Lakes Flashcards
How can lakes vary?
Physical characteristics, chemical, ecology
When is phosphorous considered limiting?
> 16:1
What are the physical descriptors of a lake?
Length width breadth depth shoreline length light availability
Name a lava dammed lake in Africa?
Lake Kivu
Name a crater lake in Africa?
Naivasha, close to lake George
Name a Rift Valley lake in Africa?
Tanganiyka, Malawi, Turkana, Edward
Name flood plain lagoons in Africa?
Bangwelu, Mweru
What is lake residence time?
Amount of time water stays in a lake?
What is the equation for residence time?
Volume / mean rate of inflow
What are the average wavelengths of active radiation?
400-700nm
What is the worlds deepest lake?
Baikal, 1620m
What are lake Baikal and Tanganyika?
Tectonic lakes
What is the middle part of a Rift Valley called?
Horst
What is the length and width of baikal?
636km by 80km
What is the shoreline length of baikal?
2,100km
What makes up baikal?
3 depressions, making up 20% of the worlds fresh water
How many species of fauna and flora live around lake baikal?
1,200 animal species 1,000 plants
What is a thermokarst lake?
Formed in tundra rapid heating then freezing, pool like
What lakes are caused by river meanders?
Oxbow lakes
How can glaciers form lakes?
I’ve scour creates cirque lakes, also kettle lakes
Describe the features of a lake used for hydropower?
Water released periodically, widely fluctuating river flow
Give an example of a dam used for hydropower?
Hoover dam
Describe a flood storage lake?
Water stored during winter, released during summer, more stable flow regime
What is a lotic body of water?
River
What is a lentic system?
Lake, standing water
How does velocity impact lakes?
Less significant than rivers
What is depth important for in rivers?
Light penetration and temperature regime
What are common in lakes over the year?
Seasonal patterns In temp
What kind of production is more prevalent?
Autochthonous, benthic algae and macro phytes
What is the upper warmer layer of the lake?
Epilimnion
What is the lower level of the lake called?
Hypolimnion
What is the separation called in the lake between the upper and lower parts of the lake?
Thermocline
Why is stratification important in the lake?
Nutrient cycling and oxygen availability
When does the thermocline form?
Summer
Why was lake Bala grounds for research in 1997?
Around summer stratification caused low oxygen at the lowest part of the lake
Which fish was endangered in Bala?
Gwyniad
What are limiting factors for plants in the lake?
Nutrients and light
Where does green algae production take place in the lake?
Top of the lake
Where does energy loss go into the lake?
Heat
Where does the major herbivore production take place?
Under the green algae layer, above carnivore layer
What is turbidity?
Light intercepted by suspended particles
Why would turbidity effect plankton growth?
Limits photosynthesis
What influences lake colour?
Dissolved substances eg humic acids in peaty waters
How can we measure light penetration?
Secchi disk, lower below water
What are oilgotrophic lakes?
Nutrient poor, low productivity, high transparency in the epilimnon high dissolved oxygen in the hypolimnon
What are eutrophic lakes?
Nutrient rich, high productivity, low transparency on the epilimnon, low dissolved oxygen
Where does meso trophic lakes sit between oilgotrophic and eutrophic?
In the middle
What are the producers in a lake?
Phytoplankton, littorella (shore weed), nuphar lutea
What animals and plants does the lake support?
Algae, macrophytes, zooplankton, benthic invertebrates, fish, birds, mammals
What adaptations do small invertebrates have to breathe underwater?
Breathing tubes
What can small phytoplankton do?
Float up and down in water, but change elevation
What is a classic lake fish?
Roach
What predators can be found in lakes?
Perch, pike, osprey and otter
What are the main consumers?
Pelagic and benthic invertebrates
What are the smaller lake invertebrates?
Cladocera, phantom midge larvae
What is a common hyaline adaptation for lake animals?
Very see through
What are normally the keystone species?
Fish
What is the keystone species of lake Bala?
Gwiniad, Lyn tegid
What does the gwyniad eat?
Plankton
Where is it common to get dominan species?
High latitudes or extreme conditions, one species adapts well
What limits growth in winter?
Chlorophyll lack of light
What happens to the lake in spring?
Plants use up all the nutrients, lots of chlorophyll
What is euphoric depth?
Within which photosynthesis is possible
What is littoral zone?
Lake bed where plants can grow
What is profundal zone?
Lake bed where there is no plant growth
How much light do phytoplankton need
At least 1%
