Energy Flow in Energy Flow in EcosystemsEcosystems

Environmental ScienceEnvironmental Science

Life Depends on the SunLife Depends on the Sun

Energy enters an ecosystem when a plant uses Energy enters an ecosystem when a plant uses sunlight to make sugar (carbohydrates)sunlight to make sugar (carbohydrates)

This process is called This process is called photosynthesisphotosynthesis

CO2 + H2O + energy C6H12O6 + O2

Plants, algae, and some bacteria use sunlight, Plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce sugar and carbon dioxide, and water to produce sugar and oxygen.oxygen.

ProducersProducers Sunlight is the ultimate source of energy for Sunlight is the ultimate source of energy for

most life on earthmost life on earth Organisms that convert sunlight into chemical Organisms that convert sunlight into chemical

energy are called energy are called producersproducers Also called Also called autotrophsautotrophs OR OR chemotrophschemotrophs

Chemotrophs the exceptionChemotrophs the exceptionto the rule – they are found at to the rule – they are found at the bottom of the ocean where the bottom of the ocean where no sunlight reachesno sunlight reaches Bacteria use hydrogen sulfide toBacteria use hydrogen sulfide tocreate energycreate energy Other organisms feed off the bacteriaOther organisms feed off the bacteria

ConsumersConsumers

Organisms that consume Organisms that consume

other organisms for energy other organisms for energy

are are consumersconsumers ((heterotrophs)heterotrophs) Types of heterotrophsTypes of heterotrophs

HerbivoresHerbivores – eat only – eat only

producersproducers CarnivoresCarnivores – eat only other – eat only other

consumersconsumers OmnivoresOmnivores – eat producers and consumers – eat producers and consumers

More consumers…More consumers…

DetrivoresDetrivores – also – also called scavengerscalled scavengers Eat animal remains Eat animal remains

and other dead matterand other dead matter

DecomposersDecomposers - - break down organic break down organic matter matter Include bacteria and Include bacteria and

some fungussome fungus

Cellular RespriationCellular Respriation

The process in which cells use sugar to create The process in which cells use sugar to create energy is called energy is called cellular respirationcellular respiration

C6H12O6 + O2 CO2 + H2O + energy

Cells use glucose (sugar) and oxygen to Cells use glucose (sugar) and oxygen to produce carbon dioxide, water, and energy.produce carbon dioxide, water, and energy.

Cellular respiration occurs inside the cells of most organisms

Energy TransferEnergy Transfer Each time one Each time one

organism eats organism eats another, energy is another, energy is transferredtransferred

Food chainsFood chains Show one-way flow of Show one-way flow of

energy in an energy in an ecosystemecosystem

Each step on the food Each step on the food chain is called a chain is called a trophic leveltrophic level

Feeding RelationshipsFeeding Relationships

Food websFood webs Includes more Includes more

organisms and organisms and multiple food multiple food chains linked chains linked togethertogether

Trophic LevelsTrophic Levels

Visualization of the Visualization of the loss of energy from loss of energy from one trophic level to one trophic level to the nextthe next

Often shown as an Often shown as an pyramidpyramid Shows relative energy Shows relative energy

movement in an movement in an ecosystemecosystem

Only 10% of the Only 10% of the energy moves to the energy moves to the next levelnext level

BiomagnificationBiomagnification

Pollution can lead to Pollution can lead to biomagnificationbiomagnification – – the concentration of toxic substances in the concentration of toxic substances in organisms as you move up trophic levelsorganisms as you move up trophic levels

Ex. DDT and birds of prey; mercury in tuna Ex. DDT and birds of prey; mercury in tuna and sharksand sharks