Wetlands of southern Europe and North Africa: Mediterranean wetlands

Abstract

Wetlands of the south of Europe and north Africa extend from Bulgaria to the Iberian peninsula, and from Tunisia to Morocco. The three main environmental factors explaining the distribution of the wetlands are: climate, topography and geology, and tides. The principal geomorphological formations containing wetlands are described in detail and numerous examples are given. They are: river deltas, coastal lagoons, riverine floodplains, inland freshwater lakes, man-made reservoirs, athalassic salt basins, intertidal systems, permanent river channels, and seasonally-flooded river channels. Many inventories and classifications of wetlands of the region have been carried out, but few of them are comparable. A new classification is proposed for the whole study area. The factors determining the ecological characteristics of the emergent and submerged vegetation of Mediterranean wetlands are identified and their impacts on the composition of the vegetation are analyzed in detail. Six vegetation categories have been determined: halophytic vegetation, emergent reedswamp communities, riverine forests, dwarf rush communities, and submerged and floating vegetation of freshwater habitats. Invertebrates, fish, birds, and mammals occurring in Mediterranean wetlands are listed and the factors responsible for their presence or absence are analyzed. As a general rule, birds are very well known, but information on invertebrates, fish, and mammals is still poor. The usage of and conservation problems of Mediterranean wetlands show that most of them are overexploited and degraded, and few are protected. Many organisms depending on these wetlands are nowadays threatened with extinction. Although the distribution and size of the Mediterranean wetlands is well known, the functioning of the ecosystems in the Mediterranean region remains poorly understood. This is a major handicap at the moment, when ways of better managing or even restoring certain Mediterranean wetlands are being talked of.

Ecosystem metabolism in a temporary Mediterranean marsh (Doñana National Park, SW Spain)

“…Our goal was to evaluate the metabolic balance (gross primary production, community respiration and net community production) and the relative contribution of submerged macrophytes, phytoplankton, and benthic microalgae as primary producers in the Doñana marsh (SW Spain), the largest marsh in the Mediterranean region (Britton and Crivelli, 1993). We achieved this goal by measuring the daily oxygen balance of the open waters in nine temporary zones supporting different aquatic communities across the marsh, and elucidating the contributions of submerged macrophytes, and their associated epiphytes, phytoplankton and benthic microalgae.…”

Three New Species of Eleocharis (Cyperaceae) from the Andean Páramos of Colombia and Ecuador

“…Grasslands, shrublands and woodlands which may at times be inundated but in which semicontinuous formations of grasses, shrubs or trees emerge at all times above the standing water surface are listed under units 37, 3A, 44 and 4A, not under unit 22.2. (Koepcke, 1961: 126-127;Britton and Crivelli, 1993 …”

Diversity of grasshoppers (Caelifera) recorded on the banks of a Ramsar listed temporary salt lake in Algeria

“…Wetlands in the Mediterranean basin are rare and their estimated total surface area is 21,000 km², of which 4,700 km² are coastal lagoons, 2,800 km² freshwater lakes and marshes and 11,600 km² temporary salt lakes, the last of which occur mainly in North Africa (Britton & Crivelli, 1993).…”