Indicator Species

Question 1

what happens if raw sewage or fertilisers containing nitrates are released into a river

Answer 1

the microorganisms in the water increase and use up the oxygen

Question 2

why are stonefly larvae and freshwater shrimps good indicators for water pollution

Answer 2

• because they are very sensitive to the concentration of dissolved oxygen in the water
• so if you find stonefly larvae in a river, it indicates that the water is clean

Question 3

what are examples of invertebrate species that have adapted to live in polluted conditons

Answer 3

• blood worms and sludgeworms

- they indicate a very high level of water pollution

Question 4

how can air pollution be monitored

Answer 4

by looking at particular types of lichen that are very sensitive to the concentration of sulfur dioxide in the atmosphere

Question 5

where is suflur dioxide usually released from

Answer 5

car exhausts and power stations

Question 6

how would you determine how clean the air is by observing the lichen in the area

Answer 6

• by observing the number and the type of lichen at the particular location
• for example, the air is clean if there are lots of lichen, especially bushy lichen

Question 7

where is blackspot fungus found and what is it sensitive to

Answer 7

• it is found on rose leaves
• it is sensitive to the level of sulfur dioxide in the air
• so its presence will indicate clean air

Question 8

what inference could you make in an exam if the question were to tell you that there were more lichen living further away from a city center

Answer 8

• you could come to the conclusion that here is less pollution outside the city center
• and the air in this area contains less sulfur dioxide and other pollutants

Question 9

what are the two ways of using indicator species to measure pollution

Answer 9

• doing a simple survey to see if a species is present or absent from an area
• or counting the number of times an indicator species occurs in an area

Question 10

what are the advantages and disadvantages of doing a simply survey to see if a species is present or absent from an area

Answer 10

• it is a quick way of telling whether an area is polluted or not
• but it is not good for telling how polluted an area is

Question 11

what does counting the number of times an indicator species occurs in an area give you and what does that info allow you do to

Answer 11

• it gives you a numerical value

- which allows you to roughly see how polluted an area is in comparison to another

Question 12

what is an advantage of using indicator species to decide whether an area is polluted

Answer 12

it is a simple and cost-effective way of saying whether or not an area is polluted

Question 13

what is a disadvantage of using indicator species to decide whether an area is polluted

Answer 13

they cant give you accurate figures for exactly how much pollution is present

Question 14

what factors other than pollution can play a role in the presence or absence of a species in an environment

Answer 14

non-living indicators

Question 15

what are dissolved oxygen meters and chemical tests used for

Answer 15

• they are used to accurately measure the concentration of dissolved oxygen in water
• to show how the level of water pollution is changing

Question 16

what are electronic meters and various laboratory tests used to do

Answer 16

• accurately measure the concentration of sulfur dioxide in the air
• to show how air pollution is changing