Ecosystems: Everything Is Connected

Ecosystems: Everything Is
Chapter 7: Aquatic Ecosystems.
Environmental Science and the Earth
Ecosystems: Everything Is Connected
• Example of the idea that
“everything is connected”
• In 1995, scientists
interested in controlling
gypsy moths, which kill
oak trees, performed an
Photo by R. Jowsey
Everything Is Connected: Example
• The scientists removed
most mice, which eat
young gypsy moths,
from selected plots of
oak forest.
• The number of young
gypsy moth eggs and
young increased
Everything Is Connected: Example
• The scientists then added
acorns to the plots.
• Mice eat acorns, therefore the
number of mice soon
increased, and…
• The number of gypsy moths
declined as the mice ate them
as well.
Everything Is Connected: Example
• This result showed that
large acorn crops can
suppress gypsy moth
Everything Is Connected: Example
Photo by R. Jowsey
• Oh but there is
• Interestingly, the
acorns also
attracted deer,
which carried ticks.
• Young ticks soon
infested the mice.
Everything Is Connected: Example
• Wild mice carry the
organism that causes
Lyme disease.
• Ticks can pick up the
organism when they
bite mice.
• Then the ticks can bite
and infect humans.
Everything Is Connected: Example
• This example shows
that in nature,
things that we
would never think
were connected—
mice, acorns, ticks,
and humans—can
be linked to each
other in a complex
Defining an Ecosystem
• The mice, deer, moths, oak trees, and ticks in
the previous example are all part of the same
• An ecosystem is all of the organisms (biotic)
living in an area together with their physical
(abiotic) environment.
Defining an Ecosystem
• Ecosystems can be large
like an oak forest or coral
reef, or they can be small
like the vacant lot next
door to your home.
• The Natick
Defining an Ecosystem
• Just like living things are connected, so to are
• Things move from one ecosystem into
• Soil washes from a mountain into a lake, birds
migrate from Michigan to Mexico, and pollen
blows from a forest into a field.
The Components of an Ecosystem
• In order to survive, ecosystems need at least
five basic components:
1. A source of energy
2. Mineral nutrients
3. Water
4. Oxygen
5. Living organisms
Photo by R. Jowsey
Biotic and Abiotic Factors
• An ecosystem is made up of both living and
nonliving things.
• Biotic factors are the living and once living
parts of an ecosystem, including all of the
plants and animals.
• The biotic parts of an ecosystem interact with
each other in various ways (food webs,
symbiosis, etc).
Biotic and Abiotic Factors
• While living things interact with each other in
an ecosystem, they also interact with the nonliving factors in an ecosystem.
• The non-living components of an ecosystem
are known as abiotic factors.
Biotic and Abiotic Factors
• Identify three biotic and
three abiotic factors that
are in the cold northern
ecosystem of Denali
National Park in Alaska
(shown in photo).
Biotic Factors
Abiotic Factors
• An organism is an
individual living thing.
• You are an organism, as
is an ant crawling across
the floor, an ivy plant
on the windowsill, and
a bacterium in your
• Organisms are classified
into 4 major groups:
Bacteria, Plants,
Protists, and Animals.
Period 1 Organism
Peter Creed
• A species is a group of organisms that are closely related.
• In order for two organisms to be classified into the same
species, they must meet thesefour criteria.
• The two organisms must able to:
Successfully mate
in a Natural Environment (not a lab or zoo, etc.)
and produce viable offspring (healthy, able to survive to adulthood)
and those offspring are fertile (can reproduce).
• All humans, for example, are members of the species group
sapiens and the genus group Homo. This produces the
scientific name for humans; Homo sapien.
• The photo shows a
• A zedonk is a cross
between a zebra and a
• The zedonk is a sterile
animal and cannot
reproduce. Therefore, a
zebra and a donkey are
NOT the same species.
• Zebras and donkeys can successfully mate, in a
natural environment and produce viable
• Are zebras and donkeys therefore members of
the same species? Why or why not?
• A population is all the members of the same
species that live in the same place at the same
• An important characteristic of a population is that
its members usually breed with one another
rather than with members of other populations.
• Populations have really cool names: pod of
bottlenose dolphins, gaggle of Canadian geese,
murder of crows, smath of jellyfish.
• The Bison will usually
mate with another
member of the same
herd, just as the
wildflowers will
usually be pollinated
by other flowers in
the same field.
• An organism does not live alone and neither
does a population.
• A community is a group of various species
that live in the same place and interact with
each other.
Photo by R. Jowsey
• A pond community, for
example, includes all
of the populations of
plants, fish, and insects
that live in and around
the pond.
• All of the living things
in an ecosystem are
members of the same
• The most obvious difference between
communities is the types of species they have.
• Land communities are often dominated by a
few species of plants. In turn, these plants
determine what other organisms live in that
• For example, the most
obvious feature of a
Colorado forest might be
its ponderosa pine trees.
• This pine community will
have animals, such as
squirrels, that live in and
feed on these trees.
• The squirrel discussed
above lives in a pine
forest. The pine forest is
the squirrel’s habitat.
• A habitat is where an
organism lives.
• The habitat of the
salamander in this photo
is a damp forest floor.
• Every habitat has specific
characteristics that the
organisms that live there
need to survive.
• A coral reef contains sea
water, coral, sunlight, and
a wide variety of other
• If any of these factors
change, then the habitat
changes because
everything is connected.
• An organism’s niche is the
role it plays in an
• Often describes where an
organism “fits” in a food
• Example: A woodpecker’s
niche is eating insects
How Ecosystems Work
Chapter 7: Aquatic Ecosystems.
Environmental Science and the Earth
Life Depends on the Sun
• The ultimate source of
energy for almost all living
things is the sun.
• Energy from the sun enters
an ecosystem when a plant
uses sunlight to make sugar
molecules in a process
called photosynthesis.
• Plants, algae, and some bacteria capture
solar energy and use it to drive a series of
photo-chemical reactions that convert carbon
dioxide and water into glucose and oxygen.
• When an animal eats a plant, some energy is
transferred from the plant to the animal.
• This energy is used to move, grow, and
Photo by R.L. Jowsey
The Chemical Equation for
6 CO2
Carbon Dioxide +
6 H2O
6 O2
Autotrophs are Producers
• Plants and other organisms that undergo
photosynthesis are known as Autotrophs.
• Autotrophs have cells with chloroplasts (tiny
organelles within the cell) which are the site
of photosynthesis.
• The green pigment chlorophyll is responsible
for photosynthesis.
Transfer of Energy
• When a rabbit eats a
clover plant, the rabbit
gets energy from the
carbohydrates (glucose)
the clover plant made
through photosynthesis.
Transfer of Energy
• When a coyote eats a
rabbit, some of the
energy is transferred
from the rabbit to the
• Rabbits and Coyotes
are heterotrophs –
also called consumers.
What Eats What?
What Eats
What in an
Energy Source
Makes its own food
photosynthesis or
chemical sources
Gets energy by
eating producers
and other
Grasses, ferns,
flowering plants,
trees, some
Mice, starfish,
elephants, turtles,
humans, and ants
Types of Consumers in an Ecosystem
• Herbivores – eat autotrophs
• Carnivores – eat other
heterotrophs (consumers).
Photo by R.L. Jowsey
Types of Consumers in an Ecosystem (cont)
• Omnivore – eat both producers and
Photo by R.L. Jowsey
• Decomposer – breaks down dead organisms in
an ecosystem and returns nutrients to the soil,
water, and air.
Types of Consumers in an Ecosystem
Photo by R.L. Jowsey
Energy Transfer
• Each time an organism eats another organism,
a transfer of energy occurs.
• We can trace the flow of energy as it travels
through an ecosystem by studying food
chains, food webs, and trophic levels.
Food Chains and Food Webs
• A food chain follows the flow of energy from
one organism to the next as each organism
eats another organism.
Food Chains and Food Webs
• A food web includes multiple food chains
interconnected within an ecosystem.
Trophic Levels
• Each step through which energy is transferred
in a food chain is known as a trophic level.
Trophic Levels
• Each time energy flows into
the next trophic level, some
is lost and less energy is
available to the next
trophic level.
• Only about 10% of energy
transferred is available to
the next trophic level.
Energy Pyramids
• One way to visualize the loss of energy at each
trophic level is to draw an energy pyramid.
Trophic Levels and
Energy Pyramid

similar documents