625
29.2.3.1 Problems with Regard
to Eutrophication
Today, many wetlands are victims of eutrophication
and consequent weed problems.
29.2.3.2 Problems with Regard
to Paddy Cultivation
Cultivation of paddy at the DSL is a common and
lucrative practice in many wetlands today. This
has been causing harm to the wetlands. In the
Indian subcontinent, due to rice culture, there has
been a loss in the spatial extent of wetlands. Rice
farming is a wetland-dependent activity and is
developed in riparian zones, river deltas and
savanna areas. Of the c 58.2 million ha (mha) of
wetlands in India, c 40.9 mha are under rice
cultivation.
29.2.3.3 Problems with Regard
to Fish Disease
The dreadful fi sh disease, called Epizootic
Ulcerative Syndrome (EUS), has been causing
large-scale mortality among the freshwater fi shes
since 1988, initially affecting four species of fi shes
very widely. Our study (Kar and Dey 1988a , 1990 ;
Kar 2000a , b , 2003 , 2004 , 2007a , b , 2010 , 2012 ; Kar
et al. 1993 , 1995a , b , 2006 ) revealed fl uctuations in
the intensity of disease in relation to species
affected. Large haemorrhagic cutaneous ulcers, epidermal degeneration and necrosis followed by
sloughing of scales are the principal symptoms of
EUS. Total alkalinity (TA) could be a predisposing ‘stress’ factor. Sick fi shes show low haemoglobin and polymorph but high ESR and
lymphocytes. Communicative nature of EUS
revealed variation in time gap between fi sh
and infection in different species. Inoculation of
microbes into the test animals did not reveal any
sign of ulceration for 2 years. Bacterial culture
revealed isolation of haemolytic E . coli , Aeromonas
hydrophila , Pseudomonas aeruginosa , Klebsiella
sp. and Staphylococcus epidermidis in the
surface lesions as well as in the gut, liver, gills,
heart, kidney and gonads of sick fi shes. All these
bacteria have been found to be sensitive to chloramphenicol, gentamicin, septran, etc. Fungal isolation
revealed the occurrence of Aphanomyces sp. with
concomitant occurrence of the same fungal genus in
histological sections of EUS-affected fi sh tissues.
Histopathological studies revealed focal areas of
increased fi brosis and chronic infl ammatory cell
infi ltrations in muscles and focal areas of fatty
degeneration of hepatocytes surrounding the portal
triads in the liver. Preliminary histochemical studies
revealed interruption of glycogen synthesis in the
liver and blockade of respiratory pathways in the
gills. Preliminary enzymological studies revealed
high values of alkaline phosphatase, SGPT, SGOT
and LDH. Inoculation of 10 % tissue homogenate
from EUS-affected Clarias batrachus into 80 %
confl uent monolayer of BF2 fi sh cell line in
Leibovitz L-15 medium revealed progressive CPE
which was passable in the subsequent cultures, thus
indicating the isolation of virus.
Preliminary electron microscopic (EM)
works done with EUS-affected tissues of Channa
punctatus and Anabas testudineus revealed the
occurrence of virus-like particles (Kar et al.
1993 , 1995a ). Detailed electron microscopic
studies done with ultra-thin sections of EUSaffected tissues of Channa striata and Anabas
testudineus revealed membrane bound and granular abnormal structures, hepatocytes with vacuolations and virus-like inclusion bodies in the
nucleus ( Kar 1999a , b ). Further, recent EM
works done with EUS-affected tissues of
Wallago attu revealed the presence of virus-like
particles (Kar 2004 ). Further works, in this
direction, are in progress. Recent electron microscopic studies revealed the presence of a virus
(possibly a Birnavirus) in the ultra-thin sections
of EUS- affected fi sh tissues (Kar 2010 ). Efforts
are being made to control the virus.
29.2.3.4 Threat to Wetlands Is a Threat
to Ecological Balance
Wetlands are one of the most threatened habitats
of the world. Wetlands in India, as elsewhere, are
increasingly facing several anthropogenic pressures. Thus, the rapidly expanding human population, large-scale changes in land use, land
covers, burgeoning development projects and
improper use of watersheds have all caused a
substantial decline of wetland resources of the
country. Signifi cant losses have resulted from its
conversion threats from industrial, agricultural
29.2 Problems
29.2.3.1 Problems with Regard
to Eutrophication
Today, many wetlands are victims of eutrophication
and consequent weed problems.
29.2.3.2 Problems with Regard
to Paddy Cultivation
Cultivation of paddy at the DSL is a common and
lucrative practice in many wetlands today. This
has been causing harm to the wetlands. In the
Indian subcontinent, due to rice culture, there has
been a loss in the spatial extent of wetlands. Rice
farming is a wetland-dependent activity and is
developed in riparian zones, river deltas and
savanna areas. Of the c 58.2 million ha (mha) of
wetlands in India, c 40.9 mha are under rice
cultivation.
29.2.3.3 Problems with Regard
to Fish Disease
The dreadful fi sh disease, called Epizootic
Ulcerative Syndrome (EUS), has been causing
large-scale mortality among the freshwater fi shes
since 1988, initially affecting four species of fi shes
very widely. Our study (Kar and Dey 1988a , 1990 ;
Kar 2000a , b , 2003 , 2004 , 2007a , b , 2010 , 2012 ; Kar
et al. 1993 , 1995a , b , 2006 ) revealed fl uctuations in
the intensity of disease in relation to species
affected. Large haemorrhagic cutaneous ulcers, epidermal degeneration and necrosis followed by
sloughing of scales are the principal symptoms of
EUS. Total alkalinity (TA) could be a predisposing ‘stress’ factor. Sick fi shes show low haemoglobin and polymorph but high ESR and
lymphocytes. Communicative nature of EUS
revealed variation in time gap between fi sh
and infection in different species. Inoculation of
microbes into the test animals did not reveal any
sign of ulceration for 2 years. Bacterial culture
revealed isolation of haemolytic E . coli , Aeromonas
hydrophila , Pseudomonas aeruginosa , Klebsiella
sp. and Staphylococcus epidermidis in the
surface lesions as well as in the gut, liver, gills,
heart, kidney and gonads of sick fi shes. All these
bacteria have been found to be sensitive to chloramphenicol, gentamicin, septran, etc. Fungal isolation
revealed the occurrence of Aphanomyces sp. with
concomitant occurrence of the same fungal genus in
histological sections of EUS-affected fi sh tissues.
Histopathological studies revealed focal areas of
increased fi brosis and chronic infl ammatory cell
infi ltrations in muscles and focal areas of fatty
degeneration of hepatocytes surrounding the portal
triads in the liver. Preliminary histochemical studies
revealed interruption of glycogen synthesis in the
liver and blockade of respiratory pathways in the
gills. Preliminary enzymological studies revealed
high values of alkaline phosphatase, SGPT, SGOT
and LDH. Inoculation of 10 % tissue homogenate
from EUS-affected Clarias batrachus into 80 %
confl uent monolayer of BF2 fi sh cell line in
Leibovitz L-15 medium revealed progressive CPE
which was passable in the subsequent cultures, thus
indicating the isolation of virus.
Preliminary electron microscopic (EM)
works done with EUS-affected tissues of Channa
punctatus and Anabas testudineus revealed the
occurrence of virus-like particles (Kar et al.
1993 , 1995a ). Detailed electron microscopic
studies done with ultra-thin sections of EUSaffected tissues of Channa striata and Anabas
testudineus revealed membrane bound and granular abnormal structures, hepatocytes with vacuolations and virus-like inclusion bodies in the
nucleus ( Kar 1999a , b ). Further, recent EM
works done with EUS-affected tissues of
Wallago attu revealed the presence of virus-like
particles (Kar 2004 ). Further works, in this
direction, are in progress. Recent electron microscopic studies revealed the presence of a virus
(possibly a Birnavirus) in the ultra-thin sections
of EUS- affected fi sh tissues (Kar 2010 ). Efforts
are being made to control the virus.
29.2.3.4 Threat to Wetlands Is a Threat
to Ecological Balance
Wetlands are one of the most threatened habitats
of the world. Wetlands in India, as elsewhere, are
increasingly facing several anthropogenic pressures. Thus, the rapidly expanding human population, large-scale changes in land use, land
covers, burgeoning development projects and
improper use of watersheds have all caused a
substantial decline of wetland resources of the
country. Signifi cant losses have resulted from its
conversion threats from industrial, agricultural
29.2 Problems