Lecture 3

Question 1

Name 2 types of glacial lakes

Answer 1

cirque

moraine

Question 2

most productive area of a lake?

Answer 2

shallow margins on shore

Question 3

retention time is…

Answer 3

amount of flow passing through and amount of time it is retained within a lake

Question 4

retention time equation

Answer 4

volume/ mean rate of inflow OR outflow + evaporation rate

Question 5

issue with retention time?

Answer 5

• doesn’t take into account the amount of mixing

Question 6

PAR?

Answer 6

photosynthetically active radiation, wavelengths between 400-700nm

Question 7

how do tectonic lakes form?

Answer 7

when tectonic plate move apart forming riff valleys (forms largest, deepest lakes)

Question 8

how are thermokarst lakes formed?

Answer 8

when layer of permafrost thaws in summer

Question 9

difference between lakes and rivers?

Answer 9

• velocity is more significant in rivers

-

Question 10

what contributes to autochtonous production?

Answer 10

• macrophyte and benthic algae in margins

- phytoplankton in open water

Question 11

when does stratification occur?

Answer 11

• in climates with seasonal difference

- summer warming of upper layers

Question 12

EPILIMINION

Answer 12

upper, warmer, surface layer

Question 13

Hypoliminion

Answer 13

deeper,cooler, lower layer

Question 14

Thermocline

Answer 14

distinct separation between 2 layers

Question 15

which seasons does mixing occur?

Answer 15

• spring and autumn

Question 16

which seasons does stratification take place?

Answer 16

summer and winter

Question 17

which layer is more well oxygenated?

Answer 17

• epilliminion (upper layer)

Question 18

which layer is less oxygenated and why?

Answer 18

• hypolimminion (lower layers) because separated from air and no photosynthesis

Question 19

Holomitic

Answer 19

mix completely all year

Question 20

Monomictic

Answer 20

mix once per year

Question 21

warm monomictic lakes?

Answer 21

stratify in summer, mixed in winter due to freezing

Question 22

Dimictic lakes (basic)

Answer 22

stratify both in winter and summer. with mixing in autumn and spring

Question 23

Meromictc

Answer 23

NEVER mix

Question 24

transparency determines…

Answer 24

depth of light penetration

Question 25

what 2 factors affect light penetration?

Answer 25

colour and turbidity

Question 26

name 2 ways you can measure nutrients and light penetration

Answer 26

Van dorn sampler and Secchi disc (transparency)

Question 27

which type of lakes are nutrient poor and have low productivity?

Answer 27

oligotrophic lakes

Question 28

which lakes are more nutrient rich with high productivity?

Answer 28

Eutrophic lakes

Question 29

Name 2 types of producers

Answer 29

phytoplankton and rooted macrophyte

Question 30

Name 2 types of consumers

Answer 30

pelagic and planktonic

Question 31

describe ecological conditions of a lake in winter

Answer 31

• well mixed
• plankton abundance is low
• limited by light and temperature

Question 32

describe ecological conditions in spring?

Answer 32

plankton increase and use up nutrients

Question 33

ecological conditions in summer?

Answer 33

lower plankton abundance, limited by nutrients

Question 34

ecological conditions in autumn?

Answer 34

first storms, mixing, thermocline breaks up

Question 35

littoral zone

Answer 35

lake bed where plants can grow

Question 36

Profundal zone

Answer 36

lake bed where ther s no plant growth