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ECOLOGY. ECOLOGY. The study of the relationships of organism with each other & their environment. The term environment refers to the external conditions in which the organism or the biotic and abiotic factors. Abiotic factors – refers to non-living things or physical factors

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  • The study of the relationships of organism with each other & their environment.
  • The term environment refers to the external conditions in which the organism or the biotic and abiotic factors.
  • Abiotic factors – refers to non-living things or physical factors
    • Climatic e.g. temperature, water availability
    • Edaphic (associated with soil) e.g. pH, texture
    • Aquatic factors e.g. salinity, amount of dissolved oxygen
    • Topographic factors

Biotic factors – i.e. living components of the environment

  • These occur due to activities from living organisms in the enviornment.
  • Includes
    • predation, symbiosis, competition and diseases
    • All feeding relationships
    • Camouflage
    • Pollination & dispersal
  • Species – a group of organisms/individuals that share physical characteristics which can interbreed e.g. humans.
  • Population – a group of organisms of the same species that are found living together in a habitat e.g. a pop’n of ants on a tree trunk
  • Community – all species of organisms found living together in a particular place e.g. a freshwater pond community
  • Niche – the role/function that a particular organism has e.g. a heron’s (a type of bird) niche is the water edge where it eats large fish

Ecosystem – a distinct, self-supporting system of organisms interacting with each other & their physical environment e.g. a pond, a mangrove swamp.

  • Order of these terms:

Species population community ecosystem

importance of abiotic environment

Sunlight – E used comes from sun. Needed for photosynthesis. Affects distribution of species

Temperature- most organism live in narrow range of temperature. Affects distribution.


Humidity – organisms need a certain level of moisture in the air

Water-needed for survival e.g. cell function. Salinity levels vary this affects distribution & osmoregulation of some species

Soil – plants depend on soil while animals depend on plants. Survival impossible if soil is too acidic or alkaline

Wind – helps disperse plant seeds. However, strong winds makes survival difficult

factors affecting distribution of organisms
  • See Atwaroo-Ali on pages 296-300
aquatic habitats
  • Abiotic factors that affect aquatic organisms:
    • Water movement & speed of flow – plants & animals that live in rivers adapt to movement of water. Organisms that live along ocean shores adapt to changing water levels
    • Depth – oxygen levels & amount of sunlight that penetrates water vary with depth.
    • Water clarity – clear water allows more sunlight to reach the bottom layers than muddy or polluted waters

O2– needed for respiration & other metabolic functions. More O2 is present in flowing water than stagnant pools

  • Salinity (the conc. of salt in the water) – important in oceanic environments. Estuaries and mangrove swamps contain a balance mixture of salt and fresh water that suits organisms in these environments. Too much fresh water or salty water will cause organisms to die off.
terrestrial habitats
  • These depend on soil.
  • Soil contains rock particles, organic matter, air, water & living organisms.
  • What are the importance of the above components?
population growth
  • Rate of pop’n growth depends on four factors: birth & death rates, immigration (movement into pop’n) and emigration (movement out)
  • These factors are affected by available space, food & water supply, predator-prey relationships, competition between organisms, diseases & natural disasters
how factors affect pop n growth
  • When BRs are high and DRs low (possibly due to healthy pop’n) – pop’n grows
  • BRs can be low when food & water are scarce – leads to low fertility rates
growth of bacterial pop n

S-shaped curve

A – New pop’n of bacteria grows slowly at 1st. Although reproduction occurs the total # doesn’t increase quickly

B – with no limiting factors, pop’n grows at rapid rate, doubling over time

C – limiting factors affect pop’n, reproduction rates slow down preventing increase in numbers

D – death of bacteria





effects of pop n growth
  • If pop’n continues to grow at an exponential or rapid rate there will be serious complications for the Earth
  • Currently, rainforests are cleared for farming & housing at a rate of 160,000 squ. km. per year
    • Leads to increased soil pollution & water resources
  • Habitat loss – extinctions, loss of biodiversity
  • Disruption of biogeochemical cycles (N2, C, H2O)
effects of man on the environment
  • Deforestation – (from what?)
  • Pollution – (?)
  • Endangered species - (?)
  • Overfishing
  • Destruction of habitats e.g. coral reefs, mangroves, forests
effects of man on the environment1
  • Greenhouse Effect -
    • A general warming effect felt on Earth’s surface, produced by greenhouse gases (CO2, methane, water vapour & nitrous oxide).
    • These gases allow incoming solar radiation to pass through the Earth's atmosphere, but trap heat by preventing some of the infra-red radiation from the Earth’s surface from escaping to outer space.
    • This process occurs naturally and has kept the Earth's temperature about 60 degrees Fahrenheit warmer than it would otherwise be. Current life on Earth could not be sustained without the natural greenhouse effect.
    • However, the greenhouse effect is becoming stronger as a result of human activities, which is causing the warming we have observed over the past century.



Climate Change

    • Climate is the long-term average of a region's weather events lumped together. For example, it's possible that a winter day in Buffalo, New York, could be sunny and mild, but the average weather – the climate – tells us that Buffalo's winters will mainly be cold and include snow and rain.
    • Climate change represents a change in these long-term weather patterns. They can become warmer or colder. Annual amounts of rainfall or snowfall can increase or decrease.

Global Warming:

    • Global warming refers to an average increase in the Earth's temperature, which in turn causes changes in climate.
    • A warmer Earth may lead to changes in rainfall patterns, a rise in sea level, and a wide range of impacts on plants, wildlife, and humans.
    • When scientists talk about the issue of climate change, their concern is about global warming caused by human activities.
ozone layer
  • Forms a thin shield high up in the sky. It protects life on Earth from the sun's ultraviolet (UV) rays. In the 1980s, scientists began finding clues that the ozone layer was going away or being depleted.
  • This allows more UV radiation to reach the Earth's surface.
  • This can cause people to have a greater chance of getting too much UV radiation. Too much UV can cause bad health effects like skin cancer and eye damage.
what is stratospheric ozone
What Is Stratospheric Ozone?
  • Ozone is a natural gas that is found in two different layers of the atmosphere. One layer, called the troposphere, is at the Earth's surface where we live.
  • Ozone in the troposphere is "bad" because it dirties the air and helps make smog, which is unhealthful to breathe. The other layer, called the stratosphere, is miles above the Earth's surface.
  • Ozone in the stratosphere is "good" because it protects life on Earth by absorbing some of the sun's harmful UV rays. Stratospheric ozone is found most often between six and 30 miles above the Earth's surface.
ozone depletion
Ozone Depletion
  • Recently, chlorofluorocarbons (CFCs) were used a lot in industry and elsewhere to keep things cold and to make foam and soaps.
  • Strong winds carry CFCs up into the stratosphere where UV radiation breaks them apart, releasing chlorine atoms.
  • Each chlorine atom can attack and break apart (destroy) as many as 100,000 ozone molecules during the time it is in the stratosphere. The chlorine from CFCs reduces (depletes) the amount of ozone in the stratosphere.
  • Other ozone-eating chemicals are pesticides such as methyl bromide, halons used in fire extinguishers, and methyl chloroform used in businesses.

What Is Being Done for the Ozone?

  • Countries around the world, including the United States, have seen the threats created by ozone depletion and agreed to a treaty called the Montreal Protocol. This Protocol will help humans to stop making and using ozone-eating chemicals.

How Ozone Depletion Affects UV Levels

  • Scientists predict that ozone depletion should peak around year 2010. As world-wide controls reduce the release of CFCs and other ozone-eating substances, nature will repair the ozone layer.
  • By year 2065 stratospheric ozone should return to the amount present in 1980. Until then, we can expect higher levels of UV radiation at the Earth's surface. We need to take care to avoid the bad health effects that could result from too much UV radiation.
natural resources
  • These are products from the environment that are used by man
  • Nature provides:
    • Food, fuel, fibre (cloth, wood)
    • Shelter and building materials
    • Protection of coastlines from erosion e.g. ??
    • Enjoyment & aesthetic benefits
    • medicines
natural resources1
  • As the nos. of people on Earth increases, the greater the demand on natural resources e.g. fossil fuels for transportation, electricity etc.
  • If we continue to be wasteful then natural resources will be depleted
  • Term global footprint which is an indication of how much of the Earth’s resources each person uses as a result of their lifestyle (food, energy, transport etc.)

In 2001, it is reported that each person has a G.F. of 2.2 ha (took 2001 world pop’n no.) i.e. we are using 21% more than the Earth can provide & sustain.

  • A carbon footprint is a measure of the impact our activities have on the environment, and in particular climate change. It relates to the amount of greenhouse gases produced in our day-to-day lives through burning fossil fuels for electricity, heating and transportation etc.
  • Which countries have the higher C.F.?
renewable vs non renewable
Renewable vs. non-renewable
  • Renewable – easily replaced naturally as they reproduce or cycle through ecosystems e.g. ?
  • Non-renewable – get consumed and can’t be replaced e.g. ?
  • Countries with natural resources – Trinidad -?, Tobago - ?, Jamaica - ?, Guyana - ?
recycle reduce reuse
  • Reducing resource use –
    • turning off lights & appliances when not in use
    • Buy only what is needed
    • Buy local products – this reduces usage of fossil fuels
  • Re-using resources –
    • Return glass bottles to store for refund
    • Reuse plastic containers
    • Compost

Recycling – means treating used objects so that they can be used again

    • Biodegradable vs. non-biodegradable
    • Non-biodegradable needs to be recycled
  • Benefits of recycling
    • Helps conserves raw materials/resources used to make goods
    • Saves a great deal of energy
    • Helps reduce amount of non-biodegradable items dumped into the environment.
conservation restoration of the environment
  • Conservation means saving for the future
  • Conservation methods
    • Passing laws
    • Signing international agreements
    • Declaring reserves & limiting access to certain areas e.g. nature reserves
    • Controlling pollution from farming & industry
    • Restoring damage caused by human activity

Controlling Pollution:

    • Gov’t can pass laws on type of fuels to use in vehicles
    • Education in schools
    • Industries can implement ways to reduce pollution e.g. using cleaner fuels, cleaning/scrubbing smoke before it’s emitted, safe disposal of wastes
    • Use of lead-free petrol which reduces Pb in atmosphere
    • Modern cars have catalytic converters which oxidises poisonous CO into less harmful CO2
  • Ozone -