FLOW OF FLOW OF ENERGY AND ENERGY AND CYCLING OF CYCLING OF

MATTERMATTER

ECOSYSTEMS REQUIRE AN ENERGY SOURCEECOSYSTEMS REQUIRE AN ENERGY SOURCE An essential characteristic of every ecosystem is they An essential characteristic of every ecosystem is they

must have a continual input of energy.must have a continual input of energy.

Imagine the operation of a city with no energy supplies Imagine the operation of a city with no energy supplies (DISCUSS)(DISCUSS)

Energy is not recycled in an ecosystem and so therefore Energy is not recycled in an ecosystem and so therefore must continually be suppliedmust continually be supplied

The forms of energy that are particularly important in The forms of energy that are particularly important in ecosystems are:ecosystems are:- radiant energy of sunlight, and- radiant energy of sunlight, and- chemical energy stored in organic matter, ie: food- chemical energy stored in organic matter, ie: food

The energy source for almost all ecosystems is The energy source for almost all ecosystems is SUNLIGHT.SUNLIGHT.

ENERGYENERGY Energy is that which can change the motion, physical Energy is that which can change the motion, physical

composition or temperature of an object.composition or temperature of an object.

Energy can neither be created nor destroyed; it can only Energy can neither be created nor destroyed; it can only be transformed.be transformed.

Energy exists in various forms which can be grouped as Energy exists in various forms which can be grouped as follows:follows:

KINETIC ENERGYKINETIC ENERGY (movement/ motion) (movement/ motion)- ThermalThermal (heat): moving atoms or molecules (heat): moving atoms or molecules- ElectricalElectrical: movement of electrons: movement of electrons- MotionMotion: objects moving forward or rotating: objects moving forward or rotating- RadiantRadiant: radiation that moves in waves: radiation that moves in waves

Energy continued…Energy continued…

POTENTIAL ENERGYPOTENTIAL ENERGY (stored energy) (stored energy)- NuclearNuclear: stored in nucleus of an atom and : stored in nucleus of an atom and

release when split (fission) or combined (fusion)release when split (fission) or combined (fusion)- GravitationalGravitational: stored in objects because of : stored in objects because of

position, eg. A ball above groundposition, eg. A ball above ground- Stored mechanicalStored mechanical: objects under an applied : objects under an applied

forceforce- ChemicalChemical: stored in the bonds of molecules: stored in the bonds of molecules

When energy is changed from one form to When energy is changed from one form to another, some of the energy is dissipated (lost) another, some of the energy is dissipated (lost) at each step as less useful energy, usually in the at each step as less useful energy, usually in the form of heat.form of heat.

Energy continued…Energy continued… The energy input to an ecosystem is in the form of The energy input to an ecosystem is in the form of

radiant energy form sunlight.radiant energy form sunlight.

It is the It is the producerproducer organisms, such as plants, that capture organisms, such as plants, that capture the radiant energy and transform it to chemical energy the radiant energy and transform it to chemical energy stored in organic matter.stored in organic matter.

This organic matter is available both for the producer This organic matter is available both for the producer organisms themselves and also directly or indirectly for organisms themselves and also directly or indirectly for all consumer organisms in the living community of an all consumer organisms in the living community of an ecosystem.ecosystem.

The transfer of energy from one organism to another is The transfer of energy from one organism to another is easiest in chemical form rather than radiant. Consider easiest in chemical form rather than radiant. Consider putting light in a box compared to sugar in a bag.putting light in a box compared to sugar in a bag.

Energy continued…Energy continued… All animals (mammals, birds, reptiles and invertebrates) are All animals (mammals, birds, reptiles and invertebrates) are

consumersconsumers..

Consumers in an ecosystem can be classified in terms of the Consumers in an ecosystem can be classified in terms of the major source of their nutrition – major source of their nutrition – herbivoresherbivores, , carnivorescarnivores, , detritivoresdetritivores, , decomposersdecomposers, etc, etc

Consumers that mainly feed directly on producers are called Consumers that mainly feed directly on producers are called primary consumersprimary consumers..

Consumers that feed on primary consumers are called Consumers that feed on primary consumers are called secondary consumerssecondary consumers..

Consumers that feed on secondary consumers are called Consumers that feed on secondary consumers are called tertiary consumerstertiary consumers or top carnivores. or top carnivores.

Decomposers cannot be identified easily in terms of their Decomposers cannot be identified easily in terms of their major source of nutrition since they feed on the dead remains major source of nutrition since they feed on the dead remains of plants and animals.of plants and animals.

Energy continued…Energy continued… Organisms in an ecosystem can also be identified in terms of their Organisms in an ecosystem can also be identified in terms of their

‘feeding’ level or TROPHIC LEVEL.‘feeding’ level or TROPHIC LEVEL.

Starfish; small fish

Antechinus; owls

Eat plant-eaters

Secondary consumers

(carnivores)

THIRD

Large fish; sharks

Snakes; eagles

Eat predatorsTertiary consumers

(top carnivores)

FOURTH

Zooplankton; whelks

Plant-eating insects; small birds; possums

Eat plants or other producers

Primary consumers

(herbivores)

SECOND

Phytoplankton; algae

Trees and shrubs; grasses; ferns

Make own food from sunlight

ProducersFIRST

Aquatic ecosystem

(coastal sea)

Terrestrial ecosystem

(open forest)

Source of food

Organisms at that level

Trophic Level

ENERGY FLOW IN ECOSYSTEMSENERGY FLOW IN ECOSYSTEMS Energy input to an ecosystem is the Energy input to an ecosystem is the

radiant energy of sunlight that is radiant energy of sunlight that is transformed by producers into chemical transformed by producers into chemical energy stored in organic matter.energy stored in organic matter.

Energy is then transferred within an Energy is then transferred within an ecosystem through feeding activities.ecosystem through feeding activities.

At each transfer, however, some energy is At each transfer, however, some energy is ‘lost’ from the ecosystem as heat energy.‘lost’ from the ecosystem as heat energy.

Energy flow in ecosystems continued…Energy flow in ecosystems continued…PRODUCERSPRODUCERS Essential to trap radiant energy (RE) and convert it to Essential to trap radiant energy (RE) and convert it to

chemical energy (CE)chemical energy (CE)

Range from phytoplankton, algae in an aquatic Range from phytoplankton, algae in an aquatic ecosystem to grasses, shrubs and trees in a terrestrial ecosystem to grasses, shrubs and trees in a terrestrial ecosystemecosystem

Different types of produces trap different wavelengths Different types of produces trap different wavelengths of light. Most trap blue and red ends of the spectrumof light. Most trap blue and red ends of the spectrum

RE to CE is through the process of photosynthesisRE to CE is through the process of photosynthesis

End products are glucose and oxygen but intermediate End products are glucose and oxygen but intermediate products differ and depends on whether plants are C3 products differ and depends on whether plants are C3 or C4 plantsor C4 plants

Energy flow in ecosystems continued…Energy flow in ecosystems continued…

NOT ALL RE which falls on the leaf is NOT ALL RE which falls on the leaf is converted to CE:converted to CE:

Of 100 units of REOf 100 units of RE 50 units cannot be used by producers50 units cannot be used by producers 5 units reflected off leaf5 units reflected off leaf 5 units travel through the leaf5 units travel through the leaf 40 units absorbed by chloroplasts40 units absorbed by chloroplasts

Of the 40 units absorbed by the chloroplasts:Of the 40 units absorbed by the chloroplasts: 30 units are lost as heat energy30 units are lost as heat energy 10 10 units of RE only are converted to CE units of RE only are converted to CE

(Glucose)(Glucose)

Energy flow in ecosystems continued…Energy flow in ecosystems continued… Producers use some of the glucose made in Producers use some of the glucose made in

photosynthesis for their own energy requiring photosynthesis for their own energy requiring process – RESPIRATIONprocess – RESPIRATION

The rest of the carbohydrate is stored as starch The rest of the carbohydrate is stored as starch and is available to consumers as “Food”. The and is available to consumers as “Food”. The amount available is known as amount available is known as net primary net primary productionproduction

Therefore in ecosystems where there are few Therefore in ecosystems where there are few producers (e.g. deserts) there is a decrease in producers (e.g. deserts) there is a decrease in primary productionprimary production

WHY?? - WHY?? - Low H2O supply, therefore low Low H2O supply, therefore low photosynthesis, low CEphotosynthesis, low CEie. Limiting factor of the desert ecosystemie. Limiting factor of the desert ecosystem

Energy flow in ecosystems continued…Energy flow in ecosystems continued… Some producers do not use RE but trap the Some producers do not use RE but trap the

energy released from chemical reactions e.g. energy released from chemical reactions e.g. Sulfur Bacteria (Sulfur Bacteria (ThiobacillusThiobacillus ssp) – ssp) – CHEMOSYNTHETIC. CHEMOSYNTHETIC.

They carry out two coupled reactions:They carry out two coupled reactions:SulphideSulphide + + oxygenoxygen sulfatesulfate

EnergyEnergy

CarbonCarbon + water + water carbon-richcarbon-rich DioxideDioxide organic matterorganic matter

No Producers = No Energy Input = No Food No Producers = No Energy Input = No Food Production = Death of ConsumersProduction = Death of Consumers

Energy flow in ecosystems continued…Energy flow in ecosystems continued…

CONSUMERSCONSUMERS It is estimated that, of RE they capture and transform to It is estimated that, of RE they capture and transform to

CE, producer organisms use between 15-70% for their CE, producer organisms use between 15-70% for their own maintenance (ie. c/f Uni- and Multicellular)own maintenance (ie. c/f Uni- and Multicellular)

Only part of the chemical energy taken in by a herbivore Only part of the chemical energy taken in by a herbivore is available to flow on to carnivores (see next slide)is available to flow on to carnivores (see next slide)

The energy converted to new tissue is the only CE The energy converted to new tissue is the only CE available for transfer to the next trophic levelavailable for transfer to the next trophic level

Mammals & birds retain less CE in their tissues than Mammals & birds retain less CE in their tissues than insects because they use energy to maintain a constant insects because they use energy to maintain a constant body temperature. This is achieved by a high rate of body temperature. This is achieved by a high rate of respirationrespiration

Energy flow in ecosystems continued…Energy flow in ecosystems continued…

R = 39 (Heat Loss)R = 39 (Heat Loss)

FE = 100 UnitsFE = 100 Units

(Food Eaten)(Food Eaten)

P = 1 (New Tissue)P = 1 (New Tissue) E = 60 E = 60

(Wastes)(Wastes)

Energy flow in ecosystems continued…Energy flow in ecosystems continued… So, of the small percentage of energy a So, of the small percentage of energy a

consumer receives from a producer, only one consumer receives from a producer, only one percent is stored in the muscle and other percent is stored in the muscle and other tissues.tissues.

Where does the ‘lost’ energy go?Where does the ‘lost’ energy go?

Some is used by the consumer for the energy-Some is used by the consumer for the energy-requiring processes that are part of being alive. requiring processes that are part of being alive. Eg. muscle contraction, active transport and Eg. muscle contraction, active transport and most important, to maintain body temperature.most important, to maintain body temperature.

Some is lost as organic matter in faeces, urine Some is lost as organic matter in faeces, urine and tissue that the consumer egests, excretes or and tissue that the consumer egests, excretes or loses. Eg. wastes, dead skin cells, etcloses. Eg. wastes, dead skin cells, etc

Energy flow in ecosystems continued…Energy flow in ecosystems continued…

Ecologists ‘Rule-of-thumb’Ecologists ‘Rule-of-thumb’ For the transfer of energy between tropic levels, ecologists For the transfer of energy between tropic levels, ecologists

use the 10-per-centrule.use the 10-per-centrule.

ie. About 10% of energy going into one trophic level is ie. About 10% of energy going into one trophic level is available for transfer to the next trophic level in the form of available for transfer to the next trophic level in the form of organic matterorganic matter in tissues for in tissues for tissue productiontissue production..

Complete the following for 100g of plant materialComplete the following for 100g of plant material

SUNSUN PLANTPLANT CATERPILLARCATERPILLAR SPIDERSPIDER

MATERIALMATERIAL

Energy flow in ecosystems continued…Energy flow in ecosystems continued…Several important conclusions arise from the fact that Several important conclusions arise from the fact that

energy is lost as heat energy at each transfer in an energy is lost as heat energy at each transfer in an ecosystem:ecosystem:

3.3. The number of trophic levels in an ecosystem is The number of trophic levels in an ecosystem is normally limited to three (there are exceptions)normally limited to three (there are exceptions)

5.5. The higher the trophic level of the organism the The higher the trophic level of the organism the greater the cost of the production of the organic matter greater the cost of the production of the organic matter i.e. organic matter in a carnivore requires more energy i.e. organic matter in a carnivore requires more energy to produce than that of a herbivoreto produce than that of a herbivore- compare a human population supported on cereal - compare a human population supported on cereal crops grown on a given area of land than supported on crops grown on a given area of land than supported on beef from cattle reared on the same area of landbeef from cattle reared on the same area of land

8.8. Energy must be continually supplied to an ecosystem. Energy must be continually supplied to an ecosystem. It is not recycledIt is not recycled

SHOWING ENERGY TRANSFERSSHOWING ENERGY TRANSFERS 2 Interactions occur:2 Interactions occur:

- Flow of energy through ecosystem- Flow of energy through ecosystem- The cycling of matter within an ecosystem- The cycling of matter within an ecosystem

Energy enters most ecosystems as RE. This is Energy enters most ecosystems as RE. This is converted to chemical energy by producers, and is in the converted to chemical energy by producers, and is in the form of starch, cellulose, protein, glucose and lipids. form of starch, cellulose, protein, glucose and lipids. Consumers eat this CE and some of these units of CE Consumers eat this CE and some of these units of CE are retained in their body structureare retained in their body structure

FOOD CHAINSFOOD CHAINS and and FOOD WEBSFOOD WEBS show the energy show the energy transfers or transfers or energy flowenergy flow in an ecosystem by indicating in an ecosystem by indicating who eats whom.who eats whom.

In food chains and webs, arrows show the direction of In food chains and webs, arrows show the direction of energy flow, but not the amounts of CE at each transfer.energy flow, but not the amounts of CE at each transfer.

FOOD CHAINSFOOD CHAINS

Food Chains (FC) show:Food Chains (FC) show:1. The energy flow through an ecosystem – “one 1. The energy flow through an ecosystem – “one way” transfer of energyway” transfer of energy2. Feeding relationships2. Feeding relationships3. Only one part of a FOODWEB3. Only one part of a FOODWEB

Food chains continued…Food chains continued… Food chains have some limitations in the imparting Food chains have some limitations in the imparting

of knowledge of feeding relationships.of knowledge of feeding relationships.- suggests an organism obtains CE from single source- suggests an organism obtains CE from single source

- suggests an organism occupies the same position in energy flow- suggests an organism occupies the same position in energy flow- suggests CE flow is only from one certain organism to another- suggests CE flow is only from one certain organism to another- do not show energy flow from dead organisms- do not show energy flow from dead organisms

Food chains always start with a PRODUCER, which Food chains always start with a PRODUCER, which converts inorganic into organic compoundsconverts inorganic into organic compounds

RERE GrassGrass WallabyWallaby EagleEagle CE CE CECE CE CE

Producer Producer PrimaryPrimary SecondarySecondaryConsumerConsumer ConsumerConsumer

Food chains continued…Food chains continued… Consumers can be classified according to their diet e.g. Consumers can be classified according to their diet e.g.

herbivores, carnivores, detritivores, omnivoresherbivores, carnivores, detritivores, omnivores

Size of organism usually increases as we move along a Size of organism usually increases as we move along a food chain. i.e. the bigger organism kills the smallerfood chain. i.e. the bigger organism kills the smaller

The population of the first order consumer (primary The population of the first order consumer (primary consumer) is much greater than that of the tertiary consumer) is much greater than that of the tertiary consumer. This is because:consumer. This is because: They have many more predatorsThey have many more predators Each predator consumes many of the primary consumersEach predator consumes many of the primary consumers

Top order consumers (predator) have a very small Top order consumers (predator) have a very small population e.g. 1 pair of eagles in an entire communitypopulation e.g. 1 pair of eagles in an entire community

The flow of energy into a lower trophic level (feeding The flow of energy into a lower trophic level (feeding level) is greater than the flow to the next trophic level.level) is greater than the flow to the next trophic level.

WHY?? Because energy is LOST as it moves along a FCWHY?? Because energy is LOST as it moves along a FC

FOOD WEBSFOOD WEBS Illustrate all the feeding Illustrate all the feeding

relationships within an relationships within an ecosystemecosystem

Organisms with a number of Organisms with a number of different food sources is fairly different food sources is fairly securesecure

Those dependant on only one Those dependant on only one or two food sources are more or two food sources are more vulnerable to any changesvulnerable to any changes

An organism may be An organism may be considered a secondary or considered a secondary or tertiary consumer depending on tertiary consumer depending on which food chain is being which food chain is being observed within the food webobserved within the food web

ECOLOGICAL PYRAMIDSECOLOGICAL PYRAMIDS1. PYRAMID OF NUMBERS1. PYRAMID OF NUMBERS Shows the number of organisms at each level per unit area of an Shows the number of organisms at each level per unit area of an

ecosystem. Can be inverted when the producers are much larger ecosystem. Can be inverted when the producers are much larger than the consumers, eg. Each tree can support thousands of than the consumers, eg. Each tree can support thousands of consumersconsumers

Draw and example of a Pyramid of Numbers (p. 453).Draw and example of a Pyramid of Numbers (p. 453).

GRASSLANDGRASSLAND WOODLANDWOODLAND

Ecological pyramids continued…Ecological pyramids continued…

2. PYRAMID OF BIOMASS2. PYRAMID OF BIOMASS Records the total DRY ORGANIC matter of organisms (biomass) at Records the total DRY ORGANIC matter of organisms (biomass) at

each trophic level in a given area of an ecosystem. Can be inverted each trophic level in a given area of an ecosystem. Can be inverted if the producers are short-lived and the biomass is measured over a if the producers are short-lived and the biomass is measured over a short period.short period.

Draw and example of a Pyramid of Biomass (p. 454).Draw and example of a Pyramid of Biomass (p. 454).

GRASSLANDGRASSLAND OCEANOCEAN

Ecological pyramids continued…Ecological pyramids continued…3. PYRAMID OF ENERGY3. PYRAMID OF ENERGY Shows the amount of energy input to each trophic level in a given Shows the amount of energy input to each trophic level in a given

area of an ecosystem. CANNOT BE INVERTED.area of an ecosystem. CANNOT BE INVERTED.

Draw and example of a Pyramid of Energy (p.454).Draw and example of a Pyramid of Energy (p.454).

RIVER ECOSYSTEMRIVER ECOSYSTEM

CYCLES WITHIN ECOSYSTEMSCYCLES WITHIN ECOSYSTEMS Unlike energy, Unlike energy, mattermatter cycles within any ecosystem cycles within any ecosystem

and is reused.and is reused.

Detritivores and decomposers (eg. Fungi and some Detritivores and decomposers (eg. Fungi and some bacteria) are important in the recycling of matter. bacteria) are important in the recycling of matter.

They convert organic matter into simple inorganic They convert organic matter into simple inorganic matter that can be taken up by producers and rebuilt matter that can be taken up by producers and rebuilt into new organic matter.into new organic matter.

Biogeochemical cyclesBiogeochemical cycles – the cycling of carbon, – the cycling of carbon, nitrogen and phosphorusnitrogen and phosphorus chemical – cycling of a chemical elementchemical – cycling of a chemical element bio – for some of the cycle, the element is in organismsbio – for some of the cycle, the element is in organisms geo – for some of the cycle the element is present in non-living geo – for some of the cycle the element is present in non-living

parts (eg. Rocks)parts (eg. Rocks)

CARBON CYCLECARBON CYCLE

Carbon cycle continued…Carbon cycle continued… Carbon atoms are recycled through the living Carbon atoms are recycled through the living

and non-living parts of an ecosystem.and non-living parts of an ecosystem.

Producers take up CO2 and build this into Producers take up CO2 and build this into organic molecules (sugars).organic molecules (sugars).

This organic matter is passed to consumers This organic matter is passed to consumers along the chain with some carbon atoms being along the chain with some carbon atoms being released as inorganic CO2 during cellular released as inorganic CO2 during cellular respirationrespiration

Decomposers play an important role in this cycle Decomposers play an important role in this cycle by releasing the carbon from dead organic by releasing the carbon from dead organic matter back into the atmosphere via CO2.matter back into the atmosphere via CO2.

The Nitrogen CycleAtmospheric

nitrogen

Atmosphericfixation

and deposition

Animalmanures

and biosolids

Industrial fixation(commercial fertilizers)

Crop harvest

Volatilization

Denitrification

Runoff anderosion

Leaching

Organicnitrogen

Ammonium(NH4)

Nitrate(NO3)

Plant residues

Biologicalfixation by

legume plants Plantuptake

Immobilization

Immobilization

Mineralization

Mineralization

Input to soilComponent Loss from soil

-+

Nitrogen cycle continued…Nitrogen cycle continued… Nitrogen atoms can be present in inorganic matter such as:Nitrogen atoms can be present in inorganic matter such as:

Nitrogen gas in the atmosphereNitrogen gas in the atmosphere Nitrate, nitrite and ammonium ions in the soil and waterNitrate, nitrite and ammonium ions in the soil and water

Nitrogen atoms are also present inorganic matter, mainly in:Nitrogen atoms are also present inorganic matter, mainly in: Proteins and amino acids of living thingsProteins and amino acids of living things Waste products, such as ureaWaste products, such as urea

Different kinds of bacteria contribute to the cycling of nitrogenDifferent kinds of bacteria contribute to the cycling of nitrogen

Convert organic nitrogen to inorganic form

Decomposer bacteria

Convert nitrates and nitrites to gaseous nitrogen

Denitrifying bacteria

Oxidise ammonium ions to produce nitrates (NO3-) and nitrites (NO2-)

Nitrifying bacteria

Convert atmospheric nitrogen (N2) to ammonium ions (NH4+)

Nitrogen-fixing bacteria

ROLE IN NITROGEN CYCLEBACTERIA

BIOACCUMULATIONBIOACCUMULATION If chemical pollutants enter the soil, water or air If chemical pollutants enter the soil, water or air

in an ecosystem the chemical may enter the in an ecosystem the chemical may enter the food chain. food chain.

If it is not readily broken down by the organism If it is not readily broken down by the organism (NON-BIODEGADABLE = PERISTENT) then it (NON-BIODEGADABLE = PERISTENT) then it will become more concentrated in organisms in will become more concentrated in organisms in higher trophic levels – higher trophic levels – Biological MagnificationBiological Magnification or or BioaccumulationBioaccumulation

Some persistent chemicals are Dieldren, DDT, Some persistent chemicals are Dieldren, DDT, hexachlorobenzenehexachlorobenzene

Bioaccumulation continued…Bioaccumulation continued…