Energy Energy TransferTransfer

Food chains, Food Food chains, Food Webs, and Trophic Webs, and Trophic

LevelsLevels

Energy flowEnergy flow

Solar energySolar energy

ProducersProducers

Consumers Consumers

Producers/ AutotrophsProducers/ Autotrophs

•Organisms that can make their Organisms that can make their own food.own food.–Ex. Green plants, some Ex. Green plants, some protists, algae, and bacteriaprotists, algae, and bacteria

–Add biomass to an ecosystem.Add biomass to an ecosystem.

•BiomassBiomass: the organic material : the organic material produced in an ecosystemproduced in an ecosystem

Consumers/ HeterotrophsConsumers/ Heterotrophs

•Organisms that consume Organisms that consume organic molecules made by organic molecules made by other organisms.other organisms.

•HerbivoresHerbivores: eat producers: eat producers

•CarnivoresCarnivores: eat other consumers : eat other consumers

•OmnivoresOmnivores: eat producers and: eat producers andconsumersconsumers

Food ChainFood Chain

•A A single pathwaysingle pathway of the of the feeding relationships in feeding relationships in an ecosystem that an ecosystem that results in results in energy energy transfertransfer..

For ExampleFor Example• Primary producerPrimary producer

• Primary consumerPrimary consumer

• Secondary Secondary consumerconsumer

• Tertiary consumerTertiary consumer

• Quaternary Quaternary consumerconsumer

•FlowersFlowers

•CricketCricket

•MouseMouse

•SnakeSnake

•EagleEagle

Eagle Mouse CricketFlowers

Snake

Food WebFood Web

•The feeding relationships The feeding relationships usually are more usually are more complexcomplex because organisms feed on because organisms feed on more than one type of food.more than one type of food.

•The The interrelated food chainsinterrelated food chains in an ecosystem.in an ecosystem.

rabbit

eagle

fox snakemous

ecricketgras

s

Trophic LevelsTrophic Levels

•An organism’s position in the An organism’s position in the sequence of energy transfers.sequence of energy transfers.

•Producers: Producers: 11stst trophic level trophic level

•Herbivores: Herbivores: 22ndnd trophic level trophic level

•Carnivores: Carnivores: 33rdrd & 4 & 4thth trophic trophic levelslevels

10% Rule10% Rule

•Energy is stored in each Energy is stored in each trophic level in the biomasstrophic level in the biomass

•Generally, only 10% of the Generally, only 10% of the energy available at one energy available at one trophictrophic level is level is transferredtransferred to the next.to the next.

•Most is lost because:Most is lost because: –not all organisms of a trophic level are not all organisms of a trophic level are eateneaten, ,

–not all not all moleculesmolecules of the prey can be of the prey can be used,used,

–energy used by prey in energy used by prey in cell respirationcell respiration is not available to the consumer,is not available to the consumer,

–heatheat energy is always lost in energy energy is always lost in energy transfertransfer

Energy pyramidEnergy pyramid

•Greatest amount of biomass Greatest amount of biomass and energy found in the and energy found in the lowestlowest trophic level and decreases as trophic level and decreases as it goes up.it goes up.

•Energy limits how many levels, Energy limits how many levels, usually usually 3-43-4 trophic levels. trophic levels.

What happens to the What happens to the biomass?biomass?

•Decomposers:Decomposers: consumers that consumers that cause cause decaydecay and break down and break down complexcomplex molecules into molecules into simplersimpler molecules.molecules.

•Makes molecules available for Makes molecules available for producers to use. This producers to use. This recyclesrecycles the chemical nutrients.the chemical nutrients.

•Energy is NOT Energy is NOT recycledrecycled..

What happens when What happens when humans destroy habitats or humans destroy habitats or over hunt populations?over hunt populations?•Accelerates rate of Accelerates rate of extinction extinction

•Decreases Decreases biodiversitybiodiversity..

•NegativelyNegatively impacts other impacts other species because they species because they interact with each other.interact with each other.

For example: For example: fisheriesfisheries

•Almost 70% of fisheries Almost 70% of fisheries are exploited.are exploited.

•Compared to 1950’s, the Compared to 1950’s, the population of big predatory population of big predatory fish, like tuna, has declined fish, like tuna, has declined 90%.90%.

•Tuna are large predatory Tuna are large predatory fish. How do you think fish. How do you think overfishing effects the overfishing effects the marine communities?marine communities?

Think!Think!

1.1.Generally, what costs Generally, what costs more, vegetables or more, vegetables or meat? Why?meat? Why?

2.2.Why don’t we farm Why don’t we farm carnivores, like bears or carnivores, like bears or wolves?wolves?

BiogeochemicBiogeochemical Cyclesal Cycles

Forms of CarbonForms of Carbon

•COCO22 in atmosphere and in atmosphere and dissolved in waterdissolved in water

•Carbonate in limestoneCarbonate in limestone

•Organic moleculesOrganic molecules

Forms of OxygenForms of Oxygen

•As oxygen gas in: As oxygen gas in: atmosphereatmosphere and and

dissolved in waterdissolved in water

Carbon and Oxygen Carbon and Oxygen CycleCycle1.1.Carbon fixationCarbon fixation

(photosynthesis):(photosynthesis): COCO22 is taken from is taken from atmosphere and put atmosphere and put into organic molecules, into organic molecules, while Owhile O2 2 is released.is released.

2.2.Carbon molecules are Carbon molecules are passed through the passed through the food food webweb..

3.3.DecompositionDecomposition: when : when organic molecules break organic molecules break down, COdown, CO22 is released into is released into atmosphere, and some atmosphere, and some carbon becomes fossil fuels.carbon becomes fossil fuels.

4.4.Cellular RespirationCellular Respiration:: COCO22 is released into is released into atmosphere as Oatmosphere as O22 is is removed.removed.

5.5.CombustionCombustion: Burning : Burning organic matter and fossil organic matter and fossil fuels uses Ofuels uses O22 and releases and releases COCO22

What happens when What happens when we burn lots of fossil we burn lots of fossil fuels?fuels?•Global warming?!Global warming?!

•Greenhouse gases: Greenhouse gases: COCO22, methane, water , methane, water vaporvapor

Greenhouse effect:Greenhouse effect:

1.1.LightLight energy passes through energy passes through atmosphere and is absorbed by atmosphere and is absorbed by earth, earth,

2.2.InfraredInfrared radiation (heat) energy radiation (heat) energy is reflected back to is reflected back to atmosphereatmosphere, ,

3.3.Greenhouse gasesGreenhouse gases trap and trap and reflect IR radiation back to reflect IR radiation back to Earth.Earth.

Effects of Global WarmingEffects of Global Warming•Changes ecosystems, especially Changes ecosystems, especially

in sensitive polar regions:in sensitive polar regions:–MeltingMelting of polar ice caps and of polar ice caps and glaciers, sea levels glaciers, sea levels risingrising..

–Changing habitat effecting Changing habitat effecting polar bears, penguinspolar bears, penguins

•Prediction for changes in Prediction for changes in rainfallrainfall, more , more severe stormssevere storms..

Water cycleWater cycle

•Availability of water is Availability of water is critical to life.critical to life.

Water on EarthWater on Earth

•Oceans & seas – 96.5%Oceans & seas – 96.5%

•Groundwater – 1.7%Groundwater – 1.7%

•Lakes, rivers, swamps – < 0.1%Lakes, rivers, swamps – < 0.1%

•Atmosphere – 0.001%Atmosphere – 0.001%

•Biological – 0.0001%Biological – 0.0001%

Water cycle:Water cycle:

• the movement of water the movement of water between these various between these various reservoirs. reservoirs.

1.1.Evaporation-Evaporation- water vapor water vapor added to the atmosphere added to the atmosphere from bodies of water.from bodies of water.

2.2.TranspirationTranspiration – water – water evaporates from leaves of evaporates from leaves of plants.plants.

3.3.PrecipitationPrecipitation – water condenses – water condenses and leaves atmosphere.and leaves atmosphere.

4.4.Runoff-Runoff- water that falls on land water that falls on land eventually flows into rivers and eventually flows into rivers and back to the ocean.back to the ocean.

5.5.Percolation-Percolation- water filters through water filters through the soil and reaches the the soil and reaches the groundwater table.groundwater table.

Acid rainAcid rain•Burning fuels releases oxides Burning fuels releases oxides

into the air: into the air: nitrogennitrogen oxide, oxide, sulfursulfur oxide. oxide.

•Combines with Combines with water vaporwater vapor and form and form acidsacids..

•Carried through the Carried through the water water cyclecycle..

•Changes in environmental pH Changes in environmental pH levels is damaging to levels is damaging to wildlifewildlife..

Forms of NitrogenForms of Nitrogen•Nitrogen is used in Nitrogen is used in organisms to make organisms to make proteinsproteins and and nucleic acidsnucleic acids..

•NN2 2 gasgas makes up 78% of makes up 78% of atmosphere.atmosphere.

•PlantsPlants cannot use N cannot use N22 gas. gas.

1.1.Nitrogen fixation-Nitrogen fixation- converting Nconverting N2 2 gas into gas into useable nitrate (NOuseable nitrate (NO33) )

2.2.Nitrogen-fixing bacteria- Nitrogen-fixing bacteria- convert convert NN2 2 to to NONO33

• Live in soil, or in roots of Live in soil, or in roots of certain plants in a certain plants in a __________ relationship.__________ relationship.

Nitrogen CycleNitrogen Cycle

mutualisticmutualistic

3.3.PlantsPlants can absorb can absorb nitrates. nitrates. AnimalsAnimals must must consume nitrogen.consume nitrogen.a.a. Organisms produce Organisms produce

nitrogen wastenitrogen waste in urine and in urine and dung. dung.

b.b.Bodies of dead organisms Bodies of dead organisms contain contain nitrogennitrogen..

4.4.AmmonificationAmmonification: Decomposers : Decomposers break down material and break down material and release ammonium (NHrelease ammonium (NH44))

5.5.NitrificationNitrification: soil bacteria : soil bacteria convert NHconvert NH44 into nitrates. into nitrates.

6.6.DenitrificationDenitrification: anaerobic : anaerobic bacteria break down nitrates bacteria break down nitrates and release nitrogen into the and release nitrogen into the atmosphere.atmosphere.

Other Human impactOther Human impact

•Human activity has had Human activity has had many effects on the many effects on the natural balancenatural balance in the in the ecosystems.ecosystems.

SustainabilitySustainability

•Human activity is Human activity is unsustainableunsustainable by the by the ecosystem when we use ecosystem when we use moremore than the ecosystem than the ecosystem can can replenishreplenish..

Renewable resourcesRenewable resources

•Rate that the resource is Rate that the resource is replenished by nature is replenished by nature is fasterfaster than it is used up. than it is used up.

•Example: Example: land, forests, land, forests, air, freshwaterair, freshwater

Non-renewable Non-renewable resourceresource

•rate that the resource is rate that the resource is replenished by nature is replenished by nature is slowerslower than it is used up. than it is used up.

•For example: For example: fossil fuelsfossil fuels

PollutionPollution

•Substances added into Substances added into the the air, water, air, water, or or soilsoil by by human activity that human activity that causes harm.causes harm.

Ozone depletionOzone depletion•Ozone (OOzone (O33) in the ) in the stratospherestratosphere

absorbs absorbs UV raysUV rays from the sun. from the sun.

•Chlorofluorocarbons (CFCs): Chlorofluorocarbons (CFCs): gases used in refrigerator gases used in refrigerator coolantcoolant, aerosol cans, and , aerosol cans, and manufacturing of plastic-foam.manufacturing of plastic-foam.

•CFCs CFCs catalyzecatalyze chain reactions chain reactions that break down that break down ozoneozone (O (O33).).

Ozone depletionOzone depletion•Ozone (OOzone (O33) in the ) in the stratospherestratosphere

absorbs absorbs UV raysUV rays from the sun. from the sun.

•Chlorofluorocarbons (CFCs): Chlorofluorocarbons (CFCs): gases used in refrigerator gases used in refrigerator coolantcoolant, aerosol cans, and , aerosol cans, and manufacturing of plastic-foam.manufacturing of plastic-foam.

•CFCs CFCs catalyzecatalyze chain reactions chain reactions that break down that break down ozoneozone (O (O33).).

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Ozone hole historyOzone hole history•1956: first measurements 1956: first measurements

of ozone in of ozone in AntarcticaAntarctica •1985: first paper published 1985: first paper published

on the on the declinedecline of ozone of ozone level in Antarcticalevel in Antarctica

Ozone hole cont.Ozone hole cont.•MeasurementsMeasurements of ozone of ozone

levels showed a steady levels showed a steady decline.decline.

•1987: 1987: Montreal ProtocolMontreal Protocol banned CFCs by 1995banned CFCs by 1995

•20502050: ozone will be : ozone will be restoredrestored