Overwiev of Lake Ecosystems Flashcards
What is a lake?
A slowly flowing or non-flowing (lentic) open
body of water in a depression and not in
contact with the ocean.
Which lake is the largest lake?
Lake Victoria (Africa) is the largest lake in terms of surface area, but Lake Baikal (Russia) is the largest lake in terms of volume.
They are 9 types of lakes, mention 3.
- Tectonic lakes
- Volcanic lakes
- Glacial lakes
- Earthslide lakes
- Sinkhole lakes
- Fluvial (oxbow) lakes
- Aeolian lakes
- Crater lakes
- Animal-created lakes
What type of lakes are some of the oldest, deepest, and most
ecologically and evolutionarily unique lakes.
Tectonic lakes
How are tectonic lakes formed?
Tectonic movements of the earths crust.
There are 2 type of tectonic lakes, what are they?
- Graben Lakes – multiple faults allow a block to
drop down and form a depression (e.g. Lake
Biakal) - Horst Lakes – single fault tips down, forming a
depression (e.g. Owens Valley)
What is the main characteristics of volcanic lakes?
Characterize by having really abnormal abiotic frames because of earlier volcanic activities in the area.
Which lake type is the most abundant?
Glacial lakes.
What are the 2 characteristics of glacial lakes?
They are mainly found in temperate regions, and they are young lakes.
There are 3 types of glacial lakes, what are they?
Those formed by glacial scouring
Those formed by glacial deposits
Those formed by the release of large volumes of water from behind ice dams
Kettle lakes are glacial lakes, how are they formed?
- Receding glacier leaves dead ice.
- Glacial outwash (sand) is deposited.
- When the ice melts, they form depression with water, forming lakes.
How are fluvial (oxbow) lakes formed?
They are formed when rivers change their shapes through erosion, and over time the swirly part of the river gets cut off forming banana shaped lakes.
How are aeolian lakes formed?
They are formed by wind
Name 2 animals that can form lakes.
Beavers, human.
Draw lake habitats, you have to include:
- Littoral zone
- Limnetic/ pelagic zone
- Benthic zone
- Photic zone
- Profundal (aphotic) zone
Name the 3 lake productivity types.
- Oligotrophic
- Mesotrophic
- Eutrophic
What is an oligotrophic lake?
Oligotrophic – nutrient-poor, low primary production, often deep with low shoreline development.
What is a mesotrophic lake?
Moderately productive lake.
What eutrophic lake?
Eutrophic – nutrient rich, high primary production, often shallow with high shoreline development.
Draw lake stratification. You have to include:
- Epilimnion
- Metalimnion/thermocline
- Hypolimnion
You also have to include how it will look during winter, spring, summer, and autumn.
They are 2 types of wind affect of mixing of lakes, what are they?
- Langmuir cells - Langmuir cells created by strong, sustained winds (gray arrows). Dark blue arrows show the movement of surface water as a result of the cells, producing downwelling convergence zones where floating material can accumulate (gray shading), and upwelling divergence zones.
- Seiche - when wind tilts the thermocline.
There are 4 lake mixing types, what are they?
- Dimictic – mixes twice per year, common in temperate and arctic regions where ice cover is present in winter
- Monomictic – mixes once per year, common in temperate regions where no ice cover forms
- Polymictic – mixes several times per year, common in tropical regions
- Meromictic (amictic) – do not mix, present in tropical regions, may contain dissolved compounds in hypolimnion that stabilize the density layers (e.g. the Dead Sea did not mix for 300 years)
