Wetlands are very diverse and productive environments
Thursday February 02, 2023
They have high levels of biodiversity and are the primary habitat for many species; for example freshwater wetlands hold more than 40% of the world’s species and 12% of all animal species. Wetlands also store genetic material like rice, which is staple food for a large part of the population, while wetland fauna and flora has been extensively used in the medical industry. It is estimated that over 20,000 medicinal plant species are currently in use, some of them from wetlands, and over 80% of the world’s population depends on traditional medicine for their primary health care needs.
2. Flood protection: When water levels are high due to “heavy” rainfall and flooding, the vegetation slows the flow of water and stores part of it in the soil or in the surface which in turn reduces flooding and erosion downstream. Floodplain and wetland restoration as well as removal of man made structures is providing a partial solution to flooding in many countries.
3. Soil erosion: The vegetation of wetlands acts as a sediment source which holds together the banks of lakes, rivers and beaches. Increased soil loss and sedimentation is a common problem when wetlands are converted and the vegetation is removed.
4. Maintenance of water quality and pollution control:
Common reed (Phragmite australis)
Common reed (Phragmite australis), photo credit: J.C. Farinha
Wetlands are natural reservoirs and can be considered as a natural sewage system. The hydrophytes – specially adapted plants – not only slow the flow of water but also purify it. Any chemicals entering a wetland (from agricultural sources, human wastes and industrial discharge) and sediment are separated and settle on the bottom, they are then absorbed by the plants and converted into nutrients which are in turn passed on to the fauna. The sediment and chemical control, as well as the nutrient recycling, protects the blockage and eutrophication of downstream water bodies.
Wetlands functions of filtering water and controlling pollution are the most unique and critical functions of wetlands. Some types of wetlands are also the source of replenishment to groundwater aquifers, which provide a large part of the drinking water world wide.
5. Storm and wind buffer: Coastal wetlands buffer the effects of storms and wind by absorbing enormous amounts of wave and wind energy and reducing the damage caused inland.
6. Climate change mitigation and adaptation: Wetlands protect us from climate change in 2 important ways. Firstly they are carbon sinks, meaning they store greenhouse gases, with estimates showing that they may store as much as 40% of the global terrestrial carbon (especially peat and forested wetlands). Secondly, their water capturing and purifying functions as well as the storm and wind buffering can protect us from some of the effects of climate change, such as changing rainfall patterns, higher storm frequencies, rising sea level and general extreme weather phenomena.
7. Wetland Products:
The range of products that wetlands provide humans directly is immense and in fact well managed wetlands can be very productive. Some such products are fruit, fish and shellfish, rice, timber, fuel wood, reed for thatching, meat like deer, crocodile and many others. Wetlands are exploited in many scales from subsistence, to cottage industries to commercial activities.
8. Recreation and Tourism: Many wetlands are spots of amazing beauty and animal and plant diversity and some are protected areas or World Heritage sites. They can offer many activities from fishing, boating, to bird watching and hunting. They can also be very educational for school children but also for the general public.
The Mediterranean Wetlands:
The Mediterranean region is unique because of its special type of climate and very long history of human use. For thousands of years, the wetlands around the Mediterranean basin have provided people not only with essential services like water, food, materials and transport, but have also played a major part in their social and cultural activities. Major civilizations were established in association with and depended on wetlands for resources like water; for example, the ancient Egyptians with the Nile, the Mesopotamians with the Tigris. Major cities like Venice and Tunis have been built in or very close to wetlands. Since major human settlements have been built in or around wetlands, significant archaeological remains can be found, like ancient ships in Marseille and Venice or even entire cities like Nikopolis in the Amvrakikos Gulf in Greece.
In the 20th century, with the advent of industrialization, intensive agriculture, urbanization, population pressures and legitimate health considerations, the bond between man and wetland was severed and hence many wetlands were destroyed (Benessaiah, 1998). Wetlands were perceived as dangerous places filled with dangerous animals, evil spirits and disease-carrying insects that needed to be “sanitized” or seen as unimportant, fallow land to be drained or converted to other uses.
Papayannis and Salathé (1998) define three specific features of Mediterranean wetlands that should be considered:
- Mediterranean wetlands are very diverse, which is caused by the climatic variability of the region. In the North the wetlands are large river deltas and lagoons and in the South they are sebkhas and marshes that are seasonal and may appear every few years. Also, artificial wetlands range from oases and salinas to contemporary reservoirs created by hydroelectric and irrigation dams like in the Nile and the Neretva rivers.
- There are strong ties between local inhabitants and wetlands. These ties are evident by the fact that Mediterranean people not only used them but lived and still live in them, like in the archaic lacustrine settlements (Hourmouziades, 1996), the Empurias in Spain. Also, Venice and Tunis, two large Mediterranean cities are built in wetlands. These choices in settlement demonstrate how local communities in the Mediterranean basin have developed strong cultural bonds with wetland sites.
- Mediterranean wetlands are in degraded condition and they are under threat. The last century has seen the loss of more than half the wetlands, which has resulted in a dramatic degradation of their functions and loss of their values. Even though many attempts have been made to counteract this trend, the degradation and loss haven’t yet been stopped or reversed.