Basic HTML Version
International Journal of Marine Science 2014, Vol.4, No.44, 1-14
http://ijms.biopublisher.ca
7
Figure 9 Serum albumin and hemoglobin concentration (mean
± SE) in the blood of elasmobranch species caught in
Sevastopol Bay (Black Sea, Ukraine)
4 Discussion
The aim of the present study was to investigate
differences between specific health variables, known
to show physiological responses to environmental
conditions, in different elasmobranch species in the
Black Sea. Given the increased anthropogenic
development, pollution, introduction of invasive
species, and resulting loss of biodiversity in the Black
Sea, understanding the physiological responses and
adaptations to these changes in elasmobranchs is of
utmost importance. Our findings demonstrated
significant differences between serum, RBC, and
hepatic biochemical parameters in three species of
Black Sea elasmobranchs. These differences may be
the result of species differences in relation to their
ecology, life history, and biology. This discussion will
focus on two main points: 1. to discuss possible
explanations for the interspecies differences; and 2. to
detect potential strategies of biochemical adaptations
in the tested species to their living conditions and
anthropogenic impacts.
Atlantic spiny dogfish
Squalus acanthias
is gregarious
benthic-pelagic fish which abundance is at the depth
of 180-200 m. However, it migrates in the upper
waters for feeding. This shark is carnivorous species,
and it consumes primary fish (horse mackerel,
pickerel, sand smelt, red mullet, and etc.). The dogfish
shark is a viviparous species, its maturation begins at
the age of 13-14 years and at the body length of 1 m.
Incubation period of the embryos continues 2 years,
each female produces 10-12 embryos and 18 eggs.
Usually the length of the adults is estimated as
150~208 cm and the weight is 14 kg. Fish life span
continues approximately 25 years, number of males in
the catches are higher than females. Liver mass of the
adult sharks is estimated as 17.9~29.6% of the total
body weight (Svetovidov, 1964).
Buckler skate
Raja clavata
is a benthic species; it is
abundant at the depth of 100 m at the bottom
sediments or at the soil. Females spawn at spring time
at the shelf. Individual female spawns from ten to one
hundred eggs on the bottom. The period of the
embryogenesis continues during 4.5~5.5 months. The
length of the male is 70 cm and the length of the
female is 125 cm. It consumes primary benthic fish
species (scomber, pickarel) and invertebrates, such as
crustacean and mussels.
Stringray
Dasyatis pastinaca
is abundant at the depth
of 200 m at the bottom sediments or at the soil. The
size of adults is estimated as 60-70 cm and the mass is
6-10 kg. It is viviparous; the development of the
embryo continues 4 months. Each female produces
4-12 embryos and 12-32 developmental eggs. The
food includes small fish species, crustacean and
mussels. Thus, the general prey categories, and trophic
level, are very similar between these species (with
S.
acanthias
is known to be an active predator of
fast-swimming prey).
The liver plays an important role in metabolism
(synthesis and degradation of various biomolecules,
biotransformation of xenobiotics), and its biochemical
characteristics reflect directly the adaptation of the
organism to the living conditions. Blood biochemistry
is also important in evaluation of fish physiological
and ecological status and biochemical adaptations to
environment. Besides that, blood biochemical
parameters directly reflect health status of the animals,
which is very important at the case of wild
populations, including elasmobranchs (Haman et al.,
2012). Therefore, the observed significant differences
between skates and the dogfish indicate the specificity
of adaptation mechanisms of the fish to environmental
conditions.
The liver is characterized by an increased metabolic
rate and includes a majority of physiological and
biochemical pathways, including those that produce
oligopeptides. Specifically, oligopeptides are formed
via protein degradation and biotransformation of
xenobiotics, thus generating multiple low molecular
weight molecules. An increase of oligopeptide levels
in tissues is associated with an increase in protein
degradation coupled with a decrease in protein
synthesis and inhibition of proteasomal function
(Vysotskaya and Nemova, 2008). Currently, the use of