Aquatics: Streams and Lakes

Question 1

Define bedload transport

Answer 1

It is where sediment grains roll or slide along the bed

Question 2

Define saltation transport

Answer 2

It is where single grains jump over the bed at a length proportional to their diameter, periodically losing contact with the bed

Question 3

Define suspension

Answer 3

It is where particles remain permanently above the bed, sustained there by the turbulent flow of the air or water

Question 4

Define solution

Answer 4

It is where particles as ions are dissolved in the water (Eg. Salts)

Question 5

What are 3 different kinds of lakes?

Answer 5

1. cirque lakes
2. oxbow lakes
3. crater lakesq

Question 6

What is a cirque lake?

Answer 6

A bowl-shaped, steep-walled mountain basin carved by glaciation, often containing a small round lake

Question 7

What is an oxbow lake?

Answer 7

A bow-shaped bend in a river formed by a former river channel

Question 8

What is a crater lake?

Answer 8

A lake created by a meteor or impact

Question 9

Besides the three main types of lakes, what are 3 other ways lakes can be created?

Answer 9

Lakes can result from:

• Tectonic plate movement
• Glaciation
• Landslides across a stream

Question 10

What is specific heat?

Answer 10

The quantity of heat (in calories) required to raise the temperature of 1 gram of a substance by one degree

Question 11

What is specific gravity?

Answer 11

The ratio of the density of a substance to the density of a standard, usually water for a liquid or solid and air for gas

Question 12

What is the specific gravity of plain water and salt water?

Answer 12

Specific gravity of plain water = 1

Specific gravity of salt water = ~1.025

Question 13

Why is specific heat so important?

Answer 13

It is important because the high specific heat of water gives lakes a more stable temperature than terrestrial environments

Question 14

Why is temperature an important factor when it comes to oxygen levels in the water? (Think where is there going to be the most oxygen?)

Answer 14

Oxygen enters the water through absorption and the amount of oxygen the water can hold depends on its temperature. Colder water holds more oxygen while warmer water holds less oxygen.

Question 15

How do the warmer temperatures during the summer months affect the oxygen levels in bodies of water?

Answer 15

During the summer months, the oxygen in lakes and other bodies of water can become layered just like the temperature. Eg. The temp near the top of the lakes will be warmer so that means there will be less oxygen near the surface. The temp will also get cooler towards the bottom of the lakes so there will be more oxygen near the bottom.

Question 16

What happens to lakes during the summer months in terms of temperature and oxygen? (Think thermocline!)

Answer 16

• During the summer, it is not very windy so the waters in the lake do not mix that much
• Temperatures rise and the temperature difference between the surface and bottom waters becomes so extreme that the two don’t mix at all
• A middle layer forms between these two extremes called the thermocline
• This is where the major change in temp and oxygen levels occurs
• Most life stays in the top layer because the bottom layer becomes so oxygen depleted because the water doesn’t mix

Question 17

What happens to lakes in the fall with regards to temp and oxygen levels?

Answer 17

• In the fall, the overall temperature starts to decrease so the surface water starts to cool down
• the upper layer starts to sink and the whole lake is now a uniform temperature
• winds pick up and mixing can now occur
• this refreshes the nutrients and oxygen throughout the lake
• This mixing is called the fall turnover

Question 18

What happens to lakes during winter with regards to oxygen and temperature?

Answer 18

• A thin layer of ice covers the top
• The water becomes oxygen-deprived
• uppermost layer stays slightly cooler
• lowermost layer stays a uniform temperature of 4 deg

Question 19

What happens to lakes during the spring with regards to temp and oxygen levels?

Answer 19

• The ice melts and the temperature throughout the lake becomes constant again
• Mixing occurs to refresh the nutrients and oxygen levels
• This is called spring turn over

Question 20

What are the different zones of a lake? (list 5)

Answer 20

• littoral zone
• limnetic zone
• profundal zone
• benthic
• compensation level

Question 21

Define the littoral zone

Answer 21

shallow water - where plants grow and light penetrates to the bottom

Question 22

Define the limnetic zone

Answer 22

Open water - The layer away from the shore where there is sufficient light for photosynthesis

Question 23

Define the profundal zone

Answer 23

Deep water zone

Question 24

Define the benthic zone

Answer 24

The bottom zone

Question 25

What is the compensation level?

Answer 25

The compensation level is where photosynthesis and respiration are equal

Question 26

Define eutrophy

Answer 26

A condition of being nutrient rich

Question 27

Define oligotrophy

Answer 27

A condition of being nutrient poor

Question 28

What is mesotrophy?

Answer 28

A condition of having a middle amount of nutrients

It is the middle layer between eutrophy and oligotrophy

Question 29

Define Diadromy

Answer 29

Diadromy is a term used to describe the movements of fishes between fresh waters and the sea

Question 30

What does anadromous mean?

Answer 30

An anadromous fish is born in freshwater, migrates and spends most of its time in the ocean, then returns to freshwater to spawn. An example of an anadromous fish is a salmon.

Question 31

What does catadromous mean?

Answer 31

A catadromous fish is born in saltwater, and lives in freshwater most of its life then returns to freshwater to spawn. An example of a catadromous fish is an eel

Question 32

What does amphidromous mean?

Answer 32

Amphidromous refers to fish that regularly migrate between fresh water and saltwater (in both directions). Examples of amphidromous fish can be found in the tropics and sub-tropics

Question 33

What are some of the main invertebrate communities in streams? and what does each feed on?

Answer 33

• Shredders - shred and chew leaves and bark
• Collectors - filter feed on fine particulate organic matter
• Grazers or scrapers - scrape and graze biofilm and algae off exposed surfaces

Question 34

Why are riparian zones so important for wildlife?

Answer 34

1. they offer the food, water, and cover wildlife require
2. greater availability of water increases plant biomass production - allows species to live where they could not without water
3. dramatic contrast of plant communities between riparian zones and surrounding areas - the gradient of water creates different zones that are each important to different wildlife

Question 35

What are the different types of wetlands?

Answer 35

1. bog
2. marsh
3. fen
4. swamp
5. shallow open waters

Question 36

Which wetlands contain peat

Answer 36

Bogs and fens

Question 37

What are the two types of food inputs into streams and what do they mean?

Answer 37

1. Allochthonous - material that is derived from outside the watercourse
   Eg. leaves or branches that fall into the stream
2. Autochthonus - material that is derived from inside the watercoure
   Eg. input provided by the photosynthesis of large plants

Question 38

What are some marine-derived nutrients?

Answer 38

Nitrogen and phosphorous

Question 39

What are the parts of a stream?

Answer 39

1. Riffle
2. Run
3. Pool