3.7.4.2 Investigating populations

Question 1

What are the 3 methods of sampling?

Answer 1

• mark-release-recapture
• random sampling
• systematic sampling

Question 2

What does mark-release-recapture measure?

Answer 2

abundance/ population estimate of motile organisms

Question 3

population estimate calculation

Answer 3

N = (total sample 1)(total sample 2) / number marked in sample 2

Question 4

What assumptions are made with mark release recapture method?

Answer 4

• no changes in population side due to births, deaths / migration (this one VERY IMPORTANT)
• mark is still visible
• marked sample has had enough time to remix in its population
• marking hasn’t impacted the individuals’ chance of survival

Question 5

What do quadrats measure?

Answer 5

number and distribution of non motile organisms

Question 6

3 methods of using quadrats

Answer 6

• count
• % cover
• % frequency / abundance

Question 7

What is random sampling used for?

Answer 7

to estimate population size

Question 8

method for random sampling

Answer 8

1. divide area into grid, assign each square coordinates
2. use random number generator (AVOIDS BIAS)
3. use numbers as coordinates to place the quadrat
4. estimate % cover, count organisms & indicate if organism is present or not
5. repeat with LARGE (v important to say this) number of quadrats so representative and reliable

Question 9

What is systematic / transect sampling used for?

Answer 9

for distribution across and environmental change (succession)

Question 10

Method for systematic sampling

Answer 10

Method for systematic sampling