2.1.4 monitoring populations

Question 1

what can the presence, absence or abundance of indicator species give information on

Answer 1

environmental qualities, like the presence of a pollutant

Question 2

what can be used to monitor an ecosystem

Answer 2

susceptible and favoured species

Question 3

what does the absence or reduction in population of an indicator species suggest

Answer 3

the species is susceptible to some factor in the environment

Question 4

what does the abundance or increased population of an indicator species suggest

Answer 4

the species is favoured by the conditions

Question 5

how does the mark and recapture technique work

Answer 5

• a sample of a population is captured and marked and released
• after an interval of time, a second sample is captured
• if some of the individuals in this second sample are recaptured, then the total population is the number of marked and captured times together and divided by the number that were recaptured

Question 6

what does the mark and recapture technique assume

Answer 6

• all individuals have an equal chance of capture
• there is no immigration or emigration
• individuals are marked and released can mix fully and randomly with the total population

Question 7

what are examples of methods of marking animals

Answer 7

banding
tagging
surgical implantation
painting
hair clipping

Question 8

what must be ensured when marking animals

Answer 8

the marking and subsequent observation must minimise the impact on the study species