228
day-in and day-out fi shing operations, thus
leading to their poor population in the Beel.
Nevertheless, the copepods have been found to
occur throughout the year. On the other hand,
the rotifers were quite abundant mainly during
early monsoon and autumn. However, the cladocerans generally exhibit abundance during
autumn and winter.
15.2.4.2 An Account of Zooplankton
of Chatla Haor Wetland
Studies conducted in c 1,600 ha Chatla Haor in
Cachar District revealed the occurrence of 18
species of zooplankton consisting of 2 species
each of Protozoa and Copepoda, 6 species of
Rotifera and 8 species of Cladocera. Occurrence
of Arcella sp. amongst the protozoans and Brachionus calycifl orus amongst the rotifers indicate eutrophy of the wetland. Two protozoans,
namely, Arcella sp. and Paramoecium sp., represented c 11.11 % of the total zooplanktonic taxa
in the wetland. There are reports of Arcella sp. in
eutrophic waters. Six rotifers constituting
33.33 % of the total zooplanktonic taxa were
also identifi ed, of which Filinia sp. and Lecane
sp. were found to be abundant. The identifi ed
copepods included the Cyclops sp. and the
Diaptomus sp., and they represented 11.11 % of
the total zooplanktonic taxa. The total zooplanktonic count was found to be 68 ± 45 units/l (Kar
and Barbhuiya 2004 ).
15.3 Wetland Productivity
Lentic bodies could be productive or unproductive in almost the same way as agricultural land.
When the input of nutrients in a lentic body
increases (either through natural processes or by
human activities), changes which occur in the
lentic body are known as eutrophication .
Conversely, lakes which have a naturally low
supply of nutrients are called oligotrophic .
Productivity refers to the amount of new living
matters formed in a certain period of time.
Net primary production (NPP) is conventionally defi ned as the difference between gross
photosynthetic production and overall respiratory
loss of dry matter. It is ecologically signifi cant as
the maximum sustenance available to consumer
organisms is better expressed as carbon per unit
area. The productivity of ecosystems may also be
described by the effi ciency of conversion of solar
radiation. Wetland ecosystems are rarely droughted and often receive supplementary nutrient
inputs. It is not surprising to fi nd that the world’s
most productive wild vegetation is reed swamp
(Lieth 1975 ).
Typically, wetlands produce more than they
decompose. However, when the accumulation of
peat or trapped sediment has raised the surface to
the mean level of the water table, it is common
for a woody species to become established in
a fen.
15.3.1 Agriculture and Utilisation
of Wetland Biota
Rice is the most signifi cant and highest-yielding
wetland grain crop in terms of both world
production and impact on man. Probably, more
than half of our population depends on it as a
staple food. It grows in hot climates and is fed
with water by irrigation of monsoonal fl ooding.
Worldwide, its total production is second only to
wheat.
Grazing of domesticated animals is the most
widespread use of wetlands next to rice. The
wetlands are used for rearing of game birds and
fur- bearing animals with little management.
They are also sometimes used as artifi cial fi sh
ponds for rearing carp and other fi sh species.
These depend on shallow-water primary production. However, freshwater grazing lands may
pose problems of parasitism, e.g. sheep liver
fl uke ( Fasciola hepatica ).
In temperate countries, thatched roofi ng has
traditionally been a wetland product, mainly
from reed swamp plants. In Europe, the common
reed ( Phragmites australis ) has been the most
widely used. The latter is also used for fencing
and windbreaks.
The wetter parts of Europe and North American
salt marshes have been traditionally used for
shellfi sh culture. This is done by taking advan15 Wetland Flora, Plankton, Productivity, Fauna and Fishes
day-in and day-out fi shing operations, thus
leading to their poor population in the Beel.
Nevertheless, the copepods have been found to
occur throughout the year. On the other hand,
the rotifers were quite abundant mainly during
early monsoon and autumn. However, the cladocerans generally exhibit abundance during
autumn and winter.
15.2.4.2 An Account of Zooplankton
of Chatla Haor Wetland
Studies conducted in c 1,600 ha Chatla Haor in
Cachar District revealed the occurrence of 18
species of zooplankton consisting of 2 species
each of Protozoa and Copepoda, 6 species of
Rotifera and 8 species of Cladocera. Occurrence
of Arcella sp. amongst the protozoans and Brachionus calycifl orus amongst the rotifers indicate eutrophy of the wetland. Two protozoans,
namely, Arcella sp. and Paramoecium sp., represented c 11.11 % of the total zooplanktonic taxa
in the wetland. There are reports of Arcella sp. in
eutrophic waters. Six rotifers constituting
33.33 % of the total zooplanktonic taxa were
also identifi ed, of which Filinia sp. and Lecane
sp. were found to be abundant. The identifi ed
copepods included the Cyclops sp. and the
Diaptomus sp., and they represented 11.11 % of
the total zooplanktonic taxa. The total zooplanktonic count was found to be 68 ± 45 units/l (Kar
and Barbhuiya 2004 ).
15.3 Wetland Productivity
Lentic bodies could be productive or unproductive in almost the same way as agricultural land.
When the input of nutrients in a lentic body
increases (either through natural processes or by
human activities), changes which occur in the
lentic body are known as eutrophication .
Conversely, lakes which have a naturally low
supply of nutrients are called oligotrophic .
Productivity refers to the amount of new living
matters formed in a certain period of time.
Net primary production (NPP) is conventionally defi ned as the difference between gross
photosynthetic production and overall respiratory
loss of dry matter. It is ecologically signifi cant as
the maximum sustenance available to consumer
organisms is better expressed as carbon per unit
area. The productivity of ecosystems may also be
described by the effi ciency of conversion of solar
radiation. Wetland ecosystems are rarely droughted and often receive supplementary nutrient
inputs. It is not surprising to fi nd that the world’s
most productive wild vegetation is reed swamp
(Lieth 1975 ).
Typically, wetlands produce more than they
decompose. However, when the accumulation of
peat or trapped sediment has raised the surface to
the mean level of the water table, it is common
for a woody species to become established in
a fen.
15.3.1 Agriculture and Utilisation
of Wetland Biota
Rice is the most signifi cant and highest-yielding
wetland grain crop in terms of both world
production and impact on man. Probably, more
than half of our population depends on it as a
staple food. It grows in hot climates and is fed
with water by irrigation of monsoonal fl ooding.
Worldwide, its total production is second only to
wheat.
Grazing of domesticated animals is the most
widespread use of wetlands next to rice. The
wetlands are used for rearing of game birds and
fur- bearing animals with little management.
They are also sometimes used as artifi cial fi sh
ponds for rearing carp and other fi sh species.
These depend on shallow-water primary production. However, freshwater grazing lands may
pose problems of parasitism, e.g. sheep liver
fl uke ( Fasciola hepatica ).
In temperate countries, thatched roofi ng has
traditionally been a wetland product, mainly
from reed swamp plants. In Europe, the common
reed ( Phragmites australis ) has been the most
widely used. The latter is also used for fencing
and windbreaks.
The wetter parts of Europe and North American
salt marshes have been traditionally used for
shellfi sh culture. This is done by taking advan15 Wetland Flora, Plankton, Productivity, Fauna and Fishes