Dr Laura Tamburello1, Dr Chiara Bonaviri, Professor Fabio Bulleri, Dr Stefania Pinna, Professor Simon Wotherspoon, Dr Teresa Alcoverro, Dr Fabio Badalamenti, Dr Jordi Boada, Professor Giulia Ceccherelli, Professor Paola Gianguzza, Dr Luigi Piazzi, Dr Chiara Ravaglioli, Professor Craig Johnson
1Stazione Zoologica Anton Dohrn, Ischia, Italy, 2Dipartimento delle Scienze della Terra e del Mare, Università di Palermo, Palermo, Italy, 3Dipartimento di Biologia, Università di Pisa, CoNISMa, Pisa, Italy, 4Dipartimento di Scienze umane e sociali, Università della Valle d’Aosta, Aosta, Italy, 5Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia, 6Centre d’Estudis Avançats de Blanes (CEAB-CSIC), Blanes, Spain, 7Dipartimento di Scienze Chimiche Fisiche Matematiche e Naturali, Università di Sassari, Sassari, Italy
Overgrazing by sea urchins, in combination with climate change and local human impacts, is fostering the decline of Mediterranean macroalgal forests formed by Fucales. Forests are reported to abruptly shift to barren grounds or to decline in favour of habitats dominated by algal turfs, with these alternative states eventually coexisting in mosaics of habitats. Transitions between turfs dominated by erect or filamentous algae and barrens in habitats deprived of forests have been poorly investigated.
We used qualitative modelling of the interactions among algae, herbivores, and predators in habitats with or without algal forests to understand the community dynamics of shallow rocky reefs. Network models were validated with generalized additive models, using data collected across six regions in the Adriatic and Western Mediterranean Sea. Also, model-based clustering applied to the same dataset identified four distinct regimes in habitats deprived of forests, while transitions between mosaics of habitats and extended barren grounds were typically embedded in forests.
Next, the effects of climate change, human-induced degradation of environmental conditions, and overexploitation of marine resources on individual species were added to the qualitative models, to predict the direction of change in the communities under the combined effect of overgrazing and human stressors. Results suggest that mosaics of habitats will persist under all human pressures, although increased storminess will reduce barrens in turf-dominated, and warming will reduce barrens in habitats with or without forests. The combined effect of climate change and sedimentation will degrade algal forests. Only protection measures can shift turfs to algal forests.
Presentation Slides – Laura Tamburello
