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Survey Techniques

It would be far to difficult to have students / scientists counting every animal and plant on the rocky shore so in our survey work we use Transects and Quadrats to allow us to build an understanding of the distribution of animals and plants.

Transects: In surveying communities biologists use transects for providing a reference point for samples that are taken. A transect is a line that cuts across the community usually positioned in a way that allows for the changes across the community to be observed.

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Transect line - Barwon Heads

   
  In our Rocky Shores studies we run the transect line from a fixed point above the high tide mark down to the edge of the water. At each 5m interval a marker on the line provides a reference point and tells how many metres away from the top of the line the samples are taken.
   

Quadrats: Quadrats are sampling devices that allow comparisons to be made between different areas of the survey site.

Quadrats are placed randomly along the transect line and students first identify the species present and then measure their abundance.

For animals students actually count individuals and record the number of each species within the quadrat. For plants an estimation is made of the % cover for each species within the quadrat.

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Quadrat and transect line

   
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For plants an estimation is made of the % cover
for each species within the quadrat.

Because the quadrats are fixed in size we can count animals and plants in one location and then move the quadrat to a different location on the transect and make comparisons between the two sets of data.

Our quadrats are 0.5m x 0.5m = 0.25m2

To ensure that data collected is scientifically fair we ask students to take 3 quadrat samples and average their results. This is the data available in the "View Results" section of the site.

   
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