Ecology Sampling Methods

What are they? Biologists need to collect data ‘in the field” This data needs to be collected in a standardised way. (why?) Two methods of doing this are; – Transect sampling – Quadrat Sampling

Transects Transect sampling is using a single line This line is stretched over the area to be studied The line is positioned to encompass the changes in a site The line has regular measurements marked on it (like a tape measure). The line must be held straight and stationary

Quadrats Quadrats enable comparisons between different areas of a survey site A Quadrat is a framed area The area within the quadrat is sectioned into a set number or squares or intercepts

Quadrats (cont) Quadrats can be placed randomly, or at regular intervals along a transect line

Types of Sampling Point-intercept along a transect line Visual estimate within a quadrat Point intercept within a quadrat Photoquadrats Transect line Quadrat

What to use when? The data collection method varies depending on; – The habitat – The question of interest – The researcher – Providing the most accurate results – Providing the most repeatable results

Data TypeAdvantagesDisadvantages Transect Data Easy Fast Good for large species Hard to generalise results Difficult to compare across groups Quadrat Data Random placement is fast Good for substrate and large species Can cause biased results Point Intercept Data Gives detailed population & % cover data Good for small & rare species Time consuming Pros and Cons

References Association, F. M. (2007, December 13). Photo Quadrat Classroom Activity. Retrieved October 18, 2010, from Farallones Marine Sanctuary Association: Authority, R. I. (2010). Experience Rottnest Island. Retrieved October 18, 2010, from About Rottnest Island: s/Flora_and_fauna.aspx Baumgartner, E. a. (2009). Measuring Abundance: Transects and Quadrats. Retrieved October 18, 2010, from EECB Graduate Fellowships in K-12 Education: Maben, A. (n.d.). Coastal Shore Investigation. Retrieved October 18, 2010, from Maine Intertidal Zone Investigation: Marine Discovery Centre, Q. (2010). Background Information. Retrieved October 18, 2010, from Intertidal Rocky Shores: