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Ecology of Aquatic Environments > Lake Ecosystems > Flashcards

Lake Ecosystems Flashcards

1
Q

What are the main factors that impact lake biota?

A

-Light
-Temperature
-Dissolved Oxygen
-Nutrient Bioavailability

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2
Q

What % of energy is absorbed in the first 1m in a lake?

A

50% of light energy

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3
Q

What takes place in the photic zone?

A

Photosynthesis + respiration

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4
Q

What takes place in the aphotic zone?

A

Respiration only

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5
Q

What affects light absorption?

A

-Water clarity
-Wave type
-Dissolved & suspended material

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6
Q

How does light absorption affect photosynthesis?

A

Constrains algal and macrophyte primary production in the littoral zone

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7
Q

Why is light absorption so important?

A

-Heating the waterbody
-Stratification
-Characteristic colour to lakes (blue, green)
-Affects organisms that are sensitive to light (the movement and migration of zooplankton & fish)

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8
Q

What is the max depth that photosynthesis can occur?

A

In the aphotic zone

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9
Q

What determines water temperature in a lentic environment?

A

Heating, cooling and movement of heat through the water determines water temperature

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10
Q

Why is water temperature important?

A

-Controls the rates of biological activity (activity, behaviour, metabolic rate

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11
Q

What are eurytherns?

A

Fish that can tolerate a wide range of temperatures ( cyprinids ie. carps and minnows)

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12
Q

What are stenotherms?

A

Fish that have a narrow temperature range (salmonids)

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13
Q

Why are fish classified as cold and warm water species?

A

This is due to different species having different optimum temperature range which a fish spp. can survive and reproduce

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14
Q

When do carp spawn?

A

Mid -July
Like slow, warm vegetated waters

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15
Q

When do trout spawn?

A

November to January
Like cool, clear waters with gravel substrates

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16
Q

What are some biotic adaptations to changing temperatures?

A

-Acclimatization
-Resting stages
-Temperature Induced-hatching
-Behavioural thermoregulation

17
Q

Describe acclimatisation

A

-When an organism can acclimatise to changing temperature regime
-Chlorella spp. show max growth rates at 20, 26 and 36 degrees
-Can get used to a range of 16 degrees

18
Q

Describe resting stages

A

-Formed by organisms under sub-optimal temperature conditions
-Plankton form thick-walled cyst that are morphologically different from vegetative cells
-Functions as a time-dispersal system, allowing rapid recolonisation after unfavourable environmental conditions

19
Q

Describe temperature induced-hatching

A

-Rutilis rutilis (roach) eggs do not hatch at same time of year
-Hatching dependent on accumulated temperature on days preceding hatching
-Eggs hatch after fixed degree-day threshold
-Availability of food and the activity of predators are also dependent on temperature

20
Q

Describe behavioural thermoregulation

A

-Diel vertical migration displayed by plankton and fish
-Spend their days in cold hypolimnion
-Move up to warmer epilimnion only during the night

21
Q

What is a key process in cold temperature lakes?

A

Seasonal thermal stratification

22
Q

`What happens in lakes during spring (thermocline)?

A

-Weak solar radiation
-Degree of vertical mixing
-Oxygen saturation levels >100%
-Well mixed nutrients- bioavailable

23
Q

What happens during the summer in lakes? (thermocline)?

A

-Thermal stratification occurs
-Solar radiation and density
-Split into the epilimnion, thermocline and hypolimnion
-Atmospheric O2 (Epilimnion)
-Anoxic (Hypolimnion)
-Storage of nutrients in hypolimnion

24
Q

What happens during the autumn in lakes (thermocline)?

A

-Autumn turnover
-Degree of vertical mixing
-Oxygen saturation >100%
-Well mixed nutrients = bioavailable

25
Q

What happens during the winter in lakes? (thermocline)

A

-Winter stratification
-Ice formation density
-Transparent ice = algal growth
-Snow and Ice = winter kill
-Storage of nutrients in hypolimnion

26
Q

What adaptations do macrophytes have to low oxygen?

A

-Aerenchyma cells
-Elongated stems
-Carnivorous plants
-Heterophylly

27
Q

What adaptations do invertebrates have to low oxygen? (Oxygen from water)

A

-Integumental respiration - O2 taken directly across body surface
-Tracheal system- transport of gases throughout the body
-Ventilatory movements - increase the flow of oxygenated water over respiratory organs
-Rectal pump- pump water in and out of tracheated rectal chamber
-Fish gills

28
Q

What adaptations do invertebrates have to low oxygen? (Oxygen from air)

A

-Siphons/ snorkels (water bugs, water scorpion)
-Store air, trap it under wings or with water repellent hairs
-Air bubbles- carried by underwater organisms

29
Q

What are behavioural and physiological adaptations to low oxygen?

A

-Migrate to more oxygen -rich habitats
-Haemoglobin

30
Q

Where does decomposition occur in lakes?

A

Decomposition of Organic matter occurs between the water-sediment interface

31
Q

What does lake stratification impact on?

A

-Temperature
-Dissolved Oxygen
-Nutrient availability
-Determines what biota is present

32
Q

What are key players in the littoral zone?

A

-Phytoplankton
-Periphyton
-Macrophytes
-Key primary producers within lakes

33
Q

What live in oligotrophic waters?

A

Dinoflagellates
Diatoms Tabelleria
Desmids
Chrysophycean Dinobryon

34
Q

What live in mesotrophic waters?

A

Dinoflagellates - Peridinium
Cyanophyta - merismopedia
Chlorophyta -
Diatoms - cyctella

35
Q

What live in eutrophic waters?

A

Cyanophyta - anabaena
Euglenophyta
Diatoms - Asterionella

36
Q

What lives in the pelagic zone?

A
37
Q

What lives in the pelagic zone?

A

-Protozoa and Fungi
-Phytoplankton
-Zooplankton
-Fish

38
Q

p=#What lives in the profundal zone?

A

Bacteria
Protozoans and ciliates
Insect larvae
Bivalves
Oligochaetes and nematodes

Ecology of Aquatic Environments (14 decks)

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