The Mediterranean Sea contains between 4% and 18% of all known marine speciesalthough it constitutes only 0.8% of global ocean surface. This unique biodiversity is being damaged by several human pressures, including fisheries, aquaculture, ever‑increasing density of coastal towns and cities, and pesticide and fertilizer runoff from agriculture.

To counteract these threats, about 100 MPAs have been established in the Mediterranean Sea. MPAs cover only a small area – less than 1%, of the total area of the Mediterranean Sea – and match with the areas with the greatest number of fish species, where species are most endangered and on areas which have species that cannot be found anywhere else on the earth (‘endemic’ species). Yet as well as sheer numbers of fish species, it is vitally important that a broad variety of different types of fish with different ecological ‘functions’ are protected. The services that ecosystems provide to humans rely on these functions being performed. Moreover, if we simply concentrate on protecting as many species as possible, we might be allowing some species to disappear that have evolved uniquely from other fishes – wiping out great amounts of the ‘Tree of Life’.

MPAs might protect species diversity, but they do not protect functional and evolutionary biodiversity. Moreover some areas are both rich in terms of biodiversity and highly threatened by human activities. These are the key findings of two studies involving an international team of researchers linked to 10 laboratories and research centers located in Australia, Canada, France, Portugal, Spain, UK and Tunisia. “These studies reveal the ongoing needs to better evaluate and expand MPAs in the Mediterranean Sea if we want to preserve marine biodiversity as a whole”, says François Guilhaumon, a researcher at the 'Rui Nabeiro' Biodiversity Chair, in Évora who participated in the research.

In the first study published in the journal 'Current Biology', the team identified areas particularly rich in fish species (the western Mediterranean, for example), areas rich in endemic fish species (such as the Adriatic Sea), areas of high functional biodiversity (such as the coast of Tunisia), areas rich in evolutionary biodiversity (such as the northwest coast of Africa), and areas with high levels of threat (such as the coasts of Italy, France and Spain) ; see maps bellow. Unfortunately these areas don’t overlap very well. “These regions are located in different areas so their simultaneous protection is problematic under restricted resources for biodiversity conservation”, says François Guilhaumon.

In the second study, to be published next month in the journal 'Global Ecology and Biogeography', the team looked for the parts of the Mediterranean Sea that are rich in marine mammals, turtles, birds, fish and invertebrates. The team looked to see which of these areas are protected by MPAs and which are most affected by human pressure. They found that the most species rich areas are concentrated in the western and eastern Mediterranean Sea. Coastal areas are especially important for fish, seabirds and invertebrates, but open ocean areas are most important for marine mammals and sea turtles. However, a large proportion of these areas are under considerable pressure from humans. Worryingly, only a tiny fraction of these threatened biodiversity hotspots (0.4%) are found within MPAs. François Guilhaumon said, “we recommend that the existing MPAs system be urgently expanded to include a greater percentage of important areas for conservation in the Mediterranean Sea”.

Reference Articles

Mouillot D., Albouy C., Guilhaumon F., Ben Rais Lasram F., Coll M., Devictor V., Meynard C.N., Pauly D., Tomasini J. A., Troussellier M., Velez L., Watson R., Douzery E.J.P. & Mouquet N. Protected and threatened components of fish biodiversity in the Mediterranean Sea Current Biology, 21: 1044-1050. http://www.cell.com/current-biology/abstract/S0960-9822(11)00532-X

Coll M., Piroddi C., Albouy C., Ben Rais Lasram F., Cheung W.W.L., Christensen V., Karpouzi V.S., Guilhaumon F., Mouillot D., Paleczny M., Palomares M.L., Steenbeek J., Trujillo P., Watson R. & Pauly D. The Mediterranean Sea under siege: spatial overlap between marine biodiversity, cumulative threats and marine reserves. Global Ecology & Biogeography. In Press.

Participating laboratories

'Rui Nabeiro' Biodiversity Chair, CIBIO - Universidade de Évora, Évora, Portugal

Institut de Ciències del Mar (CSIC), Barcelona, Spain

UMR CNRS-UM2-IRD-IFREMER 5119 ECOSYM, Université Montpellier 2, Montpellier, France

Institut des Sciences de l’Evolution, UMR CNRS-UM2-IRD, 5554, Université Montpellier 2, Montpellier, France

UMR IRD-IFREMER-UM2 212 EME, CRHMT, Sète, France

INRA, UMR CBGP (INRA / IRD / Cirad / Montpellier SupAgro), Montferrier-sur-Lez, France

Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Australia

Fisheries Centre, University of British Columbia, Vancouver, British Columbia, Canada

Laboratoire Ecosystèmes et Ressources Aquatiques UR03AGRO1. Institut National Agronomique de Tunisie, Tunis, Tunisia

School of Environmental Sciences, University of East Anglia, Norwich, UK

MAPS

Maps of the Mediterranean fish biodiversity and threats. A. total species richness, B. endemic species richness, C. threatened species richness (IUCN), D. evolutionary diversity, E. functional biodiversity, F. fishing pressure. “Hotspots” are the region with the highest values on each map.