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1、水域生态学英文第1页，本讲稿共31页Lentic EcosystemsDepressions in land 1-2,000 Depressions in land 1-2,000 meters deepmeters deepIn northern hemispheres,In northern hemispheres,glaciers left behind carved out glaciers left behind carved out basins that filled with rain and basins that filled with rain and snowsnowO
2、ther causes include:Other causes include:l lSilt,driftwood and other Silt,driftwood and other materials that block the flow materials that block the flow of streamsof streamsl lStreams that were flat get cut Streams that were flat get cut off to create“oxbows”off to create“oxbows”第2页，本讲稿共31页Lentic E
3、cosystemsCraters from extinct Craters from extinct volcanoes fill with volcanoes fill with waterwater第3页，本讲稿共31页Lake FormationMany lakes are Many lakes are formed by one of two formed by one of two mammalsmammalsHumans-dam rivers Humans-dam rivers for power,irrigation,for power,irrigation,diggingdig
4、gingBeavers-dam Beavers-dam streams to form streams to form shallow ponds or shallow ponds or lakeslakes第4页，本讲稿共31页Lake Layers3 layers3 layersl lEpilimnionEpilimnion-“upper lake”-“upper lake”consists of a free circulating consists of a free circulating upper layerupper layerl lMetalimnionMetalimnion
5、-also called-also called thermocline or“middle lake”has thermocline or“middle lake”has a rapid decline in temperature a rapid decline in temperature(1 degree Celsius for every(1 degree Celsius for every meter you go down)meter you go down)l lHypolimnionHypolimnion-“lower lake”is-“lower lake”is the d
6、eep,colder layerthe deep,colder layer第5页，本讲稿共31页Lake StructureLittoral zoneLittoral zone-shallow water-shallow water zone,light reaches the bottom zone,light reaches the bottom and it usually has plantsand it usually has plantsEmergentsEmergents-plants whose-plants whose roots and stems are in roots
7、 and stems are in water but upper stems and water but upper stems and leaves are out of the waterleaves are out of the waterLimnetic or Pelagic zoneLimnetic or Pelagic zone-open water,and has open water,and has l lPlankton-suspended organismsPlankton-suspended organismsl lNekton-free swimming fishNe
8、kton-free swimming fish第6页，本讲稿共31页Lake 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
9、water area where light does not reachdoes not reach EutrophicEutrophic-nutrient rich-nutrient rich OligotrophicOligotrophic-nutrient-nutrient poorpoor HypertrophicHypertrophic-excessive-excessive nutrientsnutrients第7页，本讲稿共31页Lake TemperaturesSummer/SpringSummer/Springl lWater is warm on top Water is
10、 warm on top and cold on bottomand cold on bottom第8页，本讲稿共31页Lake TemperaturesFall/winterFall/winterl lTemperature on Temperature on surface drops and surface drops and metalimnion sinksmetalimnion sinksl lEpilimnion increases Epilimnion increases until all water is the until all water is the same te
11、mperaturesame temperaturel lWater circulates Water circulates oxygen and nutrientsoxygen and nutrientsl lOverturnOverturn-seasonal-seasonal mixing of watermixing of water第9页，本讲稿共31页Water ChemistryDissolved Oxygen(DO)Dissolved Oxygen(DO)Enters the water through the atmosphere and Enters the water thr
12、ough the atmosphere and photosynthesisphotosynthesisAmount of oxygen the water can hold depends on Amount of oxygen the water can hold depends on pressure,temperature,and salinitypressure,temperature,and salinityCold water holds more oxygen that warm waterCold water holds more oxygen that warm water
13、As atmospheric pressure increases,so does the As atmospheric pressure increases,so does the amount of oxygen in the wateramount of oxygen in the waterOxygen absorbed by the surface is mixed by turbulence Oxygen absorbed by the surface is mixed by turbulence of internal currentsof internal currentsOv
14、erturn replenishes oxygen in the waterOverturn replenishes oxygen in the water第10页，本讲稿共31页Water ChemistryCarbon Dioxide Carbon dioxide is usually the same concentration as that in the atmosphere第11页，本讲稿共31页Water ChemistrypHpHA measure of the acidic or basic the water isA measure of the acidic or bas
15、ic the water isOn a scale of 1-14On a scale of 1-141 is very acidic and 14 is very basic1 is very acidic and 14 is very basic7 is neutral7 is neutrall lFreshwater 3-10Freshwater 3-10l lRainwater 5-6Rainwater 5-6l lStreams and lakes 6.5-8.5Streams and lakes 6.5-8.5Limestone under the water causes the
16、 pH to Limestone under the water causes the pH to increase increase(or become more basic)(or become more basic)第12页，本讲稿共31页Lotic EcosystemsFlowing water(rivers and streams)Velocity and current decide most things because it cuts channels and affects living organismsVelocity is determined by size,shap
17、e,gradient of the channel,roughness of bottom,depth,and precipitation第13页，本讲稿共31页StreamsMay begin as outlets of ponds or lakes Flow is determined by the lay of the land if the stream has not been disturbedAs water flows,it picks up debris that scrapes the bottom and makes the stream bigger第14页，本讲稿共3
18、1页TermsMeanderMeander-bends in streams(aka.Sinuosity)-bends in streams(aka.Sinuosity)WatershedWatershed-body of land where all runoff collects in a-body of land where all runoff collects in a common body of watercommon body of waterTurbidityTurbidity-the amount of particles suspended in water-the am
19、ount of particles suspended in water prohibiting light to shine through prohibiting light to shine through ChannelChannel-the stream bed and banks formed by flowing-the stream bed and banks formed by flowing water water Flood PlainFlood Plain-a strip of land that is normally dry and-a strip of land
20、that is normally dry and flat that is on the sides of a river or stream and is flat that is on the sides of a river or stream and is wet during floods.wet during floods.第15页，本讲稿共31页TermsRiparian ZoneRiparian Zone-the land and vegetation bordering-the land and vegetation bordering flowing or standing
21、 waterflowing or standing waterRiffleRiffle-a section of a stream where the water is shallow,-a section of a stream where the water is shallow,fast moving,and is broken into waves by an obstruction fast moving,and is broken into waves by an obstruction SiltationSiltation-deposition of fine particles
22、(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 deepBankfull WidthBankfull Width-where water will stop if it comes out of-where water will stop if it comes out of the stream the
23、stream 第16页，本讲稿共31页How can you tell if a stream is healthy?Stream Quality is determined by Stream Quality is determined by 1.1.Area coverArea coverDo things hang over the stream?Do things hang over the stream?2.2.EmbeddednessEmbeddednessAre there dirt particles on the bottom?Are there dirt particles
24、 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?第17页，本讲稿共31页Stream qualit
25、y continued6.6.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
26、 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 zo
27、ne widthRiparian zone widthHow big is the area on the bank where plants grow?How big is the area on the bank where plants grow?第18页，本讲稿共31页第19页，本讲稿共31页Stream ChemistrypH 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 invert
28、ebratesand bottom dwelling invertebrates Synergistic EffectsSynergistic EffectsHappens when two things combine to produce effects greater than their sumExample.)Pollutants can change the pH of a stream 第20页，本讲稿共31页Stream ChemistryDissolved Oxygen(DO)Dissolved Oxygen(DO)If dissolved oxygen drops If d
29、issolved oxygen drops below 5 mg per liter,aquatic below 5 mg per liter,aquatic life is stressedlife is stressedThe lower the concentration,The lower the concentration,the more stressthe more stressLevels below 1-2 mg per liter Levels below 1-2 mg per liter for a few hours result in“fish for a few h
30、ours result in“fish kills”kills”第21页，本讲稿共31页Stream ChemistryBOD(biochemical oxygen BOD(biochemical oxygen demand)demand)l lThe amount of oxygen needed The amount of oxygen needed for decompositionfor decompositionl lIf there is little oxygen,If there is little oxygen,decomposers that use it will dec
31、omposers that use it will diediel lToo much oxygen causes Too much oxygen causes“gas bubble disease”“gas bubble disease”l lRare Rare Oxygen blocks blood Oxygen blocks blood vessels vessels Can see bubbles on the fins and Can see bubbles on the fins and the skinthe skin第22页，本讲稿共31页第23页，本讲稿共31页Stream
32、OrdersStreams join together to form rivers.Each time one Streams join together to form rivers.Each time one stream joins another“order”changes.stream joins another“order”changes.A first order stream is one that does not have any A first order stream is one that does not have any other stream joining
33、 it.other stream joining it.A stream can only increase in order if a stream of a A stream can only increase in order if a stream of a similar order joins it.similar order joins it.l lFor example,when a first order stream runs into another first For example,when a first order stream runs into another
34、 first order stream,it becomes a second order stream.Likewise,order stream,it becomes a second order stream.Likewise,when two second order streams join each other,it becomes a when two second order streams join each other,it becomes a third order stream and so on.third order stream and so on.第24页，本讲
35、稿共31页Stream OrdersOrder is not increased when a lower order stream Order is not increased when a lower order stream joins one of a larger order.joins one of a larger order.Generally:Generally:l lFirst through third order streams are usually called First through third order streams are usually called
36、 headwater streamsheadwater streamsl lFourth through sixth order streams are usually called Fourth through sixth order streams are usually called medium-sized streamsmedium-sized streamsl lAbove sixth order,the streams become riversAbove sixth order,the streams become riversLower order streams are u
37、sually on steep slopes Lower order streams are usually on steep slopes compared to higher order streamscompared to higher order streamsHigher order streams have flood plainsHigher order streams have flood plains第25页，本讲稿共31页A A watershed watershed is a is a section of section of land where land where
38、 all the all the water water runoff runoff flows into flows into a common a common basin.basin.第26页，本讲稿共31页Stream RestorationThere are many aspects to stream There are many aspects to stream restoration,but some suggestions restoration,but some suggestions would be:would be:l lDecrease the slope of
39、the banks Decrease the slope of the banks(if it will not compromise or(if it will not compromise or eliminate the riparian zone)eliminate the riparian zone).This This is generally accomplished by is generally accomplished by using a 3:1 ratio.Stream3 ft.1 using a 3:1 ratio.Stream3 ft.1 ft.Bankft.Ban
40、k Reduces the stress on channel walls Reduces the stress on channel walls from flowing waterfrom flowing water Becomes more stableBecomes more stable Stops erosion and Stops erosion and sedimentationsedimentation Creates a surface for Creates a surface for vegetationvegetation Stream3 ft.1ft.Bank第27
41、页，本讲稿共31页Stream Restorationl lStabilize the Stream BanksStabilize the Stream Banks Riparian ForestationRiparian Forestationl lPlant 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.Th
42、e 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.sur
43、face 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.第28页，本讲稿共31页Stream Restorationl lConstruct riffles and poolsConstruct riffles and po
44、ols 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.s
45、tream.l lAllows more DO to enter the waterAllows more DO to enter the waterl lSlows 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
46、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.第29页，本讲稿共31页Stream Restorationl lCut and FillCut and Fill Widening the channel in a particular area to allow Widening the channel in a particular a
47、rea 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 botto
48、m 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.第30页，本讲稿共31页Stream Restorationl lAdd a waterfallAdd a waterfall Create a difference in elevation
49、 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.l lRemove garbageRemove garbage 第31页，本讲稿共31页