Environmental Biology Human impact on the environment

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Environmental BiologyHuman impact on the
environment

• Changes to ecosystems

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Succession

• Autogenic
• Allogenic
• Degradative

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Autogenic succession

• Natural sequence of changes resulting from
  biological processes that modify conditions and
  resources.
• Primary succession
• Secondary succession

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Primary succession
Autogenic succession
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Secondary succession
Succession
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Allogenic succession

• Changes resulting from changing external
  geophysical forces
• Climate change
• Soil development
• Animal influence
• Pathogens

Succession
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Degradative succession

• Changes resulting from the decomposition of dead
  material

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Climax communities

• Relatively stable
• Greatest variety of habitats/niches
• Greatest species diversity
• Most complex food webs

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Loss of complexity of ecosystems

• Monoculture
• Eutrophication/oxygen depletion
• Toxic pollution

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Monoculture

• Reduces competition
• Limited genetic variability
• Efficient method of food production
• Creates a fragile ecosystem due to lack of
  diversity/adaptability
• eg potato blight
  

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Potato blight
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Eutrophication

• Nutrient enrichment of water
• Promotes growth of algae and bacteria
• Leads to reduction in dissolved oxygen
• Aerobic bacteria die off
• Decomposition is not completed
• Reduction in aerobic species
• Foul smelling decay products remain

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Eutrophication
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Toxic pollution

• Lead and Agrostis tenuis
• Act as enzyme inhibitors
• Biological magnification

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Effects of intensive food production

• Monoculture soil condition
• Field size mechanisation
• Shelter and habitats
• Herbicides/fertilisers

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Increase in energy needs

• Fossil fuels finite/global warming
• Nuclear power safety/disposal
• Renewables

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Greenhouse gases

• Carbon dioxide
• Water vapour
• Methane
• Nitrous oxide
• CFCs

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Affects of global warming

• Coral bleaching

Corals and zooxanthellae form a symbiotic
relationship. Zooxanthellae are expelled from
coral by eg. high temperatures.
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Pollution

• BOD
• Biological magnification DDT
• Heavy metals
• Susceptible/favoured species
• Indicator species

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Biological oxygen demand
Biological Oxygen Demand (BOD) is a measure of
the oxygen used by micro-organisms to decompose
organic materials found within water.
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Biological magnification
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Heavy metals
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Susceptible / favoured species
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Indicator species
Scientists use lichens to determine the amounts
of certain pollutants in the air. Lichens die
when exposed to sulpher dioxide. Scientists can
estimate the amount of sulpher dioxide in the air
by observing the number and type of lichens
growing at a particular site. Lichens also absorb
metals. By analysing lichens that grow near
factories and smelters, scientists can determine
the type of metallic pollutants released.