1. Human impact on the environment The impact of human activities and environmental health sometimes needs to be monitored. This could be measuring abiotic factors such as O 2 levels, pollution or by sampling of organisms. One method to monitor the environment is to look at the presence or absence of Indicator species. This lesson will look at two examples of these.

2. Human impact on the environment Indicator species Two examples of the use of indicator species are Lichens and freshwater invertebrates. Lichens are used as indicators of air quality particularly nitrogen dioxide (NO 2 ) produced from vehicle emissions. Freshwater invertebrates are used as indicators of water quality particularly organic pollution and oxygen levels.

3. Human impact on the environment Lichens as indicator species Lichens are two organisms that have a symbiotic relationship. They are a fungus and an algae that grow together. The algal cells grow inside the fungal cells. There are more than 1,700 species of lichen in Britain. Lichens grow on surfaces such as trees and rocks. http://www.twigonglow.com/films/lichen-indicator-species-1201/

4. Human impact on the environment Lichens and air pollution Different Lichens show a range of tolerance to nitrogen gas emissions from vehicles. Usnea nitrogen sensitive species Leafy Xanthoria nitrogen loving species

5. Human impact on the environment Sampling the abundance of a variety of species including these two gives an indication of pollution levels. Fewer of this type would be found in areas of high pollution. (Usnea - nitrogen sensitive) More of this type would be found in areas of high pollution (Leafy Xanthoria - nitrogen loving)

6. Human impact on the environment Sampling Lichens How could lichens be sampled on trees or rocks? Which types of lichens would you expect to find in an urban environment? Which types of lichens would you expect to find in a rural environment? If you were to study the lichens near your house, what do you predict you would find? What other factors might effect the abundance of lichens in an environment?

7. Human impact on the environment Fresh water invertebrates as indicator species Freshwater invertebrates are used as indicators of water quality particularly organic pollution and oxygen levels. The presence or absence of some species will indicate the level of oxygen which is related to the level of organic material in the water.

8. Human impact on the environment Organic material is anything that is living or was living. Organic waste like domestic sewage or farm sewage released into freshwater will cause an increase in bacteria. These bacteria use up the oxygen in the water.

9. Human impact on the environment The level of oxygen in the water will effect the abundance of organisms that live there. Different groups will show changes in abundance as the oxygen levels change. The organisms are sampled and their abundance counted.

10. Human impact on the environment Sampling of freshwater invertebrates The collected samples are identified and counted. Samples are collected by disturbing the stream bed. At a site with fresh water a net with a flat edge is used along the stream bed.

11. Human impact on the environment These species are intolerant of low oxygen levels They include mayfly, stonefly and caddisfly.

12. Human impact on the environment These species are tolerant of low oxygen levels They include worms, rat-tailed maggots and bloodworms.

13. Human impact on the environment How would you expect the abundance of these groups of organisms to change as oxygen levels changed from high to low and back to high? What could cause the change in oxygen levels?

14. Human impact on the environment Monitoring human impact on the environment The impact of human activities and environmental health sometimes needs to be monitored. Why should these activities be monitored? What kinds of monitoring can be done? How are Lichens used to monitor the environment? How are freshwater invertebrates used to monitor the environment? What is the name for species whose presence or absence help determine environmental health?