Experimental evaluation of the feeding rate, growth and fertility of the sea urchins Paracentrotus lividus

The trophic ecology of the sea urchin Paracentrotus lividus, a key species in several shallow benthic communities, has been intensively studied, but the role of various foods in the processes of growth and gonadal maturation is still scarcely understood. This research assessed the effects of two fundamental food items for wild specimens of the sea urchin Paracentrotus lividus, the tissues of the seagrass Posidonia oceanica and of the green alga Ulva rigida, compared to the effect of a commercial compound feed on the somatic growth, gonad development, fertilization success and post-embryonic development. Consumption rates along with the C/N ratios were measured in the feeds and in the faecal pellets. We demonstrated that feeding for three months on U. rigida and P. oceanica did not affect growth and gonadal index of adults, fertilization processes and first cleavage and development, as well as field-collected animals. In contrast, a diet based on formulated pellets triggered a significant increase of gonadal index, but lack of gamete production, due to a follicular hyperthrophy. Our work will be useful for the definition of optimal diets for the production of mature broodstocks of an ecologically important marine model organism.