ARTICLE IN PRESS

0147-6513/$ - se

doi:10.1016/j.ec

�Correspond

Ecotoxicology and Environmental Safety 66 (2007) 232–243

www.elsevier.com/locate/ecoenv

Assessment of the impact of heavy metal pollution from a ferro-nickelsmelting plant using biomarkers

Catherine Tsangaris�, Evangelos Papathanasiou, Efthimia Cotou

Hellenic Centre for Marine Research, 46.7 klm, Athinon-Souniou Ave., P.O. Box 712, 19013 Anavyssos, Greece

Received 13 September 2005; received in revised form 9 March 2006; accepted 25 March 2006

Available online 6 June 2006

Abstract

A set of biomarkers was used to assess the impact of heavy metal pollution by a ferro-nickel smelting plant in Larymna bay (North

Evoikos Gulf, Greece). These included a biomarker reflecting health status of an organism (scope for growth, SFG), a cellular biomarker

of heavy metal exposure (composition of metal-containing granules), and two biochemical biomarkers reflecting oxidative stress

(glutathione peroxidase, GPX) and neurotoxicity (acetylcholinesterase, AChE) measured in mussels (Mytilus galloprovincialis) both

native and transplanted for 1 and 6 months at the coastal area of Larymna. All biomarkers in mussels at Larymna revealed differences

from mussels at a reference site, signaling effects of the increased heavy metal levels on the biota. While effects on SFG and GPX in

Larymna mussels were obvious on short-term exposure and persistent during chronic exposure, only chronic exposure induced a possibly

cumulative effect on AChE. To validate the causal relationship between heavy metal exposure and effects observed in Larymna, SFG,

GPX, and ACHE were examined in mussels exposed to a mixture of heavy metals (Ni, Cr, and Fe) under controlled laboratory

conditions. The laboratory experiment verified the causal relationship between SFG and GPX responses and heavy metals but this was

not demonstrated for AChE. Results from field-collected and laboratory-exposed mussels indicated a potential of GPX as predictive

biomarker of population-level effects of heavy metal exposure.

r 2006 Elsevier Inc. All rights reserved.

Keywords: Biomarker; Metals; Pollution effects; Scope for growth; Glutathione peroxidase; Acetylcholinesterase; X-ray microanalysis; Mytilus

galloprovincialis

1. Introduction

Responses to pollution at various levels of biologicalorganization are widely used in environmental monitoringstudies since, by definition, pollution implies hazard toliving resources. Measuring changes at the community andpopulation levels is ecologically relevant but may provideonly indirect assumptions with regard to the causes ofecosystem-level effects. On the other hand biomarkersrepresent changes from the molecular to the organism levelthat can be related to toxic effects of and/or exposure tochemical contaminants. In addition, biomarker responsesoccur prior to alterations at the population and communitylevels so they can be predictive and anticipatory. Thusbiomarkers have the ability to diagnose causes and may actas early warning signals of ecosystem-level damage.

e front matter r 2006 Elsevier Inc. All rights reserved.

oenv.2006.03.011

ing author. Fax: +30 2 2910 76 347.

Biochemical and cellular biomarkers may indicate expo-sure to specific classes of contaminants (Bucheli and Kent,1995; Viarengo et al., 1999; Marigomez et al., 2002) orreflect specific toxicity mechanisms (Livingstone, 2001;Fulton and Key, 2001; Bolognesi et al., 2004) but, to signaleffects at the population and the community levels, theyshould be related to a degree of impairment of growth,reproductive output, or metabolic function signifyingdegradation in the health of the organism (Depledgeet al., 1995). Hence linking biochemical and cellularbiomarkers with biomarkers of the overall health ofindividual organisms is important for the evaluation oftheir utility in predicting population-level effects (Allen andMoore, 2004).The small bay of Larymna located in North Evoikos

Gulf Greece, is contaminated with heavy metals by a ferro-nickel smelting plant situated on the coast within the bay.The plant extracts nickel from laterite ore and dumps the

ARTICLE IN PRESS

Fig. 1. Location of the sampling sites. Larymna, the metal-contaminated

site in Evoikos Gulf is marked by a black arrow and the reference site in

Saronikos Gulf by a white arrow.

C. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243 233

metalliferous slag at a dumping site in the North EvoikosGulf in the vicinity of Larymna. Spillages of dust, coolingwater, and slag also contribute to the contamination of thebay with heavy metals. Elevated concentrations mainly ofNi, Cr, and Fe but also of Co and Mn have been recordedin sediments, sea grass, and benthic organisms of thecoastal zone (Nicolaidou and Nott, 1989, 1990) andsediments at the dumping site (Voutsinou-Taliadouriet al., 1995). Nicolaidou et al. (1989) have previouslyreported changes at the community level which wereattributed to the indirect effects of dumping of metallifer-ous slag, causing a change in the particle size compositionof the sediment, but could not be related to toxic effects ofheavy metals in the slag. Biomarkers that can be related totoxic effects of and/or exposure to chemical contaminantshave not previously been applied in Larymna.

Mussels are commonly used as sentinel organisms forbiomarker measurements due to their wide distribution,sedentary state, ease of collection, transplantation, andmaintenance in the laboratory, and ability to accumulatehigh concentrations of a wide range of contaminantsincluding heavy metals (Viarengo and Canesi, 1991).

In the present study, an established biomarker reflectingthe overall health of an organism (scope for growth SFG);and two biochemical biomarkers reflecting differenttoxicity mechanisms, namely oxidative stress (glutathioneperoxidase GPX); and neurotoxicity (acetylcholinesteraseAChE); were measured in mussels (Mytilus galloprovincia-

lis) native and transplanted at the coastal area of Larymna.The same biomarkers were also measured in musselsexposed to a mixture of Ni, Cr, and Fe under controlledlaboratory conditions. Additionally, a cellular biomarkerof heavy metal exposure (composition of metal-containinggranules) was studied in native mussels from Larymna.Scope for growth, a physiological condition index, is ameasure of the energy balance of an organism, widely usedin environmental monitoring studies (Widdows and Don-kin, 1992; Widdows et al., 1995a, b, 2002). Glutathioneperoxidase is an enzyme of the antioxidant defense systemagainst reactive oxygen species (ROS) that can be producedby a wide range of contaminants including organicxenobiotics and heavy metals (Lemaire and Livingstone,1993). Variations in antioxidant enzyme activities havebeen proposed as biomarkers of oxidative stress (Living-stone, 2001). Acetylcholinesterase is an enzyme of neuro-transmission and its inhibition reflects neurotoxicity.AChE inhibition has been considered a biomarker ofexposure to organophosphate and carbamate pesticides(Bocquene and Galgani, 1991) but recent studies suggestthat other contaminants including heavy metals can inhibitAChE (Payne et al., 1996; Najimi et al., 1997; Guilherminoet al., 1998; Hamza-Chaffai et al., 1998; Elumalai et al.,2002). Lysosomal and inorganic granules accumulateheavy metals as part of the cellular detoxification process(Marigomez et al., 2002). X-ray microanalysis of thesegranules provides information on the bioavailable fractionof heavy metals and has been proposed as a biomarker of

heavy metal exposure (Vesk and Byrne, 1999; Correia,et al., 2002; Marigomez et al., 2002).The aim of the present study was to assess the impact of

heavy metal pollution in the coastal area of Larymna usingmultiple level biomarkers in M. galloprovincialis and to linkbiochemical biomarker responses to the health status ofindividual organisms to assess whether these biochemicalresponses show potential as predictive biomarkers ofpopulation-level effects of heavy metal exposure.

2. Materials and methods

2.1. Source of animals—field sampling

Native mussels from Larymna (North Evoikos Gulf) and farmed

mussels from Megara (Saronikos Gulf) transplanted to the same area in

Larymna and to a reference site at Agios Kosmas (Saronikos Gulf) were

used (Fig. 1). The Agios Kosmas site is considered as an area of good

environmental conditions and heavy metal concentrations in surface

sediments are low (Cotou et al., 2002; Karageorgis and Hatzianestis,

2003). Both Larymna and Agios Kosmas are areas of oligotrophic

character.

Farmed mussels of similar shell length were purchased in spring, placed

in plastic cages (approximately 100 individuals), and immersed in water to

a depth of 1–2m at the coastal areas of Larymna and the reference site

where they remained for 6 months. Additionally, farmed mussels were

purchased in autumn and transplanted as above to the Larymna site

were they remained for 1 month. Native, ‘‘1-month’’, and ‘‘6-month’’

transplanted mussel populations were collected during autumn and were

transported to the laboratory under moist/cool conditions for measure-

ments of SFG, GPX, AChE, and heavy metal concentrations in whole

tissues. Native mussels from Larymna were also collected in the winter and

transported to the University of Plymouth and Plymouth Marine

Laboratory for X-ray microanalysis.

2.2. Laboratory experiment

Farmed mussels of similar shell length were purchased from Megara in

autumn. These were placed in 2-L tanks (5mussels/L) and were acclimated

in aerated synthetic seawater for 7 days prior to heavy metal exposure.

The mussels were exposed to a mixture of Ni, Cr, and Fe in two

ARTICLE IN PRESS

123.5 J/mg ash-free dry weight is the energy content of phytoplankton

cells (Widdows et al., 1979).20.456 J/mmol O2 is the energetic equivalent of respiratory oxygen

consumption (Gnaiger, 1983).

C. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243234

combinations of concentrations for 4 weeks. The low (L) level of

concentrations comprised 20mg Ni/L, 0.5 mg Cr/L, and 400mg Fe/L and

the high (H) level of concentrations comprised 200mg Ni/L, 5 mg Cr/L, and4000mg Fe/L. The low level exposure concentrations were chosen as being

representative of the highly dissolved Ni, Cr, and Fe levels reported in

Larymna (22.6mg Ni/L, 0.48mg Cr(VI)/L, 434mg Fe/L, Nakopoulou et al.,

1985) and in highly contaminated estuaries and coastal waters (1–16mgNi/L: Cambell et al., 1988, 0.52–0.79mg Cr(VI)/L; Dahab and Al-Madfa,

1997, 170–890mg Fe/L, Chan et al., 1974). Heavy metals were added to

artificial seawater as solutions of NiCl2, NaCr2O4, and FeCl2. Both H and

L level concentrations and the control (artificial seawater with no added

metal) were used in triplicate. The seawater was renewed every 2nd day

and the mussels were fed daily with Dunaniella tertiolecta (60� 106 cells/

mussel). After 4 weeks of heavy metal exposure, SFG, GPX, and AChE

activities and heavy metal Ni, Cr, and Fe concentrations in whole mussels

were measured.

2.3. Heavy metal analysis

Whole mussel tissues were dissected, freeze-dried, and digested with

concentrated HNO3 in Teflon digestion vials under pressure at 120 1C for

12 h (UNEP, 1984). Ni, Cr, and Fe analyses were performed by atomic

absorption spectrophotometry on a Varian Spectra AA 20plus spectro-

photometer (Varian, Victoria, Australia). Heavy metal concentrations

were expressed asmg/g dry weight tissue. Analytical quality control was

achieved using certified reference material provided by the National

Research Council of Canada.

2.4. Body condition index

The body condition index was calculated according to Bayne and

Widdows (1978) as dry whole tissue weight (mg) versus shell length (mm)

per individual.

2.5. Scope for growth measurements

The procedure described by Widdows and Salked (1992) with the

modification of Cotou et al. (2002) was used to measure SFG. Clearance

rate, respiration rate, and food absorption efficiency were measured for

each mussel individually under standardized laboratory conditions. Prior

to all measurements mussels were left undisturbed in the chambers for 12 h

to recover from transportation and resume feeding. For clearance rate and

absorption efficiency measurements, mussels were placed in individual

chambers in synthetic seawater filtered through 1 and 3-mm activated

carbon cartridge filters in a closed circulated system at a flow rate of

160–180mL/min. The unicellular algae D. tertiolecta was added in the

chambers at a concentration of 6500–7000 cells/mL. Subsequently algal

cell concentrations were measured from the outfall of all chambers

including the controls (two chambers without mussels) four times at 45-

min intervals using a Z1 Coulter Counter (Coulter Electronics, Luton,

UK) calibrated to count particles above 3 mm.

Clearance rate (Cl) was calculated as

Cl ¼ FlðC0 �C1Þ=C0,

where Fl is flow rate, C0 is inflow concentration (control chamber), and C1

is outflow concentration (experimental chamber).

Feces were collected from the chambers after the mussels remained in

the system for 12 h. Feces produced during the initial 12-h recovery period

were discarded. Absorption efficiency (AE) was measured by the ratio of

Conover (1966):

AE ¼ ðF � EÞ=ðð1� EÞ � F Þ,

where F is ash-free dry mass/dry mass of food and E is ash-free dry mass/

dry mass of feces.

Respiration rate was measured for each mussel in a transparent plastic

respirometer (i.e., modified Quickfit chamber) containing 750mL of air-

saturated synthetic seawater circulated with a magnetic stirrer. Each

mussel was settled in the respirometer for 15min and subsequently the

decline in oxygen tension was monitored over a period of 30–45min using

a Strathkelvin Model 781 oxygen meter (Strathkelvin Instruments,

Glasgow, UK). Physiological rates were converted to energy equivalents

and were used to calculate SFG, the energy available for growth and

reproduction, according to the equation

SFG ¼ A� R ¼ ðC � absorption efficiencyÞ � R,

where A is energy absorbed from food, C is energy consumed from food,

and R is energy lost via respiration.

Energy lost via excretion was not included in the above equation

because it comprised less than 5% of the total energy loss.

Calculation of C, A and R were as follows:

C (J/g/h) ¼ clearance rate (L/g/h)� algae cells concentration (mg ash-

free dry weight/L)� 23.5 J/mg ash free dry weight,1

A (J/g/h) ¼ C� absorption efficiency, and

R (J/g/h) ¼ respiration rate (mmol O2/g/h)� 0.456 J/mmol O2.2

2.6. Determination of enzyme activities

2.6.1. Glutathione peroxidase activity

Samples were prepared as described by Livingstone et al. (1992).

Digestive glands from four to six individuals were pooled and

homogenized using a Potter–Elvehjem homogenizer (Heidolph Electro

GmbH, Kelheim, Germany) in 1:4 (w:v) 20mM Tris–HCl buffer, pH 7.6,

containing 1mM EDTA, 1mM dithiothietrol, 0.5M sucrose, and 0.15M

KCl. Homogenates were centrifuged at 500g for 15min and 10,000g for

30min. All preparation procedures were carried out at 4 1C. GPX activity

was assayed by the rate of NADPH oxidation at 340 nm by the coupled

reaction with glutathione reductase using H2O2 as a substrate

(GSSG+NADPH+H+-2GSH+NADP+, NADPH extinction

coefficient ¼ 6.2mM�1/cm) (Wendel, 1980). Just before the assay, a

reagent containing 48mM sodium phosphate buffer, pH 7, 0.38mM

EDTA, 0.12mM NADPH, 0.95mM sodium azide, 3.2 units glutathione

reductase, and 1mM GSH was prepared; 1mL of this reagent and 17mLof sample supernatant were added in a cuvette and the reaction was

initiated by addition of 17mL H2O2 solution. Nonenzymic rate was

measured in the absence of sample and subtracted from total rate. The

assay was carried out at 25 1C. GPX activity was expressed as nmol

NADPH consumed per min per mg protein.

2.6.2. Acetylcholinesterase activity

Samples were prepared as described by Bocquene and Galgani (1992).

Adductor muscles from four to six individuals were pooled and

homogenized using a Potter–Elvehjem homogenizer in 1:5 (w:v) 0.1M

Tris–HCl buffer, pH 7. Homogenates were centrifuged at 15,000g for

20min. All preparation procedures were carried out at 4 1C. AChE activity

was assayed at 412 nm by the method of Ellman et al. (1961); 1.5mL of

0.1M Tris–HCl buffer, pH 7, 100mL of 0.01M 5,50-dithiobis(2-

nitrobenzoic acid)and 50 mL of sample supernatant were added in a

cuvette and the reaction was initiated by addition of 50 mL of 0.075M

acetylthiocholine. The assay was carried out at 25 1C. AChE activity was

expressed as nmol of acetylthiocholine hydrolyzed per min per mg protein.

2.6.3. Total protein

The total protein content in the homogenate supernatants was

measured by the Bradford method (1976). Protein concentration was

calculated using a bovine serum albumin standard curve.

ARTICLE IN PRESSC. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243 235

2.7. X-ray microanalysis of granules

Analytical microscopy was applied to kidneys and digestive glands of

mussels. Tissues were dissected out, cut in to small pieces, and immediately

fixed by cryofixation to minimize loss of elements during chemical fixation

procedures (Nott, 1991).

The following techniques were used: (a) metal mirror cryofixation on a

Reichert MM80E (Leica, Milton Keynes, UK) followed by freeze

substitution on a Reichert AFS (Leica) and embedding in Lowcril

HM20 after UV polimerization; (b) cryofixation by plunging samples into

liquid nitrogen followed by freeze-drying and embedding in Spur’s resin.

Thick sections (2mm) were cut dry, placed on Ti grids, carbon-coated,

and examined on a JEOL 200CX (STEM mode) (Jeol Ltd.) at 200KV

equipped with a Link 860 analyzer. X-ray microanalysis was performed on

two types of granules (amorphous granules in lysosomes and spherical

granules). Background spectra of resin and tissue areas were recorded.

Background spectra of Lowcril resin showed Ti and Cu peaks that derived

from the grid and the microscope, respectively. Background spectra of

Spur’s resin revealed Ti, Cu, and Cl peaks.

2.8. Statistical analysis

Data are presented as mean7standard error of the mean. The

Kolmogorov–Smirnoff test and Levene’s test were applied to test normal

distribution and homogeneity of variance, respectively. One-way analysis

of variance (ANOVA) followed by the Tukey HSD multiple comparison

test was applied to determine differences between populations (field data)

or treatments (laboratory data). For SFG data from the field that

exhibited heterogeneity of variance, the Kruskall–Wallis and Tamhanes

multiple comparison tests were performed. To examine relationships

between GPX, AChE, and SFG from combined field and laboratory data,

values were expressed as percentage of reference site or control mussels

and linear regression was applied. Statistical analysis was performed using

the SPSS statistical package. Significance level was set at Po0:05.

3. Results

3.1. Heavy metal concentrations in mussel tissues

Ni, Cr, and Fe concentrations in mussels from Larymnaand the reference site are shown in Table 1. Both nativeand transplanted mussels at Larymna showed significantly

Table 1

Ni, Cr, and Fe concentrations (mg/g dry weight) in whole tissues of mussels (

exposed to a mixture of Ni, Cr, and Fe in the laboratory

Ni (mg/g dw)

Field mussel populations

Larymna native 21.171.3a

Larymna transplanted 6-months 50.378.6a,b

Larymna transplanted 1-month 47.073.8a,b

Reference site 4.970.4

Laboratory exposed mussels

High exposure level (H) 42.572.4a

Low exposure level (L) 8.870.8a

Control 2.570.3

Mean7standard error, n ¼ 10 (field experiment), n ¼ 8 or 9 (laboratory exper

exposure level (H): 200mg Ni/L, 50 mg Cr/L, 4000mg Fe/L.aSignificantly different from reference site or control, Po0.05.bSignificantly different from native mussels in Larymna, Po0.05.

higher levels of Ni (21.1–50.3 mg/g dry weight) and Cr(17.0–25.0 mg/g dry weight) than transplanted mussels atthe reference site (4.9 mg Ni/g dry weight and 0.8 mg Cr/gdry weight). Fe concentrations showed high individualvariability but, though they were elevated in Larymnamussels (824–1082 mg/g dry weight) compared to mussels atthe reference site (280 mg/g dry weight), the differences werenot significant. Among mussel populations in Larymna,significantly higher Ni concentrations were found intransplanted mussels (47.0 and 50.3 mg/g dry weight) thanin native mussels (21.1 mg/g dry weight), whereas there wereno differences in Cr and Fe concentrations.Ni, Cr, and Fe concentrations in mussels exposed to a

mixture of Ni, Cr, and Fe in the laboratory increasedaccording to exposure concentrations and were signifi-cantly different from corresponding concentrations incontrol mussels (Table 1). At the high exposure level,laboratory-treated mussels reached Ni concentrations(42.5 mg/g dry weight) similar to those recorded in thetransplanted mussels at Larymna (47.0 and 50.3 mg/g dryweight). On the contrary, Cr and Fe concentrations inlaboratory-treated mussels, even at the high exposure level,were one order of magnitude lower (2.5 mg Cr/g dry weight,183 mg Fe/g dry weight) than those in native andtransplanted mussels at Larymna (17–25 mg Cr/g dryweight, 824–1082 mg Fe/g dry weight).

3.2. Body condition index

The body condition index was similar in musselpopulations from Larymna and the reference site with theexception of 6-month transplanted mussels in Larymnawhich showed a significantly higher value than all othermussel populations (Table 2).In laboratory-treated mussels similar values of the body

condition index were found among those exposed to themixture of Ni, Cr, and Fe and controls (Table 2).

M. galloprovincialis) from Larymna and the reference site and of mussels

Cr (mg/g dw) Fe (mg/g dw)

20.270.9a 10827138

25.073.2a 8987298

17.072.4a 824747

0.870.3 280731

2.570.0a 183716a

1.470.0a 10578a

0.970.0 5677

iment). Low exposure level (L): 20mg Ni/L, 5mg Cr/L, 400mg Fe/L. High

ARTICLE IN PRESS

Table 2

Body condition index of mussels (M. galloprovincialis) from Larymna and

the reference site and of mussels exposed to a mixture of Ni, Fe, and Cr in

the laboratory

Body condition index

Field mussel populations

Larymna native 6.7670.25

Larymna transplanted 6-months 10.4870.52a

Larymna transplanted 1-month 5.9870.63

Reference site 6.1070.20

Laboratory-exposed mussels

High exposure level (H) 4.5670.58

Low exposure level (L) 4.6570.21

Control 5.3270.65

Mean7standard error, n ¼ 15 (field experiment), n ¼ 4 (laboratory

experiment). Low exposure level (L): 20 mg Ni/L, 5mg Cr/L, 400mg Fe/

L. High exposure level (H): 200mg Ni/L, 50 mg Cr/L, 4000mg Fe/L.aSignificantly different from all mussel populations, Po0.05.

Fig. 2. SFG (J/h/g) (a), GPX activities (nmol/min/mg protein) (b), and

AChE activities (nmoles/min/mg protein) (c) of native and transplanted

mussels in Larymna and transplanted mussels at the reference site.

Mean7standard error, n ¼ 15 (a), n ¼ 5 (b), and (c). *Significantly

different from reference site, Po0:05.

C. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243236

3.3. Biomarker responses in Larymna

3.3.1. SFG

SFG values were significantly lower in native andtransplanted mussels at Larymna than in transplantedmussels at the reference site (Fig. 2a). There were nodifferences in SFG in native, 1- and 6-month transplantedmussels in Larymna that showed negative SFG values(�5.0, �2.2, and �1.8 J/h/g).

The energy absorbed from food (A) and the energyconsumed by respiration (R) used in the calculation ofSFG are shown in Table 3. Significantly lower A valueswere found in all mussel populations from Larymnacompared to mussels at the reference site. Among Larymnamussel populations, significantly higher A and R valueswere found in native compared to transplanted mussels(Table 3).

3.3.2. GPX activity

GPX activity was significantly higher in transplantedmussels at Larymna than in those at the reference site(Fig. 2b). No differences in GPX activity were recorded for1- and 6-month transplanted mussels in Larymna.

3.3.3. AChE activity

AChE activities were lower in native and 6-monthtransplanted mussels at Larymna than in transplantedmussels at the reference site (Fig. 2c) but the onlysignificant difference was in native mussels. Among musselpopulations from Larymna, significantly lower activity wasfound in native mussels compared to 1-month transplantedmussels.

3.3.4. X-ray microanalysis of granules

In the kidney, two types of granules were investigated:lysosomal granules containing high peaks of sulfur and

heavy metals and spherical granules containing phosphate,calcium, and heavy metals. Lysosomal granules were alsofound in the kidney lumen. The lysosomal granules ofmussels from Larymna contained Ni, Co, Fe, and Zn(Fig. 3a) or pure accumulations of Ni (Fig. 3b), while at thereference site granules revealed only Fe and Zn (Fig. 3c).Ni-containing granules were also observed in the kidneylumen. The spherical granules of mussels from both sitescontained Fe and Zn (Fig. 3d).In the digestive gland, granules in digestive lysosomes

that revealed high peaks of sulfur were investigated. Thesegranules contained Ni, Fe, and Zn in mussels fromLarymna (Fig. 4) while in mussels from the reference sitethe granules contained only Fe and Zn. As also observed inthe kidney, many digestive gland lysosomes of mussels

ARTICLE IN PRESS

Table 3

Components of the energy budget (A, R) used for calculation of SFG of mussels (M. galloprovincialis) from Larymna and the reference site and of mussels

exposed to a mixture of Ni, Fe, and Cr in the laboratory

A (J/h/g) R (J/h/g) SFG (J/h/g)

Field mussel populations

Larymna native 10.870.5a 15.871.9 �5.072.1a

Larymna transplanted 6-months 7.870.4a,b 10.070.6b �2.270.6a

Larymna transplanted 1-month 7.570.4a,b 9.270.8b �1.770.6a

Reference site 33.271.3 12.671.8 20.673.1

Laboratory-exposed mussels

High exposure level (H) 19.370.9 12.970.6a 6.470.9a

Low exposure level (L) 22.573.9 11.371.2 11.273.7

Control 28.072.9 10.670.2 17.472.2

Mean7standard error, n ¼ 15 (field experiment), n ¼ 4 (laboratory experiment). Low exposure level (L): 20mg Ni/L, 5mg Cr/L, 400mg Fe/L.

High exposure level (H): 200mg Ni/L, 50mg Cr/L, 4000mg Fe/L.aSignificantly different from reference site or control, Po0.05.bSignificantly different from native mussels in Larymna, Po0.05.

C. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243 237

from the metal-contaminated site contained pure accumu-lations of Ni.

3.4. Biomarker responses on exposure to Ni, Cr, and Fe

mixture in the laboratory

3.4.1. SFG

Mussels exposed to the mixture of Ni, Cr, and Feshowed dose dependent decreases in SFG (Fig. 5a). Thesedecreases were significant at the highest concentration ofmetal mixture where SFG values decreased to 6.4 J/h/gwith regard to the components of the energy budget usedfor calculation of SFG, a gradual decrease in A and agradual increase in R with increasing concentration of themetal mixture was noted, but only the increase in R at thehighest concentration of metal mixture was statisticallysignificant (Table 3).

3.4.2. GPX activity

Mussels exposed to the mixture of Ni, Cr, and Feshowed significant increases in GPX activity compared tocontrol mussels at the highest concentration of metalmixture (Fig. 5b). At the low level of metal concentrationsa slight increase in GPX activity compared to control levelswas noted but this difference was not significant.

3.4.3. AChE activity

There were no significant differences in AChE activitiesamong mussels exposed to the mixture of Ni, Cr, and Feand among controls (Fig. 5c).

3.5. Relationship between biochemical and organism

biomarker responses

A significant linear regression relationship was foundbetween GPX activities and SFG when data from field-collected and laboratory-treated mussels were combined

and expressed as percentage of reference site or controlmussels (R2 ¼ 0:757, Po0:05, Fig. 6a) whereas there wasno significant relationship between AChE activities andSFG (R2 ¼ 0:502, P40:05, Fig. 6b).

4. Discussion

The use of biomarkers is recognized as an importantapproach for the assessment of pollution, as chemicalanalysis of environmental samples alone does not provideevidence of impacts of contaminants in biota. In this study,results obtained by chemical analysis showed elevated Ni,Cr, and Fe concentrations in mussels from Larymnacompared to mussels from the reference site and to valuesreported in Mytilus sp. from other metal-contaminatedareas (Giusti et al., 1999; Szefer et al., 2004). Accordingly,the biomarkers applied in mussels from Larymna werealtered compared to mussels from the reference site,signaling effects of the increased heavy metal concentra-tions at the organism, cellular, and biochemical levels.The parallel use of native and transplanted mussel

populations can provide information on the time courseeffects of pollution, as responses in native mussels willreflect time-integrated cumulative impacts, while in trans-planted mussels responses signal effects of recent exposure(Bolognesi et al., 2004). Our results showed that recent andchronic exposure of mussels to the polluted conditions inLarymna induced persistent SFG and GPX responses whileonly chronic exposure induced an effect on AChE.Laboratory studies can help establish cause and effect

relationships that can be used to verify and predict effectson natural populations in the field; however, it has to betaken into account that abiotic and biotic factors in thefield will modify contaminant accumulation and biomarkerresponses (Philips, 1976; Sheehan and Power, 1999; Vidalet al., 2002; Serafim et al., 2002; Reid and MacFarlane,2003; Luedeking and Koehler, 2004; Khessiba et al., 2005).

ARTICLE IN PRESS

Fig. 3. X-ray spectra derived from analysis of lysosome granules (a–c) and

spherical phosphate granules (d) in the kidney of mussels (Mytilus

galloprovincialis). (a) Kidney from Larymna, (b) kidney from Larymna,

(c) kidney from reference site and (d) kidney from Larymna.

Fig. 4. X-ray spectra derived from analysis of lysosome granules in the

digestive gland of mussels Mytilus galloprovincialis from Larymna.

Fig. 5. SFG (J/h/g) (a), GPX activities (nmol/min/mg protein) (b), and

AChE activities (nmoles/min/mg protein) (c) of mussels exposed to a

mixture of Ni, Cr, and Fe in the laboratory, L: low exposure level, H: high

exposure level. Mean7standard error, n ¼ 4 (a), n ¼ 6 (b), and (c).

*Significantly different from control, Po0:05.

C. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243238

In the present study, exposure of mussels to a mixture ofNi, Cr, and Fe in the laboratory resulted in significant Ni,Cr, and Fe accumulation and showed cause–effect relation-ships for SFG and GPX activities, thus validating thecausal relationship between the heavy metal exposure andthe effects observed in Larymna. However, the same was

not demonstrated for AChE activities. Nevertheless, tissueconcentrations of Cr and Fe in laboratory-treated musselswere much lower than those found in mussels from

ARTICLE IN PRESS

Fig. 6. Mean SFG versus mean glutathione peroxidase activities

(R2 ¼ 0:757, Po0:05) (a) and acetylcholinesterase activities (R2 ¼ 0:502,P40:05) (b), expressed as percentage of reference site mussels (field data)

or percentage of control mussels (laboratory data).

C. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243 239

Larymna. This observation may be due to the lowbioavailability of the dissolved forms of Cr(VI) and Fe(II)applied in the laboratory experiment, this having beenreported previously in mussels in comparison to Cr and Febound to proteins or natural colloids (George et al., 1977,Walsh and O’Halloran 1997; Pan and Wang, 2002) thatmay occur in the field. Walsh and O’Halloran (1997, 1998)in two parallel studies have examined Cr accumulation inmussels from an estuary receiving tannery effluent and inmussels laboratory-exposed to various forms of Cr andsuggested that protein complexes of Cr are likely to beresponsible for the high levels of Cr accumulation found inmussels in the above estuary. In addition other factorssuch as route of uptake, time of exposure, contaminantinteractions, and food availability may have influenced Crand Fe accumulation.

SFG represents the energy budget of an organism and isconsidered a robust indicator of health status ranging fromnegative values when the organism utilizes body reservesfor maintenance to maximum positive values indicatingoptimum conditions (Bayne et al., 1985; Widdows andDonkin, 1992). SFG values of native and transplantedmussels in Larymna (�1.7 to �5 J/h/g) are comparable tovalues reported in the literature for high levels of pollutionstress (o5 J/h/g; Widdows et al., 1995a, 2002), while at thereference site SFG values (21 J/h/g) coincide with thosefound in pristine environments with minimum contamina-

tion (20–25 J/h/g; Widdows et al., 1995b). Although SFGwas similar in native and transplanted mussels in Larymna,indicating a stress response by 1 month of exposure to thepolluted environment, differences among populations inthe components of the energy budget were observed asenergy absorption and energy consumption were increasedin native compared to transplanted mussels. The parallelincreased energy intake and energy expenditure in nativemussels may reflect an adaptative response to the environ-mental conditions (Bayne et al., 1985), possibly to someextent for heavy metal detoxification and excretion, whichcould also explain the lower Ni tissue concentrations ofthese mussels. Metal uptake initially seems related toenvironmental availability until bioaccumulation reachesan equilibrium depending on the available mechanisms ofdetoxification and excretion that vary for different metals(Regoli and Orlando, 1994). Thus transplanted musselsmay show higher concentrations of certain heavy metalsthan native mussels (Roesijadi et al., 1984; Mauri andBaraldi, 2003) before they adapt to a new environment.The increased GPX activities in transplanted mussels at

Larymna and in laboratory mussels exposed to the mixtureof Ni, Cr, and Fe indicate enzyme induction, possibly as aprotection mechanism against ROS since Ni, Cr, and Feaccumulated in the mussel tissues are transition metalscapable of ROS production (Stohs and Bagchi, 1995).Enzymes of the antioxidant defense system can be inducedby enhanced production of ROS as a protection mechan-ism against oxidative stress or inhibited when deficiency ofthe system occurs, predicting toxicity (Winston and DiGiulio, 1991; Cossu et al., 1997). GPX is a component of acomplex antioxidant defense system and its response ispossibly accompanied by responses of other antioxidantenzymes and scavenger molecules; however, its inductionmay provide an indication of defense against oxidativestress. Our results are in agreement with those of Sole et al.(1994) and Cheung et al. (2001, 2002), who found increasesin GPX activity in native populations of Mytilus sp. andtransplanted populations of Perna viridis with increasingcontaminant tissue concentrations. On the contrary Lio-netto et al. (2003) and Regoli and Principato (1995) foundno differences in GPX activities of native or transplantedM. galloprovincialis from clean and polluted sites andOrbea et al. (2002) found no apparent relationship betweencontaminant burdens and GPX induction in musselsfrom low to moderate contaminated areas. Responses ofantioxidant enzymes vary for different chemicals andspecies and in relation to environmental factors andduration of exposure (Winston and Di Giulio, 1991; Cossuet al., 1997; Livingstone 2001), which may explain thecontroversy among the above studies.The gradual decrease in AChE activities of 6-month

transplanted and native mussel populations in Larymnacompared to those at the reference site indicates enzymeinhibition reflecting neurotoxicity, as a time-integratedcumulative impact. AChE inhibition by Cu, Cd, Fe, andZn has been shown in laboratory experiments in mussels in

ARTICLE IN PRESSC. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243240

vitro (Najimi et al., 1997) and in clams in vivo (Hamza-Chaffai et al., 1998) while certain field studies with Mytilus

sp. suggest that a decrease in AChE activity may be anindication of metal pollution (Amiard-Triquet et al., 1998;Dellali et al., 2001). Yet no evidence of AChE inhibition inmussels after exposure to the mixture of Ni, Cr, and Fe inthe laboratory was found, which may be related to theshort duration of exposure, the lower Cr and Fe tissueconcentrations in these mussels compared to Larymnamussels which showed AChE inhibition, or the presence ofother contaminants and contaminant interactions in thefield. The sampling area in Larymna receives domestic andurban runoff wastes from the neighboring town that maycontain contaminants capable of inhibiting AchE, forexample extracts of used engine oil (Payne et al., 1996) anddetergents (Guilhermino et al., 1998). Consequently,laboratory results could not verify whether the AChEinhibition in Larymna is associated with elevated levels ofNi, Cr, and Fe and this thus remains a subject for furtherresearch.

Abiotic and biotic factors such as temperature, salinity,food supply, age, and reproductive status influence heavymetal accumulation and biomarker responses and thushave to be considered in pollution assessment studies(Philips, 1976; Sheehan and Power, 1999; Vidal et al., 2002;Serafim et al., 2002; Khessiba et al., 2005). Both theLarymna site and the study reference site are oligotrophicareas and, during the samplings in autumn, differencesin temperature and salinity were limited. The bodycondition index, which is influenced primarily by thereproductive cycle and food availability, was similar amongthe mussel populations from both areas with the exceptionof 6-month transplanted mussels in Larymna. These hadvisibly larger gonads that nevertheless did not resultin a marked dilution effect on heavy metal whole-tissueconcentrations.

X-ray microanalysis of heavy-metal-containing granuleswas performed only in native mussels from Larymna andreference mussels collected during the winter. Thereforeseasonal variations in biotic and abiotic factors precludedirect comparisons between the physiological and bio-chemical biomarker responses and the composition ofheavy-metal-containing granules. Nevertheless, X-ray mi-cronalysis results contribute to the elucidation of cellulardetoxification mechanisms in mussels chronically exposedto heavy metals in Larymna. At the cellular level,compartmentalization of heavy metals in lysosomes andtheir accumulation in inorganic granules are detoxificationmechanisms that isolate the toxic metals to prevent toxicinteractions with cellular constituents (Nott, 1993). Subse-quently metal-containing granules can be excreted by thekidney cells (Marigomez et al., 2002). In the present study,the high accumulations of Ni found in lysosome granulesof the kidney and the digestive gland in native mussels fromLarymna imply that the elevated Ni levels in the tissuesresulted in an effort to achieve Ni detoxification in thesegranules and possibly Ni excretion, as Ni-containing

granules were observed in the kidney lumen. Similarly,traces of Co previously reported at increased environ-mental levels in the area of Larymna (Voutsinou-Talia-douri et al., 1995) were also detected in lysosome kidneygranules of Larymna mussels. Fe and Zn were found inlysosome and spherical granules of mussels both fromLarymna and from the reference site, as also previouslyreported in M. edulis from a clean reference site by Georgeand Pirie (1980), implying a regulation capacity for thesemetals. On the contrary, Cr was not detected in intracel-lular granules of Larymna mussels, suggesting lowconcentration of Cr in the granules (below the detectionlimit of the method, 0.1%) and/or different cellularlocalization of Cr. Previous studies on M. edulis exposedto Cr have located Cr in kidney and digestive glandlysosome granules (Chassard-Bouchaud et al., 1989; Walshand O’Halloran, 1998), in kidney extracellular sphericalcrystals (Chassard-Bouchaud et al., 1989), and in thecytosol bound to proteins (Walsh and O’Halloran, 1998),however at higher Cr exposure or tissue concentrationsthan those in the present study. Consequently, X-raymicroanalysis results of the present study suggest that thecomposition of lysosome granules was indicative ofexposure to elevated levels of Ni and to a lesser extent ofCo but could not provide information on Fe and Crexposure.It is generally considered that pollution effects are

manifested initially at the biochemical level and subse-quently at the organismal level, leading to effects inpopulations, and thus biochemical biomarkers are sug-gested to exhibit predictive capacities of population-leveleffects. The ability of biochemical markers to provide earlywarning signals of ecosystem-level damage can be evalu-ated by their correlation with ecologically relevant bio-markers such as SFG (Sanders et al., 1991; Allen andMoore, 2004). In the present study significant relationshipsbetween GPX and SFG responses and exposure to heavymetals in the environment of Larymna and underlaboratory conditions were found, suggesting that thedecline in the overall health of the organisms may be due tosome extent to ROS production by heavy metals. Incontrast, AChE inhibition did not parallel the SFG decline.This was evident in mussels after short-term exposure toheavy metals both in the field and in the laboratory, whereit was found that when SFG decreased there was nosignificant AChE inhibition. Accordingly Rickwood andGalloway (2004) found no measurable AChE inhibition inmussels exposed in the laboratory to an organophosphatepesticide when biomarkers of physiological status, cellularintegrity, and immunotoxicity were impacted. Recently theuse of AChE inhibition as a biomarker of adverse effecthas been questioned as previous studies in fish indicate thatthe degree of inhibition is not readily correlated withtoxicological effects (Chambers et al., 2002). Our resultssuggest that GPX but not AChE shows potential as apredictive biomarker of population-level effects of heavymetal exposure.

ARTICLE IN PRESSC. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243 241

5. Conclusions

This study applied biomarker measurements in Larym-na, an area impacted by ferro-nickel smelting operations,and revealed effects at the organism (SFG), cellular(composition of granules), and biochemical (GPX, AChE)levels. SFG and GPX responses reflecting general healthstatus and oxidative stress, respectively, were moresensitive to the polluted conditions in Larymna. Effectson these two biomarkers were obvious on short-termexposure and persistent during chronic exposure, whileonly chronic exposure induced a possibly cumulative effecton AChE indicative of neurotoxicity. Laboratory experi-ments verified the causal relationship between GPX andSFG responses and heavy metals but this was notdemonstrated for AChE. The relationship between GPXand SFG responses on exposure to heavy metals suggests apotential of GPX as predictive biomarker of population-level effects of heavy metal exposure.

Acknowledgments

The authors thank R. Moate at the University ofPlymouth and L. Mavin at Plymouth Marine Laboratoryfor assistance in preparation of samples for X-raymicroanalysis, J.A. Nott at Plymouth Marine Laboratoryfor X-ray microanalysis, and C. Edge for English correc-tion of the manuscript. We are grateful to the anonymousreferees for their helpful comments on this manuscript.This work was partially supported by an ERASMUSgrant.

References

Allen, J.I., Moore, M.N., 2004. Environmental prognostics: Is the current

use of biomarkers appropriate for environmental risk evaluation? Mar.

Environ. Res. 58, 227–232.

Amiard-Triquet, C., Altmann, S., Amiard, J.C., Ballan-Dufranc-ais, C.,

Baumard, P., Budzinski, H., Crouzet, C., Garrigues, P., His, E.,

Jeantet, A.Y., Menasria, R., Mora, P., Mouneyrac, C., Narbonne,

J.F., Pavillon, J.F., 1998. Fate and effects of micropollutants in the

Gironde estuary, France: a multidisciplinary approach. Hydrobiologia

373/374, 259–279.

Bayne, B.L., Widdows, J., 1978. The physiological ecology of two

populations of Mytilus edulis L. Oecologia 37, 137–162.

Bayne, B.L., Brown, D.A., Burns, K., Dixon, D.R., Ivanovici, A.,

Livingstone, D.R., Lowe, D.M., Moore, M.N., Stebbing, A.R.D.,

Widdows, J., 1985. The Effects of Stress and Pollution on Marine

Animals. Praeger Press, New York.

Bocquene, G., Galgani, F., 1991. L’acetylcholinesterase chez les orga-

nismes marins, outil de surveillance des effets des pesticides

organophosphores et carbamates. Oceanis 17, 439–448.

Bocquene, G., Galgani, F., 1992. Assessment of biological water quality

using acetylcholinesterase (AChE) inhibition measurement. In Report

of the FAO/IOC/UNEP Training Workshop on the Techniques for

Monitoring Biological Effects of Pollutants in Marine Organisms,

pp. 133–139.

Bolognesi, C., Fenzilli, G., Lasagna, C., Perrone, E., Roggieri, P., 2004.

Genotoxicity biomarkers in Mytilus galloprovincialis: wild versus caged

mussels. Mutat. Res. 552, 153–162.

Bradford, M., 1976. A rapid and sensitive method for the quantitation of

microgram quantities of protein utilizing the principle of protein-dye

binding. Anal. Biochem. 772, 248–264.

Bucheli, T.D., Kent, K., 1995. Induction of cytochrome P450 as a

biomarker for environmental contamination in aquatic ecosystems.

Crit. Rev. Environ. Sci. Technol. 25, 201–268.

Cambell, J.A., Whitelaw, K., Riley, J.P., Head, P.C., Jones, P.D., 1988.

Contrasting behaviour of dissolved and particulate nickel and zinc in a

polluted estuary. Sci. Total Environ. 71, 141–155.

Chan, J.P., Cheung, M.T., Lau, F.P., 1974. Trace metals in Hong Kong

waters. Mar. Pollut. Bull. 5, 171–174.

Chambers, J.E., Boone, J.S., Carr, R.L., Chambers, H.W., Straus, D.L.,

2002. Biomarkers as predictors in health and ecological risk assess-

ment. Hum. Ecol. Risk Assess. 8, 165–176.

Chassard-Bouchaud, C., Boutin, J.F., Hallegot, B., Galle, P., 1989.

Chromium uptake, distribution and loss in the mussel Mytilus edulis: a

structural, ultrastructural and microanalytical study. Dis. Aquat.

Organ. 7, 117–136.

Cheung, C.C.C., Zheng, G.J., Li, A.M.Y., Richardson, B.J., Lam, P.K.S.,

2001. Relationships between tissue concentrations of polycyclic

aromatic hydrocarbons and antioxidant responses of marine mussels,

Perna viridis. Aquat. Toxicol. 52, 189–203.

Cheung, C.C.C., Zheng, G.J., Lam, P.K.S., Richardson, B.J., 2002.

Relationships between tissue concentrations of chlorinated hydro-

carbons (polychlorinated biphenyls and chlorinated pesticides) and

antioxidative responses of marine mussels, Perna viridis. Mar. Pollut.

Bull. 45, 181–191.

Conover, R.J., 1966. Assimilation of organic matter by zooplankton.

Limnol. Oceanogr. 11, 338–354.

Correia, A.D., Costa, M.H., Ryan, K.P., Nott, J.A., 2002. Studies

on biomarkers of copper exposure and toxicity in the marine

amphipod Gammarus locusta (Crustacea): I. Copper-containing

granules within the midgut gland. J. Mar. Biol. Assoc. UK 82,

827–834.

Cossu, C., Doyotte, A., Jacquin, M.C., Babut, M., Exinger, A., Vasseur,

P., 1997. Glutathione reductase, selenium-dependent glutathione

peroxidase, glutathione levels and lipid peroxidation in freshwater

bivalves, Unio tumidus, as biomarkers of aquatic contamination in field

studies. Ecotoxicol. Environ. Saf. 38, 122–131.

Cotou, E., Papathanassiou, E., Tsangaris, C., 2002. Assessing the quality

of marine coastal environments: comparison of scope for growth and

Microtoxs bioassay results of pollution gradient areas in eastern

Mediterranean (Greece). Environ. Pollut. 119, 141–149.

Dahab, O.A., Al-Madfa, H., 1997. Chromium distribution in waters and

sediments of the eastern side of the Qatari Peninsula. Sci. Total

Environ. 196, 1–11.

Dellali, M., Gnassia Barelli, M., Romeo, M., Aissa, P., 2001. The use of

acetylcholinesterase activity in Ruditapes decussates and Mytilus

galloprovincialis in the biomonitoring of Bizerta lagoon. Comp.

Biochem. Physiol. Part C 130, 227–235.

Depledge, M.H., Aagard, A., Gyorkos, P., 1995. Assessment of trace

metal toxicity using molecular, physiological and behavioural biomar-

kers. Mar. Pollut. Bull. 31, 19–27.

Ellman, G.L., Courtney, K.D., Andres Jr., V., Featherstone, R.M., 1961.

A new and rapid colorimeric determination of acetylcholinesterase

activity. Biochem. Pharmacol. 7, 88–95.

Elumalai, M., Antunes, C., Guilhermino, L., 2002. Single metals and their

mixtures on selected enzymes of Carcinus maenas. Water Air Soil

Pollut. 141, 273–280.

Fulton, M.H., Key, P.B., 2001. Acetylcholinesterase inhibition in

estuarine fish and invertebrates as an indicator of organophosphorus

insecticide exposure and effects. Environ. Toxicol. Chem. 20, 37–45.

George, S.G., Pirie, B.J.S., 1980. Metabolism of zinc in the mussel Mytilus

edulis (L.): a combined ultrastructural and biochemical study. J. Mar.

Biol. Assoc. UK 60, 575–590.

George, S.G., Pirie, B.J.S., Coombs, T.L., 1977. Absorption, accumula-

tion and excretion of iron-protein complexes by Mytilus edulis (L).

Proceedings of the International Conference on Heavy Metal

ARTICLE IN PRESSC. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243242

Environment, Toronto, Canada, Natural Research Council, Canada,

Publ. No. 2, pp. 887–900.

Giusti, L., Williamson, A.C., Mistry, A., 1999. Biologically available trace

metals in Mytilus edulis from the coast of Northeast England. Environ.

Int. 25, 969–981.

Gnaiger, E., 1983. Heat dissipation and energetic efficiency in animal

anoxibiosis: economy contra power. J. Exp. Zool. 228, 471–490.

Guilhermino, L., Barros, P., Silva, M.C., Soares, A.M.V.M., 1998. Should

the use of inhibition of cholinesterases as a specific biomarker for

organophosphate and carbamate pesticides be questioned? Biomarkers

3, 157–163.

Hamza-Chaffai, A., Romeo, M., Gnassia-Barelli, M., El Abed, A., 1998.

Effect of copper and lindane on some biomarkers measured in the clam

Ruditapes decussates. Bull. Environ. Contam. Toxicol. 61, 397–404.

Karageorgis, A.P., Hatzianestis, I., 2003. Surface sediment chemistry in

the Olympic Games 2004 Sailing Center (Saronikos Gulf). Medit. Mar.

Sci. 4, 5–22.

Khessiba, A., Romeo, M., Aıssa, P., 2005. Effects of some environmental

parameters on catalase activity measured in the mussel (Mytilus

galloprovincialis) exposed to lindane. Environ. Pollut. 133, 275–281.

Lemaire, P., Livingstone, D.R., 1993. Pro-oxidant/antioxidant processes

and organic xenobiotic interactions in marine organisms, in particular

the flounder Platicthys flesus and the mussel Mytilus edulis. Trends

Comp. Biochem. Physiol. 1, 1119–1150.

Lionetto, M.G., Caricato, R., Giordano, M.E., Pascariello, M.F.,

Marinosci, L., Schettino, T., 2003. Integrated use of biomarkers

(acetylcholinesterase and antioxidant enzymes activities) in Mytilus

galloprovincialis and Mullus barbatus in an Italian coastal marine area.

Mar. Pollut. Bull. 46, 324–330.

Livingstone, D.R., 2001. Contaminant-stimulated reactive oxygen species

production and oxidative damage in aquatic organisms. Mar. Pollut.

Bull. 42, 656–666.

Livingstone, D.R., Lips, F., Garcia Martinez, P., Pipe, R.K., 1992.

Antioxidant enzymes in the digestive gland of the common mussel

Mytilus edulis. Mar. Biol. 112, 265–276.

Luedeking, A., Koehler, A., 2004. Regulation of expression of multi-

xenobiotic resistance (MXR) genes by environmental factors in the

blue mussel Mytilus edulis. Aquat. Toxicol. 69, 1–10.

Marigomez, I., Soto, M., Cajaraville, M.P., Angulo, A., Giamberini, L.,

2002. Cellular and subcellular distribution of metals in molluscs.

Microsc. Res. Techniq. 56, 358–392.

Mauri, M., Baraldi, E., 2003. Heavy metal bioaccumulation in Mytilus

galloprovincialis: a transplantation experiment in Venice Lagoon.

Chem. Ecol. 19, 79–90.

Najimi, S., Bouhaimi, A., Daubeze, M., Zekhini, A., Pellerin, J.,

Narbonne, J.F., Moukrim, A., 1997. Use of Acetylcholinesterase in

Perna perna and Mytilus galloprovincialis as a biomarker of pollution

in Agadir Marine Bay (South of Morocco). Bull. Environ. Contam.

Toxicol. 58, 901–908.

Nakopoulou, Ch., Hatzias, V., Hadjigeorgiou, E., 1985. Levels of heavy

metals in the seawater in Northern Evoikos Gulf. In: Environmental

Effects of Dumping Metalliferous Slag in the Southern Part of Evoikos

Gulf. Technical Report. National Centre for Marine Research,

Athens, Greece, pp. 143–158 [in Greek].

Nicolaidou, A., Pancucci, M.A., Zenetos, A., 1989. The impact of

dumping coarse metalliferous waste on the benthos in Evoikos gulf,

Greece. Mar. Pollut. Bull. 20, 28–33.

Nicolaidou, A., Nott, J.A., 1989. Heavy metal pollution induced by a

ferro-nickel smelting plant in Greece. Sci. Total Environ. 84, 113–117.

Nicolaidou, A., Nott, J.A., 1990. Mediterranean pollution from a ferro-

nickel smelter: differential uptake of metals by some gastropods. Mar.

Pollut. Bull. 21, 137–143.

Nott, J.A., 1991. Cytology of pollutant metals in marine invertebrates: a

review of microanalytical applications. Scan. Microsc. 5, 191–205.

Nott, J.A., 1993. X-ray microanalysis in pollution studies. In: Sigee, D.C.,

Morgan, A.J., . Summer, A.T., Warley, A. (Eds.), X-ray Microanalysis

in Biology: Experimental Techniques and Applications. Cambridge

University Press, Cambridge, pp. 257–281.

Orbea, A., Maren, O-Z., Sole, M., Porte, C., Cajaraville, M.P., 2002.

Antioxidant enzymes and peroxisome proliferation in relation to

contaminant body burdens of PAHs and PCBs in bivalve molluscs,

crabs and fish from the Urdaibai and Plentzia estuaries (Bay of

Biscay). Aquat. Toxicol. 58, 75–98.

Pan, J-F., Wang, W-X., 2002. Comparison of the bioavailability of Cr and

Fe bound with natural colloids of different origins and sizes to two

marine bivalves. Mar. Biol. 141, 915–924.

Payne, J.F., Mathieu, A., Melvin, W., Fancey, L.L., 1996. Acetylcholi-

nesterase, an old biomarker with a new future? Field trials in

association with two urban rivers and a paper mill in Newfoundland.

Mar. Pollut. Bull. 32, 225–231.

Philips, D.J.H., 1976. The common mussel Mytilus edulis as an indicator

of pollution by zinc, cadmium, lead and copper. I Effects of

environmental variables on uptake of metals. Mar. Biol. 38, 59–69.

Regoli, F., Orlando, E., 1994. Accumulation and subcellular distribution

of metals (Cu, Fe, Mn, Pb and Zn) in the Mediterranean mussel

Mytilus galloprovincialis during a field transplant experiment. Mar.

Pollut. Bull. 28, 592–600.

Regoli, F., Principato, G., 1995. Glutathione, glutathione-dependent

and antioxidant enzymes in mussel, Mytilus galloprovincialis,

exposed to metals under field and laboratory conditions: implica-

tions for the use of biochemical biomarkers. Aquat. Toxicol. 31,

143–164.

Reid, D.J., MacFarlane, G.R., 2003. Potential biomarkers of crude oil

exposure in the gastropod mollusc Austrocochlea porcata: laboratory

and manipulative field studies. Environ. Pollut. 123, 147–155.

Rickwood, C.J., Galloway, T.S., 2004. Acetylcholinesterase inhibition as a

biomarker of adverse effect. A study of Mytilus edulis exposed to the

priority pollutant chlorfenvinphos. Aquat. Toxicol. 67, 45–56.

Roesijadi, G., Young, J.S., Drum, A.S., Gurtisen, J.M., 1984. Behavior of

trace metals in Mytilus edulis during a reciprocal transplant field

experiment. Mar. Ecol. Prog. Ser. 18, 155–170.

Sanders, B.M., Martin, L.S., Nelson, W.G., Phelps, D.K., 1991.

Relationships between accumulation of a 60 kDa stress protein and

Scope for Growth in Mytilus edulis exposed to a range of copper

concentrations. Mar. Environ. Res. 31, 81–97.

Serafim, M.A., Company, R.M., Bebianno, M.J., Langston, W.J., 2002.

Effect of temperature and size on metallothionein synthesis in the gill

of Mytilus galloprovincialis exposed to cadmium. Mar. Environ. Res.

54, 361–365.

Sheehan, D., Power, A., 1999. Effects of seasonality on xenobiotic and

antioxidant defense mechanisms of bivalve molluscs. Comp. Biochem.

Physiol. 123C, 193–199.

Sole, M., Porte, C., Albaiges, J., 1994. Mixed function oxygenase system

components and antioxidant enzymes in different marine bivalves: its

relation with contaminant body burdens. Aquat. Toxicol. 30, 271–283.

Stohs, S.J., Bagchi, D., 1995. Oxidative mechanisms in the toxicity of

metal ions. Free Radical Biol. Med. 18, 321–336.

Szefer, P., Kim, B.S., Kim, C.K., Kim, E.H., Lee, C.B., 2004. Distribution

and coassociations of trace elements in soft tissue and byssus of

Mytilus galloprovincialis relative to the surrounding seawater and

suspended matter of the southern part of the Korean Peninsula.

Environ. Pollut. 129, 209–228.

UNEP, 1984. Determination of total Cd, Zn, Pd and Cu in selected marine

organisms by atomic absorption spectrophotometry. Reference Meth-

ods for Marine Pollution Studies, No. 11, Rev. 1.

Vesk, P.A., Byrne, M., 1999. Metal levels in tissue granules of the

freshwater bivalve Hyridella depressa (Unionida) for biomonitoring:

the importance of cryopreparation. Sci. Total Environ. 225, 219–229.

Viarengo, A., Burlando, B., Dondero, F., Marro, A., Fabbri, R., 1999.

Metallothionein as a tool in biomonitoring programmes. Biomarkers

4, 455–466.

Viarengo, A., Canesi, L., 1991. Mussels as biological indicators of

pollution. Aquaculture 94, 225–243.

Vidal, M.L., Basseres, A., Narbonne, J.F., 2002. Seasonal variations of

pollution biomarkers in two populations of Corbicula fluminea

(Muller). Comp. Biochem. Physiol. 131C, 133–151.

ARTICLE IN PRESSC. Tsangaris et al. / Ecotoxicology and Environmental Safety 66 (2007) 232–243 243

Voutsinou-Taliadouri, F., Psyllidou-Giouranovits, R., Georgakopoulou-

Gregoriadou, E., 1995. Active growth of a submarine slag disposal ore

deposit in the northern Euboekos Gulf, Greece. Fresen. Environ. Bull.

4, 195–200.

Walsh, A.R., O’Halloran, J., 1997. The accumulation of chromium by

mussels Mytilus edulis (L) as a function of valency, solubility and

ligation. Mar. Environ. Res. 43, 41–53.

Walsh, A.R., O’Halloran, J., 1998. Accumulation of chromium by a

population of mussels (Mytilus edulis (L.)) exposed to leather tannery

effluent. Environ. Toxicol. Chem. 17, 1429–1438.

Wendel, A., 1980. Glutathione peroxidase. In: Jakoby, W.B., Bend, J.R.,

Caldwell, J. (Eds.), Enzymatic Basis of Detoxication. Academic Press,

NewYork, pp. 333–348.

Widdows, J., Donkin, P., 1992. Mussels and environmental contaminants:

bioaccumulation and physiological aspects. In: Gosling, E. (Ed.), The

Mussel Mytilus: Ecology, Physiology, Genetics and Culture. Elsevier,

Amsterdam, pp. 383–424.

Widdows, J., Donkin, P., Brinsley, M.D., Evans, S.V., Salked, P.N.,

Franklin, A., Law, R.J., Waldock, M.J., 1995a. Scope for growth and

contaminant levels in North Sea mussels Mytilus edulis. Mar. Ecol.

Prog. Ser. 127, 131–148.

Widdows, J., Donkin, P., Evans, S.V., Page, S., Salked, P.N., 1995b.

Sublethal biological effects and chemical contaminant monitoring of

Sullom Voe (Shetland) using mussels (Mytilus edulis). R. Soc.

(Edinburgh) Proc. 103B, 99–112.

Widdows, J., Donkin, P., Staff, F.J., Matthiessen, P., Law, R.J., Allen, Y.T.,

Thain, J.E., Allchin, C.R., Jones, B.R., 2002. Measurement of stress

effects (scope for growth) and contaminant levels in mussels (Mytilus

edulis) collected from the Irish Sea. Mar. Environ. Res. 53, 327–356.

Widdows, J., Fieth, P., Worrall, C.M., 1979. Relationships between

seston, available food and feeding activity in the common mussel

Mytilus edulis. Mar. Biol. 50, 195–207.

Widdows, J., Salked, P., 1992. Practical procedures for measurement of

Scope for Growth. In: Report of the FAO/IOC/UNEP Training

Workshop on the Techniques for Monitoring Biological Effects of

Pollutants in Marine Organisms, pp. 175–205.

Winston, G.W., Di Giulio, R.T., 1991. Prooxidant and antioxidant

mechanisms in aquatic organisms. Aquat. Toxicol. 19, 137–161.