International Journal of Aquaculture, 2017, Vol.7, No.7, 51
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Figure 2 Puntius kamalika, a. abnormal specimen, 58.5 mm TL;
b. normal specimen, 72.6 mm TL
Figure 3 Radiograph of abnormal specimen of Puntius
kamalika, 58.5 mm TL
Both water and sediments in Sri Lanka were shown to be highly polluted with different types of pollutants
(
Vidanaarachchi et al., 2006; Bandara and Hettiaratchi, 2010; Seneviratne, 2011; Kananke et al., 2014).
The developmental mechanism during the early stages of the life of the fish can easily disturb by the presence of
pollutants (Kihara et al., 2002). One example on such interference is the elevation of the level of pH due to
increase in the level of carbon dioxide. Due to such circumstances, the normal blood pH is remained due to the
presence of the normal serum osmosis. The process of bone decalcification could start as the level of the carbonic
acid rises to maintain normal blood pH (Sarkar and Kapoor, 1956; Andrades et al., 1996).
The deepest the lordotic curvature is the most severe the case is. In the present study, the lordotic angle is 95°,
which means that the vertebral column is acutely bent. High depth of the lordotic curvature support the severe
case obtained in the present study. Chang et al. (2010), Louiz et al. (2007) and Jawad et al. (2014) have reached to
similar results on thornfish,
Terapon jarbu,
some members of the family Gobiidae and
Carasobarbus luteus
and
the shad.
Tenualosa ilisha
respectively, Başaran (2006) suggested that case like the one observed in the present study may
hinders the ability of the fish to swim normally. It seems that it had been in great competition for food and such
struggle is the main component for survival in the wild environment.
The morphological changes in the case of lordosis showed in the specimen of
P. kamalika
is related
anterior-posterior (
i.e
. cranial-caudal) compression along the spine. Structural indication is present in the x-ray
showing that the normal amphicoelous (hour-glass) shape of vertebrae is distorted so that vertebral height is
reduced on the convex and is greater on the concave side of curvature. In addition, vertebrae at the approximate
bottom of the curvature are wedged so that the length on the concave side of the curve is reduced relative to the
convex length. Also, the midline width is significantly reduced for some vertebrae. Similar changes were observed
in
Poecilia reticulata
by Gorman et al. (2010). They suggested that the observed changes in vertebral bone
structure may be due to either (1) distortion of normal vertebral shape or (2) active remodeling of vertebral osteoid
bone as a consequence of extrinsic forces. The remodeling event has been described in animal models with
induced curvature in a number of teleost species (Laerm, 1976; Huysseune et al., 2000; Kranenbarg et al., 2005).
The formation of asymmetrical vertebrae demonstrates changes in growth rate along their growth plates, causing
uneven progression in longitudinal growth and consequential shape distortion in the form of wedging (Mente et al.,
1997). Therefore further study of vertebral wedging in
P. kamalika
and other fish species that will show lordosis
in the future should test cellular activity at the intervertebral region (Inohaya et al., 2007), to evaluate whether
there is modulation of growth in curved individuals.
