Lab 2b: Collecting Ecological Data

Question 1

To be representative, a sample size must be:

Answer 1

Unbiased and adequate in size

Question 2

Visualize a performance curve

Answer 2

• x axis: number of samples
  y axis: cumulative of mean

Question 3

Name two methods of estimating absolute population density

Answer 3

Quadrats and mark/recapture method

Question 4

Explain the quadrat method

Answer 4

Counting all the individuals with a known area size and then extrapolating the average density of the samples (sessile organisms)

Accuracy:
- number of individuals in each quadrat must be known
- quadrat size must be known
- quadrats must be representative of the study

Question 5

Explain the mark/recapture method

Answer 5

Capturing organism, marking them, releasing the marked individuals, and then recapturing a random sample - noting number of marked and unmarked (mobile organisms)

Accuracy:
- no change in the ratio of marked to unmarked due to BIDE
- marked and unmarked are similar in all aspects
- probability of recapture is equal for marked and unmarked