1This special issue n° 125 (2015) of the Journal of Mediterranean Geography (JMG), devoted to coastal wetlands, is new step in a series of issues exploring, for two decades now, the diversity and quality of past and present relationships between societies and coastal zones in the Mediterranean. By the early 1990s, a detailed issue about dynamics of the Rhône delta and the Camargue area was supervised and edited by the geographer and geomorphologist Mireille PROVANSAL (JMG, 1993/78 3-4,), but geomorphology of coastlines, management practices and initiatives and questions about concrete consequences of global changes for their evolution and societies living along the coast were discussed in depth during the 2000s. In 2005, research questions related to geoarcheology and past human occupation (notably by studying ancient port settings) during the Holocene shed new lights on long-term dynamics of coastal systems and paleo-environments (JMG, 2005/104). Then, paleo, current and future hazards, natural disasters, vulnerability and shoreline erosion, management and planning issues due to urbanization were investigated in 2007 (JMG, 2007/108). Environmental legislations, policies and legal frameworks for coastal protection and (sustainable) management in Europe and Maghreb, especially the application of existing national “coastal laws” were analyzed in a synthesis published in 2010 (JMG, 2010/115). At last, environmental historians Georges PICHARD and Emeline ROUCAUTE recently presented and analyzed a neglected aspect of the modern history of the Rhône river delta with an outstanding monography dedicated to the hydro-climate history of the Lower Rhône valley (JMG, 2014/HS). By bringing twelve original case studies, the issue completes and enhances this large set of works. Indeed, management issues of coastal wetlands are at the crossroads of novel, large-scale and rapid ecological, hydro-climatic and geomorphologic changes related to anthropogenic activities, recent geopolitical mutations and challenging international institutional initiatives in terms of sustainable development. It must be seen as the result of a dynamic professional, but also friendly, partnership between four French, Algerian and Tunisian guest editors. The synergy between two young researchers, Nicolas MAUGHAN and Najet AROUA with a main research interest focusing on all aspects of water management in the Mediterranean world during the modern period, and two others, Ameur OUESLATI and Jean-Marie MIOSSEC, working for decades on Mediterranean coastal regions, with a solid background and a global view resulted in an original and consistent issue. This was an opportunity to present conservation and management issues of wetlands in North Africa, with several articles from Maghreb countries, but also in the Balkan Peninsula where terrestrial and aquatic ecosystems have been subjected to a wide range of large-scale anthropogenically induced transformations, during communist then post-communist era.

2This publication received financial support from the Research Consortium ECCOREV in 2015 (FR n° 3098, Aix-Marseille Université).

• 1 The Ramsar Convention is an international treaty signed in 1971 for the conservation and sustaina (...)

Wetlands are areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six meters”
Ramsar Convention, 1971¹

3Among the 20 million hectares of wetlands in the Mediterranean, those present within coastal areas are nowadays experiencing the strongest socio-economic and hydro-climatic constraints and concentrate the major part of the environmental issues (Synthesis of the Mediterranean Wetlands Observatory, OZHM, 2012). Coastal populations and wetlands have been intertwined for centuries and these valuable ecosystems have a high ecological, economic but also historical and scientific importance (BARBIER et al., 2011; PAPAYANNIS et PRITCHARD, 2011; SCOTT et al., 2014; CAUTADELLA et al., 2015; VOLKE et al., 2015). Ecosystem service provided are important and include, for example, natural protection against chronic coastal erosion and damage to buildings and infrastructures but also impacts resulting from projected changes in extreme climate events; wetlands reduce the damaging effects of hurricanes on coastal communities (ERWIN, 2009; VASCHALDE, 2014). If coastal lagoons are of high economic value and play a significant role in the history of the Mediterranean shores, marshes are useful for reconstructing paleoenvironments and for understanding the recent shoreline evolution, together with prospective approaches in a context of sea-level rise.

4With over 135 million people, coastlines are strategic places supporting a large part of the population growth. For example, the population in the Egyptian low-elevation coastal zone along the Mediterranean coast and the Nile delta is 1075 people/km², but by 2030 population density along the Egyptian coast is expected to increase to 1902 people/km² and to 2681 by 2060 (NEUMANN et al., 2015) ! Even though the main driver is linked to the expansion of urban areas into rural lands, anthropogenic and climatic factors operating at different scales on the dynamic of coastal wetlands are heterogeneous and of various magnitude. Wetland systems are vulnerable to changes in quantity and quality of their water supply, and it is expected that climate change will have a pronounced effect on these ecosystems through alterations in hydrological regimes with great global variability (ERWIN, 2009). These questions are wide-ranging and cover, for example, some of the impacts of land use intensification and abandonment, such as uncontrolled industrial or informal sand mining on beaches and dunes, to power building and construction industry. Furthermore, risks posed to public health by emerging infectious diseases due to the range expansion of some vectors (e.g mosquitoes) are also a source of concern (PRADIER et al., 2014).

5The increasing risks of coastal wetlands submersion must also be taken into account. By the 2080s, sea-level rise could cause the loss of up to 22 % of the world’s coastal wetlands. When combined with other losses due to direct human action, up to 70 % of the world’s coastal wetlands could be lost by the 2080s, although there is considerable uncertainty. The largest losses due to sea-level rise will be around the Mediterranean and Baltic and to a lesser extent on the Atlantic coast of Central and North America and the smaller islands of the Caribbean (NICHOLLS et al., 1999). Consequently, many questions arise about physical and spatial evolution of these ecosystems and how local societies and management choices will be affected. Climate change and sea-level rise can contribute to increased rates of the shoreline erosion and retreat, with a loss of coastal protection, an increase in the salinity of estuaries or even a subsidence in deltas (CAPON et al., 2013). While sea level rise, storms, sedimentation, and changing freshwater input can directly impact coastal and estuarine wetlands (DAY et al., 2011), biological processes can modify and limit these physical impacts. Geomorphological changes to coastal and estuarine ecosystems can induce complex outcomes for the biota that are not themselves intuitively obvious because they are mediated by networks of biological interactions (biocomplexity framework). Human impacts on wetlands ecogeomorphology occur at all scales. Many coastal wetlands can adjust to predicted climate change, but human impacts, in combination with climate change, will significantly affect coastal wetland ecosystems (DAY et al., 2008).

A long-lasting memory for reconstructing coastal paleoenvironments and sea-level changes

6The first topic addresses research related to the pivotal role played by wetlands for reconstructing Mediterranean coastal paleolandscapes and paleoenvironments, especially for Tunisia. A range of recent regional geomorphological and geological studies revealed that the genesis and expansion of wetlands along the Tunisian shoreline was a recurring phenomenon during Holocene and Pleistocene interglacial periods. First, for the early Quaternary, BALESCU and his colleagues (1) showed that coastal Upper and Middle Pleistocene sedimentary sequences preserved along the eastern coast of Tunisia, near the still existing sebkhas, in the Sahelian zones of Khniss and Chebba and on Djerba Island, contain several lagoonal deposits mainly consisting of pedogenised loamy deposits. These deposits provide important chronostratigraphic markers and significant indicators for the reconstruction of paleo-environments and history of Tunisian wetlands. They performed an alternative optically stimulated luminescence dating method: the IRSL dating method (“Infra-Red Stimulated Luminesence”) which is applied herein to the feldspar detrital grains of sediments and allowing a very good discrimination between lagoonal deposits. It appears that coastal sedimentary sequences dating from the last interglacial in the Sahel and the South of Tunisia, recorded three marine cycles rather than two, each one ending with an emerging facies (paleosoil or coastal sand dunes). This multidisciplinary work is of great interest because case studies based on Pleistocene lagoonal deposits are much less frequent than those concerning Holocene deposits insofar as they are less easily accessible and well preserved. It is in the Jeffara coastal plain (South-East Tunisia), on mid-to-late Holocene deposits and on surface samples from the sebkha Boujmel that pollen analyses of JAOUADI et al. have been undertaken (2). Their preliminary results highlighted vegetation changes with large pollen taxonomic diversity and the vegetation response to both palaeoclimate change and human impact. From ca. 7000 to 4000 cal. yr. BP, during the humid Mid-Holocene episode, a grass steppe was widespread in the Jeffara coastal plain while a Mediterranean shrub covered the mountainous hinterland. At that time, human impact remains limited and major vegetation changes were triggered by climate forcing. At the Mid- to Late Holocene transition, the decrease of Mediterranean vegetation and both spreads of Artemisia and desert taxa may be related to increasing aridity. The surface samples reflect how human pressure is responsible for modern landscapes. The desert taxa develop while Olea and other pollen indicators attest to an increasing human impact on local ecosystems.

7In the last work, BRAHIM (3) presents the diachronic evolution of another Tunisian small coastal sebkha, the sebkha Ennjila, on the “longue durée” from the late Pleistocene to the present. This sebkha, surrounded by a shallow depression - a small flood plain - named “garaa”, was likely formed during the Tyrrhenian period or maybe just before, when a narrow inner beach-ridge, intersected by some inlets, has begun to isolate a partly closed lagoon from the sea (one of the four main identified lagoon type based on dominant processes). Then, the author describes the successive stages of the lagoon’s evolution after the Tyrrhenian. It evolved as a continental sebkha offering good conditions for the endoreism and the development of “lunettes”. He also showed that even if the hydrologic regime of the sebkha is strongly influenced by the semi-arid climate and rainfall seasonality it was modified by man-made structure built during the Roman period. Indeed, a canal dug through the Tyrrhenian beach-ridge was recommissioned in the early twentieth century to drain pluvial water into the sea when floods occur. The restoration of the canal has allowed occasional communication with sea and fishing in the sebkha after every flood. As for the “garaa”, the constant inundation (or soil saturation) explains the lack of ancient as well as recent human centers. These works focused on Tunisia clearly showed that an understanding of past environmental changes and their origins, “the past as prologue” as so well described by American historian and archeologist Charles REDMAN (1999), may be useful in assessing current biological integrity and ecological conditions of Mediterranean coastal wetlands, especially for the Maghreb region, and for evaluating the changes caused by both natural and human perturbations but also the possible resilience of ecosystems (DAOUD-BOUATTOUR et al., 2011).

Highly vulnerable ecosystems to global changes and littoralization process

8Through the cases of three wide coastal lagoons in Morocco and Tunisia, articles gathered in the second section particularly focus on sediment flux dynamics frequently modified in or near coastal wetlands, because of urbanization pressures and engineering works like polders, but also on growing problem of subsidence and marine transgression. OUESLATI et al. (4) present the case of the lagoon of Ghar El Melh and its annex, the lagoon of Sidi Ali El Mekki, belong to the coast of the Gulf of Tunis. Their barrier beach, or lido, is today facing major problems. The starting point was the creation in 1974 of a small fishing harbor which has affected the sediment dynamics along the shoreline. The morphology of the lido has been heavily modified and disturbances took place in the hydrological dynamics. The effects were also felt in the agricultural activity conducted on the banks of the lagoon system, including Ramli terroir resulting from an original soil use and which is of great importance to the agricultural heritage and the local patrimony. The question is all the more important as the lagoon system is threatened by marine transgression and changes in the lido morphology induced local socio-economic problems. Moreover, mitigation and conservation efforts are lacking to save this land and ensure its future. Authors herein highlight practical problems in integrating both environmental and economic goals in sustainable coastal lagoon management. Marine transgression of coastal wetlands is related to land use changes and their impact on sediment fluxes and by sea-level rise but is also controlled by subsidence phenomena which happen in major Mediterranean deltas, mainly the Nile delta in Egypt (NICHOLLS et al., 1999; ZAID et al., 2014; SHALTOUT et al., 2015). Possible options for long-term adaptive strategies to sea-level rise (for the next century) are still discussed without consensus among policymakers. For example, for wetlands in the Languedoc-Roussillon region (France), which is particularly at risk of submersion, an evaluation based on the worst case scenario of a one meter sea level rise by 2100, showed demonstrated the superiority of a strategic retreat policy (a strategic retreat of infrastructures and buildings), on a denial or a laissez-faire, which would halve the damages resulting from submersion (KUHFUSSA et al., 2016). And, although recent works have identified feedbacks between plant growth and geomorphology that allow coastal wetlands to actively resist the deleterious effects of sea-level rise, whether they continue to survive sea-level rise depends largely on how human impacts interact with rapid sea-level rise, and socio-economic factors that influence transgression into adjacent uplands (KIRWAN and MEGONIGAL, 2013).

9Also in the North-West of Tunisia, a few kilometers south, Walid CHOUARI (5), in using old topographic maps, aerial and satellite images more fieldwork data, presents the century-long process of anthropogenic alteration of natural shores, water circulation and water quality parameters of the large lagoon of Tunis, then the recent ecological restoration efforts of the lagoonal ecosystem. Thanks to a detailed cartographic analysis recent geomorphological changes of shores of both lakes - north and south - can be assessed over time. A gradual straightening and artificialization of the banks is noticed more a significant decrease in lakes’ surface up until the late 1970s. Satellite images also reveal informations related to the eutrophication process of the lagoon, very consistent with sediment and water quality measurements at that time. Then, from the early 1980s, one can note significant backfilling operations along the north lake’s banks, and a few years later in the south part, in connection with two extensive urban planning programs. The impact of present-day high average subsidence rates for newly reclaimed lands - filled areas - along the lagoon shores, is briefly discussed because it will cause significant and increasing geotechnical problems for engineers over the next decades and will require an accurate and constant monitoring; as for many other polders or artificial structures built in deltaic era around the Mediterranean (STANLEY, 1997; CAVALIÉ et al., 2015). In this work, the old topographic maps, together with aerial or satellite images complete fieldwork data and are key sources to understand landscape dynamics and environmental issues of this wetland.

10Aerial photographs and remote sensing images are also essential in the study of BOYAUZAN and IRZI (6) to capture evidence of impacts of man-made structures on sediment fluxes and water circulation around the barrier island of the Nador Lagoon in the North-East of Morocco. The barrier island system and its inlets are key units of the Nador lagoon ecosystem, designated as Ramsar site since 2005. The study of the morphological evolution of the barrier island from 1958 to 2014 is based on a joint analysis of historical aerial photographs and field observations. Results highlight major natural factors controlling the evolution of the coastline and the effects of recent artificial infrastructures on this vulnerable ecosystem Modifications of the suspended sediment flux direction are observed in eroded sedimentary bodies or others recently built. The example of Nador clearly shows that engineering structures (e.g. groynes or breakwaters to contain erosion) and large-scale shoreline modifications (e.g. beach protection, beach nourishment, leisure of fishing harbour structures) with « short-term » management goals, may cause potential severe and long-term adverse effects on lagoon morphodynamic processes, water-circulation patterns and suspended sediment fluxes (ANTHONY, 2014).

The challenging development of novel measurement and assessment tools for monitoring and management of coastal wetlands

11The third thematic section brings six studies relatives to various lagoons and lakes from three different countries, Algeria, Albania and France more a wide synthesis for the circum-Mediterranean region. Past and present temporal and spatial trends, assessment tools sustainable management issues were addressed especially the integrated coastal zone management (ICZM), a process for the management of the coast using an integrated approach, regarding all aspects of the coastal zone, including geographical and political boundaries, to achieve sustainability. It is an adaptive process to address current and long-term coastal management issues, including habitat loss, degradation of water quality, changes in hydrological cycles, depletion of coastal resources, and adaptation to sea level rise and other impacts of global climate change. It is not a substitute for sectoral planning, but focuses on the linkages between sectoral activities to achieve more comprehensive goals (DALIGAUX et MINVIELLE, 2010). In the analysis proposed by BELTRAME et al. (7) (from the Tour du Valat biology station) land-cover changes in 214 coastal wetlands located around the Mediterranean basin were characterized for 30 years (1975-2005) in using satellite image and aerial photograph datasets with remote sensing and GIS. It appears that the area of natural wetland habitats decreased by 10 % in 30 years, i.e. a loss of about 1329 km². Conversely, at the same time, artificial wetland habitats increased by 105 %, i.e. a gain of about 854 km². For example, if one consider the well-studied case of Israel, of 192 coastal ponds and salt marshes existing on historical maps along the Israeli coastal plain only 18 % still exist nowadays (35) (LEVIN et al., 2009). An extrapolation from 69 sites (hidden in historical sources), suggests that in the 19th century, long before many local wetlands were drained, converted to agricultural or urban lands, the number of wetlands in this plain was probably three times higher. The main direct pressure on natural wetland habitats was agriculture, with 71 % of them converted into agricultural areas. In their conclusions BELTRAME et al., also show that although the urbanization process had less direct impact on wetlands is lower than expected it largely affected agricultural lands, which in turn were displaced onto surrounding natural habitats. An opposite trend was registered at a local scale in a local-scale analysis realized by MAUGHAN (8) on transitional waters of the eastern shore of the Berre lagoon (Southeastern France) over the last three centuries. In this area, industrial development was the first factor responsible for the decrease in wetland surfaces, from the first decades of the twentieth century. When large hydraulic infrastructures were built (i.e. the canal from Marseille to the Rhône River), several large natural areas of the shallow Bolmon lagoon were filled. Then, from the early 1950s, the intense local urban growth induced the gradual disappearance of most of the salt marshes and other parts of the lagoon still preserved. The three Algerian selected cases are the lake Fetzara in the vicinity of the city of Annaba (located in Eastern Algeria), the coastal area of Terga (in the west of the country) and the coastal wetland of Réghaia near Algiers. For the lake Fetzara, designated as Ramsar site since June 2003, MELLOUK et AROUA (9) show that the strong urban growth of Annaba, beyond its natural borders, impacts surrounding alluvial plains and their shallow temporary lakes and marshes, located twenty kilometers south west of the city. The multi-criteria analysis method used reveals that the new urban planning project in the vicinity of Draa Errich mainly induces local physico-chemical disturbances on the hydrosystem, resulting in strong impacts on aquatic ecosystems, whose ecological integrity is seriously threatened. Final results showed a chronic ecological degradation requiring urgent conservation and restoration measures under a sustainable water and environmental management plan for this urbanizing territory. In the East of the country, in the Algiers region, LARID (10) describes and emphasizes the critical role of a feedback contribution of a coastal management planning based on an ICZM approach and focused on the protection and conservation of the Reghaia’s coastal wetland that faced ecological and socio-economic challenges for decades. In this case too, the urban growth of the sprawling Algiers metropolis threatens this ecosystem with its high biodiversity value, recognized as a Ramsar site since June 2003. It allowed the development of an integrative and inclusive process, which turned out to be an interesting and valuable experience, but highlighting some problems in starting an integrated management program, however necessary for the conservation of this natural and cultural heritage. First results support the idea that an integrated initiative is both an iterative and inclusive process. This effort offers some interesting perspectives. But, it must be linked to a better and greater involvement of local actors, an improvement of the inclusive process, robust and efficient protection policies more open access environmental databases (BILLÉ, 2006).

12With the last Algerian example GHODBANI et al. (11) give an overview of threats, challenges and management issues facing by coastal ecosystems along the north African coasts, through the case of Terga in the far west of the country. They highlight two major points: the first one concerns ecological impacts due to massive and uncontrolled (frequently illegal) sand mining along beaches and shorelines but also challenges for landscape conservation and, the second one, deals with understanding of the complex interplay among stakeholders, conflicting interests encountered for sustainable use of local natural resources and relevant environmental management tools. This study accurately describes one of the main causes of present-day coastal erosion along Mediterranean coastlines related to the important geomorphological effects from gravel and sand mining (STEINBERGER et al., 2012; SAVIOUR, 2012; UNEP, 2014; LAIMÉ, 2015).

13The last article concerns a region of the Balkans where the people-wetland dynamic received little attention in academic studies until the past decade: the Albanian coastal plain. It especially described the widespread and rapid elimination of wetlands by drainage and the concurrent land reclamation for agricultural purposes with cross-national comparisons at the same time. In this work, SHALLARI and MAUGHAN (12) explore transformations of coastal wetlands in Albania during the communist period, from 1945 to 1990, which deeply altered aquatic ecosystems, biodiversity and physical environment (especially for the coastal hydrosystem and sediment fluxes, CIAVOLA et al., 1999; CULLAJ et al., 2005). This diachronic cartographic-based analysis has allowed an understanding of the rapid anthropogenic changes that have affected the coastal plain and the evolving role of wetlands for society in socialist Albania, then during the post-socialist period from the 1990s (RUGG, 1994). The key role played nowadays for the country’s economy by the coastal plain, which contains the greatest part of the population, as well as most of the economic activity and agricultural production, induces in turn collateral damages and major environmental challenges for both the conservation and restoration of remaining wetlands.