Sampling and identification in the field

For every experiment, before putting it into practice, a protocol should be drawn up, so we know what we have to experiment/sample, and how to do it, using which material, how many times … This protocol allows us to follow clear steps, but it also acts as a track for other scientists who would like to reproduce our experiment, using this protocol.

For this field trip, the chosen sampling design (the way data are collected) is the irregular discontinuous transect. This is a method often used in ecology to study the distribution of species according to their community and density.

The irregular transect is thus carried out along a gradient, here along the shore starting from the bottom, at low tide, and going up to the top, matching the maximum height reached by the sea at high tide. Since the shore represents a large area to sample, we divide it into « belts ». A belt represents a community dominated by a species, here it is the algae that dominate, and where we find a certain homogeneity in the diversity of individuals present in each belt.

In each belt we randomly threw 6 quadrats of 50cm² and we collected several data:

Here are the photos of the quadrats of belt 3, the one of Pelvetia canaliculata being at the top of the foreshore:

Here are the photos of the quadrats of belt 2, the one with Fucus serratus and Ascophylum nodosum in the middle of the foreshore:

Here are the photos of the quadrats of belt 1, the one with Mastocarpus stellatus at the bottom of the foreshore:

All quadrats’s pictures had been taken by ©Nolwenn Béchennec.