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Zonation of molluscs

Look for an area of rocks that will give you a transect from the low to high tide zone without significant interruptions, gaps or major changes of slope.

Stretch a tape measure from knee deep in the water to the upper limit of molluscs. Use a 0.5m quadrat and start knee deep in the sea. Carry out a belt transect focusing on the molluscs present. Record the distance (centre of quadrat) and the number/percentage of each mollusc present.

For those which encrust the rock, oysters, barnacles, limpets, etc record their % cover.

For those that have mobile individuals, periwinkles, whelks, top-shells etc, record number.

Plot your results as a series of kite diagrams.

Is there a pattern to the distribution of molluscs?

What factors influence the distribution?

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