Ecosystems and Energy Flow

Energy Transfer Primary producers

• the trophic level that supports all others

• autotrophs Primary consumers

• herbivores Secondary/ tertiary/

quaternary consumers• carnivores

Detrivores/decomposers• special consumers that derive

nutrition from non-living organic matter

Decomposers

Break down/recycle organic matter

Fungi Bacteria Some

invertebrates (worms, etc)

Productivity Primary productivity- amount of light energy converted to chemical

energy by autotrophs• Gross (GPP): total energy • Net (NPP): represents the storage of energy available to consumers

• R: energy used for respiration

NPP = GPP - R Biomass: primary productivity reflected as dry weight of organic

material Secondary productivity: the rate at which an ecosystem's

consumers convert chemical energy of the food they eat into their own new biomass

Global NPP

Energy Flow Ecological efficiency

• % of E transferred from one trophic level to the next (10%)

Pyramid of productivity• multiplicative loss of

energy in trophic levels Biomass pyramid

• trophic representation of biomass in ecosystems

Pyramid of numbers• trophic representation of

the number of organisms in an ecosystem

• Follows “rule of 10”

Chemical Cycling

Biogeochemical cycles: the various nutrient circuits, which involve both abiotic and biotic components of an ecosystem• Water• Carbon• Nitrogen• Phosphorus

Pollution Water pollution

• Sewage/agricultural runoff• Excess nitrogen causes eutrophication

algal blooms kill fish• Creates “dead zones”

Air pollution• Burning of wood, coal,

chemicals, fossil fuels, etc.• Smog

respiratory problems• Acid precipitation

crop damage structural damage to

buildings/statues

Biological Magnification

Trophic process in which retained substances become more concentrated at higher levels• Buildup of toxins in

predatory fish• DDT Causes egg shells of

predatory birds to become fragile

Greenhouse Effect Warming of planet due to

atmospheric accumulation of carbon dioxide• Burning of fossil fuels• Deforestation

CO2 traps heat from sunlight like a greenhouse

Results in • Increased ocean temps

death of coral reefs• Increased global temps

melting of polar ice caps/ raised ocean levels/changes in weather patterns

Ozone Depletion Effect of chlorofluorocarbons

(CFC’s) released into the atmosphere• Takes ~50 years for results

to be seen after release of CFC’s (ie. the worst is yet to come)

Depletion of ozone increased UV rays skin cancer, crop damage, etc.