A Distinctive Eco-region: Mediterranean Biodiversity

Terrestrial environments

The Mediterranean region has high levels of endemicity that have led to its identification as a global biodiversity hotspot. This is in part due to the area being spared during the recent ice ages, the presence of significant massifs (eg Atlas, southern Taurus, Gudar, Javalambre, Levant…) and also to the long history of varying land-use by people in the area that has created and maintained a wide range of habitats.

Data for Morocco shows that it has particularly high species diversity and endemism and holds approximately 3,800 species of plant, of which 829 are endemic. Other countries with high species richness and endemism representative of the region as a whole include Syria (2,600 species, 395 endemic) and Greece (4,000 species, 554 endemic). The rate of endemism on Mediterranean islands is especially high, with 10% of species often being endemic.

The biological diversity of the Mediterranean is not limited to plants. Of 62 species of amphibians in the Mediterranean, 35 are endemic (56%), as are 111 of the 179 reptile species (62%). In Morocco, for example, there are 93 reptile species, 20 of which are endemic (21%). Of the 184 mammal species recorded, 25% are endemic and 52 species are threatened (excluding marine mammals).

The Mediterranean is also hugely important for its bird populations, being on the migration route of millions of waterfowl. An estimated 2 billion migratory birds of 150 species use Mediterranean wetlands as stopover or seasonal sites. Twenty globally threatened bird species live in the region. Seven of these breed in Mediterranean wetlands, and wetlands host about seventy other species whose populations are locally threatened. Stress on water resources in many Mediterranean countries makes this biome of particular vulnerability.

With almost 5000 islands and islets (figures differ a little from one authority to the other), the
Mediterranean comprises one of the largest groups of islands in the world. The region is of high value to global biodiversity due to its wealth of species, relatively high rate of endemism, long history, and tolerance of all kinds of disruptions, as well as its role as a natural laboratory for evolutionary studies. There are some 4000 islands of less than 10 km2 in area in the Mediterranean, and 162 islands which are at least 10km2. The nine Mediterranean islands of over 1000km2 account for 83% of the total island area.

All Mediterranean countries have created protected areas networks that seek to protect pristine or representative areas, both terrestrial and marine. Some of these are uninhabited, others depend on the active participation of local people in and around them for the maintenance of their natural values.

The Mediterranean Marine Environment

The Mediterranean Sea covers about 2.5 million km2 , with an approximate coastline of 46,000 km. It is considered as a poorly productive sea, although the most diverse in terms of species. The Mediterranean sea includes 6 percent of the worlds species for less than 1 per cent of the worlds ocean area, and while much of the fauna is of Atlantic or Red Sea origin, the levels of endemism are also high, including some emblematic species of global conservation concern. The 28% of the marine species found in the Mediterranean are endemic to the sea. In the sea, about 20 species of cetaceans from small dolphins to huge sperm and baleen whales occur and there may be significant migratory exchanges with the Atlantic through the Strait of Gibraltar.

Introduction of non-indigenous species is one of the most pervasive and irreversible impacts of human activities on natural ecosystems. In the Mediterranean Sea, the number of exotic species is estimated to be around 10006. Many of these species became invasive and have caused considerable ecological and economic impacts in some Mediterranean countries.

The Mediterranean hosts a number of critically endangered species, but the assessment of the status of some vulnerable and poorly known marine groups, like sharks and their relatives is still lacking. So far, the attention has been focused on flagship and charismatic species, like the Monk Seal or marine turtles, but a first assessment of the status of sharks has shown that some species are thought to be extinct from the Mediterranean Sea, and others threatened with extinction.