2.1. Historical and geographical characteristics of coastal lagoons

Coastal lagoons, as they can be seen today, are the result of centuries of interactions between natural dynamics and human management, as witnessed by the presence of coastal populations who used to live in coastal lagoons several thousand years ago.

2.1.1 Etymology and definition of lagoons

In the social and historical context of the Mediterranean region, coastal lagoons have always been well recognized and distinguished from other transitional water bodies such as low lands, salt marshes or wetlands. It is not a coincidence that the word “lagoon” – attested in the English language since the early seventeenth century (Oxford English Dictionary, 1971) and used worldwide to indicate a marine waterbody separated from the open sea where seawater mixes with continental freshwater – originates from the Italian word “laguna” (from the Latin “lacuna”, derivating from the word “lacus” = lake), which originally referred to the waters surrounding the city of Venice.

In general, there are many typologies to which lagoons can be ascribed, and the distinction among them is essentially based on their geological origin and on the presence of tidal influence (Brambati, 1988; Carrada and Fresi, 1988; Ciccotti et al., 2012). Typically, lagoons are ecologically defined as “shallow water bodies separated from the ocean by a barrier, connected at least intermittently to the ocean by one or more restricted inlets, and usually oriented shore
parallel” (Kjerfve, 1994). However, there is a somehow improper use of the terms “lagoon”, “coastal lake” and “pond” throughout the Mediterranean area. This confusion partly stems from the use of terms which describe local points of interest (e.g. “lagoon”, “coastal lake”, “pond”, “esteros”, “etang”, “marsh”, “marais”, “stagno”, etc.) rather than the real nature of the different environments – even in similar areas within the same country. Moreover, the term “lagoon” can have a different meaning from a biological or a geological point of view, depending on the geomorphological characteristics. According to the classification proposed by Brambati (1988), the key parameter to characterize lagoons from other coastal waters such as ponds is the presence of tidal range, which only occurs in lagoons and not in coastal ponds.
Recently, the issue of classifying Mediterranean lagoons in typologies has become topical in relation to the criteria introduced by the Water Framework Directive 60/2000/EC (WFD), which provides for the protection and sustainable management of inland water ecosystems, including transitional, coastal and ground waters. The Directive has introduced a new terminology for aquatic systems. In particular, transitional waters are defined as “surface water bodies in the vicinity of the mouth of a river, saline because of their proximity to coastal waters but essentially influenced by freshwater flows”. According to this Directive and to its subsequent interpretations (de Wit et al., 2011), Mediterranean lagoons fall within the category of coastal lagoons (in contrast, most Atlantic lagoons are considered as coastal waters, due to the predominant and determinant effects of marine tides). As transitional waters, Mediterranean lagoons can be further classified according to the influence of tide (microtidal lagoons, tidal

5 The valle is a portion of a lagoon, extremely variable in dimensions, enclosed by embankments communicating directly or indirectly with the sea (Ardizzone et al., 1988) in Northen Italy. Valliculture is one of the most ancient aquaculture practices in the history of humanity that was born thanks to the wit and power of observation of coastal fishers who started building barriers to trap fish (mostly eels and mullets) in the valli during their seasonal migrations (Ravagnan, 1992).

range > 50 cm; non-tidal lagoons, tidal range < 50 cm) and to their size, which categorizes lagoons with a surface area greater or smaller than 3 km2 (Basset et al., 2006).

2.1.2 Lagoons lifespan

Mediterranean coastal lagoons are relatively young ecosystems. Most of them have been formed during transgressional periods of sea level rise in the Holocene, 5 000–1 000 years ago. Regardless of the mechanisms that have given rise to the different coastal lagoons (de Wit et al., 2011), all share the characteristic of changing shape and dimensions in time and space, due to natural processes, and of being ephemeral ecosystems. Barnes (1980) mentions that the typical lifetime of a coastal lagoon is around 1 000 years, but several lagoons can have a longer existence. The Venice lagoon in the Adriatic Sea formed 5 000 years ago, while some lagoons have been existing since Roman times and others have formed during the medieval period (de Wit, 2011). Nevertheless, the lifespan of coastal lagoons is related to human efforts to manipulate their morphology through earthworks, dredging and other structural interventions. Coastal lagoons in their present shape are therefore the result of strong interactions between coastal dynamics and human intervention (see paragraph 2.5).

2.1.3 Surface coverage, size range and ownership

At present, the Mediterranean hosts around 400 coastal lagoons covering a surface of over 640 000 ha. The figures provided in Table 1 have been extracted from the country reports (Part 2) and compared or integrated with data from literature. Discrepancies between sources relating to the number of lagoons arise from the fact that saline lakes and other coastal swamp areas may be included or not in the count. Likewise, differences in their area extent are due to the fact that, depending on the source of information, the coastal lagoon surface may refer to the water surface only or also include the land surrounding the lagoon.
Table I: Number and surface of coastal lagoons in the Mediterranean
(*Country reports,**Hecker and Tomas Vives, 1995; Kerambrum, 1986; www.ramsar.org; http://medwet.org)

In general, Mediterranean coastal lagoons greatly vary in size, ranging from 2 ha (e.g., the Chalikiopoulou lagoon, Greece) to 78 000 ha (Manzala lake, Egypt).
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In some areas, lagoons are very extensive and they are sometimes completely or partially subdivided into smaller confined areas. For instance, the Venice lagoon, which has a total estimated surface of over 57 000 ha, hosts around 36 smaller valli ranging between 10 and 1 700 ha (Marino et al., 2009; Italy country report). In other countries, lagoons are small and scattered along the coast.
As concerns property, in many countries coastal lagoons are publicly owned, although confined areas of these lagoons may often be private. When utilized for extensive fish culture, lagoons are often managed by local regional authorities or leased to local fishers groups, cooperatives or private companies, which may or may not have exclusive fishing rights and lagoon management
obligations. Many Venetian valli in Italy have private owners; in France, more than 10 percent of lagoons have been bought by the Conservatoire du littoral, an institution dedicated to the protection of coastal zones (France country report). In Albania, Greece and Tunisia, all coastal lagoons are public domain; in Albania, 10-year licenses for fishing rights are given to fisher’s
cooperatives or to private fishers. In Tunisia, there is a system of licenses to private companies and private fishers. In Egypt, four lagoons belong to the public domain and one is owned by a public company (Tunisia and Egypt country reports).

 

2.1.4 Historical loss of coastal

lagoon surface

The surface covered by coastal lagoons is the remnant of a much larger extent of wetlands in the whole Mediterranean region and indeed, much of the original area covered by coastal lagoons has
disappeared today. Different consumptive uses of lagoon areas and of the surrounding land for agriculture, industry, and urban development have contributed to the contraction of the overall coastal lagoon surface. In several countries, reclamation interventions have deeply changed the coverage and the fate of the lagoons.
The first land and water management interventions date back to 5 000 BC, in Mesopotamia and in Ancient Egypt. As a matter of fact, the Romans achieved a lot of land reclamations in the Pontine Marshes and in Tuscany (west coast of Italy). To give an idea of the extent of the loss of lagoon surface, it is enough to consider that in Italy wetlands covered over 3 million ha in pre-Roman times, decreased to 1.3 million ha in 1865 and cover at present 160 000 ha (Rossi Doria and Bevilacqua, 1984; Italy country report). It was in the late nineteenth and early twentieth centuries, when many European countries initiated programmes of
In Spain, the process of draining wetlands started in the mid-nineteenth century and accelerated after 1918 with the introduction of a law to reclaim wetlands for agriculture and break the malaria cycle in the western Mediterranean. It is estimated that around 60 percent of Spanish wetlands have disappeared in the last 40 years (Spain country report). In Maremma (Italy), coastal wetlands have practically disappeared after the land reclamation carried out in 1828–1830; in the Pontine Marshes after the bonifica (reclamation) in the 1930s, only the four coastal lagoons (locally called lakes) of Caprolace, Monaci, Fogliano and Sabaudia survived. The Comacchio reclamation programmes reduced the extension of the valli by about 80 percent (from 73 000 ha to 13 000 ha now). The Venice lagoon also was greatly reduced, firstly in the eighteenth century with the deviation of some rivers to avoid sand stack, then between 1800 and 1900 for agriculture reclamation, and still in the period 1924–1960 as increasing urbanization and industrial development in Porto Marghera constrained even more the lagoon surface (Italy country report). In Albania, more than 50 percent of the coastal wetlands have been lost due to the development of drainage projects and marshland reclamation schemes after the 1950s (Albania country report). In Greece, the wetland surface of the Amvrakikos Gulfhas decreased from 65 percent in 1945 to 41 percent in 1999, due to the extension of artificial and cultivated areas (Greece country report). In Egypt finally, the deltaic lagoons of Edku, Burullus and Manzala have lost about 60–75 percent of their original surface in the last sixty years due to siltation, spread of aquatic weeds and conversion of land (El Mezayn, 2010; Egypt country report).

landscape sanitation to drain lowland marshes, that Mediterranean wetlands suffered the most radical contraction (Webb, 2009).

The demographic increase, the need for larger areas for agriculture, but also the urgency to address malaria that affected populations in many rural areas, led to massive land reclamation, which was also facilitated by the introduction of mechanization.
Many coastal lagoons have survived through time and through reclamation programmes only because fish production represented an income of social and economic interest. Several Mediterranean coastal lagoons would not have lasted without continuous management by local communities aimed at enhancing fish production or hunting, thus enabling not only the physical conservation of these environments but also the safeguarding of their biodiversity value. In fact, human activities that mimic natural processes and dynamics allow not only ecological communities but also economic activities to survive (see paragraph 2.5).

Molentargius lagoon (Sardinia, Italy), photo ©A. Fenza, 2011