IB Course Requirements

1. IB Course Requirements G.4.1: ‘Explain the use of biotic indices and indicator species in monitoring environmental change’

2. 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

3. Advantages of Biological Monitoring • We can detect intermittent pollution • A specific change in the Biotic index can indicate a specific type of pollutant • Food chains can accumulate pollutants (biomagnification) – particularly in higher trophic levels

4. 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

5. 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!

6. Indicator species can be monitored to indicate an increase OR decline in biodiversity • ‘Sentinel Species’ • ‘Keystone species’

7. 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

8. 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

11. IB Course Requirements G.3.1: Calculate the Simpson diversity index for two local communities G.3.2: Analyze the biodiversity of the two local communities using the Simpson index

12. Simpson’s Diversity Index Is an estimate of DIVERSITY It estimates RICHNESS and ‘EVEN-NESS’ of an ecosystem

13. 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…

14. 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…

16. Why is it important to evaluate ‘species even-ness’? Even-ness: A measure of the relative abundance of species making up the community

17. The relevance of ‘species even-ness’

19. Examples of Simpson’s Reciprocal Index1. Equal diversity of species

20. Examples of Simpson’s Reciprocal Index2. Low species diversity: Domination of a single particular species…

21. Example 3 of Simpson’s Reciprocal IndexOnly one species is present

22. Example 3 of Simpson’s Reciprocal IndexVery few individuals of certain species are present