News and dispatches about my ongoing research projects.

What do we really protect in the Mediterranean Sea ?

Marine protected areas

(MPAs) in the Mediterranean Sea do not protect all marine biodiversity, according to two studies in Current Biology [1] & Global Ecology and Biogeography [2]. MPAs might protect species diversity, but they do not protect functional and evolutionary biodiversity [1]. Moreover some areas are both rich in terms of biodiversity and highly threatened by human activities [2]. These are the key findings of the two studies.

“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”.

The Mediterranean Sea contains between 4% and 18% of all known marine species although 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) [1]. 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’.

In the first study published in the journal Current Biology [1], we 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. 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”.

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.

In the second study, in Press in the journal Global Ecology and Biogeography [2], we looked for the parts of the Mediterranean Sea that are rich in marine mammals, turtles, birds, fish and invertebrates. We looked to see which of these areas are protected by MPAs and which are most affected by human pressure. We 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.

Picture : © Camille Albouy

References :

[1] Mouillot D, Albouy C, Guilhaumon F, Ben Rais Lasram F, Coll M, Devictor V, Meynard C, Pauly D, Tomasini JA, Trousselier M, Velez L, Watson R and Mouquet N. 2011. Protected and threatened components of fish biodiversity in the Mediterranean Sea
Current Biology 21: 1044-1050.

This paper as been "dispatched" in the same issue of Current Biology by Isabelle M. Côté, head of the Tropical Marine Ecology Lab at Simon Fraser University, British Columbia.

[2] Coll M, Piroddi C, Albouy C, Ben Rais Lasram F, Cheung WWL, Christensen V, Karpouzi V, Guilhaumon F, Mouillot D, Paleczny M, Palomares ML, Steenbeek J, Trujillo P, Watson R and Pauly D. 2011. The Mediterranean Sea under siege: spatial overlap between marine biodiversity, cumulative threats and marine reserves
Global Ecology and Biogeography In press.