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International Journal of Marine Science 2014, Vol.4, No.45, 1-5
http://ijms.biopublisher.ca
4
column and enclosing the curvature are 130˚ for angle
no. 1 and 145˚ for angle no. 2. The depth of the curvature
of angle no. 1 and 2 are 15.3 and 7.8 respectively.
The deformed specimen of
T. ilisha
showed two
severe twisting of the vertebral column, the first is
between the 5
th
and 6
th
abdominal vertebrae, and the
second at the 15
th
caudal vertebra. The centra of the
vertebrae 24
th
to 26
th
are severely deformed. Slight
deformity is seen in the neural spine of the 18
th
to 21
st
abdominal vertebrae as they are not aligned,
undulation of the haemal spine of the caudal vertebrae
26
th
and 27
th
and the haemal spine of the caudal
vertebrae 27
th
to 30
th
shown to be curved backward.
The ratio of the vertebral column to the fish total
length of the deformed specimen is 0.4, while it is 0.5
in the normal specimen (Figures 9). The value of the
angles lies between the lines passing through the sides
of the vertebral column and enclosing the curvature
are 90˚ for angle no. 1 and 106˚ for angle no. 2. The
depth of the curvature for angle no. 1 and 2 are 6.2
and 28 respectively. No external lesions were
observed on the body of the deformed specimens of
the two species.
3 Discussion
The source of the causes of this disorder is not well
understood. Nutritional, environmental and genetic
causes have been cited. Environmental factors such as
density of eggs, mechanical or thermal shocks, and
presence of pollutants in the water, radiation, salinity,
oxygen depletion and light intensity have also been
reported to cause aberrations in development (Caris
and Rice, 1990). This could have happened to the two
species under investigation in this study as happened
to individuals of other species in the same area. Cases
of lordosis with variable percentages ranging between
10-18% were obtained for other fish species from
Al-Hammar Marsh area and caused concern about the
impact of deformed fish on resource sustainability
(Ali, 2006).
Both water and sediments of Al-Hammar Marsh have
been shown to have high levels of heavy metal
(Al-Imarah et al., 2000). Such levels are also present
in the tissue of several fish species including
C. luteus
and
T. ilisha
living in Al-Hammar Marsh as Al-Imarah,
et al (2006) has reported. High pollutant levels are
also recorded in both environment and fish tissue of in
areas around the area where the specimens of the two
species were collected (Al-Imarah et al., 2008).
Pollutants shown to disturb number of internal
mechanisms inside the fish body during its early life
stages (Kihara et al., 2002; Jacquemond, 2004). They
may interfere with the level of pH by elevated carbon
dioxide. Cell will react to sustain normal serum
osmosis and resume the normal blood pH. This may
cause bone decalcification due to the presence of
excessive carbonic acid generated as blood pH
normalises (Sarkar and Kapoor, 1956; Andrades et al.,
1996).
Variation in water temperature of Al-Hammar Marsh
is very large, ranging from 8-37°C (Douabul et al.,
2012). Such a large variation in water temperature will
definitely have a direct effect on the development of
the vertebral column of the fish larvae.
To elucidate the severity of the case of lordosis
observed in the present study, the curvatures caused
by the lordotic case of anomaly were evaluated by
measuring the angle between the two sides of the
lordotic part of the vertebral column. The lower the
angle is the severe the lorodosis case is. The curvature
of 90°in the case of
T. ilisha
is considered a severe
lordotic cases, while other angles in both species are
moderate. However, they are still employing actual
pressure on the daily activity of the fish. This result is
backed by the results of the depth of the curvature
(higher than that of the normal specimen) and the ratio
of the vertebral column to the total fish length (Lower
than that of the normal specimen). Similar results
were obtained by Chang et al. (2010) on thornfish,
Terapon jarbu
and Louiz et al. (2007) on some
members of the family Gobiidae. Due to the presence
of lordosis case in the present specimens of the two
species and to the fact that such anomaly is interfere
with the ability of the fish to swim normally (Başaran,
2006), it seems that they had been in great
competition for food and such struggle is the main
component for survival in the wild environment.
References
Ali S.M., 2006, Observation of fish anomalies in the southern marsh areas,
Iraq. Report presented to the Ministry of Agriculture, Iraq, pp.125
Andrades J.A., Berrara J., Fernandez-llebrez P., 1996, Skeletal deformities
in larval, juvenile and adult stages of cultured gilthead sea bream
(Sparus aurata). Aquaculture, 141: 1-11