ib course requirements
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IB Course Requirements. G .4.1: ‘Explain the use of biotic indices and indicator species in monitoring environmental change’. Biological monitoring and indicator species. What is an indicator species ? Any biological species that defines a trait or characteristic of the environment: - PowerPoint PPT PresentationTRANSCRIPT
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IB Course Requirements
G.4.1: ‘Explain the use of biotic indices and indicator species in monitoring environmental change’
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Biological monitoring and indicator species
What is an indicator species?• Any biological species that defines a trait or
characteristic of the environment:– May indicate a particular ecosystem– May indicate a disease outbreak– May indicate pollution– May indicate species competition – May indicate climate change
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Advantages of Biological Monitoring
1. We can detect intermittent pollution2. A specific change in the Biotic index can
indicate a specific type of pollutant3. Food chains can accumulate pollutants
(biomagnification) – particularly in higher trophic levels
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Disadvantages of Biological Monitoring
• Distribution of organisms may be patchy so sampling must be done carefully
• Invertebrate organisms tend to be seasonal• Some indicator species show tolerance to
different pollutants
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Biological Monitoring is frequently used to evaluate marine or aquatic pollution
• Oysters and mussels are used as indicator species (‘bio-monitors’) to assess environmental pollution of coastal waters
• Mussel Watch!
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Indicator species can be monitored to indicate an increase OR decline in biodiversity
• ‘Sentinel Species’• ‘Keystone species’
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Keystone species
• These are species which have a disproportionately significant effect on their environment
• Sometimes they are predators
• Sometimes they are ‘ecological engineers’
• Examples: Grizzly Bear, Sea Otters, Sea Stars
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Biological Monitoring is frequently used to identify pollution or presence of toxins on
land
• On land, lichens are often used as indicator species since they are sensitive to sulphur dioxide
• ‘Bushy’ lichens need pristine air• Leafy lichens can survive a small amount of
pollution• ‘Crusty’ lichens can survive in heavily polluted air• Regions devoid of lichens may indicate a high
concentration of sulphur dioxide
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IB Course Requirements
G.3.1: Calculate the Simpson diversity index for two local communitiesG.3.2: Analyze the biodiversity of the two local communities using the Simpson index
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Simpson’s Diversity Index
Is an estimate of DIVERSITYIt estimates RICHNESS and ‘EVEN-NESS’ of an ecosystem
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What is the usefulness of a Diversity Index?
They provide information about ‘rarity’ and ‘common-ness’ of species in a community
Diversity indices allow us to monitor diversity over time in changing ecosystems – for example, to monitor effects of pollution or climate change
Diversity indices allow us to compare communities
Diversity indices convert many species into a single number
Limitations!Simpson’s Diversity Index
is more sensitive for common species
(abundant) and LESS sensitive for RARE
species…
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So what is ‘species richness’• Indicates species diversity…but• Estimating ‘richness’ alone would provide only a
limited description of a community: it would not tell us anything about relative abundance of the species identified…
For example…
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Why is it important to evaluate ‘species even-ness’?
Even-ness: A measure of the relative abundance of species making up the community
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The relevance of ‘species even-ness’
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Examples of Simpson’s Reciprocal Index1. Equal diversity of species
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Examples of Simpson’s Reciprocal Index2. Low species diversity: Domination of a single particular species…
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Example 3 of Simpson’s Reciprocal Index Only one species is present
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Example 3 of Simpson’s Reciprocal Index Very few individuals of certain species are present