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Abstract - Survival of Paracentrotus lividus subjected to predation was evaluated in two different habitats and two zones with different levels of protection in the Marine Protected Area Tavolara Punta Coda Cavallo (Sardinia). Predation was higher in zones with stronger protection (B zone). However, this result was not due to predation by fish, that looks steady in the two conditions of protection, but rather to the stronger impact of bottom predators (namely gastropods), particularly in Posidonia oceanica beds, where sea urchins are able to evade visual attacks, not chemotactic predation.
Key-words: marine parks, Paracentrotus lividus, predation, benthic environment, sea grass.
Introduction - The sea urchin Paracentrotus lividus (Lamarck, 1816) is very common in shallow subtidal of the Mediterranean Sea, where it usually hides in rocky crevices or among the seagrass rhizomes to escape predation. Although sparids (i.e., Diplodus spp.) are considered the most effective fish predators of sea urchins (Guidetti, 2006), bottom predators (e.g., gastropods and sea stars) have been also reported (Sala and Zabala, 1996; Gianguzza et al., 2016). This study aims to evaluate if the magnitude of the two types of predation (fish vs bottom predators) changes in relation to the level of protection and habitat.
Materials and methods - The study was carried out...