Ecosystems
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Transcript of Ecosystems
Ecosystems
Ecosystems
An ecosystem is all of the organisms in an area, along with their nonliving environmentExample: aquarium
Trophic Levels
Organisms in a community are related to each other through feeding relationships
Each step up in the transfer of energy is known as a trophic level
All energy ultimately comes from the SUN
Primary Productivity
Primary Productivity:The amount of light energy converted to
sugars by autotrophs in an ecosystemGross vs. Net Primary Productivity
• GPP: the amount of light energy that is converted to chemical energy by photosynthesis per unit time
• NPP: GPP minus the energy used by the primary producers for cellular respiration
Limiting Nutrients
What limits primary production?Aquatic Ecosystems
• Light (depth penetration)• Nitrogen• Phosphorus
Terrestrial Ecosystems• Temperature• Moisture• Minerals
Trophic Levels Producers
Convert solar (or chemical) energy into organic compounds
Primary consumers Eat producers
Secondary consumers Eat primary consumers
Tertiary consumers Eat secondary consumers
Trophic Levels
Decomposers/ Detritivores Eat detritus
(organic waste/remains of dead organisms)
Trophic Levels Ten-Percent Law
Energy is lost through each transfer of energy Only about 10% of the energy at one trophic level is
transferred to the next trophic level
Pyramid of Numbers
Human Impact on Ecosystems Increased Eutrophication
of Lakes Eutrophication – when
lakes shift from having phytoplankton communities dominated by diatoms or green algae to having phytoplankton communities dominated by cyanobacteria
• Leads to the eventual loss of fish
• Accelerated by sewage/factory wastes, leaching of fertilizers into freshwater
Human Impact on Ecosystems Combustion of
Fossil Fuels Leads to acid
precipitation Changes the pH of
aquatic ecosystems and affects the soil chemistry of terrestrial ecosystems
Human Impact on Ecosystems Biological
Magnification Toxins become
more concentrated as they move up the food chain
The biomass at any given trophic level is produced from a much larger biomass ingested from the level below
Human Impact on Ecosystems
Increasing Carbon Dioxide Concentration in the AtmosphereBurning fossil fuels (wood, coal, oil)
releases CO2
Carbon dioxide and water in the atmosphere retain solar heat, causing the greenhouse effect