Aquatic EcologyAquatic Ecology

LimnologyLimnology- study of freshwater - study of freshwater ecosystemsecosystems

LenticLentic- standing water- standing water

LoticLotic- moving water- moving water

Lentic EcosystemsLentic Ecosystems

Depressions in land 1-Depressions in land 1-2,000 meters deep2,000 meters deep

In northern hemispheres, In northern hemispheres, glaciers left behind glaciers left behind carved out basins that carved out basins that filled with rain and snowfilled with rain and snow

Other causes include:Other causes include: Silt, driftwood and other Silt, driftwood and other

materials that block the materials that block the flow of streamsflow of streams

Streams that were flat get Streams that were flat get cut off to create “oxbows”cut off to create “oxbows”

Lentic EcosystemsLentic Ecosystems

Craters from extinct Craters from extinct volcanoes fill with volcanoes fill with waterwater

Lake FormationLake Formation

Many lakes are Many lakes are formed by one of two formed by one of two mammalsmammals

Humans- dam rivers Humans- dam rivers for power, irrigation, for power, irrigation, diggingdigging

Beavers- dam Beavers- dam streams to form streams to form shallow ponds or shallow ponds or lakeslakes

Lake LayersLake Layers

3 layers3 layers EpilimnionEpilimnion- “upper lake” - “upper lake”

consists of a free consists of a free circulating upper layercirculating upper layer

MetalimnionMetalimnion- also called - also called thermocline or “middle thermocline or “middle lake” has a rapid decline in lake” has a rapid decline in temperature (1 degree temperature (1 degree Celsius for every meter you Celsius for every meter you go down)go down)

HypolimnionHypolimnion- “lower lake” - “lower lake” is the deep, colder layeris the deep, colder layer

Lake StructureLake Structure Littoral zoneLittoral zone- shallow - shallow

water zone, light reaches water zone, light reaches the bottom and it usually the bottom and it usually has plantshas plants

EmergentsEmergents- plants - plants whose roots and stems whose roots and stems are in water but upper are in water but upper stems and leaves are out stems and leaves are out of the waterof the water

Limnetic or Pelagic zoneLimnetic or Pelagic zone- - open water, and has open water, and has

Plankton- suspended Plankton- suspended organismsorganisms

Nekton- free swimming Nekton- free swimming fishfish

Lake ZonesLake ZonesBenthic zoneBenthic zone- sediment on - sediment on bottom of lakes and pondsbottom of lakes and ponds

•Photic zonePhotic zone- where light - where light penetrates to the bottompenetrates to the bottom

•Aphotic zoneAphotic zone- under - under water area where light water area where light does not reachdoes not reach

•EutrophicEutrophic- nutrient rich- nutrient rich

•OligotrophicOligotrophic- nutrient poor- nutrient poor

•HypertrophicHypertrophic- excessive - excessive nutrientsnutrients

Lake TemperaturesLake Temperatures

Summer/SpringSummer/Spring

Water is warm on top Water is warm on top and cold on bottomand cold on bottom

Lake TemperaturesLake Temperatures

Fall/winterFall/winter Temperature on Temperature on

surface drops and surface drops and metalimnion sinksmetalimnion sinks

Epilimnion increases Epilimnion increases until all water is the until all water is the same temperature\same temperature\

Water circulates Water circulates oxygen and nutrientsoxygen and nutrients

OverturnOverturn- seasonal - seasonal mixing of watermixing of water

Water ChemistryWater Chemistry Dissolved Oxygen (DO)Dissolved Oxygen (DO) Enters the water through the atmosphere and Enters the water through the atmosphere and

photosynthesisphotosynthesis Amount of oxygen the water can hold depends Amount of oxygen the water can hold depends

on pressure, temperature, and salinityon pressure, temperature, and salinity Cold water holds more oxygen that warm waterCold water holds more oxygen that warm water As atmospheric pressure increases, so does the As atmospheric pressure increases, so does the

amount of oxygen in the wateramount of oxygen in the water Oxygen absorbed by the surface is mixed by Oxygen absorbed by the surface is mixed by

turbulence of internal currentsturbulence of internal currents Overturn replenishes oxygen in the waterOverturn replenishes oxygen in the water

Water ChemistryWater Chemistry

Carbon Dioxide Carbon Dioxide Carbon dioxide is usually the same Carbon dioxide is usually the same

concentration as that in the atmosphereconcentration as that in the atmosphere

Water ChemistryWater Chemistry pHpH A measure of the acidic or basic the water isA measure of the acidic or basic the water is On a scale of 1-14On a scale of 1-14 1 is very acidic and 14 is very basic1 is very acidic and 14 is very basic 7 is neutral7 is neutral

Freshwater 3-10Freshwater 3-10 Rainwater 5-6Rainwater 5-6 Streams and lakes 6.5-8.5Streams and lakes 6.5-8.5

Limestone under the water causes the pH to Limestone under the water causes the pH to increase increase

(or become more basic)(or become more basic)

Lotic EcosystemsLotic Ecosystems

Flowing water (rivers and streams)Flowing water (rivers and streams) Velocity and current decide most things Velocity and current decide most things

because it cuts channels and affects living because it cuts channels and affects living organismsorganisms

Velocity is determined by size, shape, Velocity is determined by size, shape, gradient of the channel, roughness of gradient of the channel, roughness of bottom, depth, and precipitationbottom, depth, and precipitation

StreamsStreams

May begin as outlets of ponds or lakes May begin as outlets of ponds or lakes Flow is determined by the lay of the land if Flow is determined by the lay of the land if

the stream has not been disturbedthe stream has not been disturbed As water flows, it picks up debris that As water flows, it picks up debris that

scrapes the bottom and makes the stream scrapes the bottom and makes the stream biggerbigger

TermsTerms

MeanderMeander- bends in streams (aka. Sinuosity) - bends in streams (aka. Sinuosity) WatershedWatershed- body of land where all runoff - body of land where all runoff

collects in a common body of watercollects in a common body of water TurbidityTurbidity- the amount of particles suspended in - the amount of particles suspended in

water prohibiting light to shine through water prohibiting light to shine through ChannelChannel- the stream bed and banks formed by - the stream bed and banks formed by

flowing water flowing water Flood PlainFlood Plain- a strip of land that is normally dry - a strip of land that is normally dry

and flat that is on the sides of a river or stream and flat that is on the sides of a river or stream and is wet during floods. and is wet during floods.

TermsTerms

Riparian ZoneRiparian Zone- the land and vegetation - the land and vegetation bordering flowing or standing waterbordering flowing or standing water

RiffleRiffle- a section of a stream where the water is - a section of a stream where the water is shallow, fast moving, and is broken into waves shallow, fast moving, and is broken into waves by an obstruction by an obstruction

SiltationSiltation- deposition of fine particles (silt) on the - deposition of fine particles (silt) on the beds of streams or lakes beds of streams or lakes

PoolsPools- water that is relatively deep- water that is relatively deep Bankfull WidthBankfull Width- where water will stop if it comes - where water will stop if it comes

out of the stream out of the stream

How can you tell if a stream is How can you tell if a stream is healthy?healthy?

Stream Quality is determined by Stream Quality is determined by 1.1. Area coverArea cover

Do things hang over the stream?Do things hang over the stream?

2.2. EmbeddednessEmbeddednessAre there dirt particles on the bottom?Are there dirt particles on the bottom?

3.3. DepthDepthIs the stream shallow or deep?Is the stream shallow or deep?

4.4. Sediment depositsSediment depositsAre there sediment build ups?Are there sediment build ups?

5.5. Channel flowChannel flowDoes water fill up the channel?Does water fill up the channel?

Stream quality continued…Stream quality continued…

6.6. Channel AlterationChannel AlterationHas concrete, rock, or anything else been added to Has concrete, rock, or anything else been added to the stream?the stream?

7.7. Frequency of riffles or bendsFrequency of riffles or bendsDoes the stream curve or have any white water?Does the stream curve or have any white water?

8.8. Bank stabilityBank stabilityAre the banks falling into the stream?Are the banks falling into the stream?

9.9. Vegetative Protection (on the banks)Vegetative Protection (on the banks)Are there plants growing on the banks?Are there plants growing on the banks?

10.10. Riparian zone widthRiparian zone widthHow big is the area on the bank where plants grow?How big is the area on the bank where plants grow?

Stream ChemistryStream Chemistry

pHpH• A range of 6-9 is ideal for running freshwater fish A range of 6-9 is ideal for running freshwater fish

and bottom dwelling invertebratesand bottom dwelling invertebrates• Synergistic EffectsSynergistic Effects

Happens when two things combine to Happens when two things combine to produce effects greater than their sumproduce effects greater than their sum

Example.) Pollutants can change the pH Example.) Pollutants can change the pH of a stream of a stream

Stream ChemistryStream Chemistry

Dissolved Oxygen (DO)Dissolved Oxygen (DO) If dissolved oxygen drops If dissolved oxygen drops

below 5 mg per liter, below 5 mg per liter, aquatic life is stressedaquatic life is stressed

The lower the The lower the concentration, the more concentration, the more stressstress

Levels below 1-2 mg per Levels below 1-2 mg per liter for a few hours result liter for a few hours result in “fish kills” in “fish kills”

Stream ChemistryStream Chemistry BOD (biochemical BOD (biochemical

oxygen demand)oxygen demand) The amount of oxygen The amount of oxygen

needed for decompositionneeded for decomposition If there is little oxygen, If there is little oxygen,

decomposers that use it decomposers that use it will diewill die

Too much oxygen causes Too much oxygen causes “gas bubble disease”“gas bubble disease”

Rare Rare • Oxygen blocks blood Oxygen blocks blood

vessels vessels • Can see bubbles on the Can see bubbles on the

fins and the skinfins and the skin

Stream OrdersStream Orders

Streams join together to form rivers. Each time Streams join together to form rivers. Each time one stream joins another “order” changes.one stream joins another “order” changes.

A first order stream is one that does not have A first order stream is one that does not have any other stream joining it.any other stream joining it.

A stream can only increase in order if a stream A stream can only increase in order if a stream of a similar order joins it. of a similar order joins it. For example, when a first order stream runs into For example, when a first order stream runs into

another first order stream, it becomes a second order another first order stream, it becomes a second order stream. Likewise, when two second order streams stream. Likewise, when two second order streams join each other, it becomes a third order stream and join each other, it becomes a third order stream and so on.so on.

Stream OrdersStream Orders

Order is not increased when a lower order Order is not increased when a lower order stream joins one of a larger order.stream joins one of a larger order.

Generally:Generally: First through third order streams are usually called First through third order streams are usually called

headwater streamsheadwater streams Fourth through sixth order streams are usually called Fourth through sixth order streams are usually called

medium-sized streamsmedium-sized streams Above sixth order, the streams become riversAbove sixth order, the streams become rivers

Lower order streams are usually on steep slopes Lower order streams are usually on steep slopes compared to higher order streamscompared to higher order streams

Higher order streams have flood plainsHigher order streams have flood plains

A A watershed watershed is a is a section of section of land where land where all the all the water water runoff runoff flows into flows into a common a common basin. basin.

Stream RestorationStream Restoration There are many aspects to There are many aspects to

stream restoration, but some stream restoration, but some suggestions would be:suggestions would be:

Decrease the slope of the Decrease the slope of the banks (if it will not compromise banks (if it will not compromise or eliminate the riparian zone)or eliminate the riparian zone). . This is generally This is generally accomplished by using a 3:1 accomplished by using a 3:1 ratio.Stream3 ft.1 ft.Bankratio.Stream3 ft.1 ft.Bank

• Reduces the stress on Reduces the stress on channel walls from flowing channel walls from flowing waterwater

• Becomes more stableBecomes more stable• Stops erosion and Stops erosion and

sedimentationsedimentation• Creates a surface for Creates a surface for

vegetationvegetation

Stream 3 ft.

1ft.Bank

Stream RestorationStream Restoration

Stabilize the Stream BanksStabilize the Stream Banks• Riparian ForestationRiparian Forestation

Plant native vegetation on the stream banks to stop Plant native vegetation on the stream banks to stop erosion. The roots of the plants will hold the soil onto the erosion. The roots of the plants will hold the soil onto the banks.banks.

• Add big structures to the banks like wood, stone, Add big structures to the banks like wood, stone, or fabric that will not wash away. Fabric provides a or fabric that will not wash away. Fabric provides a surface to hold planted vegetation.surface to hold planted vegetation.

• Drive posts into the bank to keep soil from eroding Drive posts into the bank to keep soil from eroding into the stream.into the stream.

• Make the channel bigger.Make the channel bigger.

Stream RestorationStream Restoration

Construct riffles and poolsConstruct riffles and pools• Adding large rocks and/or other materials from the Adding large rocks and/or other materials from the

site to the stream prevents natural areas from site to the stream prevents natural areas from being disturbed by trucks hauling rock to the being disturbed by trucks hauling rock to the stream.stream.

Allows more DO to enter the waterAllows more DO to enter the water Slows the velocity of flowing waterSlows the velocity of flowing water

• Before adding rock to the stream, organic matter Before adding rock to the stream, organic matter must be cleared from the bottom to be sure the must be cleared from the bottom to be sure the rock will be stable.rock will be stable.

• The rock must be lower than the bank.The rock must be lower than the bank.

Stream RestorationStream Restoration

Cut and FillCut and Fill• Widening the channel in a particular area to allow Widening the channel in a particular area to allow

water a larger surface to pass overwater a larger surface to pass over• If the channel has been cut very deep, the water If the channel has been cut very deep, the water

will not be able to get into the flood plain. By will not be able to get into the flood plain. By adding rock to the bottom of the channel, the water adding rock to the bottom of the channel, the water level is raised allowing it to reach the flood plain if level is raised allowing it to reach the flood plain if needed.needed.

Stream RestorationStream Restoration

Add a waterfallAdd a waterfall• Create a difference in elevation allowing the water Create a difference in elevation allowing the water

to fall. This will increase DO, slow the flow of the to fall. This will increase DO, slow the flow of the water, and create a habitat for aquatic life.water, and create a habitat for aquatic life.

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