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The movement of the sea urchin Paracentrotus lividus from a rocky habitat to patches of Posidonia oceanica was investigated with respect to the size of the sea urchins and their location from the edge of the patch. With this aim, a manipulative experiment was conducted (4 times) at a location where several P. oceanica patches were interspersed on rocky platforms. Each time, after an accurate removal of the sea urchins populating them, 15 of these patches were randomly assigned in sets of 3 to 5 different urchin addition treatments, using groups of 10 large or small P. lividus specimens (test diameter >50 and |
