a pilot study on effect of copper and cadmium toxicity in tilapia mossambicus

A Pilot Study on Effect of Copper and Cadmium Toxicity in

Tilapia Mossambicus

Keywords:

Toxicity, Aquaculture, Trace metals, Tilapia mossambicus.

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Dates: Received: 10 Mar 2012 Accepted: 19 Apr 2012 Published: 13 Jun 2012

Article Citation: Anushia C, Sampath kumar P and Selva Prabhu A. A Pilot Study on Effect of Copper and Cadmium Toxicity in Tilapia Mossambicus. Journal of Research in Animal Sciences (2012) 1: 020-027

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ABSTRACT: Cu and Cd is trace element for most organisms including fish, but above certain limit Cu and Cd will be toxic. The present study was conducted to evaluate the toxic effect of Cu and Cd on Tilapia mossambicus via estimating the acute 96h median lethal concentration (LC50) value. A total 120 number of Tilapia mossambicus fingerlings were subjected to 12 numbers 20-L aquaria. Fish were exposed to 0.0, 2.0, 4.0, 6.0, 8.0 and 10.0mg Cu and Cd/L for 4 days. Each dose was represented by two aquaria. Fish was daily observed and dead fish were removed immediately. The data obtained were evaluated using Behrens-Karber’s Method. The 96 h LC50 value of Cu for Tilapia mossambicus was calculated to be 6.0mg Cu/L with Behrens-Karber’s Method. The 96 h LC50 value of Cd for Tilapia mossambicus was calculated to be 4.8mg Cd/L with Behrens-Karber’s Method. The behavioral changes of Tilapia mossambicus were primarily observed. It could be concluded that Tilapia mossambicus species slightly sensitive to Cu and Cd when compare both metal cadmium is more toxic than copper for the fish species.

Authors:

Anushia C, Sampath

kumar P and Selva

Prabhu A.

Institution:

Centre of Advanced Study in

Marine Biology, Faculty of

Marine Sciences, Annamalai

University, Parangipettai-

608 502, Tamil Nadu, India.

Corresponding author:

Anushia C.

Email: [email protected].

Web Address: http://ficuspublishers.com/

documents/AS0008.pdf

Journal of Research in

Animal Sciences An International Open Access Online

Research Journal

020-027 | JRAS | 2012 | Vol 1 | No 1

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INTRODUCTION

Fishes are widely used to evaluate the health of

aquatic ecosystems because pollutants build up in the

food chain and are responsible for adverse effects and

death in the aquatic systems (Farkas et al., 2002; Yousuf

and El-Shahawi, 1999). The studies carried out on

various fishes have shown that heavy metals may alter

the physiological activities and biochemical parameters

both in tissues and in blood (Basa and Rani, 2003; Canli,

1995; Tort and Torres, 1988). Tilapia is distinguished by

its adaptation to living in fresh, brackish and nearly

saline water, and can survive in partially polluted water

(Zyadah, 1995). It is less sensitive to most toxic

substances than most other aquatic species. Any toxicant

that affects Tilapia would most likely be toxic to other

aquatic organisms (Murungi and Robinson, 1987). The

toxic effects of heavy metals have been reviewed,

including bioaccumulation (Waqar, 2006; Adami et al.,

2002; Rasmussen and Anderson, 2000; Rani, 2000;

Aucoin et al., 1999). Marine coastal ecosystems could

therefore be endangered by pollutants, such as heavy

metals, pesticides and antifoulants that could be easily

detected in the water column or in the sediment of

harbors and estuaries (Castillo et al., 2006;

Antizar, 2008; Bellas, 2005).

Heavy metals are considered the most important

form of pollution of the aquatic environment because of

their toxicity and accumulation by organisms, such as

fish (Emami Khansari, Ghazi-Khansari, and Abdollahi,

2005). Besides, the dangers involved from the presence

of metals in the environment derive not only from their

persistence and toxicity, but also from the remarkable

degree of bioaccumulation they undergo through the

tropic chain, thus becoming serious danger to man

(Bishop, 2000). Heavy metals such as cadmium, copper

and lead are found in most of the industrial, mineral

exploration and other miscellaneous anthropogenic

effluents. In Nigeria, these effluents are indiscriminately

discharged into natural waters, thereby contaminating

aquatic ecosystem (Fafioye et al., 2002).

Trace metals, such as Cu, Ni, Fe, and Cd are

accumulated over time in higher concentrations in fish

liver, gills and muscles (Taylor et al., 1985). Besides the

direct impact of heavy metals in fish, the synergistic

action of some hydrological variables and nutrients to

fish was found to enhance heavy metal toxicity in fish

(Bu-Olayan and Thomas, 2005; Franco et al., 2006). The

acute trace metal toxicity levels in fish exposed from

24 h to 96 h was statistically tested using Profit program

(USEPA, 1993) by various investigators (Abel and

Axiak, 1991; APHA, 1992; Wayne and Ming, 1998;

Franco et al., 2006). Heath (1987) described varied

pattern of inorganic pollutant bioaccumulation in

different fish tissues such as liver, muscles and gills.

Toxicity tests using aquatic organisms play an

important role in the development of proposals for

environmental management and protection, especially

for the aquaculture environment (Wall and Hanmer

1987; Hoi, 2004. In addition, it is an important step to

detect the levels of toxicants to be used in the

experimental studies of the accumulation and effect of

these toxicants to the marine organisms. There are many

studies concern with the toxicity of cadmium on

vertebrates and invertebrates (Rasmussen and Andersen,

2000, Adami et al., 2002 and Filipovic and Raspor,

2003). These metals are readily seeped by industries into

our waters daily, thereby increasing their accumulation

level. Therefore, it is necessary to study the toxicity of

cadmium and copper with a view to predict their level of

toxicity to Tilapia mossambicus.

MATERIALS AND METHODS

Fish management

Apparently healthy Tilapia mossambicus

(3.5±0.2g) were obtained from local fish farm Pinnalore,

Cuddalore Dist, Tamilnadu, India. Prior to the

experiment, fish were acclimatized for 2 weeks in 12

numbers 40-L glass aquaria under laboratory conditions

Anushia et al., 2012

021 Journal of Research in Animal Sciences (2012) 1: 020-027

(natural photoperiod 11.58-12.38 h); 10 fish per each

aquarium. The continuous aeration was maintained in

each aquarium using an electric air pumping

compressors.

Analysis of the water physico-chemical variables

Temperature

The atmospheric temperature and surface water

temperature were noticed with the help of a degree

Celsius thermometer.

Salinity

Salinity was recorded using a hand

Refractometer (Atago, Japan).

Hydrogen-ion concentration (pH)

Water pH (Negative logarithm of hydrogen ion

concentration) was noted by a calibrated pH pen

(pH Scan 1 Tester-Eutech Instruments, Singapore).

Dissolved oxygen

Dissolved oxygen was measured by using a

modified Winkler’s titration methods described by

Strickland and Parsons (1972).

Experimental procedures

The heavy metal Cu in the form of Copper

chloride anhydrous (Merck, Mumbai, India) and Cd in

the form of Cadmium chloride (Merck, Mumbai, India)

was used in the present study. The acute toxicity test was

performed for 4 days in which two replicates of seven

different Cu and Cd concentrations (0, 2, 4, 6, 8 and

10mg/L) were used (10 fish for each aquarium). At 24,

48, 72, and 96 h, fish dead were counted in the different

Cu and Cd concentrations along with the control group.

In this study, the acute toxic effects of Cu and Cd on

Tilapia mossambicus were determined by

Behrens-Karber’s method using the following formula

(Klassen, 1991):

LC50 = LC100 ∑A x B / N as mg/L;

Where LC50 and LC100 indicate the lethal doses for 50%

and 100% of the tested fish. Value ‘‘A” gives the

differences between the two consecutive doses, ‘‘B” the

arithmetic mean of the mortality caused by two

consecutive doses and ‘‘N” the number of tested fish in

each group. The dead fish were removed immediately.

RESULTS

The data obtained from the acute toxicity test of

copper for Tilapia mossambicus revealed that the Cu

toxicity increased with increasing concentration or

exposure time. The numbers of dead fishes in relation to

different Cu concentrations (2, 4, 6, 8 and 10mg/L) were

assessed and counted during the exposure in different

time intervals at 24, 48, 72 and 96 hours. Then the dead

fishes were removed immediately from the culture tanks.

No mortality was observed during the 96 h at control

(0.0mg Cu/L) and 100% mortality rate was achieved

only at 10mg Cu/L

During the toxicity tests, the temperature, salinity

and ph of the test water remained fairly constant at

28.5±1.5°C, 3.1±2.6mg/l and 7.5±0.4 respectively, while

dissolved oxygen was higher than 5.84±0.72mg/l. There


Journal of Research in Animal Sciences (2012) 1: 020-027 022

Cu dose(mg/L) No. of exposed fish No of dead fish

Overall deaths within 96 h A B AB D1 D2 D3 D4

0 10 0 0 0 0 0 0 0 0

2 10 0 0 0 1 1 2 0.5 1

4 10 0 1 1 1 1 2 1.0 2

6 10 1 4 5 5 5 2 3.0 6

8 10 6 8 8 8 8 2 6.5 13

10 10 8 10 10 10 10 2 9.0 18

∑AB =40

Table 1. The cumulative mortalities and acute 96 h LC50 of Cu in Tilapia mossambicus

according to Behrens-Karber’s method (Klassen, 1991).

Where A = differences between the two consecutive doses and B = arithmetic mean of the mortality caused

by two consecutive doses. 96 h LC50 = LC100 - ∑ (A x B)/N = 10 – 40/10 = 6. Ppm.

was 100% survival at initial exposure in the different

concentrations, but the survival rate started declining

with an increase in concentrations and time of exposure.

Effect of Copper

When exposed to copper, Tilapia mossambicus

recorded 80% and 50% mortality in 8mg/l and 6mg/l of

Cu respectively at 96h duration. The lowest

concentration (2.0mg/l) produced 10% mortality at 96 h

in Tilapia mossambicus. When compare to control

mortality was inhibited at 2mg/L in 48 hrs. The 96h

LC50 value (6.mg/L) of T. mossambicus was determined

based on measured concentration of copper with the

Behrens-Karber’s method (Table 1).

Effect of Cadmium

In Cadmium exposure percentage of mortality at

96 h was 90% in 8mg/l and 60% in 6mg/l of Cd, while

30% mortality occurred in 2mg/l and 4mg/l at 96 h.

Tilapia mossambicus had 100% mortality in 10mg/l. The

96h LC50 value was estimated to be 4.8mg/L with the

Behrens-Karber’s method (Table 2).

DISCUSSION

Toxic effect on the fish in the present study and

toxicity increased with increased concentration. The

observed increasing state of inactivity with both

increasing concentrations and exposure period agree with

the report of Ayoola, (2008a). The present investigation

showed big differences of both toxicity and

bioaccumulation rate among the aquatic organisms. A

clear variation in LC50 and acute toxicity in tested

organisms were evident. 96hr LC50 of Cu was 6.0mg

Cu/l, while in Cd was 4.8mg Cd/l. Other research

reported lower Cu concentrations 96hr- LC50 for marine

crustaceans as; 0.017mg Cu/l for Acartice tansa;

0.049mg Cu/l for Cancer magister and 0.1mg Cu/l for

Homarus americanus (Martin et al., 1981 and Mance,

1987).

The effect produced by both metals coupled is

less than the effects produced by individual metal. This

may attributed to substitution and competition between

Cu and Zn for available sites during protein synthesis as

suggested by Bryan, (1971) and Abdel-Moati and Farag

(1991). The variety degree is related to kind of species,

its sensitivity and physiological responses to pollutants.

And their uptake and depuration rate of heavy metals

(Salanki and V. -Balogh 1985; Salanki and V. -Balogh

1989). El- Gindy, et al., (1991) recorded 24h LC50 for

mo llusks B iomphalar ia alexandrina and

Bulinus truncatus of Cu and Zn toxicity as 1.38, 0.99 and

54, 40 ppm, respectively. The 96hr LC50 value for Cu in

L, balteni was 0.9 ppm (Abdel-Moati & Farag 1991), but

in Mugil fry was 1.3 ppm (El-Rayis and Ezzat 1984).

The 96h LC50 of Zn in L. bolteni was 58 ppm

(Abdel-Moati and Farag 1991), while that for

Portunus pelagicus was 100 ppm, (El-Rayis and Ezzat

(1984). However T. zillii have the ability to live in

Cd dose (mg/L) No. of exposed fish No of dead fish

Overall deaths within 96 h A B AB D1 D2 D3 D4

0 10 0 0 0 0 0 0 0 0

2 10 0 1 2 3 3 2 1.5 3

4 10 1 2 3 3 3 2 3.0 6

6 10 2 3 4 6 6 2 4.5 9

8 10 4 7 8 9 9 2 7.5 15

10 10 6 10 10 10 10 2 9.5 19

∑AB =52

Table 2. The cumulative mortalities and acute 96 h LC50 of Cd in according to

Tilapia mossambicus Behrens-Karber's method (Klassen, 1991).

Where A = differences between the two consecutive doses and B = arithmetic mean of the mortality caused

by two consecutive doses. 96 h LC50 = LC100 - ∑ (A x B)/N = 10 – 52/10 = 4.8ppm.

This value was estimated to be 4.8mg/L with the Behrens–Karber’s method (Table 2).



polluted areas for long time than other species of fish

(Zyadah, 1999). The actual and back calculated LC50 of

Cu, Zn. and Cd values for the experimental species

during the exposure periods showed a close concordance.

Other results in the world showed different LC50 of Cu,

Zn, and Cd values, where flounder fish exposed to 0.1 to

10 mg Cd/l for 15d (Larsson et al., 1976); Juvenile

striped bass was exposed to 0.01 mg Cd/l for 120d

(Dawson et al., 1977) and juvenile of shrimps

Penaeus duorarum exposed to 5 mg Cd/l for 96hr

(Nimmo et al., 1977). The rate of bioaccumulation of

heavy metals by fish and shrimp appeared within a wide

range. The bioaccumulation factor of Cd by Mysis sp.

was 1215 times more than control concentration after

48hr exposure, and reaches 858 times in T. zillii after

356hr exposure. Other studies in USA showed the

average residues of Cd in some invertebrate species to

reach approximately 1000 to 9000 times greater than

correspond control concentration after 28d exposure

(Spehar et al., 1978).

In the present study, it was observed that exposed

Tilapia mossambicus to various concentrations of

cadmium and copper were weakened progressively with

time prior to mortality. Similarly, the toxic effect of the

metals produced molting in the fish at a faster rate than

control. These facts, therefore, affirm that heavy metals

can cause physiological stress and dysfunction in

crustaceans (Gao and Zou, 1995).

The observed increasing state of inactivity with

both increasing concentrations and exposure period agree

with the report of Ayoola, (2008a). The results of

toxicity test indicated that the ionic form of Cu is more

toxic than the ionic form of Cd to Mugil seheli, and the

fingerlings are more sensitive to copper toxicity than that

of cadmium. Denton and Burdon-Jones (1986);

Cui-Keduo et al., (1987). Spehar et al., (1978) reported

that the 96 h LC50 of Cd for flag fish,

Jordanella floridae, was 2.5mg /l. Hamed, (2002) found

that the 72 h LC50 of Cd for Mugil seheli was 4.87mg/1.

El-Moselhy, (2001) stated that toxicity of Cd to

Mugil seheli decreased with increasing the exposure time

and the recording LC50 values were 12.34, 8.92, 6.01 and

3.45mg/l for 24, 48, 72 and 96 hours, respectively. The

96 h LC50 values of copper was 1.83 ppm for fish

Etroplus maculaus reported by Gaikwad, (1989).

Taylor et al., (1985) reported LC50 values of about 0.3 to

50mg Cd/1. While 96 h LC50 of Cu ranged from 0.2 to

3mg/1 for various marine fish and crustaceans (Bryan,

1971). Pagenkopf, (1986) studied the toxicity of copper,

cadmium, lead and zinc to fishes.

The values worked in the present experiment as

safe concentrations of Cu and Cd to reach LC50

concentration and total mortality dose to aquatic

organisms, these are of great practical utility for

regulating and controlling the pollution limits in the

water resources by those pollutants and to regulate their

discharge to near-by water for protect the life within the

aquatic environment.

The susceptibility of fish to a particular heavy

metal is a very important factor for LC50 values. The fish

that is highly susceptible to the toxicity of one metal may

be less or non-susceptible to the toxicity of another metal

at the same concentration of that metal in the milieu.

Similarly, the metal which is highly toxic to one

organism at low concentration may be less or non-toxic

to other organism at the same or even higher

concentrations with two juvenil Brazilian indigenous

fishes which showed that both species were more

sensitive to copper and cadmium found that with

Daphnia pulex the order of toxicity of different metals

was Cu>Cd>Ni.

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