Background According to assessments of the Census of Marine Life published in August 2010, the decrease of marine biodiversity is particularly dramatic in the Mediterranean Sea. The causes of biodiversity loss are multiple, but mainly due to human activities. These include: habitat degradation, overexploitation of natural resources, climate change, invasive species and pollution. Objectives The SUBLIMO LIFE+ Biodiversity project proposes a new approach to analysing, monitoring and reducing the loss of marine biodiversity. It will seek to identify and estimate the abundance of coastal fish species that return to colonise coastal habitats and renew the local population. One of the main goals is to analyse biodiversity at the post-larvae stage. In the fish life-cycle, the arrival and settlement of pelagically- (open ocean) spawned post-larvae in their permanent habitat is a critical phase, during which over 90% of deaths are due to predation and habitat degradation. The innovative technique proposed by the project is to catch a small number of endangered or over-exploited fish species at the post-larvae stage. The selected species will then be reared at two research centres – one in the Gulf of Lion and the other in Corsica. A key objective is to conserve their natural gene diversity. A few months after their ex situ development, the tank-reared juveniles will be reintroduced into micro-habitats (such as small artificial reefs) to reduce mortality. This will reinforce the populations of endangered or exploited species Expected results: 1. The first results relate to the inventory of post-larvae biodiversity. This will feature information on the dynamics of species (e.g. winter/spring reproduction) and will assess the level of species’ vulnerability to natural and anthropic pressures. The resulting atlas and database will be produced in both paper and electronic format in order to allow dissemination via the Internet. Both reference sources are targeted at scientists and managers, to be used for the evaluation of the biodiversity of their respective sites. A true distribution map of post-larvae biodiversity will be produced with the data from all the sites. The abiotic (salinity, etc.) and biotic parameters list will allow the definition of the environmental conditions of the post-larvae. 2. A restocking phase will commence after the rearing phase involving all captured species. Tagging and monitoring will be carried out on (i) endemic species and (ii) exploited species. This will allow for the estimation of survival rates as well as for an assessment of the restocked fishes’ interactions with existing species. The threat from non-native invasive species will also be assessed, including an estimation of their dispersal. 3. A study of management requirements will be carried out based on reports from working groups, so as to promotes suitable solutions for replenishments. The project will organise the exchange of knowledge and experiences between various partners in the Western Mediterranean. Significant dissemination activities are also envisaged, with the organisation of a workshop and the production of publications on the project’s methodological approach, the biodiversity of post-larvae, the life-cycle of the species, and biodiversity management.