Fabrizio Gianni has recently defended his PhD thesis "Conservation and ecological restoration of Mediterranean marine forests” in front of an international committee composed of Dr. Enrique Ballesteros (reviewer, Centre d’Estudis Avançats de Blanes), Pr. Ester Serrão (reviewer, University of Algarve), Pr. Alexandre Meinesz (jury president, Université Nice-Sophia Antipolis), Pr. Nick Shears (University of Auckland), Dr. Rodolphe Lemée (Université Paris 6-Observatoire Océanologique de Villefranche sur Mer), Pr. Airoldi Laura (co-supervisor, University of Bologna) and Dr. Luisa Mangialajo (supervisor, University of Nice-Sophia Antipolis).
This thesis was founded by the European Community’s Seventh Framework Programme (FP7/2007-2013) [grant number 290056] within the project MMMPA-Training Network for Monitoring Mediterranean Marine Protected Areas.
Abstract
Several important marine habitats exist worldwide, both in tropical and in temperate waters, and many of them are already suffering the effects of multiple human impacts. A widespread loss of marine forests of large brown seaweeds has been observed in the recent decades. Their loss leads to an ecosystem-shift towards less complex turf beds or sea urchin barren grounds, devoid of any erect vegetation. A wide arrays of human activities are causing this regression: eutrophication, coastal urbanisation, high sedimentation rates, destructive fishing and overfishing of sea urchins predators.
In the framework of the MMMPA project, this PhD work aimed to address some important topics related to the conservation and restoration of algal forests, with a particular attention to the role of Marine Protected Areas (MPAs) and fish herbivory. Multiple complementary approaches were used: macroalgae surveys, literature reviews, manipulative experiments in the field, tank-based experiments and GIS habitat mapping.
Results from field experiments showed that native herbivorous fish, likely Sarpa salpa (salemas), can be the most effective herbivore of intertidal Cystoseira belts both on natural and artificial substrates. Indeed, salemas strongly affected Cystoseira stricta fitness, being able to decrease the growth, biomass and reproductive output of natural forests and limit restoration success on artificial substrates. Likely, the role of the herbivorous fish in structuring macroalgal communities has been overlooked in the Mediterranean Sea so far.
A review of the existing literature showed that knowledge on marine forests forming species has improved in recent decades. However, most of the research is not in relation to MPAs, likely due to the fact that marine forests are not always included in MPAs planning and management plans. Studies on marine forests are not homogeneously distributed in the world, being concentrated in the developed countries where marine forests sustain industrial activities or where their importance is recognised. Interestingly, an increase of the awareness of marine forests importance and of the scientific interest (published papers) was observed. Nowadays, marine forests are under continuous threats and especially sensitive to multiple impacts. Hence, conservation measures and recovery strategies should be urgently set up. Degraded/lost forests should be restored according to the guidelines and suggestions discussed in this PhD work, keeping in mind that the conservation of the existing forests in MPAs has always to be considered as a priority.
Keywords
Marine forests, marine protected areas, herbivorous fishes, conservation, restoration, seaweeds, macroalgae, Mediterranean Sea, artificial structures, herbivory, monitoring, management, temperate seas