Unit 4
The Sustainability
of
Ecosystems
Page | 190
Slide 1___________________________________
Sustainability of
Ecosystems
__________________________________
__________________________________
_
_
__________________________________
__________________________________
_
_
__________________________________
__________________________________
_
_
Slide 2___________________________________
ancient Greek word for home.
Ecology and Ecosystems Textbook pages
284 onward • Ecology – [Definition]
• Ecosystem – [Definition]
2. An Ecosystem is all the interacting parts
of a biological community and it’s physical
environment.
This
includes
the
relationships between populations of
various organisms. (biotic and abiotic
1. Ecology is the study of the interactions
among living things and their nonliving
environment. The prefix “eco” is from the
Ecosystems may…
• vary in size - from a log ecosystem to a forest or ocean
• be terrestrial (on land) or aquatic (in water)
factors in the environment.
Page | 191
Ecotone - [Definition]
Ecotones are biologically diverse!
The area that connect two or more
ecosystems is called an ecotone. For
example, the marshland between a pond and
a forest is an ecotone.
In our study of ecology, we want to
make the distinction between
organism, species, population and
community
• Organism – an individual plant, animal or
single celled life form
• Species – a group of similar living
organisms capable of breeding and
producing offspring.
• Population – All of the members of the
same species in an ecosystem or habitat
• Community – The collection of all the
populations of species in the ecosystem.
From Species to Community video on
YouTube: “Ecosystem Dynamics”:
https://www.youtube.com/watch?v=57FGF
hsHtFQ
Niche and Habitat
• Niche - Niche refers to the role that a species
plays within its ecosystem. In balanced eco
systems, each species occupies its own niche.
The niche is like the organism’s profession.
▪ Each organism in an ecosystem tends
to have a different niche. This helps
reduce competition between species
for the same resources and
territory.
▪ Example: Owl and hawk feed on the
same organism but they occupy
distinctly different niches. How is
that so?
▪ Check out the diagram. Notice how each warbler
has its own niche.
Page | 192
Slide 7___________________________________
•Habitat –refers to the place where an
organism lives. This means that the
habitat of a species is different than its
niche, it is one part of its niche. The
organism’s habitat is its address - where
it lives.
Slide 8___________________________________
“What is a Niche? ” Check out YouTube:
https://www.youtube.com/watch?v=6-aGxYTUPu0
Extra Video: “Populations, Habitats and Niches
https://www.youtube.com/watch?v=fupYSpg64dM
Slide 9___________________________________
Abiotic and Biotic Components of
Ecosystems
Textbook pages 286 onward
• Abiotic factors - [Definition]
Abiotic factors include:
1. Temperature: Environmental temperature affects
biological processes and the ability of organisms
to regulate temperature. Few organisms have active
metabolisms at temperatures below 0oC or above
45oC. The temperature of an area will affect the
type of organisms found in an ecosystem.
2. Amount of sunlight: Sunlight is the ultimate source of energy
for all photosynthetic organisms, which in turn provide the
resources for other living things. Light also affects the
development and behaviour of many organisms.
Page | 193
Slide 10___________________________________
3. Strength and direction of wind: Some areas of Newfoundland
are particularly windy, and this affects not only the type of
plants that grow, but how they grow. It also affects the type of
organisms found in an area, and can affect how they behave.
Slide 11___________________________________
__________________________________
4. Soil (inorganic and organic soil nutrients): Inorganic soil
nutrients include minerals such as phosphates,
nitrates, potassium, magnesium and a host of other minerals
derived from rocks. Organic nutrients include organic
compounds in humus which promote the growth of bacteria,
fungi, and a host of other organisms beneficial to the soil.
The physical structure, water holding potential, pH, and
nutrient level of soil limit the distribution of plants and in
turn, the animals that inhabit a terrestrial region.
_
__________________________________
_
__________________________________
Planting corn in this province is a challenge! Given the last two
abiotic factors, why do you think this is so?
_
__________________________________
_
__________________________________
__________________________________
_
_
Slide 12___________________________________
_
5. Space: All organisms require enough space or territory to
insure adequate resources to food, water, shelter, and mates.
6. Oxygen: Most living organisms require oxygen for cellular
respiration, which is a process that releases energy from food.
7. Water: Water (humidity) is necessary for all life. The ability to
find water, to maintain water balance, and to conserve water,
help determine the habitat range for each species.
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Page | 194
Slide 13___________________________________
Biotic Factors
__________________________________
• Biotic factors – [Definition]
Biotic factors include:
1. Predator-prey relationships. This important biotic factor
helps to limit the size of populations within an
ecosystem. A predator is an
animal that kills and eats another animal for food. The prey is the
hunted animal. An example is the
lion and the zebra. When a lion kills
a zebra for food, the lion helps to
prevent the overpopulation of the
zebra. If the number of zebra declines
too much, the lion will starve. There
needs to be a balance between the
number of predator and prey in any
sustainable ecosystem.
_
__________________________________
_
__________________________________
_
__________________________________
_
_
__________________________________
__________________________________
_
Slide 14___________________________________
_
2. Disease is the result of infection by fungi, bacteria, virus,
and other pathogens. Disease is an important biotic
factor because disease tends to reduce the number of
organisms within the community.
__________________________________
_
__________________________________
3. Competition involves the struggle for survival which
occurs between two organisms. Competition tends to
limit the size of the population keeping it in balance
with the available resources. Populations
commonly compete for living space and / or food within an ecosystem.
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 15___________________________________
__________________________________
Two types of competition:
1. Interspecific Competition –
[Definition]
_
__________________________________
2. Intraspecific competition -
[Definition]
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
_
Page | 195
Slide 16___________________________________
_
4. Symbiosis - [Definition]
Here an osprey is nesting in a tree. What type of symbiosis is
this? Read on…
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 17___________________________________
_
Types of Symbiosis:
1. Parasitism – [Definition]
▪ Ex: Tapeworm
__________________________________
_
2. Commensalism – [Definition]
▪ Ex: Tree and nesting bird.
3. Mutualism – [Definition]
▪ Ex: Clownfish and anemone.
(Earlier YouTube video:
https://www.youtube.com/watch?v=fupYSpg64dM)
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 18___________________________________
_
Food Chains and Food Webs
In an ecosystem, certain organisms provide energy for
other organisms. These relationships are shown with food
chains and food webs.
__________________________________
_
Food chains
• Show a step-by-step sequence of which organism consumes
another in an ecosystem
• Each level in the food chain is called a trophic level.
__________________________________
• Producers are found in the first trophic level, then
consumers in all levels afterward.
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Page | 196
Slide 19___________________________________
__________________________________
• Producers (a.k.a. autotrophs)
are organisms that can make
their own food. These are
located in the first trophic level.
Producers are organisms which
use photosynthesis or another
form of chemical synthesis to
make food. Ex: plants, algae
and some types of bacteria
• Consumers (a.k.a.
heterotrophs) are organisms
that cannot make their own food,
and thus obtain nutrients from
consuming other organisms.
There are several groups of
heterotrophs: herbivores,
carnivores, omnivores and
decomposers.
_
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
Slide 20___________________________________
_
Primary consumers are
organisms that feed on the
producers, located in the second
trophic level. (These are
herbivores: they eat only plants)
Secondary consumers are
located in the third trophic level
and feed on the organism in the
second trophic level (These are
carnivores – eat only meat, or
omnivores – eat plant and meat)
Tertiary consumer is the “top
carnivore”, found at the fourth
tropic level. This is an organism
that relies on the secondary
consumers as its principal source
of energy.
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 21___________________________________
__________________________________
Check out YouTube: “The Food Chain”
https://www.youtube.com/watch?v=0ZOvqYypOuo
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
_
Page | 197
Slide 22 ___________________________________
_
Scavengers and Decomposers
Some food chains include organisms
considered to be scavengers or
decomposers:
• Scavengers consume decaying
organic material, such as meat or
rotting plant material.
• Decomposers (a.k.a Saprobes) are
organisms or microorganisms that
complete the final breakdown of
organic matter; an organism that
feeds on detritus (waste from plants
and animals, including their dead
remains) in the process releasing
nutrients to the soil and water,
where they can be used (again) by
other organisms.
How do scavengers and decomposers allow the “circle of life” in an
ecosystem to continue?
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 23___________________________________
a food web. Which organisms in the above food web would be
Food Webs
• To show all the feeding relationships in an ecosystem we can use
competing?
__________________________________
__________________________________
_
_
__________________________________
__________________________________
_
_
__________________________________
__________________________________
_
_
Slide 24___________________________________
_
Sustainable Ecosystems Depend Upon
Diverse Food Webs
__________________________________
• For an ecosystem to be sustainable there must be a balance
between food production, food consumption, and
decomposition.
_
• This means that a stable ecosystem must have:
• a source of energy (usually sunlight for photosynthesis)
• producers to capture the sunlight and make food
__________________________________
• consumers to eat the food
• decomposers to recycle the nutrients back to the producers.
• Resilience is the ability of an ecosystem to remain functional
and stable in the presence to disturbances of its parts. A more
diverse food web is directly related to a more resilient ecosystem.
Why do you think this is the case?
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Page | 198
Slide 25___________________________________
Check out YouTube: “The Food Web”
_
https://www.youtube.com/watch?v=MGODmyXkkPU
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
Slide 26___________________________________
_
The Pyramid of Energy (This is an optional topic.)
The “10 Percent Rule” mentioned in the earlier video leads to the
idea of the pyramid of energy as we go up the trophic levels in a
food chain or food web.
The pyramid of energy is a measurement or indication of the energy
present at each trophic level. Energy is measured in Joules, “J”.
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 27___________________________________
• In general, 10% of all the energy in a lower trophic level
gets passed on to the next higher level. This generalization
suggests that 90%
of the energy taken in by an organism at any trophic level is lost by
the life processes of that organism as well as lost as heat. Hence the
“10 Percent Rule”.
• As a result of this pyramid of energy, the amount of life that
can be sustained at each level, going to the top,
decreases. This is why there are so few if any fourth
order consumers in an ecosystem.
_
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
Page | 199
Slide 28___________________________________
_
Pesticide Use and Food Chains
Textbook page 310
Pests are living organisms that man
believes are undesirable, and are not
wanted around us. Examples include:
- unwanted dandelions in lawns;
- rodents or insects that eat fruits,
vegetables or other crops;
- micro-organisms that cause disease
in forest, fish, or crop resources.
Pesticides are chemicals designed to
kill pests
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 29___________________________________
_
Early Pesticide Use
Early pesticides included the use of toxic
inorganic metallic compounds such as lead salts,
arsenic, or mercury.
These substances were generally effective against
the intended pest, but also created some
environmental problems because they also killed
other beneficial organisms, and polluted water
and soil resources used by man.
Most early pesticides were non-biodegradable
(meaning that they were not broken down within
the ecosystem). As a result, these early pesticides
began to accumulate in the environment,
contaminating water and soil resources.
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 30___________________________________
_
“Modern” Pesticides
By the twentieth century, chemists began to develop
organic pesticides that were designed to be less toxic to
man and more specific toward the intended pests.
Although this was initially believed to be a step in the
right direction, man soon discovered that the organic
pesticides also caused unexpected environmental
effects. Some of these pesticides were fat soluble. This
characteristic lead to a problem known as
bioaccumulation.
__________________________________
_
__________________________________
_
Enter DDT…
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Page | 200
Slide 31___________________________________
_
A Pesticide “Legend”: DDT
DDT is a chlorine-containing organic pesticide,
developed in the earlier part of the 20th century.
DDT was one of the first chemicals in widespread use
as a pesticide. Following World War II, it was
promoted as a wonder-chemical, the simple solution to
pest problems large and small.
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 32 ___________________________________
_
Organic pesticides that contain chlorine, such as DDT,
are soluble in fat but not in water
As a result, they cannot be released in urine or sweat,
and bioaccumulate in the fatty tissues of animals
Small amounts of chemicals enter the food chain at the
lowest levels…
… but the problems gets worse and worse as the toxin
moves up the trophic levels of the food chain.
At each stage of the food chain, the concentration of
toxins gets higher; so the higher the trophic level, the
greater the amount of toxins
This process is referred to as bioamplification or
biomagnification.
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 33 ___________________________________
_
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
Page | 201
Slide 34 ___________________________________
_
One example of this problem is illustrated by the
damage done to predatory birds as a result of
bioaccumulation of DDT.
__________________________________
_
__________________________________
_
As a result of this problem, DDT has been banned
from use in North America since the 1970s.
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Slide 35___________________________________
_
Mercury and Methylmercury Bioaccumulation
See: https://www.youtube.com/watch?v=1vwjZseY-9w
__________________________________
_
__________________________________
_
__________________________________
_
__________________________________
__________________________________
_
_
__________________________________
Page | 202