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Ecosystems and Energy3
© 2015 John Wiley & Sons, Inc. All rights reserved.
Overview of Chapter 3
What is Ecology? The Energy of Life
Laws of Thermodynamics Photosynthesis and Cellular Respiration
Flow of Energy Through Ecosystems Producers, Consumers and Decomposers Path of Energy Flow: Who Eats Whom Ecological Pyramids Ecosystem Productivity
© 2015 John Wiley & Sons, Inc. All rights reserved.
Chesapeake Bay salt marshes
An estuary – semi-enclosed body of water where freshwater drains into ocean Tidal – gradual changed from fresh to salt water
Cordgrass dominates – brackish Home to insects and birds,
nursery for fish Very important buffer for
coasts against storms
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology
Ecology “logy” study of, “eco” house – study of one’s house The study of interactions among and between
organisms in their abiotic environment Biotic - living environment
Includes all organisms Abiotic - non living or physical environment
Includes living space, sunlight, soil, precipitation, etc.
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology
Organisms interact with biotic components, but also effect many physical and chemical processes
Physical – walking on soil
Chemical – CO2, O2, wastes
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology
Ecologists are interested in the levels of life above that of organism
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology Definitions
Species - A group of similar organisms whose members freely interbreed to produce fertile offspring
Population - A group of organisms of the same species that live in the same area at the same time
Community - All the populations of different species that live and interact in the same area at the same time
Ecosystem - A community and its physical (abiotic) environment
Landscape - Several interacting ecosystems (ex: bear hunting for salmon in a river, living in adjacent forest)
© 2015 John Wiley & Sons, Inc. All rights reserved.
Part of Earth that contains living organisms
Ecology
Community and physical environment
Individuals
Group of same species
All populations of species in an area
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology
Coral Reef communities – similar to rainforests for number of species and productivity
Threatened with changing climate How can communities be protected from warming waters?
What could loss mean?
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology
Biosphere contains earth’s communities, ecosystems and landscapes, and includes: Atmosphere-
gaseous envelope surrounding earth
Hydrosphere- earth’s supply of water
Lithosphere- soil and rock of the earth’s crust
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology
Lithosphere
Hydrosphere
Atmosphere
© 2015 John Wiley & Sons, Inc. All rights reserved.
Energy of Life
The ability or capacity to do work Chemical, Thermal, Mechanical, Nuclear,
Electrical, and Radiant/Solar (below)
© 2015 John Wiley & Sons, Inc. All rights reserved.
Solar radiation is the primary source of energy on planet
Energy of Life
Plants turn solar radiation into food
© 2015 John Wiley & Sons, Inc. All rights reserved.
Energy of Life
Energy exists as: Potential energy
(stored energy) Kinetic energy
(energy of motion)
Potential energy is converted to kinetic energy as arrow is released from bow
© 2015 John Wiley & Sons, Inc. All rights reserved.
Thermodynamics
Study of energy and its transformations System- the object being studied
Closed System- Does not exchange energy with surroundings (rare in nature)
Open System- exchanges energy with surroundings
© 2015 John Wiley & Sons, Inc. All rights reserved.
Laws of Thermodynamics
First Law of Thermodynamics Energy cannot be created or destroyed; it can
change from one form to another
Energy is absorbed by water and plate, but not lost
© 2015 John Wiley & Sons, Inc. All rights reserved.
Laws of Thermodynamics
Second Law of Thermodynamics When energy is converted form one form to
another, some of it is degraded to heat Heat is highly entropic (disorganized)
Water in sunlight will get warmer
Engine converts chemical energy of gasoline into mechanical energy inefficiently
© 2015 John Wiley & Sons, Inc. All rights reserved.
Photosynthesis
Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of carbohydrate (sugar) molecules
6 CO6 CO2 2 + 12 H+ 12 H22O + radiant energyO + radiant energy
CC66HH1212OO66 + 6 H + 6 H22O + 6 OO + 6 O22
Chlorophyll in plants
© 2015 John Wiley & Sons, Inc. All rights reserved.
Cellular Respiration
The process where the chemical energy captured in photosynthesis is released within cells of plants and animals
This energy is then used for biological work
CC66HH1212OO66 + 6 + 6 OO2 2 + 6 H+ 6 H22OO
6 CO6 CO22 + 12 H + 12 H22O + energyO + energy
© 2015 John Wiley & Sons, Inc. All rights reserved.
Photosynthesis and Cellular Respiration
© 2015 John Wiley & Sons, Inc. All rights reserved.
Life without Sun
1970s – discovered hydrothermal vents in deep ocean (200oC or 392oF)
Rich ecosystem supported without light Bacteria perform
chemosynthesis Similar to
photosynthesis, but use chemical (H2S) not sunlight
© 2015 John Wiley & Sons, Inc. All rights reserved.
Energy Flow Through Ecosystems
Passage of energy through an ecosystem
© 2015 John Wiley & Sons, Inc. All rights reserved.
Food Chains- The Path of Energy Flow
Energy from food passes from one organism to another based on their Trophic Level Definition: An organism’s position in a food chain,
which is determined by its feeding relationships First Trophic Level: Producers Second Trophic Level: Primary Consumers Third Trophic Level: Secondary Consumers Decomposers are present at all trophic levels
© 2015 John Wiley & Sons, Inc. All rights reserved.
Food chains
Autotrophs = Producers Auto “self” and tropho “nourishment” Produce own food from inorganic material Ex: plants via photosynthesis and hydrothermal
vent bacteria via chemosynthesis
© 2015 John Wiley & Sons, Inc. All rights reserved.
Food chains
Heterotrophs = Consumers heter “different” and tropho “nourishment” Uses bodies of other organisms as food
Omnivores – eat both plants and animals
© 2015 John Wiley & Sons, Inc. All rights reserved.
Food chains
Consumers of detritus (detritivores) Eat dead material such as leaves, carcasses,
feces Ex: crabs, worms, millipedes, snails
© 2015 John Wiley & Sons, Inc. All rights reserved.
Food chains
Decomposers or saprotrophs sapro “rotten” and tropho “nourishment” Breakdown dead organic material Release inorganic molecules (CO2 and nutrients)
that producers can use Ex: fungus,
bacteria Involved in
all aspects of food chains
© 2015 John Wiley & Sons, Inc. All rights reserved.
Food Web
Food web visualizes feeding relationships within a community More complex
than food chain Still simplified
compared to nature
© 2015 John Wiley & Sons, Inc. All rights reserved.
Humans and Antarctic food web
Base of web is algae, which is eaten by krill
Krill are eaten by many larger organisms Wastes of whales resupply
nutrients for algae and krill Ozone and climate change
are warming area
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecological Pyramids
Graphically represent the relative energy value of each trophic level Important feature - large amount of energy is lost
as heat between trophic levels Three main types
Pyramid of numbers Pyramid of biomass Pyramid of energy
© 2015 John Wiley & Sons, Inc. All rights reserved.
Pyramid of Numbers
Illustrates the number of organisms at each trophic level Fewer organisms
occupy each successive level
Does not indicate: biomass of organisms
at each level amount of energy
transferred between levels
© 2015 John Wiley & Sons, Inc. All rights reserved.
Pyramid of Biomass
Illustrates the total biomass at each successive trophic level
Biomass: measure of the total amount of living material
~90% reduction in biomass through trophic levels 100 to 10
© 2015 John Wiley & Sons, Inc. All rights reserved.
Pyramid of Energy
Illustrates how much energy is present at each trophic level and how much is transferred to the next level
Most energy dissipates between trophic levels Lost as heat and energy
to maintain each level Explains why there are
so few trophic levels
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecosystem Productivity
Gross Primary Productivity (GPP) Total amount of energy that plants capture and
assimilate in a given period of time Cellular respiration (R)
Plants use some energy of GPP to maintain themselves
Plants respire too Net Primary Productivity (NPP)
Productivity after respiration losses are subtracted What is available as food for other organisms
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecosystem Productivity
GPP is similar to gross pay in paycheck R is similar to taxes NPP is similar to take home pay
Net Primary Productivity
(plant growth per area per time)
Gross Primary Productivity (total photosynthesis per
area per time)
Plant Cellular Respiration
(per area per time)= -
© 2015 John Wiley & Sons, Inc. All rights reserved.
Variation in NPP by Ecosystem
Coral reefs are near tropical rain forests
Humans consume a large amount of global NPP ~30% but we make up
~0.5% of biomass
This represents a threat to planet’s ability to support both human and non-human inhabitants
© 2015 John Wiley & Sons, Inc. All rights reserved.
Energy and Climate Change
Humans use a large portion of global NPP If we use more biomass as energy rather than
fossil fuels, our use of NPP may increase Corn as fuel, wood for heat
How can we balance our needs with other organisms?
© 2015 John Wiley & Sons, Inc. All rights reserved.
ENVIRONEWS
Use of satellite imagery improves biomass estimates of forests Help protect tropic forests in developing countries Developed countries pay to keep forests intact
Need to ground truth satellite models with monitoring data from forest