Biodiversity patterns in Mediterranean coralligenous outcrops


Research output

medDiversa aims to estimate the diversity of macro-species of algae and invertebrates (mainly sponges, cnidarians, bryozoans and tunicates) through photographic surveys across large spatial and temporal scales. The project is based on a Regional approach, which is optimal to analyze the variability over large spatial scales following a latitudinal and oceanographic gradient and a Temporal approach (annual surveys), which is useful to determine the natural variability of these communities in order to discriminate between the observed changes due to natural factors and those related to the impact of disturbances related to global change (e.g. invasive species, dramatic storms, mass mortality outbreaks).

Example of the Regional approach

Scandola Port-Cros Marseille Medes Eivissa
Scandola Port-Cros Marseille Medes

Example of the natural variability of coralligenous outcrops among different study sites. Each quadrat is 25*25 cm. The same sampling methodology is and will be carried out during the field surveys. Each quadrat may present from 15 to 20 macro-species. Depth: 20-30 m.

Example of the Temporal approach

Example of the natural variability of coralligenous outcrops over 5 years (from 2006-2010). Overall, there are few changes concerning macro-species composition. Additionally, some engineering species show high longevity and low dynamics, making coralligenous outcrops vulnerable to disturbances.

To address these approaches, we use a hierarchical sampling procedure to measure species-level abundances among the regions, regions within localities, and localities within sites. Additionally, environmental data are integrated to the biodiversity analyses. Since 2003, members of MedRecover have progressively deployed temperature recorders at some study localities. For more information of the temperature series, please visit the site.

Temperature profiles

Temperature profiles at Medes Islands, Calanques-Marseille, Port-Cros, and Scandola along a depth gradient (5-40 m depth) from June to October 2005. Figure from Bensoussan et al (2010) Est Coast Shelf Scie 87:431-441.