Diminishing Size of Wetlands: A Review of their Rehabilitation in Africa

The academic [1], have produced a figure that states that wetlands around the world have been degraded by about 87% in the last century and a half in data existing regions. A Report from [2] and [3] has confirmed that we have lost more than half of the wetlands and the loss mainly occurred in the 20th century. A report from the Ramsar Convention Secretariat gives a figure of 35% reduction of global wetlands, with data available during the period 1970 and 2015 [4]. This shrinkage (and gradual extinction) of wetlands is not a new experience however its alarming shrinkage rate has not been widely felt until recently. Wetlands are one of the world’smost crucial and important types of ecosystems and also one of the most threatened. Climate change, biodiversity, hydrology and human health rely heavily on the functions and well-being of wetlands [5]. It is a fact that wetlands exert an effect on global and climates by supplying the atmosphere with potential or near-potential evapotranspiration and by taking up carbon dioxide and emitting methane [6]. From the aspect of biodiversity, although freshwater wetlands cover only 1% of the earth’ssurface, they are a home to more than 40% of the Earth’sspecies [7]. Hydrologically, wetlands serve to replenish groundwater, regulate water movement, and purify water, providing these important parts with an important hydrologic cycle [8]. As regards to human health, wetlands supply traditional medicines on which 80% of the world’spopulation depends on for primary healthcare [7]. Previously, humans have regarded wetlands as a harbour of mosquitoes, carriers of disease and sources of death [9; 10].

Wetlands fall into two broad categories namely natural and artificial (constructed) [10]. Natural wetlands are the original areas where water covers the soil, including swamps, marshes, fens, sloughs, and bogs while constructed wetlands are ecosystems (man-made) similar to natural wetlands, combining physical, chemical and biological processes [11]. Wetlands exhibit themselves in a number of ways that include areas of marsh, fen, peatland and shallow water bodies, [12]. As compared to rainforests and coral reefs, wetlands are among the most productive ecosystems in the world [12]. It is confirmed that marshlands bring a source of substantial biodiversity, giving life to numerous species ranging from microbes to mammals [13]. Physical and chemical features such as climate, topography (landscape shape), geology, nutrients, and hydrology (the quantity and movement of water) help to determine the plants and animals that inhabit various wetlands, [11]. Despite all of their functions wetlands have been faced with destruction, if not extinction especially in Africa. Threats to wetlands in Africa can largely be attributed to human activities, though climate change and variability also playa part. Wetlands are known as areas that are waterlogged by surface or ground water, either permanently or seasonally. It is stated by [14] that a wetland is an area of mainly saturated soil that can support the prevalence of hydrologic soil adapted plants. Wetlands are perfect combination of water and land and are the most biologically diverse ecosystems in the world [14]. There are many kinds of wetlands, including swamp, marsh and bog which are filled with trees, shrubs and moss. Functions of wetlands include:  Provide habitat for a wide variety and number of wildlife and plants.  Filter, clean and store water. In other words acting like kidneys for the ecosystems.  Collect and hold flood waters  Absorb wind and tidal force  Provide places of beauty and many recreational activities [15].

By holding flood waters and keeping rivers at normal levels, wetlands behave like sponges [14]. They are able to filter and purify water as it flows through the wetland system and the plants found in wetlands help control water erosion [15]. On our world, the existence of wetlands has very positive effects for the biologically diverse.

Wetlands are among the most productive ecosystems on Earth. They allow interaction between water, soil, vegetation and light all year round or during a greater part of the year. The depth of the water is such that it allows photosynthesis to occur, making wetlands productive life-supporting ecosystems.

Wetlands were the first ecosystems to receive international attention through the “Convention on Wetlands of International, Importance Especially as Habitats of Waterfowls”, which opened for signatories at Ramsar, Iran in February 1971 [16]. Rapid urbanisation and abuse of natural resources have degraded the wetlands [17]. The North American Wetland Conservation Act was passed in 1989 by the United States of America (USA) Congress to stop the destruction of wetlands and other types of habitats [18]. It is estimated that nearly half of available wetlands have already been destroyed because of the increased demand for land as a result of rapid population increase [18]. Evidence is abound that thousands of hectares of wetlands are converted to farmland, residential and, industrial areas every year.

The size of the wetlands (inland valley swamps) in Africa is potentially approximately 135 million hectares, and luckily only about 1.3% of this is under cultivation. The reasons for this include lack of appropriate water management and other agro-technologies, health risks, the complexity of these fragile ecosystems and an overall unfavourable socio-economic environment [18].

Globally it is quoted, but there is lack of verifiable facts or evidence, that the world has lost 50% of its wetlands (or 50% since 1900 AD) [1]. It is known that the rate of wetland loss has been 3.7 times faster during the 20th and early 21st centuries (approximately between 64-71% of wetlands have been lost during this period) [17]. The pace of wetland loss in Europe and North America has slowed down, since the 1980s, but it has remained high in Africa and Asia where large-scale and rapid conversion of coastal and inland natural wetlands are continuing [18]. There is a need to improve the knowledge of change and awareness in wetland areas worldwide, particularly for Africa, Neotropics and Oceania, and to improve the consistency of data on change in wetland areas in published papers and reports [18].

Man-kind has been training, infilling and converting both coastal and inland wetlands for many centuries, for example, since the Roman times in Europe [19]; the 17th century in North America [20] and Southern Africa [21] and for at least 2000 years in China [22]. As this transformation and degradation of wetlands continues, with the underlying drivers being:  Economic and human population growth and proximate causes being transformation at first to extensive and intensive agriculture (croplands),  Changes in water use and availability (including the downstream effects of water abstraction and major hydro-engineering schemes),  Increasing urbanisation and infrastructure development, disease control (especially for mosquitoes – to control malaria) and spread of invasive species,  On the seacoast defences, port and industrial developments and industrial developments and aquaculture [23]; [24]. The prevalent (not quantified) inland and coastal wetland drainage and transformation and particularly its impact on hunted waterfowl populations has been increasingly reported and raised as a concern since the 1920s in North America [25] and from the early 1960s in Europe [26]; [27]. It was concluded that intemperate regions drainage of wetlands is proceeding at an increased rate and without reference to their diverse values and recommended the establishment of an international convention on wetlands [27]. This led in 1971 to the global scope establishment of the Ramsar Convention on Wetlands [28], which appreciated the great importance of wetlands, the loss of which would be irreparable, to people and which has the desire to stem the loss and degradation of wetlands now and in the future, through the wise use of all wetlands, the designation and management of Wetlands of International Importance (Ramsar Sites) and international cooperation [29]; [30]; [31]. The Convention has now aggregated to 168 governmental participating parties which have designated 2303 Ramsar Sites covering over 228 million hectares of wetlands and associated habitats. See Table (A).

THE NUMBER AND AREA OF WETLANDS. SOURCE: RAMSAR OFFICIAL WEBSITE 2019 Continent Number of Wetlands Area (million hectares)

Africa 397 110 Asia 368 27.5 Europe 1004 14.2 North America 309 28.9 South America 146 39.6 Oceania 79 8.6 TOTAL 2303 228.8 Although officially Ramsar Sites are protected, unfortunately, they do face threats. The impact of dynamics of wetland can be divided into wetland transformation and wetland destruction [3]. Inmost instances the dilapidation of wetlands is affected by destructive factors, such as agriculture, infrastructure development, water use and pollution [32]; [33]; [34]; [24]. By 1985, almost 56% to 65% of wetlands in Europe and North America were drained for agriculture, with Asia, South America and Africa having 27%, 6% and 2% respectively [35].

The total wetland area of thirty Ramsar Sites in Africa has declined by just two thousand hectares, however, wetland ecosystem disintegration is more serious [33]. Seventeen percent of the river wetlands and 20% of the inland flood wetlands have degraded into non-wetlands [35]. The disturbance degradation index in Africa is high and keeps constantly increasing [36]. The Lake Chad, for example, an African transnational lake, suffered a 9% drop in lake surface and an 89% drop in seasonal herbaceous swamps between 2001 to 2013, which mainly was due to drought and drainage for irrigation [36]. The signal site with the largest area is the Ngiri-Tumba-Maindombe, located in the Democratic Republic of Congo (DRC) [37]. Now this area is under apparent threat because of pressure from the rapidly growing population and illegal mining activities, for example [38]. Climate, topography (landscape shape), geology, nutrients, and hydrology (the quantity and movement of water) are physical and chemical features that help to determine the plants and animals that inhabit various wetlands, [39].