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Sistema de Información Científica
Red de Revistas Científicas de América Latina y el Caribe, España y Portugal
Rev. Int. Contam. Ambie. 30 (2) 137-142, 2014
HEAVY METALS IN FISH AND INVERTEBRATES FROM THE GULF OF PARIA, VENEZUELA
Mairin LEMUS
1,3
*, Julián CASTAÑEDA
2
and Kyung CHUNG
3
1
Departamento de Biología, Escuela de Ciencias, Universidad de Oriente, Cumaná 6101, Venezuela
2
Departamento de Oceanografía, Instituto OceanográFco de Venezuela
3
Departamento de Biología Marina, Instituto OceanográFco de Venezuela
* Autora responsable; mlemus88@gmail.com
(Recibido enero 2013, aceptado abril 2014)
Key words: heavy metals, bioaccumulation, invertebrates, contamination, Fsh
ABSTRACT
The concentration of Hg, Cu, Cd, Cr and Ni was estimated in Fsh and invertebrates
captured in the Gulf of Paria coastal zone, Venezuela. The results show that invertebrates
have a higher bioaccumulation of metals in relation to Fsh, particularly
C. virginica
that had the highest concentrations of Hg, Cu and Cd and the snail
A. deforata
with
the highest values of Cr, Ni and Pb. In relation to Fshes,
C. spixii
(catFsh) presented
the highest values of all metals tested. The metals tested in the species do not exceed
the maximum permissible values indicated by the WHO for human consumption.
However, heavy metals are present in the Gulf of Paria.
Palabras clave: metales pesados, bioacumulación, invertebrados, contaminación, peces
RESUMEN
En el presente trabajo se evaluó la concentración de Hg, Cu, Cd, Cr, Ni en peces e in-
vertebrados capturados en la zona costera del Golfo de Paria, Venezuela. Los resultados
muestran que los invertebrados tienen mayor bioacumulación de metales en relación
a peces, particularmente
C. virginica
presentó la mayor concentración de Hg, Cu y Cd
y el caracol
A. deforata
que presentó las mayores concentraciones de Cr, Ni y Pb. En
peces el bagre
C. spixii
presentó los más elevados valores de los metales analizados.
Los metales evaluados en las especies no superen los valores máximos permisibles
señalados por la Organización Mundial de la Salud para consumo humano, sin embargo
se determina la presencia de los metales en el Golfo de Paria.
INTRODUCTION
The use of organisms to evaluate heavy metals in
environmental conditions is often a good indicator of
the health of ecosystems, especially when it comes
to persistent pollutants such as heavy metals (Islam
and Tanaka 2004, Pascual and Avollo 2005). Most
organisms can take trace metals from the sediment
and the water column and concentrate them in their
tissues. In fact, a wide variety of species can be used
as biomonitors to evaluate ecosystems affected by
trace metals (Rojas
et al
. 2009, Lemus
et al.
2010).
M. Lemus
et al.
138
Moreover, the USA Federal Drug Administration
(2001) states that authorities responsible for health
services must carry out frequent monitoring on the
quality of Fsh and shellFsh intended for human
consumption.
Some heavy metals (Hg, Cd, Pb) are regarded as
the most dangerous pollutants now existing. Others
such as Cu and Zn, although essential for living
organisms, are also toxic when certain threshold
concentrations are exceeded.
When trace metals are dumped into the aquatic en-
vironment they may be biologically Fxed into marine
organisms from the surrounding water or by ingestion
of food and sediment particles. Invertebrates and Fsh
are speciFc indicators of different environmental
compartments in relation to their habitat and trophic
chain position, and they exhibit different rates of bio-
accumulation with respect to different heavy metals.
The eastern area of Venezuela does not have
extensive industrial development, particularly the
coast of the Sucre State; however there are port ac-
tivities in Güiria, together with oil exploitation sites
and reFning plants in the southern part of the Gulf.
Directed toward this and other parts of the eastern
region, important projects are being put forward to
exploit natural gas reserves and further condensed
hydrocarbon products in offshore oil deposits. These
reserves are located to the north of Paria Peninsula,
where the basic resource extraction activities will be
carried out. This project covers an area extending to
the south-east of the peninsula.
Recently, no research has been done on metal
monitoring in the Gulf of Paria, except for metal
evaluation in
Perna viridis, Crassostrea virginica
and
Crassostrea rizophorae
in 1999 at six locations of
the gulf and three locations on the coast of Trinidad
(Rojas
et al
. 2002).
In this research, an analysis of the metals Cu, Cd,
Cr, Ni, Pb, and Hg is performed in Fsh and inver
-
tebrates from locations of the northern coast of the
Gulf of Paria.
MATERIALS AND METHODS
Fish and invertebrate specimens were collected in
four sampling areas along the northern coast of the
Gulf of Paria (
Fig. 1
). The six most abundant species,
Stillifer rastrifer, Cathorops spixii, Pellona harroweri,
Selene vomer, Lutjanus synagris, Diapterus rhombeus
and the white shrimp
Litopenaus schmitti
, were col-
lected by traditional Fshing methods in Los Trancotes,
Soro and Macuro. In addition,
Crassostrea virginica,
Cyclinella tenuis
, and
Asaphys deforata
were manu-
ally collected in Macuro, Soro and Las Salinas.
The specimens were separated by species in
labeled PVC bags and taken to Laboratory of the
Instituto OceanográFco de Venezuela (IOV) (for its
acronym in Spanish). At the IOV, their morphometric
characteristics were recorded, the specimens were
dissected and their tissues were prepared for metal
analysis.
Both Fsh and crustaceans and mollusks underwent
the extraction of all the soft tissue from six organisms,
while Fsh underwent the extraction of all the visceral
mass before processing. All organisms were washed
with distilled water and an EDTA solution at 1 %
m/v in order to eliminate metals adsorbed onto the
surface, and then they were dried in a stove at 60 ºC
until reaching a constant weight. The tissues used
to determine the quantity of mercury and the other
metals were dried separately.
To determine Cu, Cd, Cr, Ni, and Pb, the samples,
once dried, underwent a pre-digestion with 8 mL
of concentrated nitric acid (analytic degree, Merk),
during the night at room temperature with adequate
controls. A digestion was subsequently carried out
for six hours at 60 ºC, and after the sample cooled
off, about 6 mL of deionized water was added and
the Fltering of the sample was performed up to a
total volume of 25 mL in ±asks until the moment of
analysis. Results were expressed in μg/g dry weight
(DW). The method used to determine metals was vali-
dated with certiFed reference materials (DORM- 2
and LUTS-1). Standards for all metals were analyzed
simultaneously with the experimental samples
To determine Hg the samples were weighed in
plastic containers and dried until reaching a constant
weight at 60 ºC. Then nitric acid was added in a 1 g/3 mg
ratio and the sample was left to pre-digest overnight.
Fig. 1
. Map showing Fsh and invertebrate collecting areas in the
Gulf of Paria
Troncotes
–63º20'
Ubicación geográfica
MAR CARIBE
Río Caribe
Soro
Salinas
Macuro
11º20'
11º00'
10º40'
10º20'
11º20'
11º00'
10º40'
10º20'
–63º00'
–62º40'
–62º20'
–62º00'
–63º20
'–
63º00'
–62º40'
–62º20'
–62º00'
HEAVY METALS IN FISH AND INVERTEBRATES FROM THE GULF OF PARIA, VENEZUELA
139
Digestion was completed at a 60 ºC temperature for
six more hours and fnally sulFuric and hydrochloric
acids were added keeping an 8:2:1 v/v ratio between
all three acids (Rojas
et al.
2002).
The determination of Hg by cold vapor was per-
formed chemically reducing mercury to the atomic
state with NaBH
4
at 3 % in NaOH at 1 % in a tight
reaction container. The detection limit is approxi-
mately 0.000460 µg/L where a 1 % of absorbance
change represents 4.68 ng. The wavelength used was
253.6 nm and the calibration curve was 100, 200,
and 500 ng following Perkin Elmer´s instructions
(1972). The validation of the method was performed
as mentioned in the previous paragraph for the other
metals. Results were expressed in µg/g of dry weight.
RESULTS AND DISCUSSION
Heavy metal research in fsh and invertebrates
from the Gulf of Paria represents a contribution to
the understanding of metal bioaccumulation in six
fsh species and fve invertebrate species, since until
now no research has been done on metal evaluation
in several species oF this gulF. However, suFfcient
records of heavy metal levels in sediments and waters
can be found (Márquez
et al.
2000, Rojas
et al.
2005),
The results obtained in this investigation show
that the study area has no evidence oF signifcant
levels of mercury for the analyzed species. Mercury
levels for the six species ranged from 0.005 ± 0.005
to 0.016 ±0.008 μg/g, with the highest concentra
-
tion being Found in the catfsh
C. spixii
in Soro
and Trancotes locations, and
S. vomer
from Soro.
Mercury concentrations in the three bivalve species
evaluated in the Gulf of Paria were higher than those
detected For fsh, with values between 0.026 ± 0.016
and 0.148 ± 0.107 μg/g, the latter being the aver
-
age value of the oyster
C. virginica
from Macuro
location (
Table I
).
From the results of this research, none of the
species under study exceeded the maximum limit
allowable indicated by the World Health Organiza-
tion (1976), but it is important to point out that
C.
virginica
showed the highest concentration founded
(0.05 ± 0.01) in the location of Chacachacare on the
northern coast of Trinidad (Rojas
et al.
2002). These
results show that there has been an increase in the
concentration of this metal in
C. virginia
.
Although no anthropic sources of mercury are
known in the zone, it is possible that the mercury in
the oyster
C. virginica
comes from matter in suspen-
sion arriving from the Orinoco delta. This is a site
in which an elevated concentration of this metal is
found, as a result of gold mining activities (Rojas
et
al.
2005, Pirrone
et al.
2010). On the other hand, the
yearly concentration of Hg in the bivalve
P. viridis
from the north coast of the Peninsula of Paria was
0.45 µg/g of dry mass, which indicates the presence
of this metal in this zone (Rojas
et al
. 2009).
The copper content in fsh From the locations oF
the GulF oF Paria ranged From 0.62 ± 0.14 μg/g For
L. synagris
of Macuro location to 1.39 ± 0.22 for the
catfsh
C. spixii
of Los Trancotes. Fish of this same
species from Las Salinas showed a similar value
(
Table II
).
TABLE I.
MERCURY CONCENTRATIONS (µg/g
dry weight) IN FISH AND INVERTE-
BRATES FROM THE NORTHERN COAST OF THE GULF OF PARIA
Location
Total Length (cm)
Average (µg/g)
Range
Fish
Stellifer rastrifer
Trancotes
7.33 ± 0.74
0.010 ± 0.008
0.001 – 0.023
Cathorops spixii
Trancotes
8.21 ± 0.40
0.015 ± 0.010
0.000 – 0.028
Pellona harroweri
Soro
8.75 ± 0.39
0.007 ± 0.003
0.001 – 0.009
Cathorops spixii
Soro
8.76 ± 0.89
0.012 ± 0.006
0.003 – 0.020
Selene comer
Soro
6.05 ± 1.19
0.016 ± 0.008
0.005 – 0.030
Lutjanus synagris
Macuro
6.88 ± 0.96
0.005 ± 0.005
0.000 – 0.013
Diapterus rhombeus
Macuro
6.65 ± 0.75
0.006 ± 0.010
0.000 – 0.028
Invertebrates
Litopenaeus schmitti
Trancotes
10.30 ± 0.36
0.005 ± 0.005
0.000 – 0.014
Cyclinella tenuis
Soro
2.45 ± 0.12
0.049 ± 0.030
0.099 – 0.015
Asaphys deforata
Salinas
4.80 ± 0.32
0.026 ± 0.016
0.002 – 0.047
Litopenaeus schmitti
Salinas
11.71 ± 0.75
0.011 ± 0.008
0.004 – 0.027
Crassostrea virginica
Macuro
5.70 ± 0.45
0.148 ± 0.107
0.031 – 0.308
Values are showed as mean and standard deviation. Metal concentration are displayed as mean
and range
M. Lemus
et al.
140
TABLE II.
HEAVY METAL CONCENTRATIONS (µg g
–1
dry weight) IN FISH AND INVERTEBRATES FROM THE NORTHERN COAST OF THE GULF OF PARIA
Species
Location
Total length
(cm)
Weight
(g)
Cu
(µg/g)
Cd
(µg/g)
Cr
(µg/g)
Ni
(µg/g)
Pb
(µg/g)
Fish
Stillifer rastrifer
1
6.64 ± 2.22
7.65 ± 2.22
1.26 ± 0.71
0.57 – 2.64
2.71 ± 1.47
1.33 – 5.00
0.14 ± 0.12
0.04 – 0.36
0.20 ± 0.29
0.00 – 0.69
0.04 ± 0.09
0.00 – 0.21
Cathorops spixii
1
8.53 ± 0.73
9.25 ± 1.74
1.39 ± 0.22
1.11 – 1.68
6.57 ± 6.38
1.76 – 18.26
0.25 ± 0.19
0.08 – 0.61
0.18 ± 0.17
0.00 – 0.37
0.13 ± 0.11
0.00 – 0.27
Pellona harroweri
2
6.20 ± 3.84
8.73 ± 1.75
0.75 ± 0.10
0.60 – 0.85
1.29 ± 0.77
0.16 – 2.30
0.24 ± 0.25
0.00 – 0.70
0.08 ± 0.20
0.00 – 0.50
0.03 ± 0.07
0.00 – 0.18
Cathorops spixii
2
6.26 ± 3.85
7.88 ± 3.03
1.35 ± 0.38
0.88 – 1.99
3.13 ± 1.76
1.02 – 6.08
0.63 ± 0.74
0.08 – 1.93
0.12 ± 0.23
0.00 – 0.58
0.08 ± 0.20
0.00 – 0.50
Selene vomer
2
6.86 ± 3.84
9.95 ± 5.04
0.68 ± 0.21
0.47 – 1.04
3.02 ± 1.56
1.30 – 4.72
0.18 ± 0.06
0.12 – 0.25
0.01 ± 0.02
0.00 – 0.05
Lutjanus sinagris
4
3.43 ± 3.03
10.17 ± 3.97
0.62 ± 0.14
0.41 – 0.79
2.00 ± 2.41
0.03 – 6.52
0.15 ± 0.11
0.04 – 0.36
0.01 ± 0.02
0.00 – 0.04
Diapterus rhombeus
4
7.20 ± 1.30
5.48 ± 2.73
0.65 ± 0.36
0.20 – 1.11
4.71 ± 2.30
1.19 – 8.38
0.20 ± 0.12
0.04 – 0.35
0.01 ± 0.02
0.00 – 0.02
Invertebrates
Litopenaeus schmitti
4
6.95 ± 1.30
28.03 ± 6.92
6.9 ± 3.80
3.22 – 10.76
5.47 ± 2.83
2.01 – 10.58
0.47 ± 0.38
0.02 – 1.21
0.44 ± 0.61
0.00 – 1.35
0.07 ± 0.09
– 0.22
Litopenaeus schmitti
4
11.72 ± 4.18
10.78 ± 1.98
16.16 ± 3.80
9.94 – 21.19
5.60 ± 5.19
0.75 – 14.95
0.10 ± 0.08
0.02 – 0.23
0.07 ± 0.13
0.00 – 0.32
Asaphys deforata
3
5.607 ± 0.303
19.350 ± 2.619
4.87 ± 0.68
3.92 – 5.91
3.28 ± 2.18
0.61 – 5.60
1.36 ± 0.35
0.86 – 1.75
1.92 ± 0.58
1.00 – 2.52
1.89 ± 0.79
0.55 – 2.69
Cyclinella tenuis
2
3.01 ± 0.311
7.30 ± 2.22
12.71 ± 20.76
1.83 – 55.00
3.94 ± 2.09
1.25 – 6.75
0.79 ± 1.60
0.00 – 4.00
1.35 ± 1.93
0
– 4.25
Crassostrea virginica
4
8.17 ± 1.46
83.97 ± 39.07
45.18 ± 7.46
35.44 – 55.73
18.52 ± 3.68
22.31 – 73.75
0.19 ± 0.26
0.00 – 0.64
0.29 ± 0.28
0.00 – 0.61
0.14 ± 0.23
0
– 0.52
Values are showed as mean and standard deviation. Metal concentration are displayed as mean and range Locations: 1, Trancotes; 2, Soro; 3, Salinas; 4, Macuro
HEAVY METALS IN FISH AND INVERTEBRATES FROM THE GULF OF PARIA, VENEZUELA
141
As far as invertebrates are concerned, it was
evidenced that copper levels are higher than those
detected for Fsh, with the highest value being for the
oyster
C. virginica
from Macuro (
Table II
). This last
species was the only one evaluated which exceeded
the maximum level allowable. Similar results were
obtained by Rojas
et al.
(2002) in Fve of the ten sta
-
tions evaluated in the same area.
In Fsh, the highest Cd concentration was found
in the catFsh
C. spixii
from Los Trancotes and the
seabream
D. rhombeus
from Macuro. The catFsh was
the only organism exceeding the maximum level al-
lowable and the seabream approaches this limit but
the other species do not surpass it.
Cadmium concentrations in invertebrates ranged
from 3.94 to 5.47 μg/g except for the oyster
C.
virginica
from Macuro, which showed an average
value of 18.52 ± 3.69 μg/g (
Table II
). With regard
to invertebrates the white shrimp and the oyster ex-
ceeded allowable levels. This last value is consider-
ably greater than the values for this same species in
1999, when a maximum concentration of 0.530 ±
0.002 μg/g wet weight was reached.
The highest concentration of chromium in or-
ganisms from the Gulf of Paria was detected in the
catFsh
C. spixii
from the Soro location, with an av-
erage value of 0.63 ± 0.74 μg/g, whereas the lowest
was found in the guanapo porgy
L. synagris
from
Macuro. The levels of this metal in invertebrates
remained similar to those in Fsh; however, the clam
A. deforata
from Salinas showed an average value
of 1.36 ± 0.35 μg/g (
Table II
).
Nickel was not detected in the seabream
D.
rhombeus
and the highest levels were found in the
catFsh
C. spixii
from the two locations evaluated
(0.18 ± 0.17 μg/g for los Trancotes and 0.12 ± 0.23
μg/g for Soro) in the Gulf of Paria. Concentrations
in invertebrates had the same magnitude as for Fsh,
except the clam
A. deforata
from Las Salinas (1.92
± 0.58 μg/g) (See
Table II
).
Lead was not detected neither in the guanapo
porgy
L. synagris
nor
S. vomer
, and the greatest
concentration was present in the catFsh
C. spixii
from
Los Trancotes and Soro locations, with concentra-
tions of 0.13 ± 0.11 and 0.08 ± 0.20 µg/g, respectively
(
Table II
). The metal was not present in the white
shrimp
L. schmitti
, and the greatest concentrations
were detected in clams
C. tenuis
and
A. deforata
with values of 1.35 ± 1.93 and 1.84 ± 0.79 µg/g,
respectively.
These results show a differential incorporation of
the evaluated metals, with a greater tendency towards
increase of bioaccumulation in invertebrates, particu-
larly
C. virginica
and
A. deforata
. The former had
the biggest capacity for accumulating Hg, Cu and Cd,
meanwhile the second had it for Cr, Ni and Pb. Obvi-
ously bioaccumulation is a complex process that is
not only determined by the routes of exposure, either
through diet or directly through the gills and contact
between the water column, but also by geochemical
effects on the metal availability.
The regulation of metals by some species is not
less important. In such a way, many organisms have a
higher incorporation rate of puriFcation or vice versa,
which determines the total load of metal in the soft
tissue of an organism and therefore bioaccumulation
of it, without implying a toxic effect of the element
(Louma and Raimbow 2005).
Fish were juveniles in general and these organisms
are highly mobile so this would explain a lower bioac-
cumulation of metals, but the catFsh
C. spixii
was the
exception and this can be accounted to the feeding
habits of the species. This species is characterized
by omnivorous feeding, where much of their food
is made up of copepods and other organisms living
in the benthos, which is why much of the ingested
food consists on sediment, particularly mud or very
Fne sediment and thus can ingest existing metals
(Villares
et al.
2005).
ACKNOWLEDGMENTS
The preparation of this paper was supported by
the PDVSA (Petróleos de Venezuela) for the envi-
ronmental baseline Mariscal Sucre service project.
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