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 Type

Pros and Cons

Advantages Disadvantages Transect Data Quadrat Data

• • • Easy Fast Good for large species • Random placement is fast • Good for substrate and large species • Hard to generalise results • Difficult to compare across groups • Can cause biased results

Point Intercept Data

• Gives detailed population & % cover data • Good for small & rare species • Time consuming

References

• • • • • Association, F. M. (2007, December 13). Photo Quadrat Classroom Activity. Retrieved October 18, 2010, from Farallones Marine Sanctuary Association: http://www.farallones.org/education/documents/PhotoQuadActivity-legal.pdf

Authority, R. I. (2010). Experience Rottnest Island. Retrieved October 18, 2010, from About Rottnest Island: http://www.rottnestisland.com/en/About_Rottnest_Island/Flora_and_fauna/Page 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: http://www.hawaii.edu/gk-12/opihi/classroom/measuring.pdf

Maben, A. (n.d.). Coastal Shore Investigation. Retrieved October 18, 2010, from Maine Intertidal Zone Investigation: http://www.bigelow.org/mitzi/CSI.html

Marine Discovery Centre, Q. (2010). Background Information. Retrieved October 18, 2010, from Intertidal Rocky Shores: http://www.rockyshores.auz.info/back_info01.htm