The EcosystemThe Ecosystem

An IntroductionAn Introduction

EcosystemEcosystem

A community of interdependent organisms and A community of interdependent organisms and the interactions with the physical environment the interactions with the physical environment in which they live.in which they live.

It can also be defined as the abiotic and biotic It can also be defined as the abiotic and biotic factors and the interactions between them.factors and the interactions between them.

The interaction between organisms and the The interaction between organisms and the environment is the key!environment is the key!

Abiotic and Biotic factorsAbiotic and Biotic factors

Biotic Factor: A living, biological factor that Biotic Factor: A living, biological factor that may influence an organism or a system.may influence an organism or a system.

Example: predation, disease, competitionExample: predation, disease, competition

Abiotic factor: A non-living, physical factor that Abiotic factor: A non-living, physical factor that may influence an organism or a systemmay influence an organism or a system

Examples: Temperature, salinity, pH, lightExamples: Temperature, salinity, pH, light

Differentiate between the Differentiate between the following terms:following terms:

OrganismOrganism SpeciesSpecies PopulationPopulation CommunityCommunity NicheNiche HabitatHabitat

In your notebook, draw a picture In your notebook, draw a picture of a bunch of little organismsof a bunch of little organisms

Label: The organisms of the same type Label: The organisms of the same type (species)(species)

Circle: individuals of the same species Circle: individuals of the same species (Population)(Population)

Draw interactions between the populations Draw interactions between the populations (Community)(Community)

Compare the terms habitat and Compare the terms habitat and nicheniche

Sometimes people confuse these terms.Sometimes people confuse these terms.

Figure out the differences between the terms.Figure out the differences between the terms.

Niche vs habitatNiche vs habitat

A habitat is where an organism lives. The habitat A habitat is where an organism lives. The habitat must provide a source of food, water and shelter must provide a source of food, water and shelter for the organism.for the organism.

Niche: The role of the organism. This is largely Niche: The role of the organism. This is largely to do with the trophic level of the organism. to do with the trophic level of the organism.

For example: plants produce food for the rest of For example: plants produce food for the rest of the food chain. Tigers keep herbivore the food chain. Tigers keep herbivore populations under control.populations under control.

Abiotic and Biotic factorsAbiotic and Biotic factors

Biotic Factor: A living, biological factor that Biotic Factor: A living, biological factor that may influence an organism or a system.may influence an organism or a system.

Example: predation, disease, competitionExample: predation, disease, competition

Abiotic factor: A non-living, physical factor that Abiotic factor: A non-living, physical factor that may influence an organism or a systemmay influence an organism or a system

Examples: Temperature, salinity, pH, lightExamples: Temperature, salinity, pH, light

Which factors are biotic?Which factors are biotic?

RabbitsRabbits CactiCacti Daylight hoursDaylight hours PrecipitationPrecipitation MossMoss Soil compositionSoil composition BacteriaBacteria

Limiting factorsLimiting factors

An abiotic factor can limit the population size if there An abiotic factor can limit the population size if there is too much or too little of it. Even if there is the is too much or too little of it. Even if there is the right amount of other factorsright amount of other factors

Examples to consider:Examples to consider:

SunlightSunlight

PrecipitationPrecipitation

SalinitySalinity

Nutrients in the soilNutrients in the soil

Trophic levelsTrophic levels

Ecostems are often broken up and described Ecostems are often broken up and described according to feeding relationships.according to feeding relationships.

Trophic level:Trophic level: The position of an organism in a food chainThe position of an organism in a food chain

A group of organisms that occupy the same A group of organisms that occupy the same place in a food chainplace in a food chain

Trophic levels in food chainsTrophic levels in food chains

Be able to give an example of each!Be able to give an example of each! Primary producers (autotrophs)Primary producers (autotrophs) Primary consumers (herbivores)Primary consumers (herbivores) Secondary consumers(carnivores)Secondary consumers(carnivores) Tertiary consumers (top carnivores)Tertiary consumers (top carnivores) DecomposersDecomposers DetrivoresDetrivores ScavengersScavengers

Energy flow and material cyclingEnergy flow and material cycling

ProducerAutotroph - “self” + “feed”An organism that obtains organic food

molecules without eating other organisms but by using energy from the sun or

inorganic molecules to make organic moleculesRemember: This trophic level supports all

of the othersThe role of producers is to convert energy into a form useable for other organisms

ProducersProducers

Most producers are photosynthetic (e.g. algae, mosses, diatoms, some bacteria, plants etc.) but some are chemosynthetic (e.g. hydrothermal vent bacteria)(H2)

DecomposerDecomposer

An organism that obtains energy by breaking down dead organic matter, including dead plants, dead animals and animal waste, into more simple substancesExamples include: bacteria and fungiInterconnects all trophic levels since the organic material making up all living organisms is eventually broken downRole of decomposers is to return valuable nutrients to the system so they can be used again

Compare detritus feeders to Compare detritus feeders to decomposers:decomposers:

ConsumerConsumer

Heterotroph - “other” + “feed”An organism that obtains its nutrition by eating other organismsPrimary consumer (herbivore) - eats producers e.g. sea urchin, copepodSecondary consumer (carnivore) - eats primary consumers e.g. wolf eel, herringTertiary consumer - eats secondary consumers e.g. sea otter, sealQuaternary consumer - eats tertiary consumers e.g. killer whale

ConsumersConsumers

The role of the consumer is to transfer energy The role of the consumer is to transfer energy from one trophic level to the next.from one trophic level to the next.

Notice that consumers have different names, Notice that consumers have different names, depending on what they eat:depending on what they eat:

Herbivores: plant eatersHerbivores: plant eaters Carnivores: meat eatersCarnivores: meat eaters Omnivores: eat plants and animalsOmnivores: eat plants and animals

Food ChainsFood Chains

Food websFood webs

Show energy flow through an ecosystem

An ecosystem’s trophic structure determines energy flow and nutrient cycling

Food Food webswebs

Trophic levelsTrophic levels

Pyramid of biomassPyramid of biomass

Second Law of ThermodynamicsSecond Law of Thermodynamics

There is a tendency for numbers and quantities of There is a tendency for numbers and quantities of biomass and energy to decrease along food chains.biomass and energy to decrease along food chains.

The pyramids become smaller at the top because The pyramids become smaller at the top because around 90% of the energy is “lost” between each around 90% of the energy is “lost” between each level and only 10% is available in the body of the level and only 10% is available in the body of the organism for transfer to the next level.organism for transfer to the next level.

Energy transfer in a food chain: Energy transfer in a food chain: First law of thermodynamicsFirst law of thermodynamics

The end!The end!