300
AM, thus rendering poor AM biomass with corresponding low DO, pH and TA but high FCO 2
during the periods. Concomitantly, a direct relation of AM with DO ( r = 0.940 ± 0.053, P < 0.05),
pH ( r = 0.160 ± 0.443, P > 0.05) and TA
( r = 0.530 ± 0.320, P < 0.05) was recorded.
Signifi cant ( P < 0.05) phyto-social association
between C. dactylon and E. crassipes ( χ
2 , 12.44),
C. dactylon and N. indicum ( χ
2 , 10.21), H. aristata and E. crassipes ( χ
2
, 13.87) and H. aristata
and N. cristatum ( χ
2
, 18.96) was recorded during
this season. However, none of the AM species
formed signifi cant phyto-social relation with E.
ferox , possibly, due to its thorny body; and the
latter, thus, formed a monospecifi c unit.
Almost all the monsoon varieties, as stated
above, also occurred during the autumn, but with
profuse fl owering restricted mainly to N. cristatum and N. indicum . With the reappearance of dry
winter, most of the emergent varieties gradually
start reappearing with the decrease in water level
of the wetland. Euryale ferox was seen to occur
only for a limited tenure during the period from
spring beginning to midsummer. Since the plant
is generally considered by the local fi shermen as
an impediment to fi sh movement and hindrance
in fi shing, they are usually removed from the
Beel at the end of summer.
High species diversity amongst the AM species
was evident in this wetland. And the level was
found to be high (biased estimate of H′ = 2.015;
expected value, E ( H′ ) = 2.014; variance of
H′ = 1.431 E- 3) in Sone Beel (Dey and Kar 1989 ).
Plankton
‘ Plankton’, the living fraction of material, found
in water and moved passively by wind or current,
is composed of bewildering varieties of microscopic organisms. The ‘phytoplankton’, which
are predominantly autotrophic, are the primary
producers of organic matters in the aquatic habitats. The nutritionally dependent animal component constitutes the ‘zooplankton’.
An Account of Limnoplankton of Sone Beel
Fourty seven different forms of phytoplankton
belonging to fi ve groups, as indicated above,
have been recorded, till date, in Sone Beel. Of
these, the Chrysophyta included the maximum
number and Pyrrophyta, the least. The phytoplankton density in the Beel varied from 48 to
5,308 (average 1,027) units/litre. The minimum
population is generally recorded during the rainy
season and maximum during the dry season. The
cyanophytes and the euglenophytes generally
exhibit prolifi c growth during the spring and
summer with occasional abundance during monsoon. The chlorophytes usually show higher
occurrence intensity during summer and early
monsoon with infrequent richness during winter
and spring. The chrysophytes are generally
recorded throughout the year. The pyrrophytes
were found to register their presence mainly during the autumn.
Nineteen different forms of zooplankton,
belonging to fi ve groups, have been recorded in
Sone Beel. The zooplankton density varied from
6 to 380 (average 49) units/litre. Low density is
generally recorded during February–March and
high density during November–December. In
Sone Beel, a considerable portion of zooplankton
population is considered to succumb to the dayin 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
exhibited abundance during autumn and winter
(Dey and Kar 1994 ).
There is a bewildering diversity of fi shes in
the lentic systems of this region.
Fish Diversity in Sone Beel
Seventy species of fi shes belonging to 49 genera
under 24 families and 11 orders have been recorded
in Sone Beel, the biggest wetland in Assam.
20 Wetlands of India
AM, thus rendering poor AM biomass with corresponding low DO, pH and TA but high FCO 2
during the periods. Concomitantly, a direct relation of AM with DO ( r = 0.940 ± 0.053, P < 0.05),
pH ( r = 0.160 ± 0.443, P > 0.05) and TA
( r = 0.530 ± 0.320, P < 0.05) was recorded.
Signifi cant ( P < 0.05) phyto-social association
between C. dactylon and E. crassipes ( χ
2 , 12.44),
C. dactylon and N. indicum ( χ
2 , 10.21), H. aristata and E. crassipes ( χ
2
, 13.87) and H. aristata
and N. cristatum ( χ
2
, 18.96) was recorded during
this season. However, none of the AM species
formed signifi cant phyto-social relation with E.
ferox , possibly, due to its thorny body; and the
latter, thus, formed a monospecifi c unit.
Almost all the monsoon varieties, as stated
above, also occurred during the autumn, but with
profuse fl owering restricted mainly to N. cristatum and N. indicum . With the reappearance of dry
winter, most of the emergent varieties gradually
start reappearing with the decrease in water level
of the wetland. Euryale ferox was seen to occur
only for a limited tenure during the period from
spring beginning to midsummer. Since the plant
is generally considered by the local fi shermen as
an impediment to fi sh movement and hindrance
in fi shing, they are usually removed from the
Beel at the end of summer.
High species diversity amongst the AM species
was evident in this wetland. And the level was
found to be high (biased estimate of H′ = 2.015;
expected value, E ( H′ ) = 2.014; variance of
H′ = 1.431 E- 3) in Sone Beel (Dey and Kar 1989 ).
Plankton
‘ Plankton’, the living fraction of material, found
in water and moved passively by wind or current,
is composed of bewildering varieties of microscopic organisms. The ‘phytoplankton’, which
are predominantly autotrophic, are the primary
producers of organic matters in the aquatic habitats. The nutritionally dependent animal component constitutes the ‘zooplankton’.
An Account of Limnoplankton of Sone Beel
Fourty seven different forms of phytoplankton
belonging to fi ve groups, as indicated above,
have been recorded, till date, in Sone Beel. Of
these, the Chrysophyta included the maximum
number and Pyrrophyta, the least. The phytoplankton density in the Beel varied from 48 to
5,308 (average 1,027) units/litre. The minimum
population is generally recorded during the rainy
season and maximum during the dry season. The
cyanophytes and the euglenophytes generally
exhibit prolifi c growth during the spring and
summer with occasional abundance during monsoon. The chlorophytes usually show higher
occurrence intensity during summer and early
monsoon with infrequent richness during winter
and spring. The chrysophytes are generally
recorded throughout the year. The pyrrophytes
were found to register their presence mainly during the autumn.
Nineteen different forms of zooplankton,
belonging to fi ve groups, have been recorded in
Sone Beel. The zooplankton density varied from
6 to 380 (average 49) units/litre. Low density is
generally recorded during February–March and
high density during November–December. In
Sone Beel, a considerable portion of zooplankton
population is considered to succumb to the dayin 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
exhibited abundance during autumn and winter
(Dey and Kar 1994 ).
There is a bewildering diversity of fi shes in
the lentic systems of this region.
Fish Diversity in Sone Beel
Seventy species of fi shes belonging to 49 genera
under 24 families and 11 orders have been recorded
in Sone Beel, the biggest wetland in Assam.
20 Wetlands of India