Sea urchin harvest inside marine protected areas: an opportunity to investigate the effects of exploitation where trophic upgrading is achieved oleh Giulia Ceccherelli, Piero Addis, Fabrizio Atzori, Nicoletta Cadoni, Marco Casu, Stefania Coppa, Mario De Luca, Giuseppe Andrea de Lucia, Simone Farina, Nicola Fois, Francesca Frau, Vittorio Gazale, Daniele Grech, Ivan Guala, Mariano Mariani, Massimo SG Marras, Augusto Navone, Arianna Pansini, Pieraugusto Panzalis, Federico Pinna, Alberto Ruiu, Fabio Scarpa, Luigi Piazzi