limnology exam 3 Flashcards
3 legal criteria used to define wetlands
1) water saturation: frequent or prolonged presence of water at or near the soil surface
2) Vegetation: adapted to wet/waterlogged soils
- is there vegetation present? have they adapted
ex: hydrophytes- there’s a federal list of species
3) presence of hydric soil
- soils presently soaked with water develop certain chemicals
- >waterlogged (saturated)
- >anoxic, high in organic matter content
wetland classificaitons based on vegitation
- emergent wetlands
- forested wetlands
- scrub/shrub wetlands
- shallow water/pond wetlands
emergent wetlands
plants have roots in water, but stems and leaves growing out of water-emerging out of water
- dominated by grasses, sedges, rushes, forbs (non-woody)
- marshes, wet meadows, fens
forested wetlands
trees present, saturated soils= swaps
scrub/shrub wetlands
oftern border a lake or stream
lots of shrubs, plants
have a little bit of everything
shallow water/pond wetlands
aquatic macrophytes present
hydrology based categorization of wetlands
fens
bogs
swamps/marshes
fens
mostly fed by groundwater
bogs
mostly precipitation fed
swamps/marshes
fed mostly by surface flow (streams, rivers, floodplains, beaver ponds)
Wetland functions
- Habitat-biodiversity hotspots
- flood attenuation
- Water quality
Wetland function: Biodiversity hotspots
Wetlands have lots of biodiversity
difficult to generalize
provide habitat for ducks- fish and wildlife habitat nursery
3/4 of WI wildlife species are dependent on wetlands
>1/3 of US threatened and endangered species live only on wetlands
so they are considered biodiversity hotspots
Wetland function: flood attenuation
wetlands are places to store water
act like a sponge
water enters quickly (during a flood) but leaves slowly
Wetlands function: water quality
1) reduce water velocity
2) Wetlands plants take up nutrients
3) waterlogged soil effects
4)Overall wetland effect on nutrients
5) Other consequences of waterlogged soils:
decomp slows
organic carbon
1) reduce water velocity
-> so sediments settle out
good for fish
good for P levels as P sticks to sediment particles, so P enters wetlands and may not leave
2) Wetlands plants take up nutrients
2) Wetlands plants take up nutrients- so no excess nutrients go into the environments
3)waterlogged soil effects:
in normal soils, soil particles + air pockets = lots of O2 all the way through the soil
but water logged soils are anoxic
waterlogging eliminates O2 form the soil, so therefore hydric soils are often anoxic
so usually in waterlogged soils, O2 is gone within millimeters
effects: No O2 -> Denitrification (NO3- -> N2 gas) eliminate nitrate from the soil
therefore wetlands prevent dead zones
Overall wetland effect on nutrients
wetlands can reduce (but not eliminate) sediments, excess nutrients
other waterlogged soils
water logging slows microbial respiration
Organic C + O2 -> CO2 + H2O
no O2 so different microbes present so less decomposition and so organic matter accumulates which is why these soils are so rich in organic matter
i.e they have a carbon storage function
Peat= partially decayed plant material
-about 40% of terrestrial C is stored in peat soils-
predominantlyy in N. America and Eurasia= arctic places
important for locking away carbon
-wetlands can have diverse plants Ex: sphagnum moss which stores for long periods of time, makes environment acidic, important for agriculture
-peat-> millions of years to coal
-arctic permafrost thaw: thaws so locked up C going back into Circulation
-Boreal peatland flow: burning organic C -> turns it into CO2
Channel form reflects a balance between?
channel form reflects a balance between
1, sediment inputs
2. channel slope-building dams changes this
3. the river’s hydrology
Stream and river habitat
water column:since there is a current= unidirctional fow
benthic zone: upper, well oxygenated sediment layer
hyporheic zone: mixing zone between stream water and groundwater. meet and miz below the benthic zone
riparian zone/floodplain: terrestrial-aquatic interface
Discharge
Q, units: m^3/s
volume of water passing through a channel cross-section per unit time
Q=V x A
Hydrograph
graph of discharge over time
Q vs time
Habitat
water column: since there is a current= directional flow
-benthic zone: upper well oxygenated sediment layer
hyporheic zone: mixing zone between stream water + groundwater meet and mix-below benthic zone
riparian zone/floodplain: terrestrial-aquatic interference
flow regime
-characteristic discharge pattern of a river over time: magnitude, frequency, duration, timing, rate of change
-reflects regional climate, geology, and human alterations to rivers
-can be used to identify determinants of stream community composition
-also used to access extent of human alteration
>change in flow regimes over time
ex: Illinios river- dam built, coal mining so they stabilized the river, and developed farm land around it
Temperature in stream and rivers
no thermal stratification- stream and rivers are well mixed
have greater thermal variation than in lakes
variation affected by
-stream order
-groundwater inputs
small streams are in forests so shaded, and as stream size increases, less thermal buffering/inputs from groundwater
light in streams and rivers
2 controls:
- surrounding conditions: trees, canyons, banks
- water characteristics: depth, suspended and dissolved material
Small streams (light)
can either recieve lots of light or very little light based on geography and season- streams in desert get lots of light, but strea0ms in forest recieve little light
for shallow stream, light can reach bottom
Large rivers (light)
recieve lots of light due to open canopy
light rarely reaches bottom
water in large rivers usually turbid (cloudy, thick with suspended material)
not a lot of benthic communities present, present mostly near top
chemical condtions
-vertical stratification is rare
DO- rivers are well mixed so DO generally very high
>due to big air/water interface
>mixing due to turbulent water flow
-some exceptions,O2 problems in streams below sewege outfalls
steams that are slow, warm also have DO problems
-Hyporheic zones often have low O2- so different chemical reactions happen here
Biota in rivers
-major force of driving evolution of lotic organisms= adapting to flowing water
-such as: maintaining position, surviving flow extremes (flooding and drying), eating
-Some adaptations to flow:
>staying put: hooks, claws, suction cups, balast, body shape- to deal with oncoming flow
>taking advantage of flow: filter feeders- very common among benthic invertebrates ex: hawaiian gobi- crawl up waterfalls
Biota in small-medium stream
shallow, physically variable, may have lots of light
- no plankton! benthic organisms dominate, periphyton (FW organisms that cling to plants or other organisms)
- lots of macroinvertebrates also present
- small fish present
large rivers biota
deep, turbid water, range of flow velocities
-plankton develop since eep
benthic invertebrates-restricted to lateral areas as in lakes, on sides in shallow areas
big fish present ex: paddle fish, lake sturgeon spawn in river
reservoirs distribution and abundance
20% of global anual runoff is stored in revervoirs
everywhere and lots-3 years worth of rain/water can be stored in some reservoirs
between 1/3 to 1/2 watersystems are severely impacted by reservoir
over 3500 dams in WI
mostly built for farming and livestock
reservoir types
1) flow modification
-run of river
-flood control
-hydropower
-water supply, recreation
most reservoirs are multi-purpose
2) outflow types
- epilimnetic release
- hypolimentic release
- adjustable release
- size
Flow modification reservoir
run of the river
flow regime not different from when its coming in and going out
Flow modification reservoir
flood control
capture high flows and hold them back, release water during low flows
Flow modification reservoir
hydropower
most common reasons- vary in affecting river flow, release water when energy is needed- daily fluctuations
Flow modification reservoir
recreation, irrigation
to make water available when and where it is needed- watering lawns etc
Outflow type reservoir: epilimnetic release
pulling out water from the top
“run of the river”
Outflow type reservoir:
hypolimnetic release
pull water out from the bottom
Outflow type reservoir:
adjustable release
pull water from the top or bottomw or middle of river
Outflow type reservoir: size
small->large->pharonic (huge)
reservoir zones
-riverine zone
transitional zone
lacustrine zone
riverine zone
water slowing down as depth increases, still has a current
transitional zone
depth increases, velocity slows, loss of flow,
downstream
sediment begins to deposit, water begins to clear
most sediment drops ou or gets deposited in this zone
lacustrine zone
looks more like a lake, stratification, anoxia develops, no flow, clear water
primary productivity in rservoirs
age effects: howold the reservoir is
new ones have a trophic upsurge and high production, lots of algae grwoth
occurs since high nutruesnt from the decomposition of terrestrial material that has been flooded
then occurs the trophic depression: a later decline in productivity
-old reservoirs often are eutrophic, especially smaller reservoirs
Light, N&P, NEP (net ecosystem production) for riverine, transitional, lacustrine zones
light:
- riverine: low (lots of sediments)
- transitional: ,oderate (dropping sediment)
- lacustrine: high (all sediment sropped)
N&P
riverine: high (because new material beng brought in)
transitional: moderate
lacustrin: low
Net ecosystem production:
riverine: variable, moderate
transitional: high
lacustrin: low (often oligotrophic)
Cumulative effects of having reservoirs
fragmentatin: breaks up habitat
biodiversity: declines in migratory fish, mussels, riparin plant diversity, point of establishment for invasives
geomorphology: delta, beach erosion, starving some places of sediment
hydrology: redistribution of surface water
chemistry: reservoir surfaces a major source of greenhouse gases- not really a very clean energy
Lake Wingra flow
1/3 water comes from precipitation, 1/3 surface flow, 1/3 ground water
high surface outflow
Lake mendota flow
big inputs from river, very little from groundwater, some precidpitation
low surface outflow
Unsaturated zone
water is held tightly by cappilary force- water adheres to soil particles andiair pockets
lots of water=all air spaces filled = less o2
saturated zone
ground water- completely filled up air spaces between soil particles
water table
depth to saturated zone
small near permanent water bodies
depth fluctuations over time due to: changes in recharge, withdrawl, evapotranspiration
aquifer
a geological formation through which groundwater can move/store and be extracted
some rocks types are better at storing water and easier to extract from ex: sand
harder: clay
cone of depression
a local draw down of groundwater where lots of pumping occurs
occurs due to urbanization
ogallala aquifer
great plains aquifer
feeds agriculture- removig water thats been out of circulation and utting it bac into circulation- will not retur so not sustainable
highland lake
lowland lake
seepage lake
drainage lake
highland lake:hgh precipitation inputs
lowland lake: low precip, high groundwater inputs, conductivity increases, chlorophyl a increases=more productive lakes, number of species also increases
seepage lake: no streams coing in or out
drainage lake: has connections, streams in and out
effects of groungwater inputs
seepage flux: groundater discharges into lake, seepage increases which causes algae to increase
nitrates are high in groundwater to gw can fertilize algae
algal mats indicate where groundwater emerges from
groundwater and fish
spawning: dying salmon release fish eggs- fish eggs need enough o2 and cold water= allows to find location of groundwater discharge
desert ish: oxygen
build nests in areas of gw recharge
as groundwater does not have O2, and surface water provides O2 rich water to eggs
land use/ land cover LULC
identified by plant cover and land use by people
conditions favoring a strong effect of LULC on surface water body
1 Surface water: LULC will have strong effects if surface water inputs are big contributer
- water body size: and for small water basins- lots of land, not so much water
