Energy Flow Through Energy Flow Through an Ecosysteman Ecosystem

Levels of Ecological OrganizationLevels of Ecological Organization

Energy flows through these levelsEnergy flows through these levels

Species: Species: similar organisms that can similar organisms that can produce fertile offspring.produce fertile offspring.

◊ Populations: individuals that are of the same species and live together

Levels of Organization

Q: When does a population grow?Q: When does a population grow? A: When more individuals grow than A: When more individuals grow than

die die r(rate of growth)=birth rate – death rater(rate of growth)=birth rate – death rate

Communities: Communities: Different populations Different populations that live together in an areathat live together in an area

Ecosystems: Ecosystems: All the biotic All the biotic andand abiotic factors of an area.abiotic factors of an area.

Give an example of a population, community and ecosystem at ETHS

Q: Within an ecosystem, can there be Q: Within an ecosystem, can there be unlimited growth of a population? Why or unlimited growth of a population? Why or Why not?Why not?

A: No, there are not unlimited resources A: No, there are not unlimited resources and wastes accumulateand wastes accumulate

Carrying capacityCarrying capacity:The population size that :The population size that an environment can sustainan environment can sustain

Energy Flow Through an EcosystemEnergy Flow Through an Ecosystem ThermodynamicsThermodynamics:: the study of energy the study of energy

transformationstransformations Law 1: Energy can be transferred and Law 1: Energy can be transferred and

changed but it CANNOT be created nor changed but it CANNOT be created nor destroyed.destroyed.

Energy only flows through an ecosystem in Energy only flows through an ecosystem in one direction, from the sun or inorganic one direction, from the sun or inorganic compounds to compounds to autotrophsautotrophs (producers) and (producers) and then to various then to various heterotrophsheterotrophs (consumers) (consumers)

Sunlight is the main energy source for life Sunlight is the main energy source for life on Earthon Earth

Inorganic compounds (minerals) can also be Inorganic compounds (minerals) can also be energy sources (deep ocean)energy sources (deep ocean)

Trophic LevelTrophic Level:: classification of an classification of an organism based on their source of organism based on their source of energyenergy– Energy flows through the different levels Energy flows through the different levels

of an ecosystemof an ecosystem

1st Trophic Level-- 1st Trophic Level-- ProducersProducers Can harness energy directly from their Can harness energy directly from their

physical environment (sun)physical environment (sun) Transform this energy into chemical Transform this energy into chemical

energy energy used as food, combine or break down used as food, combine or break down

molecules, make cells…molecules, make cells…

Called Called autotrophsautotrophs because they can because they can make their own foodmake their own food

Examples: plants, bacteria and some Examples: plants, bacteria and some algaealgae

2nd Trophic Level -- 2nd Trophic Level -- ConsumersConsumers: :

Organisms that rely on other Organisms that rely on other organisms for chemical energyorganisms for chemical energy

Cannot harness energy directly from Cannot harness energy directly from their physical environmenttheir physical environment

Called Called heterotrophsheterotrophs because they because they cannot make their own foodcannot make their own food

Examples: animals, fungi, many Examples: animals, fungi, many bacteriabacteria

Q: Do all consumers eat the same Q: Do all consumers eat the same thing?thing?

HerbivoresHerbivores::

Energy source comes from eating Energy source comes from eating only producersonly producers

Also called Also called primary consumersprimary consumers Examples: cows, caterpillars, ducks, Examples: cows, caterpillars, ducks,

deerdeer

3rd Trophic Level-- 3rd Trophic Level-- secondary secondary consumersconsumers

Organisms whose energy source Organisms whose energy source comes from other consumerscomes from other consumers

Divided into two groupsDivided into two groups– OmnivoresOmnivores– CarnivoresCarnivores

OmnivoresOmnivores:: Eat both consumers and producersEat both consumers and producers Examples: bears, crows, humansExamples: bears, crows, humans

CarnivoresCarnivores:: Only eat other consumers Only eat other consumers Considered “meat eaters”Considered “meat eaters” Examples: tigers, snakes, owls, dogsExamples: tigers, snakes, owls, dogs

4th Trophic Level -- 4th Trophic Level -- Top CarnivoresTop Carnivores

Carnivores that consume other Carnivores that consume other carnivorescarnivores

Example: a hawk that eats a snakeExample: a hawk that eats a snake

Detritivores and Detritivores and DecomposersDecomposers::

Consumers whose energy source Consumers whose energy source comes from waste and dead bodies comes from waste and dead bodies from organisms of all trophic levelsfrom organisms of all trophic levels

Cause decay or the break down of Cause decay or the break down of moleculesmolecules

Examples: scavengers, bacteria, Examples: scavengers, bacteria, fungifungi

Q: Why are detritivores and Q: Why are detritivores and decomposers useful?decomposers useful?

Food ChainFood Chain:: Shows only one path Shows only one path of energy flowof energy flow

Food Web:Food Web: Shows multiple paths of Shows multiple paths of energy flowenergy flow

Q: What happens to the energy?Q: What happens to the energy?

1.1. Some is stored in the body used Some is stored in the body used later for things like growthlater for things like growth

2.2. Some is lost in wasteSome is lost in waste– what the body can’t digest or already has what the body can’t digest or already has

enough ofenough of

3.3. Most leaves as heatMost leaves as heat4.4. Only about 10% of available Only about 10% of available

energy is actually transferred energy is actually transferred from one trophic level to the nextfrom one trophic level to the next– as you go up in trophic levels, the as you go up in trophic levels, the

amount of useable energy goes down amount of useable energy goes down

Energy PyramidEnergy Pyramid

Producers (450,000 cal)

Primary Consumers (45,000 cal)

Secondary Consumers (4,500 cal)

Top Consumers (450 cal)

One calorie = the amount of energy needed to raise the temp of 1g (1mL) water 1ºC

Energy is lost

Energy pyramids are NOT drawn Energy pyramids are NOT drawn based on the # of organisms at that based on the # of organisms at that levellevel

Energy pyramids ARE drawn based Energy pyramids ARE drawn based on biomass and amount of available on biomass and amount of available energy at that levelenergy at that level

Biomass = total amount of living Biomass = total amount of living tissue, usually referring to what can tissue, usually referring to what can be used as fuel.be used as fuel.– The producers level usually has the The producers level usually has the

most biomassmost biomass