Chapter 3
Ecosystems and Energy
Chesapeake Bay Salt Marsh Ecosystem
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Chesapeake is an
estuary (affected by
tides)
Tidal marshes are
special because they:
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Purify water
Protect the coastline
Provide shelter and
breeding grounds for
aquatic species
Are one of the most
productive ecosystems in
terms of energy!
Chesapeake Ecosystem
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Water is salty on the ocean
side, brackish in the middle,
and fresh water at the head
of the bay
Base of the food web is
cordgrass (shown in photo).
This has an advantage since
it can grow under saline
conditions and periodic
submergence due to tides.
The bay receives high
nutrient levels (N,P) from
treated human sewage and
farm runoff, which promotes
algal growth (cordgrass too),
which serve as food for other
organisms.
What is the Chesapeake like?
Major kinds of life in the salt marsh ecosystem:
1. Insects
 Millions of mosquitoes and horseflies
2. Birds
 Sparrows, hulls, clapper rails
3. Shrimp, lobster, crabs, barnacles, worms, clams and
snails are all present and seek refuge in the cordgrass.
 No amphibians live there (salt) but the terrapin turtle
does.
4. Numerous species of fish call the Chesapeake
home…including:
 Sea trout, croaker, bluefish, striped bass
 Young species enter from the ocean.
5. Meadow voles live along the shores, and are excellent
What does the Chesapeake Tell Us?
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This ecosystem is interdependent upon human
inputs (pollutants such as nitrates, phosphates and
others like oil, gas, etc.) and also it’s natural setting.
It remains one of the most productive ecosystems on
the planet…but it is in peril!
Too much pollution…overfishing…too many
nutrients (eutrophication)…oil spills….growing
population….
It is important to protect our most productive
ecosystems!
Chesapeake Ecosystem
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Chesapeake also serves as an excellent case
study in how energy flows through an
ecosystem!
Overview of Chapter 3
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What is Ecology?
The Energy of Life
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Laws of Thermodynamics
Photosynthesis and Cellular Respiration
Flow of Energy Through Ecosystems
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Producers, Consumers & Decomposers
Ecological Pyramid
Ecosystem Productivity
Ecology
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Ecology
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Biotic - living environment
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“eco” house & “logy” study of
The study of interactions among and between
organisms in their abiotic environment
Includes all organisms
Abiotic - non living or physical
environment

Includes living space, sunlight, soil,
precipitation, etc.
Ecology

Ecologists are
interested in
the levels of
life above that
of organism
Ecology Definitions
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Species
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Population
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Al the populations of different species that live and
interact in the same area at the same time
Ecosystem
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A group of organisms of the same species that occupy
that live in the same area at the same time
Community
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A group of similar organisms whose members freely
interbreed
A community and its physical (abiotic) environment
Landscape
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Several interacting ecosystems
Ecology

Biosphere contains earth’s communities,
ecosystems and landscapes, and includes:
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Atmosphere gaseous envelope
surrounding earth
Hydrosphere earth’s supply of
water
Lithosphere - soil
and rock of the
earth’s crust
The First & Second Law of
Thermodynamics
By: Michelle Zicca
Basic Laws of
Thermodynamics

First Law of Thermodynamics
– energy can neither be created nor
destroyed
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Second Law of Thermodynamics
– naturally occurring processes are
directional
First Law of
Thermodynamics
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One form of work may be converted
into another,
or, work may be converted to heat,
or, heat may be converted to work,
but, final energy = initial energy
2nd Law of
Thermodynamics

We intuitively know that heat flows
from higher to lower temperatures and
not the other direction.
– i.e., heat flows “downhill” just like water
– You cannot raise the temperature in this
room by adding ice cubes.

Thus processes that employ heat are
inherently irreversible.
Heat/Work Conversions
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Heat transfer is inherently irreversible.
This places limits on the amount of
work that can be produced from heat.
Heat can be converted to work using
heat engines
– Jet engines (planes), steam engines
(trains), internal combustion engines
(automobiles)
Open & Closed Systems
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Open system exchanges energy with
its surroundings
A closed system is self-contained and
isolated; does not exchange energy
with its surroundings.
Where did the energy go?
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By the First Law of Thermodynamics,
the energy we put into the water (either
work or heat) cannot be destroyed.
The heat or work added increased the
internal energy of the water.
Processes that take Place
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Reversible Processes
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A reversible process is a quasi-equilibrium, or quasi-static, process with a
more restrictive requirement.
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Internally reversible process
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The internally reversible process is a quasi-equilibrium process, which, once having taken
place, can be reversed and in so doing leave no change in the system. This says nothing
about what happens to the surroundings about the system.
Totally or externally reversible process
The externally reversible process is a quasi-equilibrium process, which, once having
taken place, can be reversed and in so doing leave no change in the system or
surroundings.
Overview of
Thermodynamics
Two constraints on life processes
– Evolutionary history
– Physics and chemistry
• Living things must play by these rules
• Order is sustained in living things at
the
expense of energy and disorder to the
surroundings
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Pictures and Examples
Three Types of Process
Isothermal process
System
Adiabatic process
P
Adiabat
Isotherm
Heat bath or reservoir
Adiabatic free expansion
V
P
1
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End points
2
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27
V
Photosynthesis, Cellular
Respiration, and Chemosynthesis
By Wesley Washington
Photosynthesis
• It is a biological
process where plants
such as algae, and
some bacteria take in
light energy and
change it into
carbohydrates
(sugar).
• Glucose is the molecule
that is formed by
photosynthesis. Glucose
is the fuel source of
plants.
Photosynthesis
The carbon
dioxide(6CO2) and
water(12H2O) is
synthesized with
sunlight to form
glucose(C6H12O6).
Left over products
include water which is
stored and Oxygen
which is released.
Aerobic Cellular Respiration
• Is essentially is the process of the cells
using energy to biological work.
• All organisms need to respire. Plants use
glucose energy while most animals
breathe.
• This process usually needs oxygen,
however anaerobic bacteria hat lives in
waterlogged soil, animal intestines (like
yours!) and hydrothermal vents still respire
without oxygen.
Chemosynthesis
• Happens at
hydrothermal vents
on the bottom of the
sea floor.
• Bacteria living there is
able to with stand
temperatures of 392 F
• The vents spew out
mineral rich water and
toxic hydrogen
sulfide.
Chemosynthesis
• The bacteria takes the raw
inorganic chemicals and
process them into food of the
bacteria.
• Organisms such as the giant
red tube worms have a
symbiotic relationship with the
bacteria allowing them to live
inside their bodies in exchange
for the energy they produce.
Producers, Consumers, and
Decomposers
by: Joey Harkins
• All organisms are classified as either a
producer, consumer, or decomposer
• The basis of the classification is on how each
organism receives its nourishment
Producers
• Producers (autotrophs)organisms that manufacture
complex organic molecules from
simple inorganic substances,
such as CO2 and water, and
using the energy from the sun .
• For example photosynthetic
organisms
• Producers incorporate the
chemicals they manufacture into
their own bodies, becoming food
sources for other animals.
Consumers
• Consumers (heterophs)- use the bodies of
other organisms as a source of food energy
and bodybuilding materials.
• Four types of consumers:
primary consumers- herbivores, only eat producers
secondary consumers- eat primary consumers
tertiary consumers- eat secondary consumers
detritus feeders- consume organic matter, like
animal carcasses, leaf litter, and feces
Decomposers
• Decomposers (saprotrophs)heterotrophs that break down dead
organic material and use the
decomposition products to supply
themselves with energy.
• Decomposers release inorganic
molecules, such as CO2 and mineral
salts, that producers can reuse.
• Bacteria and fungi are some examples of
decomposers
• Producers, consumers, and decomposers all play
an important role in the ecosystem.
• Producers provide food and oxygen for the
community
• Consumers maintain a balance between
producers and decomposers.
• Decomposers keep dead organisms and waste
products to a minimum, while also releasing the
potassium, nitrogen, and phosphorus from dead
organisms.
The Path of Energy:
Who Eats Whom in
Ecosystems?
Hunter Longenberger
In an Ecosystem
• Energy passes from one
organism to the next
through a food chain
• Many interconnected food
chain forms a food web
• Within each food chain
there are trophic levels
Food web
(everything is connected)
Food chain
(just one path of energy)
Food Web
Trophic levels
Is where the organism stands in the food web
This is based on the number energy transfer steps to
that level
Tropic levels
1. Producers (organisms that photosynthesize)
2. Primary consumers (herbivores)
3. Secondary consumers (carnivores)
At every step in the food chain there are decomposers
Trophic levels
Secondary consumers
Primary consumers
Producers
Energy flow
• It is linear or one way
• Once an organism has used energy it is lost
as heat and is unavailable for any other
organism in the ecosystem
Human Impact on the
Antarctic food Web
Ryan Privitera
The Antarctic food web
 Everywhere in the world there are predators
and prey meaning the lower you are on the
web means that you are a primary source to
other species.
 Going from the diversity of the rain forest
where the web is large and complicated as
compared to one of the simplest webs, the
Antarctic.
They call us humans.
 The number one environmental problem we face
as a society simply is our population growth.
 The more humans reproduce the worse off the
planet is going to be and the number increases
each day by 353015 babies.
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 The united states alone produces 10650 a day.
That’s an outrageous number and believe it or not
this is the main reason for impacting any food web
and we seem to disturb the simplest one.
Antarctica
 This is a place of vacancy which means no
civilized human life forms live there year
round for the reason that tempters can drop
to -89.2 ° Celsius.
 This baron land is home to penguins, polar
bears, weddell seals, blackbrowed
albatross, leopard seals, elephant seals,
and crabeater seals.
Human impacts
 Antarctica is one of the most important research
centers for environmental warming and melting of
ice.
 Antarctica's clean air, water and ice of are of
importance to science for understanding how the
Earth's environment is changing both naturally and
as a result of human activity due to the increasing
hole over the Antarctic.
 Pollution drifts into the air and contaminates the
normal levels of our atmosphere.
This is the marine ecosystem.
The simplicity of the food web.
Rusting metal in antarctica.
Rusted metal waste barrells.
Warming chart
Realizing our mistakes
 The best way to fix any mistake is not to do
it again so what we have to do as a society
is realize that what we do anywhere in the
world will have serious consequences if we
keep living like Americans.
 The ignorance of others will ruin this
ecosystem if we simply keep overusing fuels
and not using renewable energies.
Ecological Pyramids
Maddie Lewis
• Most energy going from
one trophic level to the
next dissipates into the
environment due to the
second law of
thermodynamics.
• Ecological pyramids
graphically represent
relative energy levels at
each level
• There are three types of
ecological pyramids
Pyramid of Numbers
• Shows number of
organisms at each trophic
level, greater numbers
are shown by a larger
area
• In most, organisms at the
base of the food chain
are more abundant
• Inverted pyramids of
numbers are when higher
trophic levels have more
organisms, seen in
decomposers, parasites,
etc.
Pyramid of Biomass
• Biomass- quantitive
estimate of total mass
or amount of living
material, indicates
fixed energy
• Represented as live
weight, total volume
or dry weight
• Succeeding trophic
levels usually show
reduction of biomass
Pyramid of Energy
• Illustrates energy of
biomass at each level
• Usually measured in kilocalories per year
• Always have large energy
bases and get
progressively smaller
• Less energy reaches
each level because
organisms use it, and
some is lost
• Food webs are short due
to dramatic reduction in
energy
ECOSYSTEM
PRODUCTIVITY
MERICA
Gross Primary Productivity
• GPP of an ecosystem is the rate
at which energy is captured during
photosynthesis!
MERICA
Net Primary Productivity
• NPP is energy in plant tissues after
cellular respiration has occurred!
• NPP is the amount of biomass found
in excess of that broken down by
plant’s cellular respiration!
GPP=NPP + Respiration
More!
• Both GPP and NPP are expressed as
energy per unit area per unit time, or as
dry weight.
• Consumers use most energy from NPP for
cellular respiration and to contract
muscles.
RECENTLY
• In 1986 Peter Vitousek calculated how much of global
NPP is appropiated for the human economy and
therefore not transferred to other organisms. He
determined humans use 32% of the annual NPP of landbased organisms.
• In 2001 Stuart Rojstaczer reexamined Vitousek’s
experiment and agreed with his result of 32% usage.
• In 2007 K. Heinz Erb put 97% of the Earth’s forestry
information into a computer model. The model states
humans are appropriated about 25%.