What is an ecosystem?

All the living (biotic) and nonliving (abiotic) parts of an
environment as well as the interactions among them

Ecosystems may be aquatic (water) or terrestrial (land).

Interactions may include:
- producers (obtain energy by making their own
food; plants -photosynthesis)
- consumers (obtain energy by consuming their
food)
- decomposers ( get energy by breaking down dead
organisms and the wastes of living things); bacteria,
fungi (mold, mushrooms,etc) ,worms, termites,etc.
(The greatest
amount of energy
is available at the
producer level.)
(With producers and consumers, 90 % of the energy available at each level is
consumed/lost to the environment. Only 10% move up to the next trophic level.
If removed from the food web, which organism (s) would have the greatest impact on the overall food web? Explain.
The sun provides energy
To sustain producers
which are the foundation
of all ecosystems.
Produce food through
photosynthesis
http://www.brainpop.com/games/foodchaingame/ “Food Chain Game”
Abiotic & Biotic Factors

-
-
-
Abiotic Factors
(nonliving)
water
- shelter
sunlight - soil
rocks
- nutrients
oxygen/air, nitrogen
temperature/climate
space, salinity, pH

Biotic Factors
(living)
- Food
- grass
- trees
- animals, insects,
- plants
-
bacteria, fungi
Gizmo Lab: Food Chain
Worms, termites,
fungi (mold, mushrooms, etc.)
In the diagram,
1. What are the decomposers? Producers? Consumers?
2. What organisms are competing for the same abiotic resources?
3. What is the source of energy that drives or sustains the ecosystem?
Can you think of a situation where an organism
could be both a primary and secondary
consumer?
(not shown on this food web)
1.
2.
What are the producers? primary consumers? secondary consumers? tertiary consumer?
What organisms are competing for the same abiotic and biotic resources?
Phytoplankton = producers
Zooplankton = primary consumers
In the above ecosystem:
1.
2.
3.
4.
What do algae and phytoplankton contribute?
What is the role of the fungi?
What is the role of bacteria?
What does the rotting log contribute?
Biomass Energy Pyramid: Trophic Levels
Page 3 of study guide
4th trophic level
3rd t trophic level
2nd trophic level
1st trophic level
(kcal)
1.
2.
3.
4.
At what trophic level is there the greatest amount of energy available?
What percent of energy is used/lost at each trophic level of an energy pyramid?
What percent of energy is passed up to the higher trophic level?
If removed from the pyramid, which organism (s) would have the greatest impact on
on all organisms? Explain.
Food Web Analysis
Use the diagram to respond to each of
the following.
1. Identify the decomposer. What are the
benefits of decomposers?
2. What other decomposers may be in
every ecosystem but are not shown
on this diagram?
3. Identify the primary consumers.
Show what is being consumed.
4. Identify the tertiary consumer for
each food chain. What does this
consumer eat?
5. Is this a terrestrial or aquatic food
web? Explain.
6. What happens when two or more
organisms coexist in the same niche?
Some worms are primary
consumers and others (in soil)
are decomposers.)
7.Draw an overlapping terrestrial/aquatic
food chain using at least one of the
organisms shown on the diagram. Add
an organism not on this food web.
In what way may farming affect this marine ecosystem?
http://www.youtube.com/watch?v=C-lcEXI7al4 “The Nitrogen Cycle” 3:56
The Role of Nitrogen in an Ecosystem
(photosynthesis)
(photosynthesis)
respiration
http://www.youtube.com/watch?v=C-lcEXI7al4 Brainpop “The Carbon Cycle” 1:23
Ecosystem Hierarchy
 Organisms:
individuals of a species
 Populations: groups of organisms of the same
species
 Communities:
the interaction of different
populations; communities live within an
 Ecosystem: all of the abiotic and biotic parts of an
ecosystem
 Biosphere:
all of Earth’s ecosystems
Hierarchy From Atoms to Ecosystems
Levels from Largest to
Smallest










Ecosystem Level
Community Level
Population Level
Organism Level
Organ System Level
Organ Level
Tissue Level
Cellular Level
Molecular Level
Atomic Level
From Atoms to Biosphere
Ecosystem Organization
Organism (single one of species)
Mushrooms
Coyotes
Polar Bears
Prairie Dogs
Snakes
Elephants
4 Populations (same species)


Elk Population
Elephant Population


Cacti Population
Gorilla Population
Communities (many populations)
What communities are present in each of these ecosystems?
Marine (aquatic) Ecosystem
Terrestrial Ecosystem
Freshwater & Terrestrial Ecosystems
Aquatic (estuary) Ecosystems
Ecosystems make up the biosphere.
Earth is the only planet on which life exists. It consists of three components Lithosphere
(Land), Hydrosphere (Water) and Atmosphere (Air). The life supporting zone of the
earth where atmosphere, hydrosphere and lithosphere meet, interact and make life possible,
is known as biosphere.
An Arctic Food Web Activity
What overlapping aquatic/terrestrial food
chains are there in this ecosystem?
2. What population, if removed, would have the
greatest impact on the overall food web?
3. If the water was highly contaminated, what
organism/population would have the highest
level of contamination?
4. Which organism contributes dissolved
oxygen to the water?
5. Which organisms may compete for the same
food source(s)?
1.
How would the removal of algae from this arctic
food web affect both the biotic and abiotic factors?

Abiotic Factors Affected

-
dissolved oxygen
decreases
nutrients may go up or
down
more CO2 in water
water may be more turbid
temp. may change
- animal plankton pop.
-
Biotic Factors Affected
decreases
- silverside pop. decrease
- beluga whale pop. decrease
- cod pop. Decreases
- bacteria increase & use up
dissolved oxygen
**Every population is directly or
indirectly affected
Biodiversity
A
variety of species exist in all ecosystems.
What are examples of biodiversity in our
area?
- plant biodiversity
- insect biodiversity
- animal biodiversity
- fungi biodiversity
- bacteria biodiversity
Disruptions to Ecosystems: The Human Factor
Disturbances to Physical (abiotic) or
Biological (biotic) Components of Ecosystems

Disruptions lead to shifts in all populations. This changes
the biodiversity of an ecosystem.

What disruptions may occur leading to a change in the
physical (nonliving/abiotic) components in an
ecosystem?
http://www.youtube.com/watch?v=ddlrGkeOzsI Lake Peigneur disaster 9:54
1.
2.
**
3.
What affect did this disaster have on the aquatic ecosystems? Terrestrial?
What affect did this disaster have on the terrestrial ecosystems?
Include both biotic and abiotic factors when answering these two questions.
How would this disaster lead to possible “population shifts”? Be specific.
Disruptions to Physical
(nonliving/abiotic) Components
*
*
*
*
*
Volcanic eruptions
* Pollution
Hurricanes
* Clear cutting
Fires
* Floods
Drought
* Nuclear Bomb
Habitat depletion (human and natural)
- i.e. urban sprawl
How could these events change nutrients,
water, light, salinity, shelter, soil, temperature,
climate, etc. in an ecosystem?
Disruptions to Biological
(living/biotic) Components
* Volcanic eruptions
* Pollution (land & water)
* Hurricanes
* Urban Sprawl
* Fires
* Clear Cutting
* Drought
* Introduction of exotic
** Overharvesting
(non native) species
* Habitat depletion (human and natural)
How could these events change the biological
(living/biotic) components in an ecosystem?
Preventing Overharvesting









Hunting seasons
- Laws (ownership)
Laws against poaching
- Size limitations
Limit on Numbers
- Organizations
License required
- Size/types of nets
Specific places
- Limits on gender
Wildlife Reserves/National Parks
Tagging/Monitoring Programs (remote sensing)
Breeding Programs
Identification of Endangered Species
How may volcanoes disrupt ecosystems?

Producers?

Consumers?

Biotic Factors?

Abiotic Factors?
Impact of Clear Cutting
What are the impacts on biotic and abiotic factors?
Impact of Introducing Exotic Species: Kudzu
Kudzu is a serious invasive plant in the United States. It has been spreading in
the southern U.S. at the rate of 150,000 acres (61,000 ha) annually, "easily
outpacing the use of herbicide spraying and mowing, as well increasing the
costs of these controls by $6 million annually.“ Its introduction has produced
devastating environmental consequences. What do you think?
Impact of Introducing Exotic Species:
Burmese python in Florida
This snake was found in the Everglades National Park, measuring 17 feet, 7 inches
and over 165 pounds. The other record broken was the fact the snake was pregnant
with 87eggs. There is believed to be thousands thriving the moist, hot climate of the
Everglades perhaps released years ago by pet owners or from pet shops during
Hurricane Andrew in 1992. Local ordinances prohibit the import of these reptiles and
allowing them to be hunted has not put much of a dent on population control. They
have the ability to swallow large animals’ whole after coiling around their prey and
suffocating them. What do you think?
The Effect of the Brown Tree Snake in Guam
_
_
_
What led to the dramatic loss of birds on Guam? Well this part of the story isn’t actually so “natural”—
although it was unintentional. Sometime in the mid to late 1940s, brown tree snakes were introduced to
the island probably by hitching a ride on a cargo ship after World War II. Because there aren’t many large
predators on Guam, the snakes quickly took over the island. By the 1980s the birds were wiped out save
for two colonies that continue to exist on a military base. To this day the snakes are still around (one of
the attempts to control them involved dropping Tylenol-laced mice from airplanes).
What happens to spiders when you remove birds from a tropical island? The researchers found that
during the dry season Guam had 2.3 times more spider webs than neighboring islands that still have
birds. During the wet season the number of webs was a whopping 40 times higher on Guam. And the
spider webs on Guam were much larger—50% larger—than those on the other islands.
Removing birds from the equation likely changed the Guam spider population in many ways including
some (or all) of these scenarios: (1) since birds weren’t around to eat the spiders the spider population
grew, (2) the spiders no longer had to compete with the birds to eat insects so more spiders survived and
were able to reproduce, (3) the spiders didn’t have to keep spinning new webs because the birds weren’t
there to mess them up anymore, so they built larger webs and put more energy into reproduction.
Population Density
- the number of people/organisms living per
unit of an area (e.g. per square mile); the
number of people relative to the space
occupied by them
_ how full an area is: the concentration of
people or things within an area in relation
to its size
Limiting Factor
-
environmental factors that limit
population sizes in a particular
ecosystem
Limiting Factors in an Ecosystem
 Density-dependent
-
Factors
operate more strongly on large
populations and disease
triggered by increases in population
density (crowding)
* Competition for food, water, shelter & space
* Predation
* Parasitism
* Disease
Population Density: measures the number of
individual organisms living in a defined space
High Population Density
China’s Qingdao Huiquan Beach
China’s Qingdao Huiquan Beach
Low Population Density
Compare this picture to the previous one. If these were animals,

How may the spread of disease and parasites be affected by the
population densities?

How may competition for food, water, space and shelter be affected?
W



What is the relationship between the hare population and the lynx
population?
What role does competition play in this predator/prey relationship?
Why is competition important in an ecosystem?
Density-independent Factors
 Limiting
factors that occur regardless of how
large the population is and reduce the size of
all populations in the area; mostly abiotic
-
weather changes
human activities (pollution, urban sprawl, etc.)
natural disasters (i.e. fires)
Relationships Within Ecosystems:
- Coexistence and cooperation
- Competition (predator/prey)
- Parasitism