Population Ecology Factors

C.5 Population ecology (AHL)
Essential idea: Dynamic biological processes impact population density
and population growth.

Understandings, Applications and Skills
Statement Guidance
C.5 U.1 Sampling techniques are used to estimate population size.
C.5 U.2 The exponential growth pattern occurs in an ideal, unlimited environment.
C.5 U.3 Population growth slows as a population reaches the carrying capacity of the
environment.
C.5 U.4 The phases shown in the sigmoid curve can be explained by relative rates of
natality, mortality, immigration and emigration.
C.5 U.5 Limiting factors can be top down or bottom up.
C.5 A.1 Evaluating the methods used to estimate the size of commercial stock of marine
resources.
C.5 A.2 Use of the capture-mark-release-recapture method to estimate the population
size of an animal species.
C.5 A.3 Discussion of the effect of natality, mortality, immigration and emigration on
population size.
C.5 A.4 Analysis of the effect of population size, age and reproductive status on
sustainable fishing practices.
C.5 A.5 Bottom-up control of algal blooms by shortage of nutrients and top-down control
by herbivory.
C.5 S.1 Modelling the growth curve using a simple organism such as yeast or species of
Lemna.

Populations
• The total number of individuals of a species in a given
area.
Populations are affected by four main factors
population size.

Four Factors Influence the Size of a Population:
Natality: Birth Rate (offspring
produced and added to population)
population size.

Mortality: Death Rate (individuals that die)
population size.

Immigration:Immigration: Movement of members of the species into the areaMovement of members of the species into the area
population size.

Emigration:Emigration: Movement of members of the species outMovement of members of the species out
of area to live elsewhere.of area to live elsewhere.
population size.

Population Changes

Population size oscillates around the carrying capacity (K)
Time
N
K
overshoot
oscillations
C.5 U.2 The exponential growth pattern occurs in an ideal, unlimited
environment.

• Density Dependent Limits
 Food
 Water and other important nutrients
(N, C, P, O…)
 Shelter
 Disease
• Density Independent Limits
 Natural Disasters
 Humans (logging, mining, farming)
Water and shelter are
critical limiting factors in
the desert.
Fire is an example of a
Density independent
Limiting factor.
Limits on
Population Growth

This graph shows the explosion of human population over the last
10,000 years along with some relevant historical events.

How did we get here?
• When I graduated in
high school in 1975 there
were 4 billion people.
*Today there are
almost 7 billion people
environment.

About 5 million years ago
Hunter-gathers
1 million people
environment.

Neolithic Period (6000 B.C.)
No longer a Natural Setting
100 million people
environment.

Common area 2000 years ago
300 million
people
environment.

1800’s (Carbon cycle control)
Steam engineSteam engine
1 billion people
environment.

London between 1800 to 1880
• 1800 pop. 1 million
• 1880 pop. 4.5 million
• Improvements in
medicine and public
health
environment.

Life Expectance
• Neolithic it was 20
• 1900 it was 30
• 1950 it was 47
• When I original did this
PowerPoint 4 years ago
67. Current world
average is 71

1800-2000?
• From 1 billion to 6 billion? How???
environment.

1908 Control of the Nitrogen Cycle
• Up until 1908 farms
were dependent on
organic sources for
nitrogen (manure)
• Haber figured out how to
convert N2 into NH3 and
then into NH4
+
of NO3
-
• Commercial fertilizers
are born
Fritz Haber
environment.

1944 Plant Breeding
• Improves yields
• Disease resistance
improvements
• Less day-length sensitive
• Improve sharing of ideas on
plant breeding
environment.

environment.
Examples of exponential population growth
http://www.nature.com/scitable/knowledge/library/an-introduction-to-population-growth-84225544
Throughout the 1800's, hunters
decimated the American
Plains bison populations, and
by 1889, only about one
thousand bison remained.
Exponential growth can occur when one of the
density dependent factors are a factor no
longer. The US government, along with private
landowners, established protected herds in the
late 1800's and early 1900's. The herds started
small, but with plentiful resources and few
predators, they grew quickly. The bison
population in northern Yellowstone National
Park increased from 21 bison in 1902 to 250 in
only 13 years.

C.5 U.3 Population growth slows as a population reaches the carrying capacity
of the environment.

3 Phases:
1. Exponential growth Phase
2. Transitional Phase
3. Plateau Phase
Limited Growth Sigmoid (S-Shaped)Sigmoid (S-Shaped)
of the environment.

1. Exponential Growth Phase
• Population increases
exponentially.
• Resources are abundant.
• Predators and disease are
rare.
of the environment.

2. Transitional Phase
• As a result of intra-specific
competition
 for food, shelter, nesting
space, etc.,
 and the build up of
waste.
• The growth rate slows down.
 Birth rates decline and
death rate increases
C.5 U.3 Population growth slows as a population reaches the carrying capacity of
the environment.

3. Plateau Phase
• Natality and mortality are equal so population size is constant.
• When the number of individuals in the population have reached the
maximum which can be supported by the environment.
The number is called the
CARRYING CAPACITY
of the environment.

C.5 U.4 The phases shown in the sigmoid curve can be explained by
relative rates of natality, mortality, immigration and emigration.
Limiting factors are environmental factors that controls
the maximum rate at which a process, e.g. population
growth, can occur.
• build-up of toxic by products
of metabolism
• Injury
• Senescence (death from age
related illness)

All examples of competition
for resources
• Injury
related illness)
of metabolism

of metabolism
The effect of these limiting
factors increases as the
population increases. These
factors are described as
being density dependent
limiting factors.
• Injury
related illness)

of metabolism
The this limiting factor does
not increases as the
population increases. This
factor is described as being a
density independent limiting
factor.
• Injury
related illness)
Examples include:
•Climate / weather
•Availability of light (for plants)
•Natural disasters such as volcanic eruptions and fire
C.5 U.4 The phases shown in the sigmoid curve can be explained by relative
rates of natality, mortality, immigration and emigration.

C.5 U.5 Limiting factors can be top down or bottom up.
A limiting factor is an environmental selection pressure that limits
population growth. There are two categories of limiting factor:
Top-down factors are pressures
applied by other organisms at higher
trophic levels.
Bottom-up factors are those that
involve resources or lower tropic
levels.
A keystone species exerts top-down influence
on its community by preventing species at
lower trophic levels from monopolizing critical
resources, such as competition for space or
food sources. http://commons.wikimedia.org/wiki/File:Tierpark_Sababurg_Wolf.jpg
http://commons.wikimedia.org/wiki/File:Green_Sea_Turtle_grazing_seagrass.jpg

C.5 A.5 Bottom-up control of algal blooms by shortage of nutrients and top-down
control by herbivory.
An algal bloom is a rapid increase or
accumulation in the population of
algae (typically microscopic) in a water
system. http://commons.wikimedia.org/wiki/File:Mar%C3%A9_vermelha.JPG

C.5 A.5 Bottom-up control of algal blooms by shortage of nutrients and top-
down control by herbivory.
http://commons.wikimedia.org/wiki/File:Algal_bloom_20040615.jpg
• The water around coral-reef ecosystems is generally nutrient-poor.
• Nutrients in these areas are needed in small amounts are essential for the synthesis
of key proteins and other compounds, e.g. magnesium is needed to make
chlorophyll.
• Algae depend on photosynthesis for nutrition.
• Free-living algae blooms can disrupt coral reef communities by blocking sunlight
and preventing photosynthesis in the symbiotic zooxanthellae. This can cause coral
bleaching (the corals eject the no longer useful zooxanthellae) which leads to the
death of the corals.
http://resources3.news.com.au/images/2011/04/28/1226046/589887-raw-sewerage.jpg

zooplankton feed on phytoplankton

With key proteins such as chlorophyll in
short supply the rate of photosynthesis
and hence algal growth is limited.
Nutrients are therefore a bottom-up
limiting factor.
Nutrient enrichment through human activity
(fish farming, fertilizer or sewage outflows
directly or from nearby rivers) can cause
known as eutrophication – algal populations
increase rapidly (blooms) due to the removal of
nutrients as a limiting factor.

C.5 S.1 Modelling the growth curve using a simple organism such as yeast or
species of Lemna.
In the absent of equipment using one or more of the following resources to model
population growth:
•Yeast Population Growth lab and simulation by i-Biology (
http://www.slideshare.net/gurustip/population-growth-9457952)
•Bunny population growth by PhET (
http://phet.colorado.edu/files/activities/3896/04.02 - CW - bunny simulation - 2014-07-30 - vdefin
Duckweed (Lemna sp.) is a good model organism for measuring sigmoidal
population growth
• Place a small number of plants in a container, e.g. a plastic cup
• Count the number of fronds (leaves) every day until the surface of the container is
covered, i.e. the population has ceased to increase.
• Plot your results – you should obtain a sigmoidal curve
• Your investigation can be extended by considering different independent variables
e.g. nutrient availability and the surface area of the container.

Why monitor populationsWhy monitor populations ??
• Determine current status of a population
• Determine habitat requirements of a species
• Evaluate effects of management
*Complete “census” of natural
populations is often very difficult!
Population Sampling

Population vs.Population vs.
SampleSample
SampleTrue Population

RANDOM SAMPLING
• A sampling procedure that assures that each
element in the population has an equal chance
of being selected
• Sampled population should be representative
of target population
Sample Methods
•Quadrat
•Mark-Recapture
•There are MANY more…

Quadrat Sampling
• A square frame is placed in a habitat
• All the individuals in the quadrat are counted
• The process is repeated until the sample size is large
enough

• Useful for small organisms or for organisms that do not
move

Converting a population study
into a graph

MARK-RECAPTURE (Lincoln
Index)
• Capture and mark known number of individuals
• 2nd
round of captures soon after
 Time for mixing, but not mortality
• Fraction of marked individuals in recapture
sample is estimate of the proportion of
population marked in first capture
C.5 A.2 Use of the capture-mark-release-recapture method to estimate the
population size of an animal species.

Marking methods
• Paint or dye
• Color band
 birds
• Unique markings
 Large mammals; keep photo record
• Toe clipping
 Reptiles, amphibians, rodents
• Radio Collars
• Micro chips
(NPS 2000)

Lincoln Index
Using mark-recapture sampling to estimate animal
populations
Population Size P =(# initially marked) x (total 2nd
catch)
(# of marked recaptures)
Or
N1 x N2
N3

Survey 1:
N1= 12
Survey 2:
N2 = 15
N3 = 4

• You capture and mark 150 fish in a lake. (This
must be a random, representative sample.)
• You release them back into the lake, allowing
enough time for them to remix with the population.
• You trap another 220 fish, of which 25 are
recaptures (i.e., marked from the initial trapping.
• What is your estimate of the total population of fish
in the lake?
Example:

• N1 = 150
• N2 = 220
• N3 = 25
• P = [(220)(150)] / 25
= 1320 FISH
Example:

Example:
• Use the Lincoln Index to monitor this mountain gorilla
population over time

C.5 A.2 Use of the capture-mark-release-recapture method to estimate the population
size of an animal species.

Human Effect on the World Fish PopulationHuman Effect on the World Fish Population
• Overexploitation of species affects the loss of
genetic diversity and the loss in the relative
species abundance of both individual and/or groups of
interacting species. Overexploitation may include over
fishing and over harvesting
• Historically, humans have fished the oceans, which
never seemed to pose a problem due to their
abundant resources. Gear (fish trap, gill nets, electro-

Population dynamics of fisheries
• A fishery is an area with an associated fish population which is
harvested for its commercial or recreational value. Fisheries
can be wild or farmed.
• Population dynamics describes the ways in which a given
population grows and shrinks over time, as controlled by birth,
death, and emigration or immigration. It is the basis for
understanding changing fishery patterns and issues such as
habitat destruction, predation and optimal harvesting rates.
• The population dynamics of fisheries is used by fisheries
scientists to determine sustainable yields
C.5 A.4 Analysis of the effect of population size, age and reproductive status on sustainable
fishing practices.

Sampling
method
Situation in which
the method is used
Usage and limitations
Random sampling Not used. Ineffective as fish are too mobile.
Capture-mark-
release-recapture
Fish are temporarily
stunned with electric
shocks and then
counted
Used in lakes and rivers, but
recapture numbers are too small
to be useful in open waters such
as oceans.
Echo sounders Can be used to
estimate the size of
fish shoals
Only useful for schooling fish
species
Fish catches Age structure of
landed fish can be
used to estimate
population size.
Violators of fishing regulations
designed to control the age of fish
landed often do not report what
they land or they dump the
restricted fish causing a bias in
the estimates.
Estimating Fish populations
C.5 A.1 Evaluating the methods used to estimate the size of commercial stock of marine
resources.

Sampling
method
Situation in which
the method is used
Usage and limitations
Random sampling Not used. Ineffective as fish are too mobile.
Capture-mark-
release-recapture
Fish are temporarily
stunned with electric
shocks and then
counted
Used in lakes and rivers, but
recapture numbers are too small
to be useful in open waters such
as oceans.
Echo sounders Can be used to
estimate the size of
fish shoals
Only useful for schooling fish
species
Fish catches Age structure of
landed fish can be
used to estimate
population size.
Violators of fishing regulations
designed to control the age of fish
landed often do not report what
they land or they dump the
restricted fish causing a bias in
the estimates.
Estimating Fish populations
• Fish are very mobile – they pursue what is
frequently a mobile food supply.
• They often school so are unevenly
distributed.
… so how can we count/estimate their
numbers?
If we know how big fish population are we
can fish sustainably, but ….

Maximum Sustainable Yield (MSY)
Based upon:
1. the harvest rate
2. the recruitment rate of new (young) fish into the
population
• a population can be harvested at the point in their
population growth rate where it is highest (the
exponential phase)
• Harvesting (output) balances recruitment (input)
• Fixed fishing quotas will produce a constant
harvesting rate (i.e. a constant number of
individuals fished in a given period of time)

Maximum Sustainable Yield
(MSY)

Maximum Sustainable Yield
• The Largest possible catch without adversely affecting the
ability of the population to recover.

Problems with MSY
Age structure: If all the age groups are harvested
recruitment of young fish into the reproductive group
will be reduced. The answer is to use a net with a big
enough mesh size that lets the young fish escape
Age and sustainable fishing
• If a population is growing, then the relative number of
younger fish will be higher (there are many potential
breeding fish for the future).
• If a population is in decline, then the proportion of older
fish will be higher (older fish have a higher mortality and
are unlikely to be as productive in breeding).

Problems with MSY
Limiting factors: If the limiting factors in the
environment change so does the population growth rate
• Limiting factors set the carrying capacity (K) of an
environment
• Increasing limiting factors will cause K to drop
• Fixed quotas cannot cope with this
• Data: For MSY to work accurate data in fish
populations is needed (population size, age
structure, recruitment rates)
• Usually these are not well known

What is required?
• Nets with bigger mesh size
• Regulated fishing methods
• More data on fish populations (e.g. by fish tagging
investigations – mark and recapture)
• Constant monitoring to observe changes in
environmental factors (e.g. El Niño events)
• Policing of fishing industry – respect of quotas
• International agreements
• Greater exploitation of fish farming
• But this is not without its own problems (space, diseases
and pollution are all associated with intensive fish culture)

A case study: The Peruvian
Anchovy (Engraulis ringens)
Universidad de La Serena

The Peruvian Anchovy
• This is a small (12-20cm), short-lived species maturing
in 1 year
• Anchovy live in the surface waters in large shoals off
the coast of Peru and northern Chile
• Here there are cold currents up-welling from the sea
bed bringing nutrients for phytoplankton
• Plankton is at the base of the food chain.

The collapse of the anchovy fishery
• In 1972 there was an El Niño event that brought warm tropical
water into the area
• The up-welling stopped,
• the phytoplankton growth decreased
• the anchovy numbers fell and concentrated further south
• The concentrated shoals of anchovy were easy targets for fishing
boat eager to recuperate their harvest
• The political will was not there to impose reduced quotas
• Larger catches were made
• No young fish were entering the population (no recruitment)
• No reproduction was taking place
• The fish stocks collapsed and did not recover

C.3 Impacts of humans on ecosystems
Essential idea: Human activities impact on ecosystem function.

Statement Guidance
C.3 U.1 Introduced alien species can escape into local ecosystems and become
invasive.
C.3 U.2 Competitive exclusion and the absence of predators can lead to
reduction in the numbers of endemic species when alien species become
invasive.
C.3 U.3 Pollutants become concentrated in the tissues of organisms at higher
trophic levels by biomagnification.
C.3 U.4 Macroplastic and microplastic debris has accumulated in marine
environments.
C.3 A.1 Study of the introduction of cane toads in Australia and one other local
example of the introduction of an alien species.
C.3 A.2 Discussion of the trade-off between control of the malarial parasite and
DDT pollution.
C.3 A.3 Case study of the impact of marine plastic debris on Laysan albatrosses
and one other named species.
C.3 S.1 Analysis of data illustrating the causes and consequences of
biomagnification.
C.3 S.2 Evaluation of eradication programmes and biological control as
measures to reduce the impact of alien species.

5 Serious Environmental Issues
1. Reduction in Biodiversity (Invasive Species)
2. Biomagnification
3. Plastics
4. Climate Change
5. Acidification of the Oceans

What Are Native Species?
•Native species are those that normally live and thrive in a particular community.
They occupy specific habitats and have specific niches in their native environment.
They have natural predators that help to keep their populations in check.
What Are Non-Native Species?
Species that migrate into an ecosystem or are deliberately or accidentally
introduced into an ecosystem by humans.
C.3 U.1 Introduced alien species can escape into local ecosystems and become
invasive.
Non-Native Species: Purple loosestrifeNative Species: Big Brown Bat

What are Invasive
Species?
•A species introduced into an
environment that is able to
outcompete and displace
the native species
C.3 U.2 Competitive exclusion and the absence of predators can lead to
reduction in the numbers of endemic species when alien species become
invasive.

Competition II
Competition I
Competi
tion III
Realized Niche
• Competitive Exclusion Principle – complete competitors cannot
coexist.
– One species must be displaced or go to extinction
• Fundamental niche – the set of resources a species can utilize in the
absence of competition and other biotic interactions.
• Realized niche – the observed resource use of a species in the presence
of competition.
– Realized niche may be found on the edge of the fundamental niche as a
result of competitive exclusion
• Does competitive exclusion occur in natural communities?

Competition for a Niche in Nature
•Competition in nature is rare
•Competition has been very common throughout the evolutionary history of
communities and has resulted in adaptations that serve to minimize competitive
effects
– Species have evolved to reduce competition
• We currently see the results of competition
• Invasive species?
Species can live together
Species may be driven to
extinction, change habitats, or
evolve feeding differences.
Some resources are not being
used, and a benefit can be
gained by utilizing that resource.
C.3 U.2 Competitive exclusion and the absence of predators can lead to reduction in the
numbers of endemic species when alien species become invasive.

C.3 U.2 Competitive exclusion and the absence of predators can lead to reduction in the
numbers of endemic species when alien species become invasive.
• The Cane Toad is native to South America is an invasive species in Australia. The Cane Toad
was introduced Australia control agricultural crop pests (grey-backed cane beetles) on sugar
cane.
• Largest at 4 lbs., with a length of up to 9 in. They reproduce in large numbers, secrets toxic
material from there skin and will eat just about anything.
• Some effects long term effect on Australian environment are:
 the depletion of native species that die eating cane toads
 poisoning of pets and humans
 depletion of native fauna preyed on by cane toads
 reduced prey populations for native insectivores.

Example of Alien Species invasion:
Zebra Mussels
•Small “D”-shaped clams
•Dark brown and white stripes
•Native to Caspian and Black seas.
•Arrived in the Great Lakes in 1980’s in
freshwater ballast of ships

• Damage ecology of lakes
and rivers
• Colonize in thick mats on
docks, boats, motors
and submerged rocks
• Killed native mussels
• Foul beaches with sharp
shells and pungent odor
• Compete with fish for
food
• Clog water supply pipes
and boa engines

Controlling Invasive Species
•Controlling invasive species once they have become
established is difficult.
•Control is also usually very expensive!
•There are four main ways that invasive species are
controlled:
– Physical control
– Chemical control
– Biological control
– Prevention
C.3 S.2 Evaluation of eradication programs and biological control as measures to
reduce the impact of alien species.
The Impact of Invasive Species
Ecological:
• Reduce native biodiversity
• Direct predation on local species
• Spread of disease
• Upset balance of local ecosystem

Chemical Control of Invasive
Species
•Chemical control involves applying
poison to eliminate invasive species
•E.g. Eradication of rats on
Henderson Island
– Use rodenticide (rat poison)
•Insecticides & pesticides
to control insect pests
•Herbicides (weed-killer)
to control plants
Biological Control of Invasive Species
•Uses a living organism to control invasive
species
•This organism may eat the invasive
species or cause it to become diseased
•Biological control agents must be carefully
assessed before release to ensure the
control species will not become invasive
itself
Physical Control of Invasive Species
Controlling plants:
• Mechanical – excavation, trimming,
etc.
• Removal of plants by hand
• Installation of growth barriers
Controlling animals:
•Culling
•Trapping and hunting
•Putting up barriers or fences
C.3 S.2 Evaluation of eradication programs and biological control as measures
to reduce the impact of alien species.

Biotechnology
•Blocking conception in rabbits –
called immunocontraception
•Single sex in offspring for carp – to
only produce male offspring
No functional gene -> no enzyme ->
no females!
As existing females in the population
die, each successive generation will
have fewer and fewer females, until
only males.
C.3 S.2 Evaluation of eradication programs and biological control as measures
to reduce the impact of alien species.

1. Soil tainted with pesticides
washes into a river system
where it enters the bodies of
zooplankton
2. A hundred of these small
organisms are eaten by one
small fish
Biomagnification is a process in
which chemical substances become more
concentrated at each trophic level. DDT,
dioxins, pesticides, TBT and mercury are
all examples of highly toxic chemicals that
are biomagnified.

1. Soil tainted with
pesticides washes into a
river system where it
enters the bodies of
zooplankton
organisms are eaten by
one small fish
fish are eaten by one
large fish
Biomagnification of DDT
Cause: DDT is a synthetic pesticide sprayed on crops and can be used against
malaria
Mosquitoes . It is washed into waterways in low concentrations, where it is biomagnified
up the food chain. It is highly toxic at high concentrations

C.3 U.3 Pollutants become concentrated in the tissues of organisms at higher trophic
levels by biomagnification.
1. Soil tainted with pesticides
washes into a river system
where it enters the bodies
of zooplankton
organisms are eaten by
one small fish
fish are eaten by one large
fish
4. A predatory bird eats 10
large fish
Consequences: Store in fats and accumulates quickly. Very high concentrations in
large
Fish and seabirds. It is responsible for reduced reproductive function and shells thinning
in birds, which has impacted populations of large birds of prey (e.g. bald eagle or
osprey) heavily.
In humans, it has been linked with cancers, fertility and development problems in
humans.

C.3 S.1 Analysis of data illustrating the causes and consequences of biomagnification.
Analysis questions:
1.Describe the trend shown by the
data.
2.Deduce the strength of the
correlation
3.Evaluate the limitations of the data
in supporting the link between DDT
and the decrease in Osprey.
http://fresc.usgs.gov/products/papers/2345_Henny.pdf
Biomagnification of DDT
effect on
Osprey (Pandion haliaetus):

Analysis questions:
4.Describe the trend shown
by the data in relation to
the use of DDT
5.Estimate the percentage
change in egg shell
thickness between 1972
and 2008
6.Suggest why the range of
egg shell thickness
increased after 1972.

Analysis questions:
7.Describe the correlation between DDE and egg shell thickness.
8.Evaluate the limitations of the data supporting the link between DDT and egg shell
thickness in Osprey.
9.Explain why egg shell thickness is correlated with sightings of Osprey

C.3 A.2 Discussion of the trade-off between control of the malarial parasite and DDT
pollution.
Sources of DDT
•DDT in soil can be absorbed by some growing plants and by the animals or people who eat those plants
•DDT in water is absorbed by fish and shellfish in those waterways
•Atmospheric deposition
•Soil and sediment runoff
•Improper use and disposal http://www.epa.gov/pbt/pubs/ddt.htm
What is DDT (dichlorodiphenyltrichloroethane)?
Prior to 1972 when its use was banned (in the US), DDT was a commonly used
pesticide.
What is it used for now?
Some parts of the world continue to use DDT in disease-control programs.
Why Are We Concerned About DDT?
Even though DDT has been banned since 1972, it can take more than 15 years to break down in our
environment.
What harmful effects can DDT have on us?
•Human carcinogen (e.g. liver cancer)
•Damages the liver
•Temporarily damages the nervous system (damages
developing brains)
•Reduces reproductive success (lower fertility and
genital birth defects)
•Damages reproductive system
How are we exposed to DDT?
•By eating contaminated fish and shellfish
•Infants may be exposed through breast milk
•By eating imported food directly exposed to
DDT
•By eating crops grown in contaminated soil

DDT pollution.
http://www.npr.org/templates/story/story.php?storyId=6083944
http://www.scientificamerican.com/article/ddt-use-to-combat-malaria/
http://www.telegraph.co.uk/news/science/science-news/10600234/Banned-pesticide-DDT-may-raise-risk-of-Alzheimers-disease.html

DDT pollution.
Pros Cons
• Affordable and effective at killing
mosquitoes that carry malaria
• It is sprayed inside homes and
buildings and people exposed may
suffer serious health effects (inc.
reduced fertility, genital birth
defects, cancer and damage to
developing brains)
• Where the use of DDT was
discontinued for malaria vector
control malarial rates and deaths
increased.
• Alternative strategies were not as
successful.
• Persists in the environment for long
periods of time (more than 15 years)
• Health costs (of treating malaria)
greatly reduced
“DDT should really be the last resort against malaria, rather
than the first line of defense” http://www.scientificamerican.com/article/ddt-use-to-combat-malaria/

environments.
The “Little Blue
Dot”
Our Planet is made up of
70% water.
There Is
326,000,000,000,000,000,
000 gallons (326 million
trillion gallons of water on
the Earth).
96% of water on the
Earth is ocean water

environments.

Facts on Ocean Pollution
Fourteen billion pounds of
garbage, mostly plastic, is
dumped into the ocean every
year
Over 80% of the pollution in the
ocean is runoff from the Land
Almost 90% of all floating
materials in the ocean are plastic
Marine debris, especially plastic,
kills more than one million
seabirds and 100,000 mammals
and sea turtles every year
Dead Zones which are areas of
oxygen deficient water were life
ceases to exist, have increased
drastically over the past decade.
environments.

environments.
• Large visible
plastic debris >
1mm (e.g. bottles,
nets, bags, buoys)
is defined as
Macroplastic

environments.
• Plastic debris < 1mm is defined as Microplastic
< 1mm. It is harder to see but it is estimated to
account for 65% of all ocean debris
Sources include:
 plastic bottles and bags
 detergent containers
 food wrapping
 synthetic clothes (fibers released after every
wash)
• Most plastics are not biodegradable and may
persist for centuries.

C.3 A.3 Case study of the impact of marine plastic debris on Laysan
albatrosses and one other named species.
• Bits of plastic debris litter the shore:
bottle caps, toys, cigarette lighters,
fishing line and other garbage.
• Plastic trash leaves a wake of death
and disease that directly affects
seabirds.
• In many areas of the globe, birds
inadvertently feed on plastic floating
on the water, mistaking it for food
• A report by scientists studying the
stomach content of Laysan Albatross
chicks on Midway Atoll in the Pacific
Ocean revealed disturbing results:
Forty percent of Laysan Albatross
chicks die before fledging.

C.3 A.3 Case study of the impact of marine plastic debris on Laysan
albatrosses and one other named species.
Zooplankton:
•Typically these tiny animals are found near the
surface in aquatic environments. Usually weak
swimmers and usually just drift along with the
currents .
•Zooplankton are at the bottom of a food chain for an
entire food web stretching from the smallest fish to
the largest whale. Many of the ocean's largest animals
feed on zooplankton. When they ingest zooplankton
they are ingesting plastic with them.
•Microbeads are nano-size plastic fragments which are
easily absorbed by sea life from plankton, which are
then eaten and remain in the food chain in larger fish -
and even humans.
•Some lab tests have shown that these fragments can
even enter cells and cause tissue damage.
Read more:
http://www.dailymail.co.uk/sciencetech/article-3330671/The-hidden-PLASTIC-lurking-food-Hundreds-tiny-micro-beads-sea-salt-swallow-1-000-year.html#ixzz

Essential idea: Concentrations of gases in the atmosphere affect climates
experienced at the Earth’s surface.
4.4 Climate change
Aerial view, meltwater on Greenland ice sheet
http://wired.tw/posts/balog_glacier_photographs

Statement Guidance
4.4 U.1 Carbon dioxide and water vapour are the most significant
greenhouse gases.
4.4 U.2 Other gases including methane and nitrogen oxides have
less impact.
The harmful consequences of ozone depletion
do not need to be discussed and it should be
made clear that ozone depletion is not the
cause of the enhanced greenhouse effect.
4.4.U.3 The impact of a gas depends on its ability to absorb long
wave radiation as well as on its concentration in the
atmosphere.
Carbon dioxide, methane and water vapour
should be included in discussions.
4.4 U.4 The warmed Earth emits longer wavelength radiation
(heat).
4.4 U.5 Longer wave radiation is absorbed by greenhouse gases
that retain the heat in the atmosphere.
4.4 U.6 Global temperatures and climate patterns are influenced
by concentrations of greenhouse gases.
4.4 U.7 There is a correlation between rising atmospheric
concentrations of carbon dioxide since the start of the
industrial revolution 200 years ago and average global
temperatures.
4.4 U.8 Recent increases in atmospheric carbon dioxide are
largely due to increases in the combustion of fossilized
organic matter.
4.4 A.1 Threats to coral reefs from increasing concentrations of
dissolved carbon dioxide.
4.4 A.2 Correlations between global temperatures and carbon
dioxide concentrations on Earth.
4.4 A.3 Evaluating claims that human activities are not causing
climate change.

http://www.sumanasinc.com/webcontent/animations/content/globalcarboncycle.html
The surface of the Earth absorbs short-
wave solar energy and re-emits at longer
wavelengths (as heat).
Approx. 25% of
solar radiation is
absorbed by the
atmosphere.
Approx. 75% of solar
radiation penetrates the
atmosphere and reaches
the Earth’s surface.
Up to 85%* of re-emitted heat is captured
by greenhouse gases in the atmosphere.
*This value, though variable, is known to be
rising; very likely the result of human activities.
Heat passes back to the surface of
the Earth, causing warming
How the greenhouse effect works
1
2
3
4
5
4.4 U.4 The warmed Earth emits longer wavelength radiation (heat).
4.4 U.5 Longer wave radiation is absorbed by greenhouse gases that retain the heat in the
atmosphere.

http://www.sumanasinc.com/webcontent/animations/content/globalcarboncycle.html
The surface of the Earth absorbs short-
wave solar energy and re-emits at longer
wavelengths (as heat).
Approx. 25% of
solar radiation is
absorbed by the
atmosphere.
Approx. 75% of solar
radiation penetrates the
atmosphere and reaches
the Earth’s surface.
Up to 85%* of re-emitted heat is captured
by greenhouse gases in the atmosphere.
*This value, though variable, is known to be
rising; very likely the result of human activities.
Heat passes back to the surface of
the Earth, causing warming
(GLOBAL WARMING)
Remember the Greenhouse Effect is a natural process!!!
1
2
3
4
5
If the Earth had no atmosphere, and hence no
greenhouse effect, the average surface
temperature would be approx. -18oC. Suggest the
impact to life on Earth if this occurred.
Watch a Greenhouse
animation HHMI

4.4 U.5 Longer wave radiation is absorbed by greenhouse gases that retain the
heat in the atmosphere
• The ability of the Earth’s surface to reflect light is called the albedo effect.
• Light colored and white objects such as snow and ice, have a high albedo
and therefore little light is absorbed and less heat is produced. Black and dark
colored objects like asphalt and pavement have a low albedo, and therefore
absorb more light and produce more heat.
•With the spread of
urban cities and
areas, a greater
amount of heat is
being produced

4.4 U.3 The impact of a gas depends on its ability to absorb long wave radiation
as well as on its concentration in the atmosphere.
The Earth is kept much warmer by gases in the atmosphere that retain
heat. These gases are referred to as greenhouses gases. The
greenhouse gases that have the largest warming effect on the Earth are:
carbon dioxide, water vapor, Nitrogen oxides and methane
Greenhouse gases together make up less than 1% of the atmosphere.

Where does the CO2come and go?
Atmospheric CO2 is formed from (The
sources…)
• Volcanic outgassing
• Burning of organic matter (Fossil
Fuels)
• Respiration of living organisms
• …
CO2can be stored in (The Sinks…)
• Highly soluble in water: forms H2CO3
(Carbonic Acid)
• Dissolved CO2 in water can interact
with silicate minerals to form
carbonated minerals…
• …
4.4 U.1 Carbon dioxide and water vapor are the most significant greenhouse
gases.
• CO2 is removed by photosynthesis
and absorption by the oceans

4.4 U.1 Carbon dioxide and water vapor are the most significant greenhouse
gases.
Sources of Water Vapor
• Water is formed by the
evaporation of the oceans, seas
and lakes and transpiration in
plants
• It is removed from the atmosphere
by precipitation (rainfall and snow)
• Water continues to retain heat
after it condenses to form droplets
of liquid water in the clouds
• Water reabsorbs heat energy and
radiates it back to Earth’s surface
and also reflects the heat energy
back
• This explains why the temperature
drops so quickly at night in areas
with clear skies than those with

• Earth is undergoing global warming
because of human-generated
greenhouse gases are causing the
atmosphere to retain more and
more heat
• Carbon dioxide, methane, and
oxides of nitrogen are main culprits
Oxides of nitrogen (NOx) :
 released naturally by bacteria
in some habitats and also by
agriculture and vehicle exhaust
Methane (CH4) :
 emitted from marshes, other
water-logged habitats and
from landfill sites containing
organic wastes
4.4 U.2 Other gases including methane and nitrogen oxides have less
impact.
http://extras.mnginteractive.com/live/media/site525/2
013/1103/20131103__EPT-L-LANDFILLS-
1104~p2_500.jpg

http://radioviceonline.com/wp-content/uploads/2009/11/knorr2009_co2_sequestration.pdf
Industrial revolution
has started
Large increases in
usage of fossil fuels
The link between human emissions and atmospheric levels of CO2
Key points
•There is a strong correlation
between human emissions and
atmospheric levels of CO2
•As atmospheric CO2 levels have
increased the amount of CO2
absorbed by carbon sinks has
increased (only about 40% of
emissions have remained in the
atmosphere)
anthropogenic = human caused

• Climate refers to the patterns of temperature and precipitation that
occur over long periods of time, thousands or millions of years
• Climatologists collect and study data about atmospheric conditions in
recent decades and from the distant past in order to infer what the
climate was like thousands to millions of years ago
• Since greenhouse gases cause the earth to retain heat, one can infer
that the more greenhouse gas there is in the atmosphere, the
warmer the earth will be.
• This does not mean that the amount of greenhouse gas is the only
reason for the Earth warming and cooling; however, there is a
correlation between the Earth’s temperature and the amount of
greenhouse gas
– Other factors such as the cycles in the Earth’s orbit around the
sun, variations in the amount of solar radiation due to sunspot
activity, past volcanic activity, and changes or oscillations in ocean
currents
4.4 U.6 Global temperatures and climate patterns are influenced by
concentrations of greenhouse gases.

4.3 A.2 Analysis of data from air monitoring stations to explain annual fluctuations.
Monitor CO2 in the middle of nowhere

4.3 A.2 Analysis of data from air monitoring stations to explain annual fluctuations.
•CO2 levels fluctuate
annually (lower in the
summer months when long
days and more light increase
photosynthetic rates)
•Global CO2 trends will conform to
northern hemisphere patterns as it
contains more of the planet’s land
mass (i.e. more trees)
•CO2 levels are steadily
increasing year on year
since the industrial
revolution (due to increased
burning of fossil fuels)
•Atmospheric CO2 levels are
currently at the highest levels
recorded since measurements
began
Atmospheric CO2 concentrations have been measured at the Mauna Loa
Observatory (in Hawaii) since 1958. From these continuous and regular
measurements a clear pattern of carbon flux can be seen below:

4.4 U.7 There is a correlation between rising atmospheric concentrations of carbon dioxide since
the start of the industrial revolution 200 years ago and average global temperatures.
4.4 U.8 Recent increases in atmospheric carbon dioxide are largely due to increases in the
combustion of fossilized organic matter.
Key points
•Global temperatures
show large variations (for
various reasons)
•(despite this) there is
strong support for
correlation between
atmospheric carbon
dioxide and global
temperatures
Watch Video

• To deduce historic carbon dioxide
concentrations and temperatures
ice cores are drilled in Antarctic
ice sheets
• A cylinder of ice was collected by
drilling from to the bottom of the
Antarctic ice sheet. The total
length of the core was 2083
meters.
• The core shows annual layers,
which can be used to date the air
bubbles trapped in the ice.
• Analysis of the gas content of the
bubbles gives both the
concentration of carbon dioxide in
the atmosphere and the air
temperature (from oxygen
isotopes) at the time ice was
formed.
Sample ice
core
The Long-Term Stability of Earth’s Climate−400,000
years

4.4 A.2 Correlations between global temperatures and carbon dioxide
concentrations on Earth.
The atmospheric
concentration of CO2
measured from Antarctic
ice core data implies
that Earth’s climate has
being pretty stable over
the past 400,000 years
It also shows a rapid
increase of about 30%
in the past few
centuries…
280 ppm (parts per
million) to 380 ppm
CO2 concentration and
global temp are
correlated but not
directly proportional as
other variable factors
affect temperature.

4.4 A.3 Evaluating claims that human activities are not causing climate change.
http://www.skepticalscience.com/
Many claims that human activities
are not causing climate change have
been made in the media, whether it
be in newspapers, on television or on
the internet.
It is important to realize that not all
sources are trustworthy and it is
important to know the motivation of
those publishing claims on either side
of the debate.
Video: The Truth About Global
Warming - Science & Distortion
- Stephen Schneider

Example of criticisms
•There is some evidence showing that the current temperature isn’t really that warm
when compared to what was two to three thousand years ago. The figure to the
right shows that the temperature of Sagaso Sea fluctuates in a range of 3.6°C.

There are also evidence showing that the solar activity seems to have
some influence on atmospheric temperature. But there are many
questions here. Especially on how and how much.

• At this point, it appears that
the warming itself is real – the
surface temperature indeed
becomes higher in the last few
decades.
• The question is – Is the
warming caused by the
greenhouse gases (especially
CO2)?
• Some groups, especially the
IPCC members argue strongly
for it. But there are other
groups that are not convinced.
The summary to the right is
from Robinson et al. (1998).
Not everybody is convinced of the greenhouse gases - global warming theory

What is ocean acidification?
•Ocean acidification is the ongoing decrease in the pH of the
Earth's oceans, caused by the uptake of carbon dioxide from the
Earth’s atmosphere.
•pH of surface layers of the earth’s oceans in the late 18th
century ≈ 8.1179
currently ≈ 8.069, which represents about a 30% acidification.
4.4 A.1 Threats to coral reefs from increasing concentrations of dissolved
carbon dioxide.
• Over 500 billion
tones of CO2
released by
humans since the
start of the
industrial
revolution have
been dissolved in
the oceans
The burning of fossil fuels releases
11 BILLION TONS
of carbon dioxide into the atmosphere
every year

• Reef-building corals that use calcium carbonate in their exoskeletons need to absorb
carbonate ions from seawater.
• The concentration of carbonate ions is low in seawater because they are not very soluble.
• Dissolved CO2
makes the carbonate concentration even lower as a result of some
interrelated chemical reactions
• If the carbonate ions concentrations drop it is more difficult for reef-building corals to
absorb these ions to make their exoskeletons
•Also, if seawater ceases to be a saturated solution of carbonate ions, existing calcium
carbonate tends to dissolve, so existing exoskeletons of reef-building corals are threatened.

Ocean acidification: Impacts on individual
marine organisms
Thinner, smaller and weaker shells in shellfish
• Especially larval stages, which already have thin
shells
•Fitness effect: Lower survival due to
 increased crushing and drilling by
predators,
 increased risk of desiccation during low
tide Normal
Acidic
Really
acidic
carbon dioxide.

Ocean acidification: Impacts on individual marine organisms
Reduced fertilization of gametes in corals and other marine organisms
• Deformed flagellum in sperm that impacts their swimming
• Fitness effect: lower population growth
Normal
Acidic
Natural range in the ocean
carbon dioxide.

• Volcanic vents in the Gulf of Naples have been releasing carbon dioxide
into the water for thousands of years, reducing the pH of the seawater.
• In this area of acidified water there are no corals, sea urchins or other
animals that make their exoskeletons from calcium carbonate.
• In their place other organisms like invasive algae and sea grasses flourish.
• Unfortunately this could be the disheartening future for coral reefs around
the world if carbon dioxide emissions continue to rise.

4.4.A1 Threats to coral reefs from increasing concentrations of dissolved carbon dioxide.
Ocean acidification – the causes and effects
Research indicates that, by 2100 coral reefs may erode faster than they can be
rebuilt. This could compromise the viability of these ecosystems and the
(estimated) one million species that depend on coral reef habitat.

C.4 Conservation of biodiversity
Essential idea: Entire communities need to be
conserved in order to preserve biodiversity.

Statement Guidance
C.4 U.1 An indicator species is an organism used to assess a specific
environmental condition.
C.4 U.2 Relative numbers of indicator species can be used to calculate the value
of a biotic index.
C.4 U.3 In situ conservation may require active management of nature reserves
or national parks.
C.4 U.4 Ex situ conservation is the preservation of species outside their natural
habitats.
C.4 U.5 Biogeographic factors affect species diversity.
C.4 U.6 Richness and evenness are components of biodiversity.
C.4 A.1 Case study of the captive breeding and reintroduction of an endangered
animal species.
C.4 A.2 Analysis of the impact of biogeographic factors on diversity limited to
island size and edge effects.
C.4 S.1 Analysis of the biodiversity of two local communities using Simpson's
reciprocal index of diversity.
The formula for Simpson’s
reciprocal index should be
known by students.

Monitoring pollution Scientists monitor
pollution of water, air and land. Below is a list
of groups who keep track of environmental
changes
• Some are researchers at
universities
• International organizations
• Governments
• Local authorities
• Power companies
Ways to monitor pollution
•Data recorders: measure changes in
concentrations of particular chemicals.
•There are plants and animals (indicator
species) scientists look to for longer-term
effects of pollution.
C.4 U.1 An indicator species is an organism used to assess a specific
environmental condition.
Different Lichens are susceptible to
differing levels of air pollution (e.g.
sulfur dioxide, which causes acid

Low pollution
high pollution
Shrubby lichen
Leafy lichen
Crusty lichen
Lichen
•Lichens are sensitive to the
amount of sulphur dioxide,
some species more than
others.
•The species present and
number of different species
give clues about air
pollution.
•Lichens grow slowly, they
indicate long-term purity of
the air.
•Air pollution is also
monitored daily with
chemical tests
Animals
•Invertebrate animals are
good indicators of water
pollution. Some can live in
very polluted water others
can only live in clean water
Clean
water
Very polluted
water
Stone fly
nymph
Freshwate
r shrimp
Sludge worm
C.4 U.1 An indicator species is an organism used to assess a specific environmental condition.

Biotic Index: Measure tolerance to
pollution
•Biotic Index (BI) and the Family Biotic Index (FBI) have
tolerance values range from 0 for organisms very
intolerant of organic wastes to 10 for organisms
very tolerant of organic wastes.
•BI and FBI values provide an overall environmental
assessment of an ecosystem
•A change in the biotic index over time indicates a
change in the environmental conditions
http://lakes.chebucto.org/ZOOBENTH/BENTHOS/tolerance.html
Culicidae (sow bugs)
(FBI) of 8
C.4 U.2 Relative numbers of indicator species can be used to calculate the
value of a biotic index.
The formula for
calculating the Biotic
Index is:
Dixidae (dixid midges)
(FBI) of 1

Evenness
If a habitat has similar abundance for
each species present, the habitat is said
to have eveness.
Biodiversity
is variety of organisms present in an ecosystem
Richness
The number of different species
present.
More
species
therefore
highest
richness
Greatest evenness as the
two populations have
similar abundance.
http://www.nature.com/nature/journal/v405/n6783/images/405212aa.2.jpg

Simpson diversity index
The index of diversity is used as a measure of the range and numbers of
species in an area. It usually takes into account the number of species
present and the number of individuals of each species. It can be calculated
by the following formulae:
D= Diversity index
n = number of individuals of a each species found in an area.
N = total # of organisms of all species found in an area.
The simpson diversity index is a measure of species richness.
A high value of D suggests a stable and ancient site.
C.4 S.1 Analysis of the biodiversity of two local communities using Simpson's reciprocal
index of diversity.
D =
N (N - 1)
Σ n (n - 1)

Example 1:
Crested newt 8
Stickleback 20
Leech 15
Great pond snail 20
Dragon fly larva 2
Stonefly larva 10
Water boatman 6
Caddisfly larva 30
N = 111
N(N-1) = 111(111-1) = 12,210
∑n(n-1) = (8x7) + (20x19) + (20x19) + (15x14) +
(20x19) +
(2x1) + (10x9) + (6x5) + ( 30x29) =
2018
D = 12,210 =6.05
2018
C.4 S.1 Analysis of the biodiversity of two local communities using Simpson's reciprocal
index of diversity.
Example 2: In another pond there were:
Crested newt 45
Stickleback 4
Leech 18
Great pond snail 10
N=77
N(N-1) = 77(77-1) = 5,852
∑n(n-1) = (45x44) + (4x3) + (18x17) + (10x9)
D = 2.6
Comparing both indices, 6.05 is an indicator
of greater diversity. The higher number
indicates greater diversity

Compare the biodiversity of the
two samples:
D =
N (N - 1)
Σ n (n - 1)
Simpson’s Reciprocal Index
total of organisms of all species
number of organisms
of a single species
the sum of
(all species)

C.4 S.1 Analysis of the biodiversity of two local communities using
Simpson's reciprocal index of diversity.
Compare the biodiversity of the two samples:
Species* Count
A 6
B 1
C 1
Total 8 *correct names not required
Species* Count
A 4
B 4
Total 8

two samples:
D =
N (N - 1)
Σ n (n - 1)
number of
organisms of a
single species
the sum of
(all
species)
Species* Count
A 6
B 1
C 1
Total 8
Sample A
D =
8 (8 - 1)
6 (6 - 1) + 1 (1 - 1) + 1 (1 - 1)
D = 1.87
56
30 + 0 + 0
=

two samples:
D =
N (N - 1)
Σ n (n - 1)
number of
organisms of a
single species
the sum of
(all
species)
Species* Count
A 4
B 4
Total 8
Sample B
D =
8 (8 - 1)
4 (4 - 1) + 4 (4 – 1)
D = 2
56
12 + 12
=
Sample B has slighter higher
biodiversity

Extinction Example: Humans hunting and inadvertently introduction of rats,
cats and pigs to the island of Mauritius. In addition human activity altered the
habitat of the island, driving the Dodo into extinction. Humans have greatly
accelerated rate of extinction on Earth.
Dodo bird
Extinction of a particular animal or plant species occurs when there are no
more individuals of that species alive anywhere in the world - the species has
died out

In situ: (advantages)
• Conservation of species in
their natural habitat
• E.g. natural parks, nature
reserves
• The species will have all the
resources that it is adapted
too
• The species will continue to
evolve in their environment
• The species have more space
• Bigger breeding populations
can be kept
• It is cheaper to keep an
organism in its natural habitat
• Habitat remains available to
other endangered species
or national parks.
Set in the Coral
Triangle, the island of
Borneo is protecting
of orangutans and
their habitat

Sometimes In Situ conservation is the only way to preserve life due to the diversity of an
area it would be impossible to recreate in an Ex situ example:
Example
•The Coral Triangle is a nursery of the seas live 76% of the world’s coral species, 6 of
the world’s 7 marine turtle species, and at least 2,228 reef fish species.
•Only 2.6 percent of the Coral Triangle’s reefs are currently protected
•A nature reserve of this size can:
 Be protected by laws
 Make it more difficult of invasive species to crowd out natives
 Limit human exploitation
or national parks.

Island size on biodiversity
• Found in the coral triangle, Papua
New Guinea comprises about 600
small islands.
• Size of the island plays a large part
in the biodiversity found on that
island

Critical issues for nature reserve: Size Population studies show that large
parks and protected areas in Africa contain larger populations of each species than
small parks
C.4 A.2 Analysis of the impact of biogeographic factors on diversity limited to island size and edge
effects.
Large Nature Reserves
Benefits :
•More niches
•Opportunity for migration
•Increase Biodiversity
•Increase resource
•Increase in breeding sites
•Increase in habitats

Critical issues for nature reserve: Buffer zones
1.zoning
2.model
–reserve core
–buffer zone (compatible with core goals)
–transition zone (can link several reserve systems)

Corridors (Increase Biodiversity)
• periodic movement
• migration, seasonal
movements
• immigration & emigration
Critical issues for nature reserve: Connecting fragmented habitats

Critical issues for nature reserve: edge effects refer to the changes
in population or community structures that occur at the boundary of
two habitats. Areas with small habitat fragments exhibit especially pronounced
edge effects that may extend throughout the range. As the edge effects
increase, the boundary habitat allows for greater biodiversity.
The amount of forest
edge has increased in the
United States.
Dragonflies have trouble
surviving on the forest
edges.

Critical issues for nature reserve: Design Population studies show that
compositions of parks and protected areas may determine how success effort are at
protection.
C.4 A.2 Analysis of the impact of biogeographic factors on diversity limited to island size and
edge effects.

Ex situ conservation
•Conserving species in isolation of
their natural habitat
•E.g. zoos, botanical gardens, seed
banks
•Captive breeding of endangered
species is a last resort
•These species have already reached
the point where their populations
would not recover in the wild
•It works well for species that are
easily bred in captivity but more
specialised animals are difficult to
keep (aye aye)
•Isolated in captivity they do not
evolve with their environment
habitats.
e.g. Captive breeding of Pandas at the W
Smithsonian’s National Zoo
(only about 2,000 still exist in the wild)

habitats.
Zoos: The land of the living dead?
•They have a very small gene pool in which
to mix their genes
•Inbreeding is a serious problem
•Zoos and parks try to solve this by
exchanging specimens or by artificial
insemination where it is possible
•In vitro fertilization and fostering by a
closely related species has even been tried
(Indian Guar – large species of cattle -
cloned)
•Even if it is possible to restore a
population in captivity the natural habitat
may have disappeared in the wild
•Species that rely on this much help are
often considered to be “the living dead”

C.4 A.1 Case study of the captive breeding and reintroduction of an
endangered animal species.
• California condors (Gymnogyps
californianus) are the largest land
birds in North America with a wing
span of over nine feet.
• Lead poisoning has been the single
greatest threat to the survival of
condors. Along with micro trash,
Condors sometimes eat plastic, glass
and other trash and the pesticide
DDT.
• The first species to be listed under
the Endangered Species Act in 1973.
By 1987, the entire wild population
had been reduced to 22 wild birds,
which were taken into captivity.
• Reintroduction of birds into the wild
took place in 1992.
• There are more than 200 condors
now fly free and 180 more live in
breeding programs in zoos across
the country.

C.4 A.1 Case study of the captive breeding and reintroduction of an
endangered animal species.

The Conservation of Biodiversity
1. Ethical reasons for conserving
biodiversity are that all species
have a right to live on this planet.
2. Ecological reasons are that
species live with great interaction
and dependence on each other.
If one species dies out, a food
chain is disrupted, therefore
disrupting all of the other species
as well.
3. Economic reasons are that the
rainforest is a source of materials
important to human life.
Medicinal substances can be
taken from a variety of plants in
the rain forest, and ecotourism
offers a new source of funds for
the many impoverished nations
these forests exist in.
4. Aesthetic reasons are that the
tropical rain forest is one of the
most beautiful attractions on this
planet. There is variety
everywhere in the rainforest.
Dodo bird

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