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Ecological restoration

CONTEXT – AIMS OF THE PROGRAMME

Shallow, semi-enclosed and sheltered from the open sea, with the presence of a Cymodocea seagrass meadow : the Le Brusc lagoon, that borders the Island of Les Embiez, possesses all the attributes necessary to serve as a nursery for numerous fish species. The larvae, initially washed in by the sea currents, then find their way to shallow coastal habitats where they can develop safe from predators. But the meadows of the marine plant, Cymodocea nodosa, have strongly regressed in recent years.

The Paul Ricard Oceanography Institute has been mandated by the water management agency for southern France (Agence de l’Eau Rhône Méditerranée Corse) and the local authority (Conseil Général du Var) to undertake research on the theme : "Ecological restoration of Mediterranean coastal shallow bottoms".

The LANDEAU programme, planned for a period of 18 months for the purpose of supporting sustainable fishing and the management of fisheries resources, will enable the Institute’s researchers to work with a two-fold focus :
- to draw up a survey of the current state
- to assess methods to restore the environment

First phase, inventory of biodiversity

Luminous traps are placed around the island of Les Embiez and the lagoon. The local fishers’ guild (Prud’homie) and the Le Brusc fishers are associated with this part of the programme for the placing and removal of the traps. And the particular configuration of the Le Brusc lagoon, with three passages towards the open sea, means that the species that actually colonise the site can be caught using small nets. The
observations are completed by means of diving surveys.

Once caught, the post-larvae of the fishes are taken to the Institute’s aquaculture facility where they areidentified, photographed and reared for several months. They are then released at various sites.

The impact of the sampling is negligible since it is carried out before the colonisation phase and thesamples represent only a tiny part of the flow of larvae populating the coastal waters. In addition, it is estimated that about 95% of the post-larvae disappear naturally up on their arrival in the coastal habitat.

Second phase, restoration of habitats

In the second phase, it is planned under the LANDEAU programme to attempt restore the habitat in the lagoon which is favourable for the development of larvae : the Cymodocea (Cymodocea nodosa) seagrass meadow. The idea is to transplant cuttings from sectors in a good state of preservation (in particular the former salt pans on the island of Les Embiez). On these re-implanted meadows, associated or not with
micro-reefs, will be released after marking post-larvae reared in the hatchery, in order to monitor their behaviour and to attempt to determine their rate of persistence. Identical releases will also be carried out in natural seagrass meadow areas.

PARTNERSHIPS

Scientific
- Ecocean, for the capture and rearing of post-larvae
Link to Ecoceanwebsite
- SM2 Solutions Marine, for transplantation and cuttings
Link to SM2 Solutions Marine website
- CEFREM – UPVD - UMR 5244 CNRS
Link to CEFREM website

Financial
Agence de l’Eau Rhône Méditerranée Corse (water management agency for southern France)
Link to website
Conseil Général du Var (local authority)
Link to website

Programme labelled by Pôle Mer Méditerranée.

BIBLIOGRAPHY

Guidetti P., Bussotti S., 2000. Fish fauna of a mixed meadow composed by the seagrasses Cymodocea nodosa and Zostera noltii in the Western Mediterranean. Oceanologica acta, Vol. 23 – N° 7.

Lecaillon G., Blin E., Lenfant P., Murenu M., Felix-Hackradt F., Garcia-Charton J. 2011- Des solutions opérationnelles et innovantes de restauration des populations de poissons marins côtiers associés à des aménagements littoraux. Conférence Méditerranéenne Côtière et Maritime, Édition 2, TANGER MAROC.

Lecaillon G., Murenu M, Felix-Hackradt F., Lenfant P. 2012. Guide d’identification des post-larves de Méditerranée.

Tuya F., Martin J.A., Luque A, 2006. Seasonal cycle of a Cymodocea nodosa seagrass meadow and of the associated ichthyofauna at Playa Dorada (Lanzarote, Canary Islands, eastern Atlantic). Ciencias Marinas (2006), 32(4) : 695–704.