aquatic ecology limnology- study of freshwater ecosystems lentic- standing water lotic- moving water
TRANSCRIPT
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.
Remove garbageRemove garbage