coastal wetlands upstream where the influence of marine
water is minimal, and the conditions are less severe for
plant growth.
There is a wide variety of wetlands around the world,
depending on the type of vegetation, amount of water present during the year, type of sediment, redox condition,
amount of organic matter, and dominant vegetation. The
different terms applied to wetland-like environments
depend on the region of the world, mainly because the
type of vegetation varies from one environment to another
and the local names of plants and animals are not the same.
For example, in North America the term “swamp” refers to
a wetland with abundant wood plants (trees) present. This
term cannot be applied in northeastern Europe, where
there are no forested wetlands. Peat-accumulating wetlands are common in this part of the world, and the term
“bog” is of common use. In addition, European wetlands
have an abundance of nonwoody plants called “reed
grass,” giving rise to the name “reedswamps” for these
systems. In Australia, the term “billabong” is used for wetlands formed from river meanders (Shiel, 1994). In North
America, this same type of wetland is known as oxbow.
World diversity
European wetlands
In the Mediterranean Sea, the Rhone River Delta supports
one of the most extensive wetlands in Europe, the
Camargue, with an area $9,000 ha. This wetland is a major
nesting site for flamingos. Formerly, this site was used as
rice fields (Mesléard et al., 1995). The Rhine River flows
into the North Sea, and its delta is expansive. Currently,
7 % of this country (The Netherlands) is registered in the
Ramsar Convention as a wetland of international importance (Wolff, 1993). In these wetlands, 250 waterfowl species can be found, including herons, cormorants, and
spoonbills. Some of the most significant wetlands include
the Oostvaardersplassen, which was artificially created
40 years ago as a wildlife sanctuary (Mitsch and
Gosselink, 2000). The Wadden Sea has an extension of
8,000 km
2 of shallow waters, abundant mud flats, and
marshes; it supports most of the fisheries from the North
Sea, 60 % of brown shrimp, 80 % of plaice, and almost
all herring (Maltby, 1986; Dugan, 1993). In the Baltic
Sea, there are also important wetlands, and some of them
are impacted by eutrophication due to nitrogen inputs
from agricultural activities. This was the case in Langholm
Bay (southwest Sweden), where macro- and microalgal
blooms contributed to major losses of oxygen (hypoxia)
during the 1970s and 1980s (Fleischer et al., 1994). Restoration efforts have been proposed to reduce the amount of
nutrients entering from the inland (Kessler and Jansson,
1994). In Europe, there are important nontidal wetlands
like those found along the Danube River and the Volga
River. Unfortunately, both rivers have experienced environmental degradation as a consequence of drainage, agricultural activities, dam construction, and industrial
pollution (IUCN, 1993).
African wetlands
Some of the wetlands in this continent are larger than those
found in Europe, examples being the Inner Nigger Delta of
Mali (320,000 km
2
), the Zaire swamps (200,000 km
2
),
and the Sudd of the Upper Nile ($30,000 km
2
) (Denny,
1993; Dugan, 1993). Fauna supported by these wetlands
include elephants, crocodiles, buffalos, and many bird
and fish species. Even indigenous tribes benefit from the
shelter provided by these vast wetlands, as do urban
populations, like the town of Maun (Mitsch and
Gosselink, 2000). Some floras found in these wetlands
include hyacinth (Eichhornia crassipes), kariba weed
(Salvinia molesta), papyrus (Cyperus papyrus), and cattail
(Typha domingensis). African wetlands can be classified
as swamps according to European terminology and as
marshes according to North American terminology. In
the Ngorongoro crater, there are three exceptional wetlands: Mandusi Swamp, Gorigor Swamp, and Lake
Makat. Wildlife is abundant in all of these marshes
(Hanby and Bygott, 1998).
Australian wetlands
Seasons of dry and wet conditions produce wetlands that
are intermittent along the east and west coasts of Australia
(McComb and Lake, 1990). As noted above, the most representative Australian wetland is the billabong, an intermittent feature developed from an overflowing river
channel (Shiel, 1994). One species of flora characteristic
of the billabong is the river red gum (Eucalyptus
camaldulensis), which surrounds these wetlands and provides habitat for many species of birds and fish. There has
been severe loss of wetlands on this continent as well;
along the west coast of Australia, 75 % of the wetlands
in the Swan Coastal Plain has been lost (Chambers and
McComb, 1994). Wetlands in New Zealand have experienced an even greater loss (90 %) of its former coverage.
New Zealand possesses environmental conditions which
are favorable for the development of wetlands, with an
annual rainfall of up to 10 m (Mitsch and Gosselink,
2000). Common floral species in these wetlands are raupo
(Typha orientalis), flax (Phormium tenax), and kahikatea
(Dacrycarpus dacrydioides).
Asian wetlands
Most wetlands in this part of the world are located in Bangladesh, China, India, Indonesia, Myanmar, Papua New
Guinea, and Vietnam. Water supply for these rivers and
deltas originates in the highest parts of the Himalayas,
flowing into a water delta of 600,000 km
2
. In central
Russia, the Ob River Estuary is one major site for waterfowl breeding (Dugan, 1993). Agricultural intensification,
industrialization, deforestation, and damming are human
activities that degrade the quality of these ecosystems
(Beilfuss and Barzen, 1994). The Mekong Delta in Vietnam provides relevant ecosystem services as a source of
fuel, medicine, and fisheries, providing more than 50 %
of the protein requirements for the 20 million people living
WETLANDS
739
water is minimal, and the conditions are less severe for
plant growth.
There is a wide variety of wetlands around the world,
depending on the type of vegetation, amount of water present during the year, type of sediment, redox condition,
amount of organic matter, and dominant vegetation. The
different terms applied to wetland-like environments
depend on the region of the world, mainly because the
type of vegetation varies from one environment to another
and the local names of plants and animals are not the same.
For example, in North America the term “swamp” refers to
a wetland with abundant wood plants (trees) present. This
term cannot be applied in northeastern Europe, where
there are no forested wetlands. Peat-accumulating wetlands are common in this part of the world, and the term
“bog” is of common use. In addition, European wetlands
have an abundance of nonwoody plants called “reed
grass,” giving rise to the name “reedswamps” for these
systems. In Australia, the term “billabong” is used for wetlands formed from river meanders (Shiel, 1994). In North
America, this same type of wetland is known as oxbow.
World diversity
European wetlands
In the Mediterranean Sea, the Rhone River Delta supports
one of the most extensive wetlands in Europe, the
Camargue, with an area $9,000 ha. This wetland is a major
nesting site for flamingos. Formerly, this site was used as
rice fields (Mesléard et al., 1995). The Rhine River flows
into the North Sea, and its delta is expansive. Currently,
7 % of this country (The Netherlands) is registered in the
Ramsar Convention as a wetland of international importance (Wolff, 1993). In these wetlands, 250 waterfowl species can be found, including herons, cormorants, and
spoonbills. Some of the most significant wetlands include
the Oostvaardersplassen, which was artificially created
40 years ago as a wildlife sanctuary (Mitsch and
Gosselink, 2000). The Wadden Sea has an extension of
8,000 km
2 of shallow waters, abundant mud flats, and
marshes; it supports most of the fisheries from the North
Sea, 60 % of brown shrimp, 80 % of plaice, and almost
all herring (Maltby, 1986; Dugan, 1993). In the Baltic
Sea, there are also important wetlands, and some of them
are impacted by eutrophication due to nitrogen inputs
from agricultural activities. This was the case in Langholm
Bay (southwest Sweden), where macro- and microalgal
blooms contributed to major losses of oxygen (hypoxia)
during the 1970s and 1980s (Fleischer et al., 1994). Restoration efforts have been proposed to reduce the amount of
nutrients entering from the inland (Kessler and Jansson,
1994). In Europe, there are important nontidal wetlands
like those found along the Danube River and the Volga
River. Unfortunately, both rivers have experienced environmental degradation as a consequence of drainage, agricultural activities, dam construction, and industrial
pollution (IUCN, 1993).
African wetlands
Some of the wetlands in this continent are larger than those
found in Europe, examples being the Inner Nigger Delta of
Mali (320,000 km
2
), the Zaire swamps (200,000 km
2
),
and the Sudd of the Upper Nile ($30,000 km
2
) (Denny,
1993; Dugan, 1993). Fauna supported by these wetlands
include elephants, crocodiles, buffalos, and many bird
and fish species. Even indigenous tribes benefit from the
shelter provided by these vast wetlands, as do urban
populations, like the town of Maun (Mitsch and
Gosselink, 2000). Some floras found in these wetlands
include hyacinth (Eichhornia crassipes), kariba weed
(Salvinia molesta), papyrus (Cyperus papyrus), and cattail
(Typha domingensis). African wetlands can be classified
as swamps according to European terminology and as
marshes according to North American terminology. In
the Ngorongoro crater, there are three exceptional wetlands: Mandusi Swamp, Gorigor Swamp, and Lake
Makat. Wildlife is abundant in all of these marshes
(Hanby and Bygott, 1998).
Australian wetlands
Seasons of dry and wet conditions produce wetlands that
are intermittent along the east and west coasts of Australia
(McComb and Lake, 1990). As noted above, the most representative Australian wetland is the billabong, an intermittent feature developed from an overflowing river
channel (Shiel, 1994). One species of flora characteristic
of the billabong is the river red gum (Eucalyptus
camaldulensis), which surrounds these wetlands and provides habitat for many species of birds and fish. There has
been severe loss of wetlands on this continent as well;
along the west coast of Australia, 75 % of the wetlands
in the Swan Coastal Plain has been lost (Chambers and
McComb, 1994). Wetlands in New Zealand have experienced an even greater loss (90 %) of its former coverage.
New Zealand possesses environmental conditions which
are favorable for the development of wetlands, with an
annual rainfall of up to 10 m (Mitsch and Gosselink,
2000). Common floral species in these wetlands are raupo
(Typha orientalis), flax (Phormium tenax), and kahikatea
(Dacrycarpus dacrydioides).
Asian wetlands
Most wetlands in this part of the world are located in Bangladesh, China, India, Indonesia, Myanmar, Papua New
Guinea, and Vietnam. Water supply for these rivers and
deltas originates in the highest parts of the Himalayas,
flowing into a water delta of 600,000 km
2
. In central
Russia, the Ob River Estuary is one major site for waterfowl breeding (Dugan, 1993). Agricultural intensification,
industrialization, deforestation, and damming are human
activities that degrade the quality of these ecosystems
(Beilfuss and Barzen, 1994). The Mekong Delta in Vietnam provides relevant ecosystem services as a source of
fuel, medicine, and fisheries, providing more than 50 %
of the protein requirements for the 20 million people living
WETLANDS
739