reduction (Legislation to reduce nutrient content of inflowing water, Wastewater treatment, Diversion of nutrient-rich water)
    2) P precipitation
    3) Harvest of macrophytes
    4) Dredging of sediment
    5) Hypolimnetic aeration
    6) Lake drawdown
    7) Selective discharge of hypolimnetic water
    8) Biomanipulation
83
Q

Point vs non-point?

A

Point: any single identifiable source of pollution from which pollutants are discharged, such as a pipe, ditch, ship or factory smokestack” (EPA definition)
Non-point: nutrients are difficult to control because they come from many different sources and locations

84
Q

Summary of eutrophication

A

Eutrophication is a process that scientists have been studying for about 100 years.
Major advances have been made in controlling point sources
Non-point sources continue to be a major issue
Major challenge for the next century: meeting the demands of feeding the planet while maintaining adequate water quality

85
Q

What is trophic control?

A

In bottom-up models nutrients control community organization by controlling plant numbers. Also known as donor-control
In top-down models, predation is the structuring factor because predators control the number of herbivores. Also known as trophic cascade

86
Q

What is biomanipulation

A

A lake improvement procedure that puts trophic cascade theory into action to reduce phytoplankton biomass (especially nuisance blooms) and to increase water clarity

87
Q

How did Shapiro and Wright (1984) convince readers that biomanipulation as was at least partly responsible for increased water transparency?

A

Ran in-situ mesocosm experiment where Daphnia densities and nutrients altered but their treatments not replicated

88
Q

What were Carpenters conclusions?

A

In the Planktivore Lake, phytoplankton were stimulated more by enrichment than by release from zooplankton grazing.
In the In the Piscivore Lake, the positive effect of enrichment was lessened by the increased grazing pressure from zooplankton
A 1-mm change in mean zooplankton length had about the same effect on chlorophyll as a decrease in P input rate of 1 ug Lg L-1 d-1.
Among lakes (in general) the range of zooplankton lengths ≈ 1 mm, whereas the range of P input is substantially > 1 substantially > 1 ug Lg L-1 d-1.
Therefore, the potential for increasing for increasing eutrophication by P input exceeds the potential for controlling eutrophication by food web manipulation.

89
Q

Other reasons biomanipulation might be unsuccessful

A
  • predator avoidance
  • phytoplankton composition shift to inedible algae
  • planktivorous fish are not the only zp predators
  • many fish switch from planktivory and piscatory
  • Highh recruitment of young-of-the-year fish follows reduction of planktivorous fish
90
Q

Current thought on biomanipulation?

A

manipulation is only expected to be successful if the P loading is below a certain threshold (~ 0.6 g m-2 a-1), e.g. in oligotrophic and mesotrophic lakes.
The decrease of in-lake phosphorus is an indispensable prerequisite for long-term reduction in phytoplankton biomass.

BIOL 432 (1 decks)

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