During my internship for my diploma in nature conservation, I was fortunate enough to be placed at Table Bay Nature Reserve which has a wetland within its boundaries. I was involved with bird counts, fish surveys, water quality tests, environmental education and more.
Wetlands are highly important ecosystems and contribute many valuable services to the environment and community. Some of these functions include; maintaining good water quality, preventing flood damage and promoting ground water recharge, but most of all, it is a feeding ground and refuge area for many bird and animal species. Wetlands across the world have been undervalued and the understanding of their function, distribution and structure is minimal. Scientists define wetlands into three groups; marine systems, estuarine systems and inland systems. Over 50% of wetlands around the world have been destroyed in the past century, while the remaining wetlands have become degraded in different aspects due to the adverse human activities which include agriculture, development and recreation. The degradation and loss of these wetlands have affected the water birds which rely heavily on these wetland ecosystems. Hence, the inconvenient ecosystem.
The use of synthetic wetlands used for conservation purposes is an added strategy managers are thinking of due to South Africa being a water scarce country.
The blend of aquatic and terrestrial conditions that make what we know as ‘wet-lands’ makes these ecosystems among the most complicated on earth. The wetlands environmental characteristics are hydro-logical processes which may show daily, seasonal or longer-term changes, in regards to regional climate and geographic location of the site. These factors determine a great range of wetland types worldwide. As a consequence, the variety of living organisms which has adapted to the different wetland habitats tends to be high, with all major groups of plants and animals benefiting. Varying topographic gradients occur in wetlands and these affect the nature of the colonizing vegetation. Further variability is exhibited in inland wetlands by seasonal fluctuations in the rainfall. The area which is influenced by a wetland may expand and contract with the seasons and thus produce a border of plant communities adapted to alternate flooded and dry conditions. Much like organisms on rocky shores along a coastline.
The availability of water which delivers nutrients and removes waste products, along with the frequent association between plant roots and microscopic organisms able to use nitrogen, enable the wetland plants to grow rapidly and produce large quantities of organic matter. In tropical wetland plants, such as mangroves, this primary production can go on all year and reach levels comparable to the most intensively mechanized agricultural production, for example sugar cane crops. Plants provide an important role in the structure and productivity of coral reefs in wetlands close to coastlines. A variety of different kinds of birds with a diverse range of feeding and breeding habits are found in wetlands. Among the 104 species can be seen in the Black River Morass, Jamaica, were 11 seabirds, 36 waterfowl, 7 birds of prey, a kingfisher and 49 forest birds while 251 species have been found in the Cache River Basin, Illinois, USA some 40 species of birds commonly breed in the restricted wetland forests in Western Europe. In South Africa the St. Lucia estuarine system (a Ramsar site), some 350 species of birds have been recorded, including 90 species of waterfowl, such as ducks, geese, two species of flamingo and 15 species of herons and egrets. A large amount of bird life can be found at Rietvlei wetland which forms part of Table Bay Nature Reserve. Some of these birds include the Great white pelican (Pelecanus onocrotalus) , Greater flamingo (Phoenicopterus roseus), Great Crested Grebe (Podiceps cristatus), Black winged stilt (Himantopus himantopus) and malachite kingfisher (Corythornis cristatus).
Wetlands are incredibly productive and support a large amount of ecosystem goods and services. At local scales wetlands provide food, fiber, filtering of contaminants, sediment storage, flood control, wildlife habitat, recreation and aesthetics. On a broader level wetland-rich landscapes help regulate regional climate and provide important habitat for continental and intercontinental migrating bird species. Despite these important benefits, wetlands have been drained extensively worldwide to increase land space for cultivation of crops and to accommodate human settlement expansion. Wetlands continue to be at risk from changes in land use and management, however increased rates of climate change have also increased the complexity of maintaining functioning wetlands.
There is a great need to monitor the status of wetlands. Field monitoring is highly informative about changes in wetland functioning and the related environmental drivers and consequences of those changes. However, monitoring on site is expensive, and many wetlands are in remote areas or are otherwise logistically challenging to monitor or have restricted access. In this case it is only practical to monitor a small subset of the world’s wetlands on site. It is also important that we obtain information at broader scales to provide regional, national, and global context in order for better management and awareness. Remote monitoring of wetlands is a more attractive option because it is comparatively inexpensive and can give data over a range of broader scales, however it has been complicated to map wetlands remotely with levels of accuracy and consistency sufficient to monitor change in the wetlands.
Difficulty in Monitoring Wetlands
Why is it so hard to map wetlands from the skies? One main problem is that wetlands are not unified by a common land-cover type or plant form in the way that forests are populated with trees, grasslands with grasses, and shrub lands with shrubs. Wetlands share a characteristic presence of water, however it can be above the earth’s surface or below the surface in the rooting zone of plants. This water may be present all the time, seasonally, or only in some years, but is present enough to influence the development and condition of the soil and support vegetation adapted to wet conditions. The connections with water, soils, and vegetation form a wide variety of wetland types and features, as well as processes and functions. Daily tidal actions add further complexity in coastal areas. Wetlands can support submerged, floating-leaved, and emergent plant species, as well as hydrophytic vegetation including trees.
Destruction of Wetlands
Humans have been draining, in-filling and converting both coastal and inland wetlands for many centuries: for example since Roman times in Europe, at least the 17th century in North America and southern Africa and for at least 2000 years in China. This destruction and degradation of wetlands continues, with the main drivers being economic and human population growth, and proximate causes being conversion at first to extensive and then intensive agriculture. Changes in water use and availability (this includes the downstream effects of water abstraction and major hydro engineering schemes), accelerating urbanisation and infrastructure development, disease control, spread of invasive species, while on the coast, sea defences, port and industrial developments, and aquaculture. Widespread inland and coastal wetland drainage and conversion, and particularly its impact on hunted waterfowl populations, have been increasingly reported and raised as a concern since the 1920s in North America and from the early 1960s in Europe.
The research I conducted for my degree last year (2017) looked at the population trends of water birds from the year 1975 to 2017 at Zandvlei estuary nature reserve. What I found was that over the years many specialist and migratory birds like the curlew sandpiper (Calidris ferruginea) and little stint (Calidris minuta) have decreased many generalists such as the Egyptian geese (Alopochen aegyptiaca), Red knobbed coot (Fulica cristata) and Kelp gull (Larus dominicanus) have increased. These increasing and decreasing species can be attributed to the reasons mentioned above.
Wetlands in the news
I found a couple of news articles concerning wetlands. The articles describe the monetary value of wetlands globally. The other articles depict how mankind is still threatening wetlands.
The growing concern of the degradation of the wetlands globally called for an international convention to protect the remaining wetlands around the world. On February 3rd 1971, in the little Iranian town called Ramsar, the representatives of 18 nations put their signatures to the text of a remarkable treaty. The Ramsar Convention was the first of the modern conventions looking to conserve natural resources on a worldwide scale. It remains the only world-wide treaty which restrains the countries joining it from the thoughtless exploitation of their natural wetland resources. These are shallow open waters – lakes, ponds, rivers and coastal fringes – and any land which is regularly or occasionally covered or saturated by water – marshes, bogs, swamps, flood plains and the like.
The disappearance of wetlands was leading to undesirable problems, including the loss of groundwater storage due to the need for irrigation, flash floods, shoreline destruction and the accumulation of pollutants and to other subtle problems. Many useful plants and animals dependent on wetlands were declining with them. People involved with the conservation of birds particularly water birds and fish were taking the lead in calling for a stop to wetland destruction in the developed countries. Losses were increasing as efficient machinery and modern techniques for draining wetlands were put into place. The developing countries required aid to avoid making the same mistakes, to treat their resources wisely.
International action is necessary for a number of reasons. Many wetlands lay across national boundaries or derived their water supplies from adjoining countries. Fish hatched in the wetlands of one country might be caught as adults in a neighboring one or on the high seas. Water birds, migrating over thousands of kilometers / miles twice a year, also don’t conform to boundaries and needed the wetlands of a number of countries in order to rest, feed and breed. The developing countries need to be helped to use their wetlands in the proper manner and there must be international arrangements for the provision for awareness and technical and financial aid.
The Convention as it is now
The Ramsar Convention is fully operational and a very active organization. It is based in Gland, Switzerland, and funded by the subscriptions of the Convention’s Parties. By the beginning of 1993 there were 75 of these parties. The Ramsar convention now runs over 108 million square kilometers, this is 75% of the world’s lands. The Convention now has 168 governmental Contracting Parties, which have designated 2185 Ramsar Sites covering over 208 million hectares of wetlands and associated habitats. I also read in an article the other day that Poland has declared 3 new Ramsar sites within its borders, which is great news to hear.
The research I did for my diploma was to determine whether Table Bay Nature Reserve was eligible for Ramsar status in regards to criterion 6. Ramsar have 9 criteria which need to be met until Ramsar will help and support the wetland. Criterion 6 states that a wetland is of international importance if it holds 1% of a certain water bird species. I found that the Hartlaubs gull (Chroicocephalus hartlaubii) and the Common tern (Sterna hirundo) met that criteria which is very good to see, however the wetland would also need to meet the other 8 criteria to be able to get Ramsar status.
Wetlands play a critical role in the environment. Like many other ecosystems we have destroyed and altered them for our own benefit. We have actually been doing ourselves a disservice because we rely so much on them. Luckily mankind woke up before it was too late, but at what cost? Ongoing awareness and protection is needed for fluctuating ecosystems. So next time you want to go out for the day how about visiting your nearest wetland and lets be grateful for the great benefits it offers.
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Dallas, H., Seymour, C., Snaddon, K. & Ewart-Smith, J. (2006). Identification and Collation of Existing Information on the wetlands of the Western Cape. Africa, 1-10.
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