Lecture 15- Lentic Systems Flashcards

1
Q

Freshwater characteristics are determined by ______ and ______

A

-Heat budget
-Topography

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2
Q

Lakes only stratify in _____

A

Summer

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3
Q

What does topography alter?

A

Stream characteristics

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4
Q

What drives northern freshwater systems?

A

-Persistent cold temperatures
-Prolonged ice cover
-Freeze thaw cycle
-Extreme seasonality of solar radiation

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5
Q

The dates of freeze and thaw influence what?

A

-Light availability (primary productivity)
-Gas transfer
-Solute concentrations
-Heat exchange
-Mixing processes (stratification)

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6
Q

Frozen thaw cycles generally have ______ productivity

A

Low

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7
Q

Species are adapted to what?

A

-Tolerance of cold temperatures
-Rapid conversion of food to lipid storage
-Migration

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8
Q

What are the two types of freshwater systems?

A

-Lentic
-Lotic

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9
Q

What is a lentic system?

A

-Still, flat water
-Lakes, shallow open water

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10
Q

What is a lotic system?

A

-Flowing water
-Rivers, streams

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11
Q

Describe shallow open water characteristics

A

-Kettle ponds and thermokarst lakes
-Shallower than 2m deep
-Form in flat topography of tundra
-Surrounded by low tundra vegetation
-Freeze to the bottom

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12
Q

Fully freezing shallow open water limits _______

A

What biota can live in them

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13
Q

Describe some characteristics of arctic ponds

A

-Water flows between ponds only during spring thaw
-Typically have small drainage basins
-Water and sediments frozen from september to mid-june
-Ponds thaw in spring-summer
-Water temperatures remain cold but can reach 16C
-Sediments mostly organic material
-Typically boarded by grasses and sedges
-Phytoplankton and invertebrates persist in frozen sediments

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14
Q

In the winter, _______ are often cut off from surroundings by ice wedges that push up in the tundra

A

Arctic ponds

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15
Q

When do Arctic ponds get movement of water between ponds?

A

Only during spring thaw

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16
Q

The sediments in arctic ponds are composed of _______ because of ______

A

-Organic materials
-Low decomposition

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17
Q

Can anything survive in the frozen sediments of Arctic ponds?

A

Yes (phytoplankton and invertebrates)

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18
Q

Describe the Arctic pond food web

A
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19
Q

What are the two main zones in lakes?

A
  1. Photic zone
  2. Profundal zone
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20
Q

What are the zones inside the photic zone in a lake?

A
  1. Littoral zone
  2. Limnetic zone
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21
Q

What is the photic zone in a lake?

A

Area that receives sunlight

22
Q

What is the littoral zone in lakes?

A

Area that plants can root

23
Q

What is the limnetic zone in lakes?

A

Area that is too deep for plants, phytoplankton photosynthesis

24
Q

What zone is inside the profundal zone in lakes?

A

Benthic zones

25
What is the benthic zone?
Area that does not receive sunlight
26
Is there photosynthesis occurring in the profundal zones of lakes?
No photosynthesis
27
Where do nutrients come from in profundal zones in lakes?
Nutrients come from detritus
28
\. C| \. | B A \------------------------------------------ \ \ D E \___________________________ Label the zones of a lake
A-Photic zone B-Limnetic zone C-Littoral zone D-Benthic zone E-Profundal zone
29
What happens during spring turnover?
-Ice is melting -Oxygen can enter water from air -Winds and waves increase oxygen dissolution -Water warms to 4C -Dense warm water sinks to bottom and delivers oxygen to bottom of lake
30
What happens when the water stops mixing?
Get stratification
31
What are the three layers of stratification in lakes?
1. Epilimnion 2. Hypolimnion 3. Thermocline
32
What is epilimnion?
The top layer that remains warm
33
What is hypolimnion?
Bottom layer that remain cool
34
What is thermocline?
Middle layer where temperature fluctuate
35
Label the stratification layers \ A \---------------------------------------- \ B \------------------------------------- \ C \________________________
A= Epilimnion B= Thermocline C= Hypolimnion
36
Describe some characteristics of northern lakes
-Very weakly stratified -Can only have one mixing period (monomictic) = takes longer to warm to 4C -Low species diversity -Oligotrophic -Long period of ice cover = lower oxygen levels -Ice can buffer organisms from colder temperatures
37
What is amictic, monomictic and dimictic?
Amictic = No mixing (ice covered) Monomictic = Only one mixing period Dimictic = Two mixing periods
38
What are some limiting nutrients in the north?
-Lake generally nitrogen or phosphorus limited -Boreal lakes limited in phosphorus -Arctic lakes limited in most nutrients
39
Why can nitrogen be limited in the north?
Because it is tied to microbial activity
40
What is poikilothermic?
Internal temperatures varying
41
What are some characteristics of freshwater fish in the north?
-Near 0C = metabolism slows -Some enter state of dormancy (remain suspended in water column) -Some acclimate (change in enzyme concentration and increases red muscle) -Lakes are cold and unproductive, therefore solution is to migrate to sea
42
Why would a fish chose to migrate to northern marine systems?
Because northern marine systems are more productive
43
What is a diadramous fish?
A fish that migrates from freshwater to saltwater
44
What is a anadromous fish?
A fish that migrates from salt water to freshwater
45
Migrating animals move ______ between ecosystems
Nutrients
46
_________ = significant input of nutrients into freshwater systems
Anadromous salmon
47
Where is Arctic Char found?
Hazen lake, Ellesmere island
48
Arctic Char are _______ and ______
-Partially anadromous -Land locked populations
49
Arctic Char is important for ______ for many northern lakes
-Middle trophic level
50
Describe the Arctic lakes food web