The wetlands consist of permanent or temporary bodies of fresh or brackish water, and land adjacent to them. They include all lakes, sebkhats, lagoons and rivers. Tunisia has more than two hundred and fifty six (256) wetlands many of which are of international importance. The majority of these environments is north, especially near the coast. Currently 40 wetlands included in the list of the Ramsar Convention http://www.ramsar.org/wetland/tunisia.
Wetlands provide a wide variety of plant species to grow, a large number of invertebrates, amphibians, reptiles, birds and mammals, take advantage of this vegetation as habitat and / or as a food source.
Each year, more than 75,000 flamingos, 400,000 ducks of different species and 250,000 coots and moorhens, use wetlands for wintering, rest during their migration and nesting.
The most important ecosystems :
The lagoons of Tunisia cover an area of about 105,000 hectars. These environments have hydrodynamic characteristics and different farms hydrobiological; the characteristics of the 10 lagoons (Table 1), revealing three categories of lagoons, depending on the geographical distribution, surface area and average depth.
All these lagoons are subject to traditional fisheries based on fish migration, in recent years the various aquaculture activities are grafted to these lagoons. The recent enrichment of these environments, caused by closures and obstructions graus, aquaculture discharges and urban pollution, manifested by almost cyclical blooms leading to disruption of environments and fatalities at the stand. We present here the main interactions between Hydrobiology environments and populations.
Biodiversity Tunisia lagoons is rich than 200 species of microflora, 142 species of macroflora, 95 species of micro fauna and 250 species of macrofauna 45 fish, two turtles, one aquatic mammal and more than 220 birds.
Principal characteristics of the lagoons of Tunisia
lagoons Area (ha) Depth (m) Activities Yield kg / hectar / year common Species Exchanges Sea / lagoons Ichkeul 8500 1 Fish reserve 7 à 9 Mugilidae sanguilles Oued Tinja écluse Bizerte 15000 7 Fishing aquaculture 7 à 10 sparidae oyster / mussel Channel Bizerte Ghar El Melh 2800 1 Fishing 15 à 25 Mugilidae eels Passe Tunis 2900 1.5 Fishing 13 à 30 Mugilidae eels Canal Kheireddine Canal Rades Korba 175 0.5 Mugilidae mugilidés Passe Hergla 800 0.5 Fishing anguilles sparidés shallows Khneiss 340 1 Fishing aquaculture sparidae Mugilidae Hauts fonds Bou Grara 50000 7 Fishing aquaculture 6 à 11 sparidae Mugilidae Canal Ajim El Kantara Biban 30000 5 Fishing 9 à 25 sparidés mugilidés moronidés Passes
registered since 1980 on the list of UNESCO World Heritage Site covers 12,600 hecatars (http://whc.unesco.org/fr/list/8/). It is a permanent lake, brackish water, located in the plain of Mateur, northern Tunisia. It is 20 km southwest of Bizerte and 60 km north-west of TunisIn summer, when the water level is low, the lake covers about 8,500 hecatars. It is surrounded by 2,737 hectars of marsh. After winter rains, water covers about 10,000 hectars. The maximum depth of water in winter is 3.7 m and 1.5 m in summer only. The lake is bordered to the south by the Djebel Ichkeul, which rises to 508 m. Five permanent streams and more temporary wadis draining a watershed of 2,089 km², and flow into the lake. The main rivers are the wadis Joumine, Sejnane El Melah Ghezala and Douimis.
These rivers spoof on average one million m3 of sediment in the lake, which three-quarters are discharged through the wadi Tinja between Lake Ichkeul Lake Bizerte. In summer, the sea water flowing into Lake Ichkeul where the water level is lower, and conversely in winter.
The vegetation of Lake Ichkeul and surrounding marshes is varied but sparse. In open waters, the pondweed dominates submerged vegetation, especially in the west of the lake where they are an important feeding ground for waterbirds. The species Zannichellapalustris is also common in winter among the submerged species; however, in summer there are the Chara genres, and Callitriche Ruppia. On the banks of the lake, Phragmites form bands separating the lake marshes dominated by bulrushes and rushes. Typha angustifolia grows along the canals of the marshes where we also find Tamarix africana. The salty areas are dominated by Salicornia and Suaeda.
The lake's marshes are among the few sites were found several species of rare plants and Ranunculusophioglossum Sparganuim erectum.
Jebel is covered with scrub consists of training in oil-mastic and where we can see the caper, the tree spurge, carob, juniper, rosemary and African cyclamen.
For fauna, several mammalian species of Jebel Ichkeul go down in the marshes to feed: hedgehog, four bat species, mongoose, jackal, red fox, hare, wild boar, and several species of rodents, well as the otter is a rare species in Tunisia, have been reported there. The buffalo is the largest mammalian species Ichkeul.
In terms of birds, Lake Ichkeul is the most important wetland for birds in North Africa and one of the most interesting sites in the Mediterranean; around 4% of the world population of the white-headed duck was observed at Ichkeul. It is also a traditional nesting site for the Marbled Teal, which is rare, and many other species. Migratory birds use the lake during their winter stay. At the peak of migration, 150 to 200000 ducks and 5 to 7000 greylag geese are present. The numbers of wigeon are 39,000 of those 6,500 shoveler, the pochard 120,000, which gives the lake its international importance. More than two hundred species of birds have been reported in Lake and Jebel. Among the nesting species are cited and crested grebe grebes, herons ash and the night heron, the Pratincole necklace, nightingale, the warbler effarvette, etc .The settlements of invertebrates are limited to euryhaline species in areas where salinity is very fluctuating. On rivers where the salinity is lower (Joumine), these stands are very rich and diverse. Among fish fauna, eel, barbel, shad, sole, mullet, etc., are exploited for fishing. The herpetofauna includes several species of lizards (Lacerta) of ophidians (Montpellier snake, Natrixmaura ...) and the freshwater turtle. Amphibians include green toads of Mauritania and common, the marsh frog and painted Discoglossus.
It is located north-east of Lake Ichkeul, covers 13,000 hectares and its waters are saltys. The lake receives in the winter and spring of fresh water of Lake Ichkeul, reducing salinity at 35 g/l. It has a depth greater than 2 m and the deepest point reaches 12 meters. Adjacent marshes are located in the East Lake and carry halophyte vegetation.
The marine flora includes 145 species. The number of species decreases at Oued Tinja due to reduced salinity. The Lake includes Zosteranoltii, Zostera marina, Ruppia maritima and Cysmodoceanodosa. The algae comprise Chlorophyceaes (Ulva, Cladophora...), Pheophyceaes (Dictyota, Padina, Cystoseira ...) and Rhodophyceaes (Corallina, Jania, Halimedia ...).
Around Lake Bizerte mammals encountered such as the fox, jackal, hare, mongoose, the country gerbil and dormouse.
Because of its depth, Lake Bizerte is frequented by some of the bird species that frequent the lake Ichkeul, such as terns and gulls. On the east side of Lake you can see egrets, herring gull, the winged Tern and chimney swallow.
The marine environment, including sponges, Suberitesdomunicula, Leuconiaaspera and among cnidarians, Anemonia sulcata and Bunodactisverrucosa and as annelid polychaete Nereis diversicolor, Hermione hystrix, Sabella pavonia, Perenereis cultrifera.
The Lake of Tunis
It separates the city of Tunis from the sea. It covers 4,500 hectares and consists of three separate units: North and South lakes and navigation canal. The North and South lakes are less than 2 m deep or less than 1 m and navigation channel depths of 5 m. The lake is connected to the sea by the canal Kheireddine, North and that of Rades, south. North Lake includes a small island Chikli where is an ancient fortress which was erected in nature reserve
The Lake of Tunis is highly eutrophic and its waters are brackish, hence the low diversity of vegetation. The outlet to the sea is covered by the sea lettuce and algae form a layer at the surface of standing water in the summer.
The mammalian fauna is reduced to rodents such as gerbil’s country and the jerboa and some bat species. The presence of the hare, jackal and fox is not accidental, given the large human activity around the lake.
The Chikli Island is one of the nesting sites of the little egret in Tunisia. The Cormorants, herring gulls and kestrels also nest there. Mallard and Marbled Teal were nesting on the island. The Lake of Tunis is very important for water birds wintering as the great crested grebe and castagneur, cormorant (1000-1500), the flamingo (8,000 to 10,000), the pintail, shoveler (6,000), heron guard oxen, spoonbill and stilt. Among the other birds of the lake, it cites the chimney swallow, gray heron, marsh harrier, the mocking little tern and gull.
Lake Ghar al Milh
Located north of the estuary of the Oued Mejerda, it covers an area of 3000 hectares (2600 hectares at the main lagoon), with a length of 7 km and a width of 4.5 km. Its average depth 1 m, does not exceed the maximum of 2 m.
In its western part, it is powered by three freshwater wadis; in the East, it communicates with the sea by three passes with the broadest measure 70 m. These passes tend to be blocked by the alluvial deposits of the Mejerda, which is not without causing changes to the water conditions from within the lake. The average salinity is 39.5%; it ranges from 14.5% to 54.5% in winter in summer.
In border the vegetation consists of Zostera marina in association with Cladophora In teromorpha and Ulma, marshes are dominated by Phragmites. The lagoon and the delta in general is an important wetland for rodents, snakes and wintering and migratory birds; Periodically a large number of ducks, herons and flamingos.
The salt marshes of Sahline
They are located to the west of Monastir and cover more than 1,000 hectares, most of which is divided into evaporation ponds. They are more continental than Lake Monastir. The banks don’t allow free flow of water. The low water circulation and high salinity limit the establishment and growth of vegetation. The shores of the salt are dominated by Salicornia, Halocnemum, and Arthrocnemum. A Carpets of green filamentous algae dominate the less salty offshore regions.
The hares live in the halophytic vegetation covering the banks of ponds, mongoose and red fox found it occasionally. The gerbil country lives between basins and extends into the surrounding grounds.
Several species of water birds feed in the marshes, and many other nest like little egret and shelduck. The majority of bird species found in the Gulf of Hammamet and Gulf of Gabes stop at Lake Monastir and salt in the region. Among the birds of this region, mention the little grebe, gray heron, flamingo, avocet, redshank, mocking the little tern and gull.
The salt also host particularly interesting species of microalgae Dunaliella salina halophyte or crustacean Artemia Tunisian.
The salt marshes of Thyna
These lagoons located just south of Sfax, separated from the sea by a bank. They cover 860 hectares and a depth less than 3 m. The substrate is muddy or sandy. The halophyte vegetation (Arthrocnemum, Halocnemum) occupies the banks of ponds, but the low salinity areas contain abundant algae and phytoplankton.
The Fox and some species of rodents are found on the banks of ponds, but their numbers are reduced. Marshes are an important site Thyna rest and nesting for many waterbird species. The majority of species found in the Gulf of Gabes meet there, such as the black-necked grebe, Eurasian Spoonbill, shelduck (breeding), Avocet, sandpipers variable and minute, barker knights and Sandpiper, Ruddy Turnstone, Curlew, Black Terns, gulls mocking (dead), the billed tern, tern pierragarin (breeding), etc ..
Lagoon El Bibane or "Bhiret El Bibane "
It is located in southern Tunisia where it indicates the presence of a reef Neogoniolithon (calcareous red algae) along more than 30 km and unique in the Mediterranean. This hyper salt lagoon (41 to 49%) is essentially lined by seagrass Ruppiamaritima, Cymodoesanodosa and the pheophycaeCystoseirasp, occupying almost all the available substrate while Posidonia oceanica is confined in the "El Marsa" and Caulerpa prolifera is found only in the area of "El Oued" and "El Marsa." In this area and to a depth of 2 m Posidonia tasks reach a diameter of between 0.6 to 2 m², and a density of beams between 187-375 F / m².
Mega-invertebrates are represented by a dense population of Pinnanobilis and P. rudis (3-10 individuals keep / m²) and a population of sponges, undiversified but having a density of individuals of high Aplysinaaerophoba, Irciniachevreuxi, Irciniafasciculata, Tethyaauarantium, Tethyacitrina, while other species are common only in some areas as Dysideasp. Haliclonamediterranea, Haliclonasp., Irciniasp. reported in El Marsa. The population of the sea squirt Ecteinacsidiaturbinata is also well represented in the lagoon at densities up to 18 colonies / m² at the end of spring.
The study of "El Wadi" area, which connects the lagoon to the sea, is very interesting. Due to the presence of a strong current and the relatively large depth of this area (3-17 m). Large slabs partially cover the oued. The most common sponges are represented by Cacospongiamollior (5 individuals / m²) Irciniafasciculata (10 to 15 individuals / m²).
We also find the anthozoan Sargartiatroglodyles (5 colonies / m²) and Bryozoa Pentaporafoliacea (2 colonies / m²) and Schizoporellasp. But the peculiarity of this site is the presence of a kind of "reef" sponges, built primarily by Irciniasp and Fasciospongiacavernosa which can expand to 2 m² area, and are wide from 0.4 to 0.8 m; This is the first time that such training are described in the Mediterranean.
Sebkhats and chotts
The sebkhats and chotts occupy about 2 million hectares. We distinguish 15 sets including eleven and four sebkhats chotts, it is :
- Sebkhat Ariana, 10 km from Tunis to N0, covers 2500 hectares;
- Sebkhat Sedjoumi, SW Tunis, covers 2700 hectares, its banks N and E connqissent strong urbanization;
- Sebkhat Kourzia, 10 km northwest of El Fahs, it covers an area of 1,000 hectares ;
- Sebkhat Kalbia, 20 km NE of Kairouan, covers nearly 13,000 acres with a maximum depth of 2.5 m, its water surface varies from 0 to 11 000 hectares and salinity varies (1 g / l to saturation);
- Sebkhat Sidi El Hani, located 25 km E-SE of Kairouan;
- Sebkhat El Djem, 12 km south of El Jem, 20 km west of the sea and covers 3,000 ha, with emerging islands ;
- Sebkhats Sidi Mansour and in Noual respectively 60 and 70 NW of Gabes and 11 000 hectares and 3000 hectares;
- Small sebkhats low steppes, totaling several hundred hectares and consist of :
- Sebkhat Moknine;
- The sebkhats Sidi Khlifa of Ajjriba of Halk El Menzel, etc ..., located along the coast Hergla-Salloum;
- Sebkhat Menzel Dar BelOuaer;
- Sebkhats EchCherita, El Gherra, Mecheguig, El Bahira et Menzel Chaker;
- EchChabba of a few hundred meters from the coast, is Sebkhat El Bradaa;
- Lake Metbasseta;
- The Djeffara complex in the Libyan border, salt lakes in Tunisia complex covers an area of 160 000 hectars. It includes sebkhats El Melah and Bou Djemel, large coastal salt lakes side Bahiret El Bibane, Sebkhat Tader which extends over 70 km in the mainland from the coast, Sebkhat Oum El Krialate, Garaet Djedid, and SebkhatAreg el Makriene Garaet Djedid. resting site for migratory birds;
- Sebkhat Guettar, also called Chott El Guettar, 15 km SE of Gafsa, covers 7400 hectares of which 5000 ha of halophytic vegetation;
- Sebkhat El Hamma, 25 km to the O-NO Gabes, with an area of 5000 hectares and contains a hot water (70 ° C) ;
- Chott El Fedjej, covers 570,000 hectares in western El Hamma sebkhat;
- Chott el Jerid, located west of Chott El Fedjaj connected to it, Chott el Jerid, the largest saline lake in the Maghreb, covers 700,000 hectares;
- Chott el Jerid, located On west of Chott El Fedjaj connected to it, Chott el Jerid, the saline Largest lake in the Maghreb, covers 700,000 hectares;
- Artificial Lakes near Kebili, near the southeast edge of the Chott El Jerid, and 15 km of Kebili, is a series of small brackish lakes with an average size of 200 hectares. These are Nouiel lakes, Graad, Taffaya, Menchia and Fatnassa, which are fed by excess irrigation water oasis and drainage water. They are less salty than sebkhats and are not generally dry