Advances in Environmental Biology Portunus pelagicus Asalouyeh coast, Iran

Advances in Environmental Biology, 8(13) August 2014, Pages: 722-727
AENSI Journals
Advances in Environmental Biology
ISSN-1995-0756
EISSN-1998-1066
Journal home page: http://www.aensiweb.com/AEB/
Investigation of Cadmium accumulation in Portunus pelagicus along the
Asalouyeh coast, Iran
1Forouzan
Fatemi, 2Shahrzad Khoramnejadian, 3Mehdi Shamsaei Mehrjan
1
Department of the Environment, Damavand Science and Research Branch, Islamic Azad University, Damavand, Iran.
Department of the Environment, Damavand Branch, Islamic Azad University, Damavand, Iran.
3
Department of Fisheries, Faculty of Agricultural and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran,
Iran.
2
ARTICLE INFO
Article history:
Received 25 June 2014
Received in revised form
8 July 2014
Accepted 14 September 2014
Available online 10 October 2014
Keywords:
Blue Swimmer Crab, Heavy metal,
Portunus pelagicus, Cadmium
ABSTRACT
The levels of heavy metals in marine ecosystems have increased considerably as a
result of heavy Industrialization and urbanization. These metals can accumulate through
food chain and finally reach the tissues of human beings leading to serious effects on
their health. This study examines concentration of Cadmium (Cd) in the soft tissue of
Blue Swimmer Crab (Portunus pelagicus) collected from Asalouyeh region (Northern
Persian Gulf) in Iran as bioindicator of environmental conditions. Crab samples were
collected from three stations over a three month winter period in 2014. Cadmium
analysis was carried out by Atomic Absorption Spectrophotometer. The results showed
that the mean concentration (mg/kg dry weight) of Cadmium in the soft tissue of
P.pelagicus in January, February and March was 0.33 ± 0.48, 1.27 ± 0.70 and 1.34 ±
1.01 respectively. There was a significant difference (sig ˂ 0.05) between stations and
also between months at 95% confidence level. The highest concentration of Cadmium
was observed for station 1 (1.64 ± 0.97) and the lowest one was for station 3 (0.42 ±
0.36). The present values revealed that, Cd concentrations in the both stations 1 and 2
were found higher than the maximum limits (MLs) set by Codex, EU, ESFA and
NHMRC. Therefore, the present study suggests that consumers avoid eating this crabs.
© 2014 AENSI Publisher All rights reserved.
To Cite This Article: Forouzan Fatemi, Shahrzad Khoramnejadian and Mehdi Shamsaei Mehrjan., Investigation of Cadmium accumulation
in Portunus pelagicus along the Asalouyeh coast, Iran. Adv. Environ. Biol., 8(13), 722-727, 2014
INTRODUCTION
Over the past few decades, the pollution of aquatic ecosystems with a broad concentration range of heavy
metals has become a major problem in the world due to their tendency to bioaccumulate in organisms [8, 9, 16].
Metal contaminants settle on the bottom sediments eventually, after entering aquatic areas [2]. Once these toxic
chemicals are present in the environment, can have adverse effects on both human and the marine ecosystem [1,
8, 16, 21]. Heavy metals enter into aquatic ecosystems from natural sources though human activities have
significantly raised contents of these metals in the environment [15, 17, 21]. While there are several heavy
metals which are vital for well-being of organisms, the excessive levels can be very dangerous [1, 3]. Having the
ability to accumulate in living organisms make heavy metal contamination as one of the most serious
environmental issues [21].
Cadmium is a heavy metal that is scarcely found in the nature; however, it is very damaging to marine
organisms even at low levels. Based on Cadmium chemical structure that can effects on its damaging level, the
toxicity of this metal to aquatic species is variable [6]. Being exposed to cadmium can lead to deleterious health
effects and is extremely hazardous for general public via the food chain [7]. The accumulation of this heavy
metal in the various tissues of human body can affect major systems including urinary system, reproductive
system and skeleton development [3, 7, 13].
Benthic crustaceans have ability to accumulate heavy metals through sediments, water column and the
varied diet in their body over time. Non-essential metals such as Cadmium can alter the physiology, molting
ability, the process of renewal and restoration of the missing limbs and sensitive growth process of a crustacean
[19]. The Blue Swimmer Crab, Portunus pelagicus, is one of the species with high economic value which its
population has declined because of overfishing [20, 22]. This creatures have an important role in the food chain
of marine ecosystems. The blue crab species can cause changes in the life of other creatures on the sea floor by
Corresponding Author: Shahrzad Khoramnejadian, Department of the Environment, Damavand Branch, Islamic Azad
University, Damavand, Iran.
Phone numbers: +989357970978; E-mail: [email protected]
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Forouzan Fatemi et al, 2014
Advances in Environmental Biology, 8(13) August 2014, Pages: 722-727
preying on them or feeding activities (for example bioturbation) which affect the structure and functioning of
this community [19]. Having direct contact with sediments and being a part of human diet made this crabs one
of the best environmental indicators [16].
Many natural sources and human activities have severely damaged the Persian Gulf ecosystem. While the
marine environment of this Gulf is threatened with toxic chemicals contribute to contaminant discharges from
surrounding countries, the Gulf has been faced with frequent oil spillage which associated with shipping
accidents and recent wars in the region. In addition, onshore and offshore petroleum exploration and large
petroleum tankers are posing a serious danger to the marine life in this waterway [8]. Unfortunately, because of
considerable stress the Persian Gulf has experienced in recent years, the mortality rate of many marine species
has increased and the fishing industry which is the main occupation of local people in the study area has been
faced with many problems.
Asalouyeh is considered as economic hub of Iran and is located in the heart of the one of the biggest energy
producing areas in the world [11]. This area has huge and numerous refinery and petrochemical units where
industrial activities in the region have created a potential source of heavy metals contamination in Persian Gulf
environment. Increasing in population of coastal regions in combination with industrial development in this
areas is obvious [4]. While seafood including crab and fish is considered as one of the dominant part of the
population's diet [12], the consumption of these foods may have dramatic effects on their health because of
heavy metals accumulation behavior [16]. Persian Gulf waters in Asalouyeh port is the place where P.pelagicus
can be found. Therefore, in the present study, the concentration of Cadmium in blue swimmer crab Portunus
pelagicus collected from Asalouyeh region was investigated.
MATERIALS AND METHODS
The study was carried out at Persian Gulf waters in Asalouyeh region for Cadmium analysis. Asalouyeh is a
port in southern Iran, in Bushehr Province which is located on the shore of the Persian Gulf. This area is
recognized as the most important economic centers of Iran and the closest land point to the largest independent
natural gas field in the world. Due to its great location, a substantial number of petrochemical, petroleum and
natural gas industries are established in the Asalouyeh region.
Twenty-seven Samples of Blue Swimmer Crabs were collected from three sampling stations within 100
meters of each other at Persian Gulf waters in Asalouyeh area between January and March 2014 (3 samples per
station and 9 samples per month). The geographical coordinates of the stations that were recorded by GPS
receiver are listed in Table 1. All three of the stations were marked on the map (Fig. 1). Also, the samples were
caught based on general abundance in the area and similarity of their size with the help of local people using
trap and trawl nets. Then, the crab samples were washed with sea water at the point of collection, separated by
stations and transferred to the laboratory under ice boxes for analysis.
In order to perform sample analysis, First of all, all equipment applied were washed with hot water,
detergent, 10% Nitric Acid (HNO3) and four to five times in deionized water carefully and were dried at 60 °C
(centigrade) for 24 hours in an oven before use. Then, the crabs of each station were washed with deionized
water separately and were kept at a temperature of -20 °C until they were prepared for chemical digestion. After
that, the soft tissue of crabs was dissected and homogenized and was placed in clean watch glass and weighed to
5 g (± 0.001 g) using an electronic weighing balance. The weighted samples were dry-ashed in oven 550 °C for
8 hrs. The dried samples were milled with a mortar and pestle. In the next step, the completely pulverized
samples were put in a glass beaker and were digested with 50 ml 6N HCL and 20 ml 0.1M HNO3. Following
that, Deionized water was added to bring the solution up to 50 ml and finally was aspirated into a Graphite
Furnace Atomic Absorption Spectrophotometer (Varian Spectrum AA 600 Zeeman) for Cadmium
determination.
The results of this study were analyzed using Microsoft Excel 2013 and SPSS v.22 statistical packages for
windows. In order to test the normality of data, both Kolmogorov-Smirnov test and Shapiro-Wilk tests were
performed. Since the results showed a non-normal distribution, log of the data was taken for variance analysis.
The two-way analysis of variance (ANOVA) test was applied to determine any significant differences in
cadmium levels between the stations and also between the months. In addition, Fisher's Least Significant
Difference (LSD) and Duncan tests were used to compare the group means at the 0.05 level.
RESULTS AND DISCUSSION
Increasing absorption rate of heavy metals than the elimination rate results in the bioaccumulation of these
contaminants in the body of organisms [15]. The metal uptake in crustaceans mainly occur from ingestion of
food or across permeable respiratory surfaces such as gills [12, 19]. Because of serious danger of heavy metals
that threaten the health of consumers, The levels of heavy metals in marine organisms including crabs is
considered one of the most important issues facing the world today. Hence, in present study an attempt was
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Advances in Environmental Biology, 8(13) August 2014, Pages: 722-727
made to investigate the concentration of Cadmium, an extremely toxic heavy metal, in the soft tissue of
Portunus pelagicus.
The concentration of Cadmium in different stations is presented in Table 2. The results showed that the
highest concentration was recorded in station 1 (1.64 ± 0.97), while the lowest was in station 3 (0.42 ± 0.36).
This result was expected due to the location of station 1 in the vicinity of Asalouyeh dock, fishing and cargo
ships traffic in the surrounding area and ballast water discharges by ships. In addition, Station 1 is the nearest
station to the Pars Special Energy Economic Zone (PSEZZ) of Asalouyeh where there are huge petrochemical
and gas refinery plants results in the discharge of wastewater containing a high concentration of heavy metals in
surrounding water. Earlier studies also reported that the increase in concentration of metals including Cd in the
studied area was because of probable causes including discharges Associated with municipal and domestic
sources and also agricultural activities in the surrounding area [4, 13, 16].
The results from monthly concentration of Cadmium are summarized in Table 3. It indicates that the
highest concentration was in March (1.34 ± 1.01) and the lowest value was in January (0.33 ± 0.48).
Temperature and metabolic activity are considered as important factors that have an impact on the metal
removal from the body of aquatic organisms [1, 12]. As for this study, higher concentration of Cadmium in
March can possibly also be ascribed to the fact that as the temperature increased during the winter, the rate of
metabolism increased which results in higher uptake of Cadmium in marine organisms in March. A study from
Lagos lagoon in Nigeria has been reported that concentration of Cadmium in the tissues of Bagrid catfish
C.nigrodigitatus was found higher during the rainy season than during the dry season [18]. A study on the
temperature and salinity impacts on size at sexual maturity of female blue crab Callinectes sapidus from several
bay systems in Texas indicates that as there are differences in the temperature and salinity from bay to bay, the
size at maturity can differ along the coast of Texas [22].
Figure 2 provides information about the changes in Cd concentrations in the crab from different stations
during three-month sampling period. As we can see from this graph, there were the upward trends for both
station 1 and station 2. The concentration of Cadmium in Blue Crabs at station 3 fall gradually from February to
March. Besides temperature and salinity factors, levels and accumulations of metals in marine animals generally
change as the alteration in a group of seasonal factors such as seasonal foods [1, 4]. When it comes to the
Portunus pelagicus, they classified as omnivores and, therefore, in the present study, changing their diet during
different months by changing in temperature and using a cadmium-rich source of food seems inevitable. In a
study from the Gulf of Thailand results show that the concentration of Cadmium in mangrove crabs was in
highest value in the wet season (January, August, and October) when the salinity level was low [4].
The results of analysis of variance for Cadmium levels in the samples are displayed in Table 4. Regarding
this table, there was significant difference (sig<0.05) between the levels of Cadmium in the three sampling
stations. Moreover, significant differences (sig<0.05) between sampling months (sig<0.05) and stations by
month's interaction were observed. A study on fresh water fish (Erpetoichthys calabaricus) from Nigeria found
that among the stations, analysis of variance showed significant differences (P<0.05) in Cd seasonal mean levels
while differences between the dry and rainy season levels of metals including Cd in the fish at each of the
sampling stations were not significant [17]. Different results from research studies can be attributed to the
differences in various factors including geographical conditions, environmental conditions, different types of
samples and laboratory conditions.
The result from comparison of Cadmium levels in the soft tissue of crabs from different stations with both
LSD and Duncan test revealed that there was significant difference at the 95% confidence level (sig<0.05) in the
Cd concentration between different sampling stations. While station 3 showed the highest mean value, lowest
mean value for the station 1 was found. Furthermore, whereas the levels of cadmium in February and March
varied, there were no significant variation (sig >0.05) in cadmium concentration between these two months and
the least concentration of Cd was obtained in January.
According to Table 5, the results from present study in comparison with the maximum levels (MLs) of
Cadmium in food established by different organizations indicate that Cd concentration in station 1 and station 2
were above the maximum levels set by all listed standards. Also, in station 3 Cd concentration was above the
NHMRC standard while this value did not exceed than the ML set by other standards. In addition, Cadmium
levels in February, and March were above all of the standards whereas for January this level was only higher
than NHMRC recommended level. Although Cadmium is found in the earth crust naturally, the industrial
development of the study area that results in high pollution levels, and lack of controls on industrial wastewater
make our results unavoidable. In spite of these findings, the Cd concentration observed for fishes Acanthpagrus
Latus and Euryglossa orientalis from Persian Gulf northwest coasts of Iran was higher than FAO/WHO
standards [9]. However, in a study on concentration of metals in Blue Crab (Callinectes sp.) collected from
Brazil metal levels was considered safe for the human consumption [14]. However, there are several factors
affecting Cd uptake by marine organisms. These include various types of industries, age of marine organisms
and the principle of industrial wastewater treatment which cause differences in the results.
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Advances in Environmental Biology, 8(13) August 2014, Pages: 722-727
Table 1: Geographical coordinates of sampling stations
Longitude
Latitude
52° 36' 24.41" E
27° 28' 13.56" N
52° 36' 27.29" E
27° 28' 11.55" N
52° 36' 30.14" E
27° 28' 9.54" N
Sampling Stations
Station 1
Station 2
Station 3
Table 2: The mean concentration of cadmium (mg/kg dry weight) in soft tissue of Portunus pelagicus in the stations during the sampling.
SD ± Mean
n
Sampling Stations
1.64 ± 0.97
9
Station 1
0.89 ± 0.74
9
Station 2
0.42 ± 0.36
9
Station 3
n: number of samples
Table 3: The mean concentration of cadmium (mg/kg dry weight) in soft tissue of Portunus pelagicus in three month winter period.
SD ± Mean
n
Sampling Months
0.33 ± 0.48
9
January
1.27 ± 0.70
9
February
1.34 ± 1.01
9
March
n: number of samples
Table 4: Two-way Analysis of variance (ANOVA) test results for Cadmium concentration in P.pelagicus from three stations during
sampling.
P value (sig)
Dependent variable
Source
0.000‫٭‬
Cadmium Concentration (mg/kg)
Stations
0.000‫٭‬
Cadmium Concentration (mg/kg)
Months
0.002‫٭‬
Cadmium Concentration (mg/kg)
Stations × Months
*.Showing significant differences at the 0.05 level.
Table 5: International standards for maximum levels (MLs) of Cadmium concentration (mg/kg) in food.
Standards
Value (mg/kg)
References
Codex
0.5
[10]
EU
0.5
[5]
NHMRC
0.05
[16]
ESFA
0.5
[7]
EU: European Union; NHMRC: National Health and Medical Research Council; ESFA: European Food Safety Authority
Fig. 1: Map of Asalouyeh port; showing sampling stations and the study area.
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Fig. 2: The mean concentration of Cadmium (mg/kg dry weight) in Portunus pelagicus in the stations during the
sampling.
Conclusion:
To sum up, the results of present study revealed that considering Blue Swimmer Crab Portunus pelagicus
bioaccumulate different levels of Cadmium, and the point that this species feed on benthic organic matter, they
can use as a reliable bioindicator of metal pollution in ecosystems. The high concentration of Cadmium in
P.pelagicus samples compared to international standards is considered as a great alarm about an urgent need for
regular monitoring of Persian Gulf waters quality. In addition, because the Blue Swimmer Crab is a
commercially important species and consumption of this species by local people is high, crab with high levels of
Cadmium in the area results in public health problems. Therefore, effective oil pollution management, applied
environmental study before implementing business plans, and public awareness can play a major role in
controlling the pollution level entering the Asalouyeh region.
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