Environmental Management: Principles and practice

Wetlands
Wetlands comprise a wide range of ecosystems, the functioning of which depends
on water. They include marshes, fens, bogs, peatlands, swamps, delta areas, mangrove
forests, floodlands, coastal marshlands and man-made wetlands—irrigated land,
reservoir drawdown areas. Roughly 6 per cent of the Earth’s land surface could be
classed as wetland (Maltby, 1986:41). Some of the world’s most productive habitats
are wetlands: they may be breeding and feeding areas for fish and other fauna, and
potentially very sustainable cropland. Some wetlands are rich in biodiversity and
merit better conservation. Wetlands often play a vital role in regulating streamflow
and river flooding, and may help cleanse runoff of pollution and excess sediment.

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DIFFICULT SITUATIONS
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People often depend on wetlands for food, fuel or building materials and there
is potential for domesticating wetland plant and animal species for aquaculture. Some
of these areas are heavily populated, like the deltalands of Bangladesh or Egypt.
Unfortunately, there are many ways in which wetlands can be damaged: by drainage;
by dam or barrage construction; by canal building or channel improvement; by
pollution; by over-exploitation of plants and animals; through climate or sea-level
change; and by reduction or diversion of inflow.
Mangrove swamps have suffered world-wide as a consequence of land
development for real estate, aquaculture ponds, oil-spills, logging and clearance
for agriculture. By 1990 it is likely that the world’s mangrove forests had decreased
by about 79 per cent and the loss is accelerating (Kunstadter et al., 1989:8). Global
warming might cause even greater losses, leaving tropical coastlands more exposed
to storm damage, resulting in serious loss of biodiversity and of habitats where a
wide variety of marine animals, including commercially valuable species, breed
and feed. The costs of mangrove damage have been realized and there is some
interest in conservation and reafforestation, and in sustainable management
(Kunstadter et al., 1989).
Around the world, coastal wetlands, marshlands, peatlands and floodlands are
being converted to agriculture or cleared for building at an alarming and accelerating
rate. For example, in southern Iraq extensive wetlands are drying out as a consequence
of river diversion, in South America there is a chance that the huge Pantanal wetlands
could be damaged by river navigation and canal projects, and things look gloomy
for the Mekong Delta and many other wetlands. Often the benefits of ‘development’
are short-lived and land is left degraded. Where peats are drained the oxidation adds
to global atmospheric carbon (Barrow, 1991:117–128; Turner and Jones, 1991; Mitsch
and Gosselink, 1993; Roggeri, 1995).