FORM 5

MAN AND THE ENVIRONMENT

*** To have students be able to distinguish and give examples of each of the
following definitions.

DEFINITIONS:

Habitat: the place where an organism lives. Eg. earthworms in soil

Environment: the factors which surround and act on an organism. These are divided
into abiotic/physical factors and biotic factors.

Population: a single species living together in a particular habitat. Eg. all the parrot
fish on a coral reef.

Community: a variety of species living and interacting in the same habitat. Eg.
woodland community.

Ecosystem: self-contained system of organisms interacting with each other and their
abiotic environment. Egs. Pond, swamp, coral reef etc…

Niche: the role and location of an organism in an ecosystem. Eg. earthworms increase
soil fertility and they are primary consumers.

Ecology: the study of the relationships of living organisms to each other and to their
natural environment.

**To have students understand the difference between abiotic and biotic factors,
and the importance of each in maintaining balance within an environment.

Emphasise those factors which will affect the soil and refer students to relevant
pages in various texts dealing with soil types.

ABIOTIC VS BIOTIC FACTORS AFFECTING AN ENVIRONMENT

ABIOTIC(physical/non living factors) BIOTIC(other living

organisms)
Climatic-temperature, rainfall, humidity, Predators
winds, sunlight etc… Parasites
Edaphic- soil; pH, mineral content, humus content Competitors
etc… Pathogens etc…
Aquatic- water; salinity,currents, wave action,
dissolved oxygen etc…
Physiographic- physical features of earth; topography
(land shape)
HAVE STUDENTS REVIEW FOOD CHAINS, FOOD WEBS, TROPHIC
LEVELS, NUTRIENT CYCLES (WATER, CARBON AND NITROGEN) AND
SYMBIOTIC RELATIONSHIPS FROM FORM 3 NOTES OR CHECK INDEX
IN TEXTS AND QUESTION THEM NEXT LESSON.

**To have students understand how to carry out an ecological study using
various types of methods and illustrate devices such as the quadrat, sweep net
and line transect.

STUDYING AN ECOLOGICAL ENVIRONMENT

Organisms can be observed and simply counted. Eg. counting the number of banana
trees in your school yard. The quadrat and grid methods can also be used to count
organisms within a specific area and then that number is used to estimate the
organisms within the entire area of study. A quadrat is a square frame of known area
(eg. 1m2) placed or thrown in an ecosystem whereby organisms in it are counted. The
grid method involves a quadrat with nylon/string in it in a number or small squares.
Both are used to determine species density, species cover and species frequency.

A DAFOR scale is commonly used by scientists to describe how abundant a species

is. It has six categories with descriptive words as shown in the table below, and it can
be adapted for different types of ecosystems.

Rating Description What is means

5 Dominant Found all the time in great numbers; has the greatest effect on
the system
4 Abundant Found all the time
3 Frequent Found often
2 Occasional Sometimes found, but not often
1 Rare Hardly ever found
0 Absent Not found at all

For species that move around a lot the capture-recapture method can be used to
measure the population. When this is done you capture a sample of the organisms and
mark them (with permanent marker or nail polish) and release them into their
environment. After a suitable time to allow mixing and resettling, you capture again
to determine if you get any from the original capture (those that you marked) and then
calculate how much is estimated to be in the population. This is used for beetles,
snails, other insects etc…

Line transects- this is a horizontal line placed across an ecosystem or part of it. The
species of plants or animals touching it at regular intervals are noted and their heights
measured. It is used to monitor changes in vegetation (eg. mangrove succession) and
also changes in habitat. Transect maps of profile diagrams are then drawn.

Sweep nets- This is used to sample insects or other organisms by a sweeping motion
of the net.
Other means of sampling species include: setting traps, using a pooter to suck insects
from barks of trees into a jar, placing traps for eggs to be laid, butterfly nets, plankton
nets, hand nets, Tullgren funnel( used to filter insects from leaf litter).

Species Density: the average number of individuals of each species.

Species Cover: the percentage of ground covered by a species; used if individual

organisms were difficult to count.

Species frequency: the percentage of quadrats in which a particular species was

found.

*** TO CALCULATE THE ABOVE, REFER TO SBA HANDOUT.

**Distribute hand outs regarding SBA field trips to Brighton Salt Pond and
Rawacou and explain procedures to students.

**To help students understand that all populations of organisms will grow either
negatively or positively depending on many factors within their respective
environments.

FACTORS AFFECTING GROWTH OF NATURAL POPULATIONS

The growth of a population may be represented by a sigmoid growth curve. This

growth curve has a log phase (birth rate exceeds death rate), a stationary phase
(birth and death rates are equal) and a lag phase (where little growth occurs).

The growth of a population may be affected by:

1. Food shortages
2. Overcrowding (increased competition for space, mates, shelter, light etc…)
3. Diseases (can spread more rapidly)
4. Predators (can increase in number)
5. Natural disasters(hurricanes, storms, floods, droughts, earthquakes, volcanic
eruptions etc…).
6. Immigration and emigration

** To stimulate discussion among students on the factors that affect human

population growth and the effect of such growth on resources.

HUMAN POPULATIONS

Human populations are affected by most of the same factors that affect natural
populations, however over time the growth of human populations have increased and
still shows signs of increasing. It is still in the log phase of the growth phase.
Improvements in the following can be attributed to the growth:
1. Agricultural techniques
2. medicine
 3. water supplies
4. sanitation
5. housing
6. nutritional understanding
7. few predators

The human populations reached 6 billion in 2000 and is expected to reach 7 billion by
2013 and 8 billion by 2028. War is however one of the crucial factors that will kill
many humans and possibly interfere with the population growth.

EFFECTS OF HUMAN POPULATION GROWTH

Increased numbers of humans leads to increased need for land space and hence
decreases in natural resources, rainforests, biodiversity(different species in an
ecosystem), extinctions, increased pollution etc… In the past 100 years, species
extinction has increased by as much as 1000 times, and fish stocks have been
tremendously reduced. Eventually, diseases, overcrowding and shortages of food,
land and resources will cause a decrease in the human population.

Specific Examples Of Effects Of Increased Human Populations:

Depletion of natural resources:

Non-renewable resources (those present on earth in finite amounts) such as land,
minerals, crude oil, coal etc… are running out because of man’s increasing demands
for them.
Renewable resources (those that can be replaced) are being exploited to the point of
extinction because of man egs. Lobsters, whales, conch, turtles, mink, seal, elephant
etc…

Deforestation:
Forests are cut down to provide wood for fuel, building materials, land for housing,
paper etc… This removal causes destruction to habitats and hence extinction, a
reduction in water entering the water cycle from transpiration, reduction in
photosynthesis which increase CO2 in the air contributing to the greenhouse effect,
and increased soil erosion.

Soil Erosion:
Less soil from overgrazing, poor farming practices, and deforestation lead to less soil
for growth of plants.

Industrialisation:
Increased production of CO2 and other human waste eg. sewage, and industrial waste
eg. plastics result because of an increase in size of urban communities and use of land.

Disruption of food chains:

Food chains and webs are offset by removing organisms for food as well as adding
organisms as biological controls to control another organism.
** To establish awareness among students that resources of various kinds are
slowly depleting in their already limited states with specific reference to fossil
fuels.

RESOURCES AND THEIR LIMITS

The resources in the region that we use are renewable and non-renewable. The non-
renewable ones are finite as they are used up and cannot be replaced. In the
Caribbean region, we are not very rich in mineral resources, but we do have some in
the form of bauxite, nickel and in the case of energy resources, oil. Bauxite can be
found and mined in Guyana, Dominican Republic, Haiti and Jamaica. Nickel and
nickel ore can be found in Cuba and the Dominican Republic. Oil is found in
Trinidad, Barbados and Cuba but Trinidad is the most important in terms of supply to
the region. Trinidad also has asphalt to surface roads. Natural gas is being tapped
from the pitch lake in Trinidad as an energy source for the island.

With an increasing population, our demand for these finite resources increases; more
cars mean more fossil fuels, more appliances mean more electricity. The use of finite
resources is more than the earth can provide and hence alternative sources and
recycling must be utilised.

**To have students recognise and understand the importance of recycling within
our environment and methods of doing this.

Three ways of conserving resources:

1. Reduce the amount of resources used
2. Re-use resources and materials
3. Recycle waste materials to recover resources

The use of many resources can be reduced in order to conserve them. Turning off
light switches and other appliance switches when not in use; buying local products;
reusing scrap metals etc are many examples of reducing resource use. Reusing
plastics and bottles is also another means of conserving resources.

RECYCLING

Biodegradable materials are those which can be broken down naturally by bacteria.
Egs. Food waste, paper, human wastes (sewage)

Non-biodegradable materials are those which can not be broken down by bacteria.
Egs. Plastics, metals, paper

Recycling is where used objects are treated so that they can be used again. Benefits
include:
1. Conservation of raw materials
2. Energy is saved
3. Reduced amount of non-biodegradable items dumped in the environment
Difficulties of recycling deal primarily with collection, transport and storage and are
outlined in the table below:

Difficulties Possible Solutions

People are apathetic and don’t bother Incentives, laws which state that certain
to recycle goods have to be recycled, education
campaigns, deposits on containers which are
refunded if they are returned for recycling.
Goods need to be sorted by type and Organisations can issue separate bins, local
stored separately. storage and collection points.
Items for recycling need to be clean Education campaigns, volunteers to help
and dry which can be inconvenient with cleaning goods for recycling.
when persons wish to simply throw
things away.
Plastics are bulky and heavy when Develop new methods of recycling to reduce
they are compacted, so it is expensive costs and increase profits, add cost of
to transport them and not much money recycling to the containers, reduce plastic-
is made from recycling. use.
It takes time and costs money to sort Special subsidies and tax breaks for
items at the depot. companies to encourage them to employ
people to do this, working with organisations
to provide sheltered employment for the
disabled.
Not all paper or glass can be recycled. Separate containers for office and clean
Paper can only be recycled 4 or 5 paper, bins for different coloured glass.
times before it becomes useless,
brown glass is not very useful in
recycling.
Recycling depots and large containers Consult with community to find best
are not always central and accessible location, use local shopping centres and
to everyone in the community, these other community centres.
also take up space.
Recyling companies will not pick up Organise local collection and dumping
small individual loads. depots so that loads are consolidated.
Large companies may not recycle Laws and regulations to force companies to
unless they see some economic recycle, fines and penalties, incentives for
benefit. recycling, educate companies about reduced
waste removal charges when good are
recycled.

In the Caribbean the overall process of recycling is labour intensive, energy intensive
and the output is insufficient to the inputs required(cost) which makes the entire
process uneconomical.
** To have students suggest the effects that they have on their environments
looking specifically at the habitats localised below.

EFFECTS OF MAN’s ACTIVITIES IN THE CARIBBEAN:

FORESTS
1. Soil erosion
2. Decreased water resources due to increased evaporation
3. Infertile soil due to increased removal of minerals by crops and leaching
4. Loss of natural habitats Eg green parrot

MANGROVE SWAMPS
1. Loss of nursery grounds for reef fish
2. Loss of breeding grounds for birds eg. the egret
3. Loss of natural habitat of many invertebrates eg. mangrove oyster

CORAL REEFS-These are being destroyed by:

1. Smothering by silt from soil erosion, red mud waste from bauxite plants, dust
from construction work an cement plants.
2. Collection for sale.
3. Dynamited for fish.
4. Polluted by raw sewage, insecticides, fertilisers, hot water, industrial and
kitchen waste, garbage.
5. Blown apart for construction purposes eg deep water harbours
6. Damaged by anchors.
**Destroyed reefs lead to coastal erosion.

REEF FISH- These have decreased because of:

1. Overfishing
2. Destruction of reefs and mangroves
3. Dynamiting
4. Use of fish pots to trap fish

THE GREEN PARROT- Virtually extinct:

1. Killed for food
2. Catching for export
3. Removal of forests

**To help students understand the implications of pollution on the environment,

specifically marine and wetlands.

Sources of Air Pollutants:

Pollutants Source Effects
Carbon dioxide Burning fossil fuels, vehicle Greenhouse effect
emissions
Carbon Vehicle emissions and Combines with haemoglobin to
monoxide industrial processes reduce oxygen uptake, continued
inhalation will lead to death
Sulphur dioxide Burning fossil fuels in power Irritates mucous membranes,
 stations and factories causes asthma, bronchitis, lethal
at levels as low as 0.5%;
combines with water vapour to
from acid rain
Hydrocarbons Unburned chemicals in exhaust Combine with nitrous gases to
fumes, some emissions from form smog, have been linked to
factories cancers
Nitrogen oxides Formed at high temperatures in Cause breathing problems and
factories, mining industries and respiratory diseases. Combine
metal works, vehicle emissions with water vapour to form acid
rain.
Lead Exhaust gases from cars, Toxic to humans, build up in
compounds burning coal and industries ecosystems and cause nervous
making metal ores system and digestive diseases;
can cause retarded development
in children and foetuses.
Dust and other Grit, dust, fumes and smoke Dirty the environment; breathed
particulates that get into air from power in, they carry toxins into the body
stations, railways, steel and via the lungs.
chemical works, factories and
exhaust emissions.

EFFECTS OF AIR POLLUTION

Acid rain is often formed when air pollutants from factories combines with rain water
making it acidic (pH 4 or lower). Sulphur dioxide and nitrogen oxides are just a few
of these chemicals that can combine with rain to make it acidic. Acid rain reacts with
minerals in the soil causing leaching. When it enters rivers, lakes, and seas it also
affects the fishes and other organisms causing suffocation in some cases.

The greenhouse effect causes global warming occurs from an increase in air pollutants
such as CO2 and deforestation. The burning of fossil fuels releases a good amount of
CO2 into the atmosphere. This CO2 absorbs heat energy and prevents it from
reflecting back to space hence contributing to the greenhouse effect.

POLLUTION OF MARINE AND WETLANDS

Aquatic environments like the sea contain coral reefs. When polluted by sewage,
fishing, dynamites, poisons, anchors, and walking on the corals we interfere with the
habitat which provides food and money through tourism.

Wetlands are mangrove swamps, these are very important as they protect our
coastlines and river estuaries. They are polluted with construction and development
waste, deforestation and shrimp farming which interferes with ecological balances in
the swamp.

Sources of Water Pollutants:

Pollutants Source Effects

Oil Spilled from tankers or off- At sea, forms a thick layer of slick
 shore oil rigs, illegally which can travel vast distances
dumped when tanks are and end up on the shore, where it
cleaned at sea, poured into ruins beaches and kills sea life
sewers by motorists
Detergents Drains, used to clean and Kill organisms living in the water
break-up oil spills
Sewage Spills, drainage systems Decomposed by bacteria which
uses up the oxygen in the water;
fish and other organisms suffocate
and die.
Fertiliser Run off from farm lands Nitrates lead to algal growth and
eutrophication, when algae die,
bacteria numbers increase and
oxygen is depleted.
Warm water Local power stations, Raises temperature of water,
nuclear power stations allows bacteria to multiply
quickly, can kill other organisms
used to cooler temperatures
Insecticides Drift from crop sprays, Toxic, builds up in the bodies of
washed from crops and organisms and carried up through
other plants, used to kill food chain
mosquitoes in water
Chemical and Discharged from factories Can kill organisms quickly if
industrial wastes into water supplies concentrated, at lower levels build
up in tissues and passed up
through the food chain
Solid waste Washes into water from Unsightly, takes a long time to
(paper, plastic, storm drains when it rains, degrade, can harm sea animals
bottles, cans and left on beaches, dumped especially if they get caught in
other litter) from ships and boats, blown plastic or swallow solid waste
into water by wind thinking it is food

HOW FERTILISER AND SEWAGE AFFECTS WATER SUPPLIES:

1. Algae grow fast, using up lots of oxygen and blocking sunlight

2. Aquatic plants begin to die
3. Dead matter provides food for microbes
4. Competition for oxygen increases
5. Water becomes deoxygenated- fish die

** To allow students understanding of conservation practices in our

environment and stimulate discussion on such practises present in SVG
encouraging them to become involved.
CONSERVATION AND RESTORATION OF THE ENVIRONMENT

1. Reduce pollution:
o Stop burning fossil fuels, and use alternative, non-polluting energy sources
eg. solar energy, wind energy, biogas etc…
 o Ban harmful insecticides and herbicides- develop biodegradable
insecticides or use biological control
o Treat all sewage
o Use unleaded petrol
o Improve safety standards for tankers
o Purify effluent from factories
o Ban the use of so-called disposable bottles, use recyclable materials
o Improve safety standards for nuclear reactors

2. Conserve natural resources:

o Use alternative energy sources
o Recycle resources eg. paper, glass, metal
o Replace renewable resources eg. reafforestation
o Impose closed seasons and size restrictions on harvesting over-fished
species eg. sea eggs, lobsters, conch
o Set up fish farming and aquaculture programmes eg. tilapia, shrimp
etc..

3. Conserve soil
o Reafforestation
o Crop rotation
o Terracing
o Preventing overgrazing.

4. Protect endangered species

o Ban the killing of species in danger of extinction eg. green parrot, West
Indian manatee, turtles
o Set up breeding programmes for species in danger of extinction.
o Set up National Parks

5. Improve land used in mining

o Replace vegetation
o Fill mined areas with soil and use for agriculture.

6. Restore production on infertile land

7. Prevent upsetting the balance of nature