spring 2008. lentic is describe as standing water habitats inland depressions that hold water range...
TRANSCRIPT
Spring 2008
Lentic is describe as standing water habitats
Inland depressions that hold waterRange from 1 meter to 2000 metersFormation
Glacial RetreatCutting of the valley Oxbow Lakes Building of damsVolcanic Crater
Lentic systems may be formed by two mammalsBeavers
Dammed streams to make shallow but extensive ponds
HumansCreate artificial lakes by damming rivers and
streamsUsed for power, irrigation, and water storageCan also be used for water, fishing and wildlifeUnion Canal (Stovers, Lions Lake, Strikes Dam)
Quarries to fill in
Because of high specific heat, lentic ecosystems do not experience sharp daily temperature changesResults in seasonal stratification of the systemEach season change brings about changes in
the system
Epilimnion - upper, warm layerGreek for “upper layer”
Metalimnion - middle layer - layer of changeAlso known as ThermoclineRapid decrease in temperature as
descending in depth1°C per meter in depth
Hypolimnion - bottom laterColdest layer (4°C)Cut off from air above
Stratification breaks down during fall and spring called overturn
When fall begins, upper layer become coolerWhen it gets cooler than lower level, it falls
Due to increase density of the waterLower level is lifted up
Brings nutrients from benthic (bottom)Nutrients are evenly distributed in the system,
creating high productivity
As water becomes cooler than 4° C, water becomes lighter
In the spring… water heats above 4°C, and become denseFalls to bottom surface
Slightest winds can cause circulation
Overturn creates uniform dispersal of nutrients
Increase plant growthIncreases productivity of a system
Why would fish spawn in the spring, and fatten up for winter in the fall?
In air, oxygen is rarely limitedIn water, oxygen is limited or excessive
At saturation, dissolved oxygen becomes problematic and meager
Organisms are dependent on oxygen levelsTrout must have high oxygen, which is a
correlation with temperature
Absorption from atmospherePhotosynthesis - produces 7x amount of
oxygen need for respiration of plantsAt night, plants respire!
Amount of oxygen is dependent on:Temperature - lower temperature, increase
oxygenPressure - more force to keep oxygen in solutionSalinity - increase salinity decreases oxygen
levelsHence why marine organisms breed in brackish water
(mixing of fresh and salt water) because of higher oxygen concentration for mating and nursery Also nutrients
Oxygen levels are stratified based on temperature and photosynthetic levelsIn the summer, increase of oxygen near the
surface due to increase photosynthesisOxygen reaches lower level during turn over or if
light penetrates
Carbon dioxide dissolved in water creates Carbonic AcidLow concentration is held as an acid due to gas
lawsOther Forms: carbonate and bicarbonates
Formation of Carbonic AcidCO2 + H2 <--> H2CO3
H2CO3 <--> HCO3- + H+
HCO3 <--> H+ + CO32-
Amount of acid need to free CO2Gauge of buffering capacity of the carbonate
- CO2 equilibrium Seawater and hard water (increase and
high pH) are high bufferspH levels
Freshwater varies = 3 to 10Rainwater = 5-6Usual Range - 6.5-8.5
Low as 3.5 in seasonal (later summer)
Calcium Carbonate helps with buffering high pH Lebanon Valley is a limestone valley with a
pH around 8.0 to 8.5