International Journal of Marine Science 2015, Vol.5, No.21, 1-5
2
Describe if Mn, Fe, Co, Cu, Zn and Pb levels were
significantly different between months, 3) Determine
if these heavy metal levels were significantly different
between dorsal and liver tissues, and 4) Compare any
Mn, Fe, Co, Cu, Zn and Pb levels present with the
guidelines set down European Commission
Regulation and FAO/WHO for the safe consumption
limits of
P. chinensis
.
1 Materials and Methods
Fish samples were collected monthly from Karachi
Harbour during 2013. The samples were prewashed
with clean sea water at the point of collection and
packed in polyethylene plastic bags. The collected
samples were kept in ice box and transferred to the
Fisheries Laboratory of the Marine Reference
Collection and Resources Centre, University of
Karachi. The total length (TL) of all fishes were
measured by using wooden measuring tray (nearest
0.1 cm) and weighed (W) by electronic balance
(nearest 0.1g). There were Six individuals from each
month were chosen, rinsed with sea water, placed in
plastic bags and freezed at -21°C until the analysis.
Both muscle and liver tissues of the fish were
prepared for analysis according to the method
described by Bernhard (1976). All samples of dorsal
muscles and entire liver tissues homogenised and
dried in an oven until constant weight was obtained.
Samples were then ground and calcinated at 500
o
C for
3 hours until it turned to white or grey ash and
digested with HCl (Gutierrez et al., 1978). The filtered
extracts diluted with 1 N HNO3 (UNEP, 1984 and
1985). All reagents used during analysis were of
analytical reagent grade. Calibration of the instrument
was done by standard solutions. The solutions were
analysed by using the equipment (Analyst 700) with
background correction and acetylene as fuel and were
prepared programme win lab 32 software for Mn, Fe,
Co, Cu, Zn and Pb. The heavy metal analyses in the
fish samples were recorded as means ±standard error
(SE) of triplicate measurements. The values of heavy
metals are expressed as mg/kg dry wt. of the sample.
Statistical analysis (ANOVA) was performed to test
the differences between seasons and Tukey test was
used to determine the differences (Zar, 1984).
2 Results
The mean lengths (cm) and weights (g) of
P. chinensis
from Karachi Harbour was given in Figure 1 during
January - December 2013. The lengths and weights of
collected fish samples ranged from 21 to 36 cm and 96
to 208 g, respectively. There was no statistical difference
(p>0.05) both lengths and weights between months.
Figure 1 Lengths (cm) and weights (g) of the Chinese silver
pomfret
Pampus chinensis
from Karachi Harbour between
January and December of 2013
The Figure 2 showed that Fe concentrations were the
highest followed by Zn and Cu; Pb being the lowest in
the tissues both muscle and liver. Similar results for
different fish species were found by many researchers
(Tepe et al. 2007; Türkmen et al. 2008 and 2009).
Since essential metals play important roles in
biological systems (Türkmen et al. 2009) and metal
uptake rates are positively related to the metabolic rate
in fish. Analysis of variance (ANOVA) indicate that
the concentrations of all measured heavy metals were
considerably higher in liver tissues of
P. chinensis
than those in muscle tissues (P<0.05) and that there
was a statistically significant difference between the
concentrations of the metals among months. It may be
suggested that the monthly variations of these metals
in the Chinese silver pomfret are attributed to
physiological conditions, environmental variations
and feeding activity.
3 Remarks
Fish are very good bio-indicators because of their
rates of growth, body sizes, life strategies and food
preferences (Jakimska et al., 2011). If fish are exposed
to polluted waters with various metals, the
biologically available metal ions are up-taken through
gills and skin or through the ingestion of contaminated
food. Canli and Atli (2003) showed that target tissues
of heavy metals are metabolically active organs
especially liver compare to the lower metabolism
tissues like muscle tissues. Thus metals are
accumulated in the organ of metabolic activity like
liver, their deposition also occur later in the muscle
