ABSTRACT

In spite of the huge conservation efforts and the continuous implementation of environmental management measures aimed at preserving marine ecosystems’ abilities to produce goods and services needed for human wellbeing, the global oceans are experiencing unprecedented rates of change. These changes pervade all hierarchical levels of ecological organization, from individuals to populations, from communities to ecosystems. Indeed, >40% of the global ocean is exposed to multiple stressors, including, among the others, pollution, destructive fishing practices, overfishing, aquaculture, spread of invasive species, eutrophication, oil and gas operations, offshore renewable energy search and development, coastal engineering and development. In addition to these disrupting factors, climate change (CC) is severely impairing marine habitats integrity and ecosystems’ functioning. While we still need to understand how CC will modify in the near future marine ecosystems, there is an urgent need also to identify societally sustainable solutions aimed at counteract, wherever possible, or adapt to CC induced ocean modifications.

Local management practices adopted so far for mitigating human threats to ecosystems and based only on the protection and conservation principles can represent valid solutions to reverse nature change, but they could not be sufficient in the near future. Therefore, active restoration actions are now considered reliable and profitable strategies to return ecosystems to their original state in a reasonable time frame. In this context, marine restoration, due to the inherent operational difficulties in manipulating aquatic ecosystems, is still at its infancy, but some recent studies indicate that optimal conservation outcomes could be achieved through the restoration of degraded marine habitats.

The project “Marine habitats restoration in a climate change-impaired Mediterranean Sea” (MAHRES), by means of an unprecedented integration of meta-analyses, field and manipulative experiments and modelling exercises, aims at testing the reliability and efficacy of protocols of restoration of selected marine Mediterranean habitats (Posidonia oceanica seagrass meadows, vermetids and coralligenous bio-concretions) under expected conditions simulating sea warming and hypoxia due to CC and other sources of disturbance. We chose P. oceanica, vermetids’ reefs and coralligenous habitats as they, by providing a number of ecosystem functions (e.g. biodiversity distribution, nutrient recycling etc.), are among the largest providers of ecosystem services in the Mediterranean Sea. At the same time, they are among the habitats most threatened by local, regional and global anthropogenic drivers of change, including climate change, eutrophication and hypoxia. The project will also focus on the facilitative role of holothurians (a formidable bioturbator) and Cystoseira sp. (key canopy algae) in restoration of P. oceanica and vermetid reefs, respectively.

Specific objectives of MAHRES include: i) evaluating geographical spreading and success of marine restoration actions in the Mediterranean Sea, through literature systematic maps and meta-analyses and field surveys reviews; ii) assessing, by means of lab and field experiments, the vulnerability of the selected habitats and species to different environmental conditions resembling CC, with specific reference to sea warming and oxygen availability; iii) testing the reliability of restoration in different temperature conditions; iv) assessing the reliability of new restoration protocols based on the use of untested yet species (e.g., holothurians) or habitat-forming species (Cystoseira sp.); v) modelling the ‘ecological costs’ of restoration under different environmental conditions.

The ultimate ambition of MAHRES is to provide robust and evidence-based data, information and models to predict the effectiveness of marine restoration actions in different environmental conditions expected due to CC, with an eye to the maintenance of biodiversity and key ecosystem functions.

MAHRES will work through inter-connected work-packages (WP) respectively dedicated to the project management (WP1), to the systematic review of marine restoration outcomes in the Mediterranean Sea (WP2), to the assessment of the selected habitat and species vulnerability to CC expected conditions (WP3), to the deployment of pilot restoration actions in different environmental contexts (WP4).