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International Journal of Marine Science 2014, Vol.4, No.44, 1-14
http://ijms.biopublisher.ca
10
dogfish and stringray
.
However, several authors have
shown that the level of plasma aminotransferases in
rays was lower than in sharks. For instance, AST
activity in plasma of the ray
Dasyatis americana
was
approximately 3-fold lower than in shark
Sphyrna
tiburo
(Cain et al., 2004; Harms et al., 2002). We
propose that the differences of aminotransferases
activity in blood serum may be linked with the
specificity of fish habitat, foraging ecology, and life
history. For instance, aminotransferase activity in the
muscle of elasmobranchs decreases significantly with
the depth at which they exist. For example, muscular
enzymatic activity in black dogfish
Centroscyllium
fabricii
caught at a depth of 500~1000 m was
significantly lower than in
S. acanthias
caught at the
depth of 180 m (Treberg et al., 2003). Our findings
support this; the concentration of aminotransferases is
lower in the serum of dogfish and stringray (abundant
at the depth of 180-200 m) than in buckler skate
(abundant at the depth of 100 m)
.
Hemoglobin concentration was the similar in red
blood cells of examined elasmobranchs. Serum
albumin-like proteins level ranged from 2.4 g/L in
D.
pastinaca
to 6.2 g/L in
R. clavata
and 2.95 g/L in
S.
acanthias
. In the liver it varied lower. Several
researchers also showed variations of serum
albumin-like proteins in elasmobranch, which
were fluctuated between 3-5 g/L (Harms et al.,
2002).
Finally, interspecies variations of tested hepatic and
blood biochemical parameters of Black Sea
elasmobranchs may be the result of different
sensitivities to pollution. Previously we described the
significant anthropogenic impact in Sevastopol Bay
(Black Sea, Ukraine) and the resulting negative
consequences for fish health (Rudneva, 2011;
Rudneva and Petzold-Bradley, 2001). In our recent
publication (Rudneva et al., 2012) we have also
shown that the concentration of several trace elements
in buckler skate and stringray was higher than in
dogfish (Table 3). Specifically, the concentrations of
Cu, As and Hg were significantly higher in the skate’s
and ray’s tissues than in shark. Furthermore, the
concentration of nitrosamines in tissues of buckler
skate and stringray was also greater than in dogfish
(1.8+0,1, 1.9+0.01 and 1.6+0.05 ng/kg wet weight
respectively) (Rudneva et al., 2012) because skates
and rays live on the bottom, they are exposed to
toxicants, including heavy metals, which tend to
concentrate in the bottom sediments.
Table 3 Concentration of trace elements in skeletal muscle (mg/kg, mean ±SE) of Black Sea elasmobranchs (Rudneva et al., 2012)
Trace elements
Species
Legal
levels
(Ukraine)
S. acanthias
D. pastinaca
R. clavata
Cu
0.32±0.02
0.41±0.01
0.36±0.01
10.0
Pb
0.23±0.01
0.36±0.1
0.22±0.01
1.0
Cd
0.015±0.003
0.015±0.005
0.015±0.005
0.2
Zn
4.15±0.04
4.6±0.3
4.0±0.2
40.0
As
1.52±0.12
4.52±0.4
2.06±0.1
5.0
Hg
0.18±0.01
0.26±0.06
0.25±0.04
0.4
Elasmobranchs are at the top of the food web and as
such, they are at a greater risk of ingesting pollutants,
including trace elements that have been biomagnified
up the food web (Da Rocha et al., 2009; Sole et al.,
2009). Increased levels of trace metals and
nitrozamines in ray and skate may the result of
increased
exposure
due
to
ingestion
of
toxicant-containing sediments and food (Goksoyr et
al., 1996; Porte et al., 2000; Da Rocha et al., 2009;
Sole et al., 2009). Dietary differences among ray,
skate and shark seemed to be the most important
causes for differences in their trace elements and
nitrosamine levels in the body, which in turn modify
biochemical parameters such as those investigated in
this study.
Many investigators reported the highest antioxidant
enzyme activities in fish liver, because it plays the
major part in the detoxification processes of
xenobiotics and endogenously generated metabolites
that can not be metabolized by the other organs
(Goksoyr et al., 1996; Sole et al., 2009). In this study,