Mediterranean Wetlands Vegetation and Fauna
Seagrasses are found on the seaward edges of lagoons, where the two types of environments blend together.
In the intertidal zones, the vegetation is generally dominated by eelgrasses Zostera spp, which are generally replaced by Ruppia spp in the calmer, more enclosed, and warmer waters of saline ponds. These two herbaceous plants are perennials and form important spawning beds and feeding zones for coastal fish, and attract many herbivorous waterfowl
On the banks, in marshy zones that are seasonally flooded, there are annual halophyte species which germinate in the dry season, when the water recedes below the surface of the ground; in particular, Salicornia, Arthrocnemum, and the grasses of brackish marshes that are resistant to both winter flooding and intensive grazing.
Salicornia (glassworts) occupy wide areas of brackish marshland in the Mediterranean Basin, in particular in the deltas, on the edges of lagoons, and around salt lakes in Northern Africa They help maintain these structures by capturing sediments, which leads to the emergence of a characteristic land form dotted with mounds.
Other communities of halophyte plants proliferate on the edges of marshes, such as rushes Juncus spp., which can form a belt just a few metres wide around ponds, at the upper limit of the zones that are flooded in winter, just before the tamarisks Tamarix spp., which give way to wet grassland as you move away from the shore.
The rushes form a part of the most distinctive plant communities in the Mediterranean Basin; a great number of these very diverse plants, and in particular several species of Quillworts Isoetes spp. can only be found in this region.
The emergent macrophytes of freshwater marshes
The reed Phragmites australis is clearly a dominant species among the large emergent macrophytes of freshwater marshes. This species grows everywhere where conditions remain wet through most of the year. In areas that are permanently flooded it can form floating masses.
When there is intensive grazing, the reeds can be replaced by prostrate grasses such as Aeluropus littoralis, or by sea club-rush Scirpus maritimus, which tolerate salt better, and flourish in lightly grazed areas, often on the banks of deep lakes.
Sawgrasses Cladium spp. prefer permanent wetlands. They are rare in the Mediterranean Basin. The most extensive beds are found in the Daimiel wetland in the centre of Spain and in the marshes of the Crau in the Camargue.
The river forests
Most river forests have disappeared from the European floodplains, although in certain deltas, some fragments remain, as is the case at the Nestos, in Greece, in which there remain sixty hectares of seasonally-flooded deciduous forest, or in the Ebro delta where there are stands of poplars Populus spp., alders Alnus spp., and white willows Salix alba.
Submerged and floating freshwater plants
Many species of submerged plants are types of pondweeds, such as Potamogeton pectinatus, which covers one third of the area of lake Ichkeul in Tunisia, and is the main species consumed by wintering duck populations When the water is saltier, the pondweeds are replaced by tasselweeds Ruppia, whereas in areas that remain dry for more than one month, there are shallow water communities such as stoneworts Chara spp., which can withstand summer drought.
The lakes and fresh and salt water marshes in the Mediterranean Basin are not only breeding and wintering sites for millions of birds, but they also play a role as stopover sites for an even larger number of birds that feed and rest there during their annual migration between Africa and Northern Europe and Asia. The main migratory flyways skirt the Mediterranean, through Turkey and the Rift valley in Israel. Other more direct routes cross the sea at the narrowest crossings, between Tunisia and southern Italy, via Malta, or between Libya and Greece and the Balkans, via Crete.
Mediterranean wetlands are a refuge for mammals that are poorly adapted to the hot, dry summers of the Mediterranean climate. Their undisturbed wide-open spaces are important habitats for rare animals (for example, the Spanish lynx Lynx pardina in the south of Spain, in Doñana).
There is a high degree of endemism among amphibians and reptiles. In the Mediterranean islands, the current fauna is to a large extent determined by former connections between the islands and the European or African continent, but also by artificial introductions. On the islands in the western Mediterranean basin, the endemicity values for frogs and toads are high because of the length of time the fauna has been established there, as well as their low capacity for dispersal. Whether in terms of new species, sub-species, or small, isolated populations, this range of genetic variation is very often the most threatened. Any damage to the habitats in these areas will have irreversible consequences.
The freshwater fish fauna of the northern Mediterranean region is particularly remarkable, with 226 endemic taxa (128 species and 98 sub-species) divided into 13 families: the Cyprinids which make up the most important group, the Cobitidae, the Gobiidae, the Cyprinodontidae and Salmonidae, the Petromyzontidae, the Acipenseridae, the Siluridae, the Percidae, the Blennidae, the Cottidae, and the Gasterosteidae. Most of these species live in lowland rivers and natural lakes, to a lesser extent in mountain springs and brooks, and rarely in marshes, coastal lagoons, artificial canals, and reservoirs. Four species (known from a single site) have already disappeared, and more than 70% of the endemic species are threatened in one way or another.