Federico Pinna1, Giovanni Romagnoni2,3, Antonio Calò4, Teresa Alcoverro5, Jordi Boada11,5, Giulia Ceccherelli6, Antonio Di Franco1, Daniele Grech7, Ivan Guala7, Candela Marco Mendez5, Paolo Guidetti1, Bernat Hereu8, Gabriella La Manna6, Skye Markris8, Martin Marzloff9, Mario Minguito Frutos5, Arianna Pansini6, Luigi Piazzi6, Alessandra Puccini6, Matteo Sinerchia1110, Laura Tamburello11, Simone Farina11
1Stazione Zoologica Anton Dohrn, Italy - 2Leibniz Centre for Tropical Marine Research, Germany - 3Christian-Albrechts-University, Germany - 4University of Palermo, Italy - 5Centre d’Estudis Avançats de Blanes, Spain - 6University of Sassari, Italy - 7Fondazione IMC - International Marine Centre, Italy - 8Universitat de Barcelona, Spain - 9IFREMER, France - 10CNR-IAS - Institute for the Study of Anthropic Impact and Sustainability in the Marine Environment, Italy
Abiotic and biotic factors, together with additional direct anthropogenic pressures, can shape species abundance trajectories over time. In addition to undergoing environmental variability, commercially valuable species can also exhibit sudden changes in population dynamics due to direct harvesting. In the Mediterranean Sea, the sea urchin Paracentrotus lividus acts as a key species playing a pivotal role in the trophic cascade that encompasses predatory fish, sea urchins, and macroalgae. Conversely, the non-edible sea urchin Arbacia lixula can also affect ecosystem functionality through spatial competition. Thanks to 30-year monitoring of ecological changes from 1992 to 2023, this study first characterises long-term variability in the densities of these two sea urchin species inside and outside two Marine Protected Areas (MPAs, i.e. Medas and Tavolara Islands) in the Western Mediterranean Sea. Secondly, time series analyses aim to identify major drivers of long-term trends as well as interannual changes. We analyzed biogeochemical conditions (e.g., sea temperature) and local factors (e.g., predatory fish biomass) as explanatory variables. Preliminary results reveal distinct temporal trends across regions and protection levels, suggesting that density fluctuations are likely linked to local environmental factors and/or fishing activities during specific years. Overall, Tavolara hosts higher sea urchin densities compared to Medas, although this pattern varies between the two species. Effect of protection by MPAs seems buffered by complex ecological dynamics, such as the intensification of predator prey interactions as supported by the population structures within the MPAs characterized by a dominance of larger size classes and a lower contribution of recruits with respect unprotected areas. An analysis of the two species highlights that P. lividus remains dominant overall. This unique time series offers valuable insights to guide effective management strategies.
Biography
Federico Pinna’s research focuses on understanding the biological and physical processes that shape benthic marine communities, with a focus on the responses of key and engineering species to local and global stressors. His studies combine long-term monitoring, manipulative experiments, and biodiversity assessments, particularly in Mediterranean subtidal ecosystems, addressing sea urchin population dynamics and the resilience of coralline algae under climate change and human impacts.