Marine Pollution Bulletin 58 (2009) 858–877

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Marine Pollution Bulletin

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Benthic foraminifera as bio-indicators of trace element pollution in the heavilycontaminated Santa Gilla lagoon (Cagliari, Italy)

Fabrizio Frontalini a,*, Carla Buosi b, Stefania Da Pelo b, Rodolfo Coccioni a, Antonietta Cherchi b, Carla Bucci a

a Università degli Studi di Urbino ‘‘Carlo Bo”, Dipartimento di Scienze dell’Uomo, dell’Ambiente e della Natura, Campus Scientifico, Località Crocicchia, 61029 Urbino, Italyb Università di Cagliari, Dipartimento di Scienze della Terra, via Trentino 51, 09127 Cagliari, Italy

a r t i c l e i n f o

Keywords:Benthic foraminiferaTrace elementsForaminiferal testESEM-EDSSanta Gilla lagoon (Sardinia)Nanoparticles

0025-326X/$ - see front matter � 2009 Elsevier Ltd.doi:10.1016/j.marpolbul.2009.01.015

* Corresponding author. Tel.: +39 0722 304254; faxE-mail address: fabrizio.frontalini@uniurb.it (F. Fro

a b s t r a c t

In order to assess the response of benthic foraminifera to trace element pollution, a study of benthic fora-miniferal assemblages was carried out into sediment samples collected from the Santa Gilla lagoon(Sardinia, Italy). The lagoon has been contaminated by industrial waste, mainly trace elements, as wellas by agricultural and domestic effluent. The analysis of surficial sediment shows enrichment in trace ele-ments, including Cr, Cu, Hg, Ni, Pb and Zn. Biotic and abiotic data, analyzed with multivariate techniquesof statistical analysis, reveal a distinct separation of both the highly polluted and less polluted samplingsites. The innermost part of the lagoon, comprising the industrial complex at Macchiareddu, is exposed toa high load of trace elements which are probably enhanced by their accumulation in the finer sedimentfraction. This area reveals lower diversity and higher percentages of abnormalities when compared to theoutermost part of the lagoon.

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1. Introduction

Benthic foraminifera (class Foraminifera, phylum Granuloretic-ulata) constitute the most diverse group of shelled micro organ-isms in modern oceans (Sen Gupta, 1999). They play a significantrole in global bio-geochemical cycles of inorganic and organic com-pounds, making them one of the most important animal groups onearth (Haynes, 1981; Lee and Anderson, 1991). Since foraminiferahave a short life-cycle, they react quickly and can be used as earlywarning bio-indicators of both short and long-term changes inmarine and transitional-marine environments on a global and a lo-cal scale (e.g. Alve, 1991, 1995; Yanko et al., 1994, 1998, 1999; Coc-cioni, 2000; Samir, 2000; Debenay et al., 2001, 2005; Samir and El-Din, 2001; Murray and Alve, 2002; Geslin et al., 2002; Coccioniet al., 2003, 2005; Armynot du Châtelet et al., 2004; Frontaliniand Coccioni, 2008). The use of benthic foraminifera as bio-indica-tors of environmental quality may be investigated in terms of pop-ulation density and diversity, assemblages’ structure, reproductioncapability, test morphology, including size (dwarfism), prolocularmorphology, ultrastructure, pyritization, abnormality, and chemis-try of the test (e.g. Alve, 1991, 1995; Yanko et al., 1994, 1999; Ges-lin et al., 1998).

The study of pollution effects on benthic foraminifera and theiruse as proxies started in the 1960s (Resig, 1960; Watkins, 1961;Boltovskoy, 1965), and has increasingly developed in recent dec-

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ades through environmental research (e.g. Boltovskoy et al.,1991; Alve, 1991, 1995; Yanko et al., 1994, 1998, 1999; Stouffet al., 1999; Coccioni, 2000; Geslin et al., 2000, 2002; Debenayet al., 2001, 2005; Coccioni et al., 2003, 2005; Coccioni and Marsili,2005; Ferraro et al., 2006; Frontalini and Coccioni, 2008; Polovodo-va and Schönfeld, 2008; Romano et al., 2008).

Morphological abnormalities in foraminiferal tests have beennoted by researchers as long ago as the past two centuries (e.g.Carpenter, 1856; Rhumbler, 1911). In some modern assemblages,deformed tests are conspicuously abundant and the causes there-of are of great interest. In particular, abnormalities have been re-ported in areas contaminated by trace elements, domesticsewage, and various chemicals, including liquid hydrocarbons(for reviews see Boltovskoy et al., 1991; Alve, 1995; Yankoet al., 1998). The percentage of abnormal foraminifera can in-crease dramatically in polluted areas (e.g. Lidz, 1965), and mostof the authors mentioned above have suggested that the presenceof deformed tests of benthic foraminifera is a powerful in situ bio-indicator of trace element pollution. In particular, Coccioni et al.(2005) introduced the Foraminiferal Abnormality Index (FAI) toindex and compare the percentages of morphological abnormalityoccurring at different sites. More recently, the possibility of usingthe trace element content of calcareous benthic foraminiferaltests as a reliable tracer of environmental quality has also beenexplored. Following on from this, and within integrated programs,benthic foraminifera could be used as valuable bio-indicators ofcontemporary environmental changes and disturbances causedby pollution.

F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877 859

The main objectives of this study are: (i) to outline the healthquality of the Santa Gilla lagoon (Sardinia, Italy) on the basis ofchemical (trace element content) characteristics, (ii) to documentthe suitability of using living benthic foraminifera as bio-indicatorsof trace element contents in sediment within the lagoon, (iii) andto present a new, high-quality dataset of trace elements measuredin calcareous tests of porcelanaceous foraminifera retrieved fromthe lagoon of Santa Gilla.

2. Study area

The Santa Gilla lagoon covers an area of about 15 km2 and is lo-cated on the southern coast of Sardinia (Italy) (Cottiglia et al.,1973). It is an elongated, NW–SE orientated depression, roughlydeltoid-shaped, and delimitated by the Paleozoic relief of Capoter-ra to the west and by the city of Cagliari to the east. In the south, itconnects to the Mediterranean Sea through a narrow channel, andits extension is limited by a sand bar which sets the beach apartfrom the Gulf of Cagliari. It is separated from the Molentargiusand Quartu S. Elena lagoons by the miocenic hills of Cagliari. Onthe northern shore, the lagoon has two major freshwater inflowsfrom the Fluminimannu and Cixerri rivers (Fig. 1).

The average water depth is 1 m, with a maximum of 2 m in theartificial channel connecting the lagoon with the sea. The water ex-change is faster in the southern basin (2–3 days) than in the innerareas (8–12 days) (Degetto et al., 1997). The rivers drain a widecatchment area, and flow at an average rate of 12 m3 s�1, withpeaks of 30 m3 s�1 in winter. Due to recent improvements, how-ever, these inflows have been reduced and the salinity has, conse-quently, also increased, as have the fertilizers (Cottiglia, 1995). Theecological conditions of the lagoon are quite different from thoseencountered in other transitional-marine environments (i.e. la-goons at Orbetello, Tuscany and Lesina, Puglia, Italy) which usuallyexperience eutrophication (Lenzi, 1992; Manini et al., 2003).

The Santa Gilla lagoon is filled with sediment, representedmainly in the form of sandy-silt, to a thickness of about 50 m fromthe upper Pleistocene to present (Orrù et al., 2004). This data sup-ports the importance of the Würm regression (stage 2, 15/18 ka),which produced a strong erosion of the Tyrrenian marine sediment(‘‘Panchina Tirreniana” Auct.) (Pecorini, 1986; Ulzega, 1995). Thesilty sands with subordinate gravel, which are attributed to thealluvional contribution of the Fluminimannu and the Cixerri rivers,

Fig. 1. Satellite image of th

create sedimentary bodies at the north-western shore of thelagoon.

In the past century, the area has been the subject of major envi-ronmental changes and transformations that have deeply affectedits morphology. In particular, these changes have included itsextension, the sea front and the catchment area of the main tribu-taries of continental waters, works of reclamation of Cixerri andFluminimannu (mid-1900s), implementation of saltworks by Con-tivecchi (the 1920s) (Cottiglia, 1995), the establishment of thelarge industrial complex of Macchiareddu–Grogastu (the 1960s),and finally, the construction of the Porto Canale (industrial port)(the 1970s).

Prior to these changes, the typical macrobenthos biocenosis in-cluded lamellibranches (Tapes decussatus, Scrobicularia plana, Abraovata and Cerastoderma glaucum), crustaceans and decapods (Car-cius mediterraneus and Palaemon adspersus), amphipods (Gammarusaequicauda and Corophium volutator), and isopods (Sphaeromahoockeri, Idotheatra and Cyathura) (Cottiglia, 1995). As for plant life,the only phanerogam was Ruppia maritima, and the thallophytescommonly growing in the lagoon included Ulva espansa, Gracilariaconfervoides, and several species of Entermorpha, Cladophora, andChaetomorpha. Cottiglia (1995) also reports phosphateconcentrations similar to basic production, high total nitrogen thatdecreases inwards and saturated oxygen conditions. The amount ofparticulate organic matter is extremely low for a lagoon, due tosparse concentrations of phytoplankton (remnants ofmacrophytobenthos).

The lagoon has received industrial discharges of Hg, Pb and Zncompounds, as well as, for several decades, municipal untreatedsewage from the urban area of Cagliari (ca. 400,000 inhabitants),its industrial area (Macchiareddu–Grogastu), and other anthropo-genic related activities (i.e. airports, railways, port activities, refin-eries, incinerators, etc.). In particular, a petro-chemical plant wentinto operation (1960s) for the production of chloride, which in-volved processing sodium chloride in electrolytic cells on a mer-cury bed (Cottiglia, 1995). In 1986, a restoration plan wasimplemented in order to improve the ecological quality of the la-goon. This largely consisted of isolating the most polluted area infront of the industrial complex with dykes and then covering itwith sediment dredged from cleaner areas. According to Degettoet al. (1997), the environmental quality of the lagoon has im-proved. The possible presence of unremoved pollutants and their

e lagoon of Santa Gilla.

860 F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877

potential mobility may, however, require special monitoringprograms.

The Santa Gilla lagoon is one of the most important wetlands inSardinia. It is recognized in the official lists of wetlands to be pro-tected, and is classified as both a Special Protection Area (SPA) un-der Directive No. 409, 1979 (Birds) of the European Union, and as aWetland of International Importance under the Ramsar Conven-tion. It is also included in the ecological network of Natura 2000.A management plan has recently been developed in order to guar-antee the conservation of habitats, internationally protected birds,and the landscape of the area.

3. Previous benthic foraminiferal studies in the Santa Gillalagoon

The first comprehensive and detailed analysis was provided byZampi and d’Onofrio (1984), who explored the benthic foraminif-eral distribution in six surficial sediments in the study area. Theyfound oligotipic assemblages dominated by Ammonia beccarii,Elphidium gunteri and Protelphidium anglicum and characterizedby great numbers of abnormal specimens.

They also noted a great morphological variability and a highnumber of megalospheric forms of A. beccarii. The morphology ofthis species was correlated with the peculiar environmental condi-tion of the lagoon. More recently, Foresi et al. (2006) investigatedthe relationship between the morphology of Triloculina rotundaand the environmental conditions of the area. Abnormal testshapes and assemblages, dominated by megalospheric forms, wereobserved. They reported incompletely calcified test walls in re-sponse to stressful conditions, and suggested that reproduction oc-curs before adult characters have developed.

4. Materials and methods

4.1. Sampling

This study is based on 18 surface sediment samples (codified asSG) collected from the lagoon of Santa Gilla in October 2006. Twosets of samples were taken by means of a Van Veen grab samplerwhich collects sediment over a surface area of about 400 cm2

Fig. 2. Location map of the study area with sampling stations. Main pollutionsources: (a,b,h) urban drainage; (c–f) airport discharge; (g) electric powerdischarge; and (i) industrial sewage.

(Fig. 2). Scott et al. (2001) consider that Van Veen samplers areadequate for soft-sediment total population investigations. At eachstation, the temperature, pH, salinity, Eh and DO (dissolved oxygenexpressed as mg/l) of seawater were measured in a vertical profile.The positions of the sampling stations were determined using theglobal position system (Table 1). On board, the grab was immedi-ately and carefully opened in a container, where the sedimentwas deposited in its initial position. Two aliquots from each samplewere taken at each station and stored in polyethylene jars. The firstwas used for a thorough study of the foraminiferal assemblagesand the second to measure trace element contents in the sediment.In the laboratory, following Walton’s technique (1952), a constantvolume (about 50 cm3) was stained with buffered rose Bengal dye(2 g of rose Bengal in 1000 ml of ethyl alcohol) for 48 h to differen-tiate between living and dead foraminifera. There are a wide vari-ety of methods that can be used to distinguish between these, andthe choice of technique depends on the objectives of the study. Therose Bengal method remains the most practical way of quantifyingliving foraminifera because it is quick and ideal for dealing withlarge numbers of samples (Bernhard, 2000; Murray, 2006).

4.2. Foraminiferal analysis

All samples were dried at 50 �C and weighed. They were thengently washed with tap water through a 63 lm sieve to removeclay, silt and any excess dye. The residual fraction so obtainedwas re-dried at 50 �C and weighed again to determine by differ-ence the mud fraction.

The number of specimens and species will decrease withincreasing sieve size, and this may give misleading information(Schröder et al., 1987). Accordingly, the quantitative analysis ofbenthic foraminifera was performed on the fraction >63 lm. Fol-lowing de Stigter et al. (1998, 1999), only specimens containingdense, brightly red-stained protoplasm were counted as alive.Three hundred stained specimens were picked from each sampleand identified following the generic classifications of Loeblichand Tappan (1987).

Several foraminiferal parameters have been calculated speciesdiversity (S, number of species per sample), foraminiferal density(FD, number of specimens per 1 g of dry sediment), Fisher a index(relationship between the number of species and the number ofindividuals in an assemblage, Fisher et al., 1943; Murray, 1973),dominance (D), Shannon–Weaver index or information function(H) (Shannon and Weaver, 1963), Simpson index (1 � D), evenness(J), and equitability (E). The above mentioned diversity indiceswere calculated using the PAST – PAlaeontological STatistics dataanalysis package (version 1.68).

In addition, the FAI corresponding to the total percentage ofabnormal foraminiferal specimens in each sample and the Forami-niferal Monitoring Index (FMI, defined as the percentage of abnor-mal species within the assemblage) (Coccioni et al., 2005) werecalculated for each sample. The recognized species were ecologi-cally characterized, largely following Jorissen (1988), Murray(1991, 2006), Barmawidjaja et al. (1992) and Alve (1995). Normaland deformed specimens were carefully observed and photo-graphed by a scanning electron microscope.

4.3. Trace element contents in foraminiferal tests

The trace element content was investigated in porcelanaceoustests. An appropriate number of miliolids of each sample werewashed by mechanical agitation with ultrapure water (MilliQ�)in order to remove detrital grains. In a teflon beaker with 3 ml ofultrapure HNO3 (67%), samples were dried, accurately weighed,and digested by slow heating at 30 �C in a temperature bath. Solu-tions were diluted with ultrapure water to 10 ml in volumetric

Table 1Geographic coordinate of sampling station, water depth, and physicochemical characteristics of the bottom water.

Station Lat. (N) Long. (E) Depth (m) T (�C) pH Salinity Eh DO (mg/l)

SG1 39�13,2490 009�05,2020 1.6 22.19 7.8 35.01 17 7.96SG2 39�13,1190 009�05,6580 1.9 22.14 7.71 36.74 158 6.68SG3 39�13,6950 009�05,3470 1.6 22.26 7.63 35.86 150 6.96SG4 39�14,2670 009�05,0370 1.8 22.62 7.73 34.55 �108 6SG5 39�14,5660 009�04,8060 1 23.01 8.24 32.65 2 12.92SG6 39�14,1620 009�04,3350 1.4 22.51 8 32 31 9.71SG7 39�14,3890 009�04,1970 1.5 22.55 7.7 33.45 60 8.33SG8 39�15,3200 009�02,8730 1.8 22.92 7.8 31.98 64 7.9SG9 39�15,5480 009�02,3680 1.8 23.06 8.15 30.51 62 14.94SG10 39�15,9810 009�02,0900 0.9 23.77 8.19 28.56 10 1.86SG11 39�15,8950 009�01,2850 0.4 24.18 8.33 22.4 �173 13.81SG12 39�15,0240 009�01,6840 1.4 22.84 8.14 31.67 18 10.83SG13 39�14,8290 009�01,7110 0.8 21.03 7.96 21.71 104 7.23SG14 39�14,5060 009�01,8500 1.6 22.96 7.97 32.06 42 8.78SG15 39�14,3240 009�02,1690 1.6 22.68 7.76 31.94 52 5.53SG16 39�13,8410 009�03,8090 1.5 22.01 8.06 31.82 102 9.12SG17 39�13,9430 009�04,1970 1.9 22.37 7.76 34.73 49 7.4SG19 39�14,1020 009�1,2890 0.4 23.68 7.48 24.58 137 10.88

F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877 861

flasks, and transferred to new HD-polyethylene bottles for storage(Jarvis, 1992). Trace elements analyses determined by ICP-AES andICP-MS were performed at the Earth Sciences Department of theUniversity of Cagliari.

Moreover, normal and deformed specimens of Ammonia tepidawere crushed and observed with an environmental scanning elec-tron microscope (FEI ESEM, Quanta 200) to qualitatively character-ize the occurrence of trace element nanoparticles or foreignelements within the foraminiferal test. The ESEM, coupled withan energy dispersive spectrometer (EDS), is used to assess thechemical composition of particles within the foraminiferal test.The EDS is a technique employed to collect and determine the en-ergy and the number of X-rays that are given off by atoms in amaterial (Goldstein et al., 2003).

Prior to chemical analysis, the analyzed tests were carefullycleaned in an ultrasonic cleaner, washed thoroughly with distilledwater, and oven dried at 60 �C to minimize the probability of vol-atile metal loss (Siegel et al., 1994). The observation was carriedout in low vacuum (0.2–1.2 Torr) conditions, secondary and back-scattered electron mode, and with energy varying from 25 to12 kV.

Due to the heterogeneous distribution of trace metals (Severin,1990), at least three points on each test were measured to checkfor internal variability of shell composition. Care was taken toavoid the edges and pores of specimens, so as to minimize the pos-sibility of contamination in the obtained data.

4.4. Trace element analysis

The second set of samples was dried, reduced to a fine powder,and used to determine trace element contents in sediments. Acti-vation Laboratories Ltd. (Ontario, Canada, http://www.actl-abs.com) analyzed a fraction of �0.5 g of a sample for 32elements using inductively coupled plasma optical emission spec-trometry (ICP-OES), which is a multi-element technique capable ofmeasuring concentrations at very low detection limits (mg kg�1 tolg kg�1). The sample material was digested with aqua regia (0.5 mlH2O, 0.6 ml concentrated HNO3 and 1.8 ml concentrated HCl) for2 h at 95 �C. The sample was cooled, diluted to 10 ml with de-ion-ized water and then homogenized. The samples were then ana-lyzed using a Perkin–Elmer OPTIMA 3000 Radial ICP for theelement suite. A standard matrix and a blank were run every 13samples. A series of USGS-geochemical standards were used ascontrols. A further aliquot of a sample (�0.5 g) was digested withaqua regia at 90 �C, and the Hg in the resulting solution was oxi-

dized to the stable divalent form. Since the concentration of Hgwas determined via the absorption of light at 253.7 nm by Hg va-por, Hg(II) was reduced to the volatile free atomic state using stan-nous chloride. Argon was bubbled through the mixture of sampleand reductant solutions to liberate and transport the Hg atoms intoan absorption cell. The cell was placed in the light path of an atom-ic absorption spectrophotometer. The maximum amount absorbed(peak height) was directly proportional to the concentration ofmercury atoms in the light path. Measurement was performedautomatically using a flow injection technique (FIMS). Hg analysiswas performed on a Perkin–Elmer FIMS 100 cold vapor Hganalyzer.

In this paper, only concentrations of Ag, As, Cd, Cr, Cu, Fe, Hg,Mn, Ni, Pb, V, and Zn were evaluated. The detection limits for heavymetals are Ag: 0.01 mg kg�1, As: 3 mg kg�1, Cd: 0.2 mg kg�1, Cr:2 mg kg�1, Cu: 1 mg kg�1, Fe: 0.01%, Hg: 5 lg kg�1, Mn: 1 mg kg�1,Ni: 1 mg kg�1, Pb: 2 mg kg�1, V: 1 mg kg�1, and Zn: 1 mg kg�1.

4.5. Grain size analysis

The samples which were to be used for grain size analysis weretreated with an H2O2 solution to reduce the organic matter, andwere then sieved and dried at 40 �C. Grain size analysis was con-ducted by Sedigraph (Micrometrics 5100) to determine the per-centage of silt and clay (<63 mm), whereas the >63 lm fractionwas dried and fractionated by ASTM micro-sieve. Shepard (1954)grain size classification was used.

4.6. Statistical analysis

Multivariate statistical techniques of cluster analysis (CA) andprincipal component analysis (PCA) were performed using theWindows SPSS 13.0 program and Statistica 6.0.

In order to reduce the background noise, only species with anabundance greater than 2% in at least one sample were consideredfor statistical treatment.

A correlation matrix (Pearson) was calculated for transformedtrace elements, grain size, assemblage parameters, and relativeabundance of species.

The PCA was used to determine the community’s relationship toabiotic parameters at sampled stations. The PCA attempts to iden-tify the underlying factors which explain the pattern of correlationwithin a set of observed variables. It is used to reduce data in sucha way as to identify a small number of factors that explain most ofthe variance observed in a much larger number of manifested vari-

Fig. 3. Grain size (sand, mud, silt and clay) distribution pattern and main physicochemical features of the lagoon of Santa Gilla. Sampling stations are shown here as blackdots.

862 F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877

ables. Prior to statistical analysis, and to avoid negative numbers(Brakstad, 1992; Manly, 1997), normalize the data, and increasethe importance of smaller values such as the mid-range species,an additive logarithmic transformation log(1 + X) was performedto remove the effects of orders of magnitude difference betweenvariables.

A distance of CA is given in Euclidean, while similarities in thenew fused clusters were calculated by adopting the Ward’s linkagemethod which produces dendrograms with exceptionally well-de-fined clusters (Parker and Arnold, 1999). The CA classified the sam-ples into associations (clusters), where each cluster includesstations with a similar spatial distribution pattern (Samir et al.,2003).

5. Results

5.1. Hydrological features

During the sampling period, the water temperature of the SantaGilla lagoon varied from 21 to 24.2 �C, while salinity showed acomplex pattern ranging from 21.7 to 36.7 (Table 1). In particular,the innermost part of the lagoon is influenced by the freshwater in-flow of two rivers and a reduced water exchange with the sea(Fig. 3). The dissolved oxygen content showed a complex patternof distribution and changed between 1.9 and 14.9 mg/l. The pHof the lagoon was alkaline, varying from 7.5 to 8.3 (Table 1).

5.2. Grain size distribution patterns

Bottom sediments are composed primarily of mud (�60%; 17%of silt and 43% of clay) with an average percentage of sand of24.7 (Table 2 and Fig. 3). When present, the coarser fraction ismade up of gravel and/or some fragments of mollusks.

5.3. Trace element contents

Concentrations of trace elements are shown in Table 2. Thehighest concentrations are encountered in the innermost part of

the lagoon. Compared to the ER–L (effect range–low) and ER–M(effect range–median) values reported for the United States Envi-ronmental Protection Agency’s (USEPA) sediment guidelines (Longet al., 1995; Ligero et al., 2002), the Santa Gilla lagoon shows higherconcentrations of Ag, As, Cd, Cu, Hg, Ni, Pb, and Zn than the ER–Llevels, whereas Hg and Zn show higher values than ER–M (Table2). Moreover, as established by D.M. 367/2003, by comparing traceelement concentrations to the standard quality in sediment fromcoastal marines, lagoons and coastal lake waters, almost all ofthe collected samples show an enrichment in Hg (up to 8.63 mg/kg, SG19), Cd (up to 1.5 mg/kg, SG19), Ni (up to 36 mg/kg, SG14),and Pb (up to 205 mg/kg, SG11). Some stations are occasionally en-riched in As (up to 17 mg/kg, SG2) and Cr (up to 53 mg/kg, SG14).

The highest concentrations of trace elements are found in theinnermost part of the lagoon, in those stations located in front ofthe industrial complex which results more industrialized com-pared to the outer area (Fig. 4).

5.4. Benthic foraminifera

A total of 37 benthic foraminiferal species, belonging to 21 gen-era, is identified in the living assemblage (Table 3 and Appendix A).The relative abundance of recognized species varies from station tostation, with only 12 species showing relative abundances greaterthan 2% in at least one sample.

Living assemblages are largely dominated by A. tepida (62.7% onaverage) reported by Zampi and D’Onofrio (1984) as A. beccarii,Haynesina germanica (20.3% on average) reported as P. anglicumby Zampi and D’Onofrio (1984), Elphidium oceanensis (7.7% on aver-age) reported as E. gunteri by Zampi and D’Onofrio (1984), and sub-ordinately by Quinqueloculina laevigata, Q. costata, Q. seminula,Rosalina globularis, Bolivina striatula, B. dilatata, B. spathulata, B.variabilis reported as Brizalina variabilis by Zampi and D’Onofrio(1984), and finally, Fursenkoina punctata also reported as Fursenko-lina punctata by Zampi and D’Onofrio (1984) (Fig. 5 and Table 3).

During the sampling, S varies from 3 (SG12 and SG14) to 26(SG2). The highest FD is found in station SG19 (180), with a meanof 46.9. The Shannon–Weaver index varies from 0.54 (SG17) to

Table 2Trace element concentrations, grain size values and classification (Shepard, 1954). Trace element contents compared to background concentrations (per-industrial age) reported by Degetto et al. (1997), quality standard in sedimentsfrom coastal marine, lagoon and coastal lake waters, as established by D.M. 367/2003 and ER–L (effect range low) and ER–M (effect range median) values reported for the sediment guidelines of USEPA by Long et al. (1995) and Ligeroet al. (2002).

Station Ag (mg/kg)

As (mg/kg)

Cd (mg/kg)

Cr (mg/kg)

Cu (mg/kg)

Fe(%)

Hg (mg/kg)

Mn (mg/kg)

Ni (mg/kg)

Pb (mg/kg)

V (mg/kg)

Zn (mg/kg)

Gravel(%)

Sand(%)

Mud(%)

Silt(%)

Clay(%)

Sediment type

SG1 1.1 13 0.5 20 17 1.7 0.381 237 13 56 38 101 30.05 37.93 32.02 11.40 20.62 Gravellysediment

SG2 1 17 0.8 33 27 2.17 0.644 304 20 109 53 159 31.30 20.84 47.86 16.08 31.78 Gravellysediment

SG3 1.2 6 0.4 14 14 1.39 0.206 173 10 42 31 76 18.52 37.97 43.50 15.88 27.63 Gravellysediment

SG4 0.5 3 0.9 47 40 3.69 0.547 458 30 125 69 206 1.63 8.73 89.64 23.49 66.15 Silty claySG5 1.2 8 0.5 16 15 1.49 0.382 248 12 110 31 81 8.87 43.63 47.50 14.53 32.96 Clayey sandSG6 1.5 6 0.2 5 6 0.59 0.169 370 4 26 17 31 59.21 26.28 14.50 4.39 10.11 GravelSG7 0.8 12 0.9 30 30 2.8 0.574 635 22 120 47 172 18.83 19.82 61.35 16.69 44.66 Gravelly

sedimentSG8 0.5 11 0.9 38 39 3.36 0.637 438 29 138 53 195 8.34 5.76 85.90 20.53 65.37 Silty claySG9 0.4 16 1.1 43 39 3.65 0.635 427 32 164 60 210 17.85 6.74 75.41 16.74 58.67 Gravelly

sedimentSG10 0.9 6 1 35 24 2.05 0.766 399 17 192 34 162 21.48 36.15 42.37 14.96 27.42 Gravelly

sedimentSG11 1 7 1.3 32 26 2.1 0.224 432 18 205 42 199 6.88 10.49 82.63 35.78 46.85 Silty claySG12 0.5 15 1.3 48 44 4.03 0.48 531 33 149 73 243 4.12 12.91 82.97 25.81 57.17 Silty claySG13 0.3 6 1.1 20 12 1.54 0.211 349 14 80 35 194 5.21 80.97 13.82 5.57 8.25 SandSG14 0.4 10 1.2 53 45 4.04 1.11 467 36 156 73 257 7.85 8.55 83.60 20.15 63.45 Silty claySG15 0.6 12 0.9 29 27 2.56 0.963 460 21 101 44 143 14.38 22.40 63.22 16.88 46.34 Gravelly

sedimentSG16 1.2 6 0.4 12 13 1.27 0.365 295 10 49 27 72 10.46 45.72 43.82 11.70 32.12 Gravelly

sedimentSG17 0.5 13 0.6 32 32 3.39 0.156 422 27 59 58 152 9.27 11.17 79.57 18.62 60.95 Sandy claySG19 0.5 11 1.5 52 72 3.45 8.63 623 32 135 55 443 0.13 8.53 91.34 17.17 74.17 Silty clay

Background(mg/kg)

20 25 <0.01 20 50 <60 130

D.M. 367/2003(mg/kg)

12 0.3 50 0.3 30 30

ER–L (mg/kg) 1 8.2 1.2 81 34 0.15 20.9 46.7 150ER–M (mg/kg) 3.7 70 9.6 370 270 0.71 50 218 410

F.Frontaliniet

al./Marine

PollutionBulletin

58(2009)

858–877

863

Fig. 4. Trace element (Ag, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn) distributions in the lagoon of Santa Gilla. Sampling stations are shown here as black dots.

864 F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877

2.27 (SG2), J from 0.25 (SG17) to 0.81 (SG12), D from 0.15 (SG2) to0.74 (SG11), E from 0.19 (SG5) to 0.81 (SG12), and 1-D from 0.26(SG17) to 0.85 (SG2). The Fisher a index ranges from 0.44 (SG14)to 5.18 (SG2), with mean values of 1.99 (Fig. 5 and Table 3).

In the investigated area, morphological abnormalities have beenobserved in all stations. The FAI varies from station to station,ranging from 4.5 (SG3) to 10.34 (SG4) with an average value of6.67. The FMI is between 30 (SG6) and 100 (SG12 and SG14)(Fig. 5 and Table 3). The deformities are mainly restricted to thespecies A. tepida, E. oceanensis, H. germanica, B. striatula, B. spathu-lata, B. variabilis, and R. globularis (Table 3). These species, there-fore, display morphological deformities in their tests which are

independent of their taxonomic affinities, mode of life, and testmorphotype. The living deformed assemblages are largely domi-nated by A. tepida (48.2% on average) and H. germanica (32% onaverage), and subordinately by E. oceanensis (11.7% on average)(Plates 1 and 2).

Following Alve (1991), Sharifi et al. (1991), Almogi-Labin et al.(1992) and Yanko et al. (1994, 1998), nine different modes ofdeformities have been recognized (1) aberrant chamber shapeand lack of sculpture, (2) double aperture, (3) abnormal growthof last chamber, (4) wrong coiling, (5) anomalous protuberance,(6) siamese twin, (7) high spire giving spiroconvex test, (8) addi-tional chamber and (9) poor development.

Tabl

e3

Faun

alpa

ram

eter

san

dre

lati

veab

unda

nce

ofse

lect

edsp

ecie

s.Th

eas

teri

skm

arks

indi

cate

that

the

spec

ies

affe

cted

bym

orph

olog

ical

abno

rmal

itie

s.FA

I=fo

ram

inif

eral

abno

rmal

ity

inde

xan

dFM

I=fo

ram

inif

eral

mon

itor

ing

inde

x.

Sam

plin

gst

atio

ns

SG1

SG2

SG3

SG4

SG5

SG6

SG7

SG8

SG9

SG10

SG11

SG12

SG13

SG14

SG15

SG16

SG17

SG19

Am

mon

iate

pida

*54

.02

26.1

961

.80

55.1

768

.95

55.0

157

.43

74.4

761

.81

68.3

084

.50

48.0

861

.32

56.8

543

.19

72.9

785

.06

80.3

8Bo

livin

adi

lata

ta2.

251.

540.

310.

000.

340.

000.

000.

000.

000.

000.

000.

000.

000.

000.

330.

000.

280.

00Bo

livin

asp

athu

lata

*4.

1821

.05

5.12

0.00

1.89

1.69

0.61

0.94

0.17

0.00

0.00

0.00

0.00

0.00

0.00

0.42

0.41

0.00

Boliv

ina

stri

atul

a*3.

2213

.35

1.71

0.00

0.51

1.95

0.61

0.47

1.22

0.00

0.00

0.00

0.00

0.00

0.00

0.84

0.00

0.00

Boliv

ina

vari

abili

s*0.

968.

341.

550.

000.

511.

172.

440.

470.

350.

120.

000.

000.

000.

002.

330.

420.

830.

00El

phid

ium

ocea

nens

is*

12.2

20.

7710

.56

15.5

24.

637.

670.

618.

9010

.94

1.11

8.47

6.49

16.7

62.

032.

6610

.08

0.83

17.3

1Fu

rsen

koin

apu

ncta

ta2.

892.

570.

933.

450.

170.

910.

610.

470.

000.

000.

000.

000.

000.

000.

000.

000.

140.

00H

ayen

sina

germ

anic

a*14

.47

3.08

11.6

518

.97

19.7

311

.05

33.8

112

.88

21.8

828

.99

6.55

45.4

314

.41

41.1

249

.17

13.7

312

.17

1.92

Qui

nque

locu

lina

cost

ata

0.00

1.16

0.16

0.00

0.86

2.08

0.61

0.00

1.04

0.00

0.16

0.00

5.44

0.00

0.33

0.00

0.00

0.00

Qui

nque

locu

lina

laev

igat

a0.

008.

221.

091.

720.

342.

600.

000.

470.

870.

610.

320.

000.

880.

000.

330.

420.

000.

00Q

uinq

uelo

culin

ase

min

ula

0.00

2.31

0.31

0.00

0.17

1.82

1.22

0.00

0.00

0.12

0.00

0.00

0.29

0.00

0.00

0.14

0.00

0.00

Ros

alin

agl

obul

aris

*2.

895.

523.

421.

721.

2010

.40

1.43

0.70

1.74

0.00

0.00

0.00

0.00

0.00

1.33

0.14

0.14

0.38

S(s

peci

esri

chn

ess)

1226

168

1520

1110

910

53

113

911

94

FD(f

oram

inif

eral

den

sity

)14

.26

12.7

314

.66

3.91

10.5

979

.12

26.9

236

.03

96.8

154

.56

50.9

446

.12

10.6

857

.86

10.5

272

.93

65.1

418

0.56

Fish

era

inde

x2.

485.

182.

972.

522.

813.

752.

001.

831.

511.

610.

740.

451.

860.

441.

751.

851.

450.

67D

(dom

inan

ce)

0.33

0.15

0.41

0.37

0.52

0.33

0.45

0.58

0.44

0.55

0.73

0.44

0.43

0.49

0.43

0.56

0.74

0.68

H(S

han

non

–Wea

ver

inde

x)1.

582.

271.

401.

331.

041.

681.

080.

891.

120.

760.

560.

891.

150.

771.

030.

910.

540.

581�

D0.

670.

850.

590.

630.

480.

670.

550.

420.

560.

450.

270.

560.

570.

510.

570.

440.

260.

32J

(eve

nn

ess)

0.63

0.70

0.51

0.64

0.39

0.56

0.45

0.39

0.51

0.33

0.35

0.81

0.48

0.70

0.47

0.38

0.25

0.42

E(e

quit

abil

ity)

0.40

0.37

0.25

0.47

0.19

0.27

0.27

0.24

0.34

0.21

0.35

0.81

0.29

0.72

0.31

0.23

0.19

0.44

FAI

4.82

5.13

4.50

10.3

47.

555.

599.

376.

326.

255.

286.

077.

376.

627.

366.

315.

325.

8110

.00

FMI

50.0

030

.77

37.5

037

.50

33.3

330

.00

45.4

550

.00

33.3

340

.00

60.0

010

0.00

36.3

610

0.00

33.3

336

.36

33.3

375

.00

No.

spec

imen

s31

177

964

458

583

769

491

427

576

814

626

339

680

394

301

714

723

260

F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877 865

Some morphological abnormalities co-occurred in the samespecimen (complex forms), making it impossible to determineeither which part of the test is affected or even the foraminiferaltaxon. Ammonia tepida shows a great morphological variability,and most of the specimens of this species are megalospheric andcharacterized by high spire.

The results of the trace element content in the porcelanaceoustests are reported in Table 4. For each sample (except for SG19),concentrations of Fe, Zn, Sr, Cd, Pb, Mn and Mg are measured andreported as against Ca. Normalization of the different trace ele-ments to calcium allows a direct comparison among samples char-acterized by a variable number of specimens and different weights.The analyzed trace elements in the porcelanaceous tests showgreat variability (Fig. 6). In particular, high concentrations of Fe(in all stations, excepted SG4) varying from 4756 to 22944 lmol/mol (mean 9351 lmol/mol), of Zn (in SG4, SG13 and SG14) rangingbetween 465.0 and 5217 lmol/mol (mean 1268 lmol/mol), of Pb(in SG2, SG11, SG10 and SG14) ranging between 26.3 and687 lmol/mol (mean 129 lmol/mol), and of Cd varying from 0.7to 3.8 lmol/mol (mean 1.5 lmol/mol) are recognized (Table 4).

X-ray diffraction and ESEM-EDS analyses of normal specimensof A. tepida collected in the studied area show that the tests aremade of calcite (Fig. 7a). Iron sulphides are represented by framb-oidal aggregates within the foraminiferal test (Fig. 7b). In the inter-nal chamber-surface, the deformed tests exhibit the occurrence ofnanoparticles and foreign elements including Ba and S (Fig. 7c),and La, Ce, Nd and S (Fig. 7d).

5.5. Statistics

A Pearson correlation matrix was constructed for geochemicaland sedimentological parameters, foraminiferal taxa, and bioce-notic parameters (Table 5). The sample SG4 is not considered inthe statistical analysis due to the low number of living specimenstherein.

Correlation analysis shows high coefficients among some traceelements such as Ag, Cd, Cr, Cu, Fe, Ni, Pb, V and Zn (Table 5). Theseresults indicate that such elements have a similar occurrence and asimilar pattern of distribution. This could be explained by thestrongly positive correlation between trace elements and mud con-tents. In particular, Cu, Ni, Pb, Zn, Cr, Fe and V are positively corre-lated with the percentage of finer fractions (silt and clay) in thesediment. In this way, our data confirms that trace element con-centrations are deeply influenced by sediment grain size and accu-mulate in muddy sediment.

Mud, silt and clay contents appear to negatively influence thedistribution of Q. costata and the diversity indices (S, H, and Fishera). On the other hand, the FD is negatively correlated with the sandcontent (Table 5). FAI and FMI show positive and significant corre-lation coefficients with most contaminants (Cd, Cu, Fe, Hg, Mn, Niand Zn). Species richness and the Fisher a index show a negativecorrelation with most of trace elements (Cd, Cr, Cu, Fe, Mn, Ni,Pb, V, and Zn) (Table 5).

The correlation matrix shows that there are significant correla-tions among foraminiferal species and trace elements (Table 5).Accordingly, R. globularis has a significant negative correlation withCd (�0.62) and Zn (�0.62), whereas B. spathulata correlates withMn (�0.64).

The Q mode cluster analysis results in the grouping of samplesinto two separate clusters (A and B) according to their degree ofpollution (Fig. 8). Cluster A (less polluted) includes stations locatednear the middle-outermost part of the lagoon, whereas Cluster B(most polluted) comprises samples located in the innermost partof the study area.

The PCA shows that �83% of data variance can be explainedby the first two principal components (factors). In particular,

Fig. 5. Distribution of the most abundant species (Ammonia tepida, Haynesina germanica and Elphidium oceanensis) and of the biocenotic parameters in the lagoon of SantaGilla. Sampling stations are shown here as black dots.

866 F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877

eigenvalues of component 1 (horizontally, 73.8 of inertia) andcomponent 2 (vertically, 9 of inertia) are 8.9 and 1.1, respectively.

Percentages of sand, silt, and clay, as well as contents of mosttrace elements, are the predominant elements in the first compo-nent, while the major contribution in the second is due to As andHg (Fig. 9).

By projecting onto the environmental components the plottedposition of the species and biocenotic parameters (as a secondaryor additional variable, without contributing to the results of theanalysis), it appears that most species are negatively affected bytrace element contents.

Ammonia tepida and H. germanica are the least affected speciesin the assemblages (Fig. 9). Moreover, a strongly positive relation-ship between FAI and FMI and most of the analyzed trace elementscan be highlighted, whereas a negative relationship is evidencedbetween the diversity indices and most of the trace elements(Fig. 9).

The PCA analysis bunched stations according to their environ-mental conditions, in approximately the same groups obtainedwith the Q mode cluster analysis (Fig. 10). Accordingly, those sta-tions localized on the left part of the plane (Group B) can be con-sidered to be heavily polluted, whereas those localized on the

Plate 1. SEM photomicrographs of the dominant foraminiferal taxa bearing different morphological abnormalities: (1) Elphidium oceanensis, aberrant chamber shape; (2)Ammonia tepida, abnormal additional chamber(s); (3) Elphidium oceanensis, distorted chamber arrangement and abnormal additional chamber; (4) Ammonia tepida, umbilicalview shows protuberances in the form of bulla-like chamber covering the umbilicus; (5) Ammonia tepida, Siamese twins; (6) Elphidium oceanensis, complex form; (7)Haynesina germanica, specimen with aberrant chamber shape and size; (8) Elphidium oceanensis, complex form; (9) Ammonia tepida, spiral view shows abnormal growth anddistorted chamber arrangement; (10) Elphidium oceanensis, specimen with aberrant chamber shape and size; (11) Ammonia tepida, megalospheric form; and (12) Elphidiumoceanensis, distorted chamber arrangement. Scale bar = 100 lm.

F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877 867

right part of the plane (Group A) are moderately affected by tracemetal pollution (Fig. 10).

6. Discussion

Sediment is the final host of contaminants in marine and tran-sitional-marine environments, and it can record sources and path-ways of pollution. However, trace elements may be recycled andtransformed through biological and chemical processes beforebeing incorporated into sediment (Campbell and Tessier, 1989;Degetto et al., 1997).

The lagoon of Santa Gilla has been strongly affected by traceelement pollution. In fact, it has received industrial discharges ofmercury, lead and zinc compounds, as well as municipal untreatedsewage, for several decades (Degetto et al., 1997). A restorationprogram was implemented in the mid-1980s to control the pollu-tion in the lagoon. It was estimated that during the 1960s–1970sabout 26 tons of inorganic Hg were released by an on-shorechlor-alkali plant, and high mercury concentrations in sediment,fish, and crustaceans were found nearby (Cottiglia et al., 1977).These results were also confirmed by further investigations (Sar-ritzu et al., 1982; Contu et al., 1983, 1984, 1985). Contu et al.

Plate 2. SEM photomicrographs of the dominant foraminiferal taxa bearing different morphological abnormalities: (1) Elphidium oceanensis, complex form; (2) Haynesinagermanica, specimen with aberrant chamber shape and size; (3) Elphidium oceanensis, complex form; (4) Ammonia tepida, spiral view shows abnormal additional chamber; (5)Elphidium oceanensis, specimen with aberrant chamber shape and size; (6) Haynesina germanica, specimen with aberrant chamber(s) shape and size; (7) Ammonia tepida,spiral view shows aberrant chamber shape; (8–10) Haynesina germanica, specimen with aberrant chamber shape and size; (11) Miliolinella subrotunda, specimen withaberrant shape of several chambers. Scale bar = 200 lm; (1–2) scale bar = 100 lm.

868 F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877

(1984) suggested that mercury was bound to the organic matterfraction. The same results for mercury, lead, copper, zinc and ironwere detected by Degetto et al. (1997) who also reported the back-ground values (mean concentration values observed in sedimentlayers relating to pre-industrial age) and Hg to be limited only inthe upper 10 cm of the sediment layer. Comparing trace elementcontents with these background concentrations, the lagoon resultsheavily enriched in Cr, Cu, Hg Ni, Pb and Zn. Furthermore, mercuryshows values which are up to 10 times higher than the backgroundlevel.

The comparison of the trace element concentrations to the na-tional guidelines legislation (D.M. 367/2003), the values reportedfor the USEPA’s sediment guidelines, and the background values(Degetto et al., 1997) show that the investigated lagoon resultsfrom moderately to severely contaminated by Hg, Zn, Pb, Ni and As.

The trace elements measured in the study area are comparableto the values reported for the industrial site at Bagnoli (Naples)(Romano et al., 2008) and those at the Granili dock (Naples harbor).They are, however, lower than those encountered in the Diaz dock(Naples harbor) (Ferraro et al., 2006).

Table 4Concentrations of selected trace elements in foraminiferal tests (values are reported in lmol/mol).

Station Fe/Ca(lmol/mol)

Zn/Ca(lmol/mol)

Sr/Ca(lmol/mol)

Cd/Ca(lmol/mol)

Pb/Ca(lmol/mol)

Mn/Ca(lmol/mol)

Mg/Ca(lmol/mol)

SG1 17493.8 830.6 1793.1 1.9 106.6 2530.0 104577.9SG2 22944.4 947.8 1635.7 2.7 686.8 2172.2 111711.2SG3 8033.4 603.7 1854.2 1.2 152.1 2033.3 114193.4SG4 n.a. 5216.8 2105.0 n.a. 72.3 3800.0 133014.7SG5 7133.0 612.2 2388.3 0.9 37.5 3961.1 109886.2SG6 8168.2 1093.4 2117.3 1.3 37.1 5317.1 103423.3SG7 11450.2 711.4 2023.3 1.2 43.7 7066.6 103179.4SG8 6251.9 811.1 2052.5 1.3 32.8 4116.6 102854.0SG9 5408.6 1268.6 2271.5 1.4 44.7 5837.4 106747.4SG10 9807.3 621.4 1673.6 1.8 224.4 3884.7 110906.2SG11 4755.6 608.2 1699.3 1.3 247.7 2927.8 110764.0SG12 10036.5 465.0 1617.6 1.5 111.5 3340.1 107559.8SG13 6572.9 2649.7 2164.7 1.9 77.4 7109.8 115290.4SG14 7036.1 2217.6 2106.4 3.8 227.5 6301.6 115347.8SG15 7812.5 1694.7 2247.3 1.2 39.9 6065.7 105806.3SG16 7444.3 559.1 2423.8 0.8 28.5 5354.8 104284.4SG17 9274.1 646.7 2165.7 0.7 26.3 6319.6 103641.5

Fig. 6. Mean molar ratio of selected trace element/Ca in porcelanaceous foraminiferal tests reported for each station of lagoon of Santa Gilla.

F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877 869

Yet, our values of Hg and Zn are higher than those mea-sured in the Goro lagoon (Coccioni, 2000). According to traceelement distributions and contents revealed by CA and PCA,the greatest degree of pollution is found in the innermost-mid-dle part of the lagoon, which corresponds to the stations lo-cated in front of the industrial complex. Pollution recorded inthis area (Cluster B) seems to be associated with the silty-clayfraction. This result is also confirmed by PCA, in which sandhas no statistical affinity with any variable such as pollutantsor foraminiferal species.

Numerous studies dealing with the relationships betweenforaminifera and pollution have considered trace elements to bean important parameter acting on benthic foraminiferal eco-sys-tems (e.g. Alve, 1991, 1995; Yanko et al., 1994, 1998; Coccioni,2000; Samir and El-Din, 2001; Armynot du Châtelet et al., 2004;Burone et al., 2006). Following on from this, we draw attention

to a possible control of these toxic elements on the foraminiferalcommunity composition and parameters, and the development oftest abnormalities within the surveyed area.

Most of the studies carried out in polluted environments haveshown that a lowering in density and diversity can be viewed asa measure of environmental stress on benthic foraminiferal com-munities caused by pollution (e.g. Schafer, 1973; Yanko et al.,1998). Increased pollution has also been reported as being thecause of a high number of individuals belonging to a few opportu-nistic species (Murray, 1973; Pearson and Rosenberg, 1976; Ellisonet al., 1986). It has been noted that as greater concentrations oftrace elements and other chemicals are discharged, the populationmay decrease, eventually leading to a barren area (Samir, 2000;Elberling et al., 2003; Ferraro et al., 2006). Despite the high pollu-tion conditions of the investigated lagoon, benthic foraminifera arenot so severely affected to disappear.

Fig. 7. Energy dispersal X-ray analyses show the qualitative elemental composition as measured in normal (a) and deformed (b–d) specimens of Ammonia tepida.

870 F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877

According to the PCA, low S, H and Fisher a index values werefound in stations more affected by trace element pollution. In fact,species richness and the Fisher a index show negative correlationwith most of trace elements (Cd, Cr, Cu, Fe, Mn, Ni, Pb, V, andZn). On the other hand, the statistical analysis highlights that thereis not a significant correlation between FD and trace element con-centrations, this could be explained considering that foraminiferalpopulation density may increase in the vicinity of sewage outfalls(Watkins, 1961; Tomas et al., 2000; Mojtahid et al., 2008).

The most abundant species are A. tepida, H. germanica, and E.oceanensis, which constitute more than 91% of the living assem-blages. Common species recognized in the lagoon are B. spathula-ta, B. striatula and B. variabilis. Our data show higher S in theoutermost part of the lagoon, which was probably favored by fas-ter water renewal and a reduced influence of urban discharges.On the other hand, the middle-innermost part, which is severelyinfluenced by freshwater input and industrial discharge, is char-acterized by an oligotipic assemblage, mainly represented by A.tepida, H. germanica, and E. oceanensis, in agreement with Zampiand D’Onofrio (1984). These authors, also, reported lower diver-sity values in recent assemblages from Santa Gilla when com-pared to those found in Holocenic sediments of the formerlagoon in the Gulf of Cagliari (Gandin, 1979). These very low-diversity assemblages, composed of forms which have differentmodes of life, are comparable to the Ammonia associations withH. germanica that are characteristic of lagoons along the Mediter-ranean coast (see Murray, 1991, 2006). These species tolerate awide range of environmental parameters (salinity, temperature,oxygen concentration) which are typical of marginal marine envi-ronments characterized by restricted conditions and decreasedmarine influence (Almogi-Labin et al., 1992; Debenay et al.,2000, 2005).

Ammonia tepida is the most abundant species in the lagoon. Ithas been found in shallow marine environments, lagoons and del-taic zones (Jorissen, 1988; Almogi-Labin et al., 1992; Coccioni,2000; Abu-Zied et al., 2008), and is known for its great tolerance

to chemical and thermal pollution, fertilizing products, and hydro-carbons (e.g. Setty and Nigam, 1984; Yanko and Flexer, 1991; Coc-cioni, 2000). It is even capable of supporting very pollutedenvironments and high concentrations of trace elements (e.g. Ferr-aro et al., 2006). Yanko et al. (1994) found that megalosphericforms of A. tepida was dominant at stations where the toxic tracemetal pollution was prevalent. Haynesina germanica, the secondmost abundant species throughout the study area, has been con-sidered by Armynot du Châtelet et al. (2004) and Stubbles et al.(1993) as a tolerant species to trace element pollution, and itsincreasing dominance is an indicator of stress environmentalconditions.

Bolivina genus, a taxon characterized by an infaunal microhab-itat, is particularly resistant to oxygen-depleted environments andis also recognized as an opportunistic and pollution tolerant taxon(Murray, 1991). Generally, taxa which are tolerant to oxygen defi-ciency are typical of muddy environments that sometimes containhigh amounts of organic carbon (Van der Zwaan et al., 1999). Thehigh frequency of A. tepida is normally accompanied by the pre-dominance of individuals with small test and large proloculus,the so-called megalospheric forms. Sexual reproduction would bethe most common mode of reproduction within these forms sinceit increases the genetic variability within a population, which isadvantageous under either fluctuating environmental conditionsor stress. The causes of stress can be multiple, including changesin salinity, nutrients and trace element pollution (Furssenko,1978). The occurrence of high numbers of megalospheric formswas recognized by Zampi and D’Onofrio (1984), who reported acomplete dominance thereof in dystrophic environments (Mac-chiareddu saltwork). This also accords with the culture experimentconducted by Bradshaw (1957).

Trace elements and stressful conditions can inhibit metabo-lisms and protein synthesis (Ganote and Van der Heide, 1987). Asa result, the organism may devote its energy to protecting itselfand, therefore, prefers mitosis to meiosis (Baserga, 1985). The highpercentages of A. tepida and their megalospheric forms recognized

Table 5Correlation matrix (Pearson). Values (p < 0.01, two-tailed test) in bold and (p < 0.05, two-tailed test) in italics.

Ag As Cd Cr Cu Fe Hg Mn Ni Pb V Zn Salinity

Ag 1.00As �0.43 1.00Cd �0.74 0.34 1.00Cr �0.74 0.61 0.87 1.00Cu �0.67 0.65 0.79 0.95 1.00Fe �0.79 0.70 0.75 0.94 0.95 1.00Hg �0.33 0.23 0.53 0.49 0.64 0.42 1.00Mn �0.59 0.36 0.69 0.60 0.65 0.65 0.48 1.00Ni �0.81 0.68 0.81 0.97 0.95 0.99 0.45 0.62 1.00Pb �0.51 0.34 0.86 0.84 0.74 0.70 0.35 0.55 0.76 1.00V �0.76 0.76 0.74 0.93 0.91 0.97 0.35 0.53 0.97 0.67 1.00Zn �0.80 0.47 0.95 0.94 0.90 0.85 0.60 0.64 0.91 0.80 0.85 1.00Salinity 0.34 0.39 �0.58 �0.17 �0.08 �0.01 �0.28 �0.35 �0.08 �0.37 0.03 �0.42 1.00DO (mg/l) �0.04 0.22 0.07 �0.02 0.10 0.11 0.04 0.09 0.08 0.00 0.15 0.05 �0.13Gravel 0.57 �0.05 �0.66 �0.54 �0.61 �0.51 �0.65 �0.44 �0.55 �0.43 �0.47 �0.71 0.57Sand 0.47 �0.57 �0.51 �0.66 �0.78 �0.76 �0.38 �0.62 �0.71 �0.50 �0.70 �0.56 �0.01Mud �0.39 0.54 0.54 0.77 0.87 0.83 0.40 0.47 0.81 0.64 0.77 0.64 0.11Silt �0.25 0.42 0.55 0.73 0.74 0.70 0.18 0.31 0.70 0.69 0.70 0.59 0.02Clay �0.42 0.57 0.51 0.76 0.88 0.84 0.45 0.50 0.81 0.59 0.77 0.63 0.15A. tepida �0.10 �0.44 0.06 0.00 0.07 0.05 0.10 0.12 0.03 0.06 �0.11 0.09 �0.44E. oceanensis �0.02 �0.29 0.01 �0.24 �0.18 �0.24 0.16 �0.24 �0.23 �0.21 �0.25 �0.04 �0.46H. germanica �0.22 0.04 0.04 0.10 0.00 0.21 �0.36 0.16 0.15 0.16 0.14 �0.05 0.23Q. laevigata 0.36 �0.02 �0.31 �0.34 �0.39 �0.44 �0.21 �0.36 �0.39 �0.25 �0.31 �0.36 0.19Q. costata �0.05 �0.21 �0.12 �0.40 �0.52 �0.44 �0.27 �0.12 �0.39 �0.24 �0.37 �0.23 �0.31R. globularis 0.58 0.11 �0.62 �0.56 �0.47 �0.51 �0.18 �0.41 �0.55 �0.57 �0.45 �0.62 0.52B. striatula 0.50 0.27 �0.46 �0.32 �0.31 �0.36 �0.20 �0.51 �0.34 �0.36 �0.20 �0.40 0.54B. dilatata 0.33 0.39 �0.33 �0.10 �0.15 �0.18 �0.13 �0.53 �0.15 �0.25 �0.01 �0.20 0.49B. spathulata 0.55 0.18 �0.52 �0.33 �0.32 �0.38 �0.23 �0.64 �0.36 �0.39 �0.22 �0.42 0.60B. variabilis 0.37 0.35 �0.40 �0.21 �0.19 �0.21 �0.18 �0.25 �0.20 �0.30 �0.10 �0.32 0.63F. punctata 0.50 0.25 �0.49 �0.31 �0.31 �0.35 �0.21 �0.49 �0.35 �0.43 �0.20 �0.39 0.56Q. seminula 0.46 �0.01 �0.39 �0.44 �0.42 �0.46 �0.19 �0.10 �0.46 �0.36 �0.37 �0.43 0.30FAI �0.47 0.24 0.57 0.45 0.55 0.50 0.61 0.74 0.49 0.46 0.41 0.57 �0.34FMI �0.40 0.19 0.63 0.59 0.62 0.59 0.43 0.46 0.56 0.48 0.59 0.61 �0.24S 0.60 �0.17 �0.74 �0.67 �0.69 �0.69 �0.44 �0.62 �0.67 �0.57 �0.63 �0.70 0.42FD �0.18 0.01 0.25 0.23 0.38 0.30 0.44 0.53 0.24 0.15 0.17 0.25 �0.24D �0.28 �0.25 0.31 0.28 0.35 0.32 0.23 0.36 0.31 0.29 0.16 0.34 �0.46H 0.45 0.12 �0.51 �0.48 -0.52 �0.50 �0.32 �0.53 �0.49 �0.47 �0.36 �0.52 0.481 � D 0.26 0.21 �0.31 �0.30 �0.37 �0.32 �0.24 �0.36 �0.32 �0.30 �0.19 �0.36 0.45E �0.39 0.41 0.54 0.51 0.50 0.52 0.30 0.36 0.49 0.35 0.61 0.49 �0.05J �0.05 0.38 0.09 0.09 0.05 0.10 0.00 �0.05 0.08 �0.02 0.25 0.04 0.28Fisher a 0.61 �0.10 �0.73 �0.65 �0.65 �0.67 �0.39 �0.62 �0.65 �0.57 �0.59 �0.69 0.47

DO (mg/l) Gravel Sand Mud Silt Clay A. tepida E. oceanensis H. germanica Q. laevigata Q. costata R. globularis B. striatula B. dilatata

AgAsCdCrCuFeHgMnNiPbVZnSalinityDO (mg/l) 1.00Gravel �0.29 1.00Sand �0.36 0.31 1.00Mud 0.22 �0.47 �0.79 1.00Silt 0.16 �0.38 �0.64 0.92 1.00Clay 0.23 �0.48 �0.81 0.99 0.85 1.00A. tepida 0.18 �0.45 �0.16 0.20 0.14 0.20 1.00E. oceanensis 0.46 �0.35 0.09 �0.24 �0.25 �0.24 0.34 1.00H. germanica �0.21 0.21 0.08 0.06 0.07 0.07 �0.08 �0.30 1.00Q. laevigata �0.14 0.52 0.21 �0.43 �0.36 �0.44 �0.63 �0.13 �0.43 1.00Q. costata 0.11 0.22 0.44 �0.73 �0.69 �0.71 �0.28 0.17 �0.09 0.51 1.00R. globularis 0.07 0.70 0.16 �0.43 �0.46 �0.40 �0.53 �0.01 �0.25 0.65 0.32 1.00B. striatula 0.02 0.61 0.18 �0.30 �0.25 �0.30 �0.67 �0.09 �0.41 0.77 0.21 0.79 1.00B. dilatata �0.12 0.41 0.26 �0.17 �0.07 �0.19 �0.54 �0.12 �0.25 0.31 �0.05 0.49 0.72 1.00B. spathulata �0.06 0.53 0.25 �0.26 �0.17 �0.28 �0.59 �0.14 �0.43 0.70 0.13 0.74 0.93 0.77B. variabilis �0.20 0.59 0.15 �0.13 �0.11 �0.12 �0.73 �0.50 �0.17 0.64 0.16 0.70 0.76 0.60F. punctata �0.10 0.60 0.21 �0.33 �0.25 �0.34 �0.55 �0.09 �0.33 0.50 0.08 0.75 0.87 0.83Q. seminula �0.09 0.56 0.25 �0.47 �0.45 �0.46 �0.59 �0.35 �0.28 0.76 0.51 0.71 0.68 0.22

(continued on next page)

F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877 871

Table 5 (continued)

DO (mg/l) Gravel Sand Mud Silt Clay A. tepida E. oceanensis H. germanica Q. laevigata Q. costata R. globularis B. striatula B. dilatata

FAI 0.36 �0.65 �0.36 0.38 0.21 0.42 0.20 �0.03 0.08 �0.46 0.02 �0.35 �0.49 �0.46FMI 0.22 �0.59 �0.47 0.51 0.52 0.48 0.15 0.14 0.14 �0.54 �0.48 �0.51 �0.42 �0.23S �0.23 0.71 0.54 �0.61 �0.56 �0.59 �0.36 �0.14 �0.25 0.71 0.46 0.74 0.72 0.46FD 0.23 �0.33 �0.58 0.36 0.16 0.41 0.49 0.14 �0.20 �0.24 �0.34 �0.26 �0.31 �0.55D 0.13 �0.62 �0.35 0.48 0.42 0.47 0.90 0.12 �0.03 �0.70 �0.45 �0.72 �0.80 �0.58H �0.07 0.69 0.41 �0.58 �0.51 �0.57 �0.77 �0.01 �0.14 0.75 0.48 0.84 0.88 0.621 � D �0.14 0.62 0.38 �0.50 �0.45 �0.49 �0.87 �0.08 0.13 0.63 0.45 0.70 0.73 0.52E 0.26 �0.34 �0.38 0.33 0.34 0.32 �0.32 0.08 0.20 �0.20 �0.22 �0.22 �0.10 �0.01J 0.16 0.17 �0.02 �0.11 �0.07 �0.12 �0.73 0.07 0.18 0.26 0.13 0.34 0.42 0.33Fisher a �0.20 0.71 0.51 �0.59 �0.55 �0.58 �0.46 �0.14 �0.27 0.74 0.44 0.80 0.78 0.54

B. spathulata B. variabilis F. punctata Q. seminula FAI FMI S FD D H 1 � D E J Fisher a

AgAsCdCrCuFeHgMnNiPbVZnSalinityDO (mg/l)GravelSandMudSiltClayA. tepidaE. oceanensisH. germanicaQ. laevigataQ. costataR. globularisB. striatulaB. dilatataB. spathulata 1.00B. variabilis 0.77 1.00F. punctata 0.89 0.69 1.00Q. seminula 0.62 0.72 0.57 1.00FAI �0.49 �0.29 �0.45 �0.10 1.00FMI �0.40 �0.53 �0.26 �0.43 0.48 1.00S 0.74 0.70 0.63 0.67 �0.53 �0.87 1.00FD �0.48 �0.49 �0.42 �0.20 0.28 0.35 �0.49 1.00D �0.71 �0.68 �0.71 �0.68 0.33 0.29 �0.58 0.52 1.00H 0.82 0.72 0.80 0.72 �0.45 �0.47 0.76 �0.53 �0.95 1.001 � D 0.64 0.62 0.65 0.63 �0.31 �0.27 0.55 �0.53 �0.99 0.93 1.00E �0.17 �0.25 �0.08 �0.18 0.31 0.84 �0.69 0.19 �0.15 �0.07 0.16 1.00J 0.33 0.21 0.40 0.28 �0.02 0.39 �0.10 �0.20 �0.72 0.56 0.74 0.77 1.00Fisher a 0.81 0.75 0.71 0.71 �0.51 �0.81 0.99 �0.52 �0.66 0.83 0.63 �0.59 0.02 1.00

872 F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877

in the lagoon of Santa Gilla appear to be related to the stress con-ditions occurring there.

The assemblages of the Santa Gilla lagoon are characterized by ahigh number of abnormalities, probably in response to the anthro-pogenic discharge of pollutants and/or fluctuating environmentalparameters, as also reported by Zampi and D’Onofrio (1984). Thehighest FAI values are identified at stations SG4 and SG19, locatedin front of the city of Cagliari and close to the industrial complex atMacchiareddu, respectively. On the basis of CA and PCA, two mainGroups (A and B) have been identified. The less affected Group Ashows lower values of FAI than group B, which includes those sta-tions located in the middle-innermost part of the investigatedlagoon.

Stouff et al. (1999) observed about 1% of abnormal tests in lab-oratory cultures of Ammonia under normal conditions, whereasMorovan et al. (2004) found 1.75% of abnormal tests in a monospe-cific culture of A. tepida living in an unpolluted microcosm with

35‰ salinity. Following Alve (1991), the threshold at the level of1% of total abnormal tests in a non-stressed population has beenselected. These values are lower than those found in the lagoonof Santa Gilla, where FAI ranges from 4.50 (SG3) to 10.34 (SG4)with an average value of 6.7.

Deformities are mainly restricted to the species A. tepida, E.oceanensis, H. germanica, B. striatula, B. spathulata, B. variabilis,and R. globularis. According to Geslin et al. (1998), abnormalitiesin hyaline specimens seem to be related to imperfect biominerali-zation. This may be due to the development of cavities in the wall,or to disorganization in the pattern of crystallites. The cause of thisdisorganization could be linked to pollution and/or environmentalstress. Regenerations after mechanical damage or dissolution ofthe test may lead to deformities. Our specimens do not, however,exhibit any scars or signs of regeneration.

Trace element concentrations in foraminiferal calcite have lar-gely been documented and their values have also been summarized

Fig. 8. Dendrogram classification of stations produced by Q mode cluster analysis using Euclidean distance.

F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877 873

by Lea (1999). Compared to tests of normal individuals collected inboth a non-industrialized site (Capitana, Gulf of Cagliari) and a pol-luted area (Portoscuso, Southern west Sardinia), porcelanaceousforaminiferal tests have higher Mg/Ca values (Cherchi et al., 2008)(Table 6). Increases of Mg/Ca values are generally attributed to cal-cification of shells in warm waters (Lea, 1999) as well as to the pres-ence of trace elements (Yanko et al., 1999). Several studies havereported enhanced Mg/Ca ratios in abnormal foraminifera, espe-cially in severely polluted areas (Sharifi et al., 1991; Yanko andKronfeld, 1993). The increased Mg concentration in abnormal testsmight suggest that trace elements directly affect the crystal struc-ture of the calcite shell and/or foraminiferal cytoskeleton. More-over, the trace element toxicity affects the foraminiferalmetabolism in ways that indirectly influence Mg/Ca ratios during

Fig. 9. PCA ordination diagram of sampling based on the selected trace elements.

calcification. Other cations (e.g. Ba and Cd) can also be included inthe crystal structure of the test (Lea and Boyle, 1989). It is likely thatbiochemical transport systems and sites for the Ca2+ binding cannoteasily distinguish between these ions. Foraminiferal tests in theSanta Gilla lagoon show concentrations of Fe, Mn, Pb and Zn whichare more than one order of magnitude greater than those collectedat Capitana (Table 6, Fig. 11), while Sr content, which is also depen-dent on temperature, is lower. Moreover, the concentration of Mn ishigher than Portoscuso, Fe, Pb and Sr are lower, while Zn is the samein the two areas. This introduction of alien elements into the crys-talline framework during calcification may produce a crystallinedisorganization leading, ultimately, to test abnormalities.

Sharifi et al. (1991) conducted a set of culturing experimentswhich revealed higher concentrations of trace elements (in partic-ular Cu and Zn) in deformed specimens than in their non-deformedcounterparts. Enhanced concentrations of Cd, Co, and Pb werefound in abnormal specimens of Ammonia by Banerji (1992), whoalso observed that Cu, Zn and Cr are better absorbed in foraminif-eral tests than Ni and Pb. Saraswat et al. (2004) cultured juvenilespecimens of Rosalina leei that had been exposed to different Hgconcentrations (0–180 ng/l) and documented the adverse effectof this element on both the normal functioning of the foraminifers’cytoplasm and on the addition of abnormal chambers. The absorp-tion of Pb by foraminifera is very limited, whereas, Cu, followed byZn and Cr are more easily absorbed, regardless of their concentra-tions in the sediment (Samir and El-Din, 2001). This could be ex-plained by following the sequence of complex stability (Irvingand Williams, 1948), where Pb has the greatest ability to make sta-ble complexes such as lead carbonate. Goldberg (1965) highlightedthat the ability of marine organisms to concentrate metals gener-ally follows the Irving–Williams succession. Moreover, Pb2+ is thelargest when compared to Cu2+, Zn2+ and Cr2+ ions. Consequently,Pb2+ will be absorbed the least by marine organisms such as foram-inifera. This confirms what was found in the Santa Gilla lagoon,where the concentration of Pb in shells is lower than Zn, whilethe sediment concentration is higher. The increase of Zn concentra-tion could be due to short-term increases in the disposal of house-hold detergent products, since most enzyme detergents containamounts of Zn, Fe, and Mn. These authors suggest that the relation-ship between pollution and foraminifera is rather difficult to

Fig. 11. Comparison of mean molar ratio of selected trace element/Ca in porcelanaceous foraminiferal tests from the polluted lagoon of Santa Gilla, the unpolluted area ofCapitana and the industrial polluted area of Portoscuso.

Table 6Trace element concentrations in foraminiferal calcite. Values reported from the unpolluted area of Capitana, the polluted industrial area of Portoscuso. Cherchi et al. (2008), andthe lagoon of Santa Gilla. The values quoted for benthic foraminifera are the normal observed ranges of shell abundance by Lea (1999).

Capitana Portovesme–Portoscuso Santa Gilla Benthic foraminifera

Mean Max Min Mean Std. dev. Max Min Mean Std. dev. Min Max

Mg (lmol/mol Ca) 39814.9 127238.1 97967.7 111206.5 14833.7 133014.7 102854.0 109599.3 7428.5 500.0 10000.0Cd (lmol/mol Ca) 0.3 40.6 3.7 20.6 18.6 3.8 0.7 1.5 0.8 0.02 0.25Fe (lmol/mol Ca) 4387.1 21989.2 7031.4 15268.9 7593.4 22944.4 4755.6 9351.4 4687.4 <0.1Mn (lmol/mol Ca) 158.8 1490.2 571.1 1093.2 472.1 7109.8 2033.3 4596.4 1694.5 1.0 500.0Pb (lmol/mol Ca) 5.6 1900.1 322.2 862.0 899.2 686.8 26.3 129.2 162.1 n.a. n.a.Sr (lmol/mol Ca) 4208.6 4628.4 3737.6 4157.2 447.6 2423.8 1617.6 2020.0 261.3 900.0 1600.0Zn (lmol/mol Ca) 38.3 1804.1 996.1 1322.2 425.9 5216.8 465.0 1268.1 1190.8 1.5 6.0

Fig. 10. Scatter diagram plotting factor 1 and factor 2 of sampling stations.

874 F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877

F. Frontalini et al. / Marine Pollution Bulletin 58 (2009) 858–877 875

understand, because the pollutant being discharged into an envi-ronment and its effect on disparate species is very different. In fact,pollutants which may be favorable for some species could, at thesame time, be harmful to others.

More recently, Romano et al. (2008) analyzed the chemicalcomposition of Miliolinella subrotunda, which shows the presenceof Fe ions in deformed specimens. Although the percentage of M.subrotunda was not correlated to Fe concentrations in sediments,they suggested that pollution could be the cause of this foraminif-eral response. Our analysis, which has been performed on the innerpart of the chamber test, differs significantly from that of theseauthors who analyzed the surficial chemical composition of theforaminiferal test. The presence of nanoparticles, including Feand S, Ba and S, and La, Ce and Nd, is observed in abnormal spec-imens. According to Geslin et al. (1998), the occurrence of foreignelements or nanoparticles within foraminiferal tests may interferewith the crystalline organization of carbonate tests. Iron sulphidesare represented by framboidal aggregates of pyrite. Framboidaltexture (basically a spherically packed aggregate of microcrystals)is one of the principal occurrences of pyrite in sedimentary envi-ronments (Schoonen, 2004; Merinero et al., 2008). The main reasonfor sulphidization of foraminiferal tests has not yet been estab-lished. It might, however, be related to the metabolization of or-ganic matter, under anaerobic conditions, by sulphate-reducingbacteria, the diffusion of sulphate into sediments, the concentra-tion and reactivity of the iron minerals, and the production ofelementary sulphur (Kravchuk, 2006). The pyritization of forami-niferal tests in oxygenated sediments may also occur in responseto trace element contamination (Alve, 1991; Yanko et al., 1994,1999; Buzas-Stephens and Buzas, 2005). The presence of sulphurin deformed foraminifera was also observed by Le Cadre and Deb-enay (2006), who suggested that foraminifera could have a detox-ification mechanism with metallothionein. Metallothionein is afamily of cysteine-rich, low molecular weight proteins which havethe capacity to bind trace elements through the thiol (–SH) groupof its cysteine residues and thus decrease the toxic effect of traceelements (Amiard et al., 1989; Kumari et al., 1998; Ngu and Still-man, 2006). It can also act as a scavenger of free radicals andreactive oxygen metabolites (Bresler and Yanko, 2000). The accu-mulation of trace elements such as Cd, Ba and Mn in foraminiferaltests has been described by many scientists (e.g. Boyle, 1981; Leaand Boyle, 1989). It has been postulated that these trace elementsare associated with the organic shell material and their accumula-tion may be a result of molecular and ionic mimicry (Langer andGehring, 1993; Bresler and Yanko, 2000).

7. Conclusion

The present study has been conducted in order to evaluate thedegree of pollution and its influence in the benthic foraminiferalcommunity in the Santa Gilla lagoon. The surveyed transitionalarea is particularly affected by trace element content, mainly byCr, Cu, Hg, Ni, Pb and Zn. Mercury shows values up to 10 timeshigher than the background level. High trace element concentra-tions in surface sediment apparently depend on their accumulationin the muddy sediment from previous decades. The PCA and Qmode cluster analysis, based on sediment geochemistry, reveal amarked separation between the more and less polluted samplingsites. The innermost part of the lagoon (industrial complex at Mac-chiareddu–Grogastu) shows trace element concentration valuesthat are, generally, higher than the USEPA ER–L levels. They arealso higher than ER–M for Zn and Hg, indicating a possible impor-tant influence of these toxic elements on the benthic ecosystem.The oligotipic assemblage and the occurrence of abnormalities,particularly emphasized in the innermost part of the lagoon, testify

an important chemical stress in this area which is determined bytrace elements. In contrast, high diversity values and lower per-centages of abnormality are recognized in the outermost partwhich is probably favored by faster water renewal and the reducedinfluence of urban discharge. This reflects a limited influence oftrace element concentrations in the sediment. Analysis of trace ele-ments in biogenic carbonate of porcelanaceous foraminifera re-veals higher concentrations than those reported in unpollutedenvironments. Accordingly, this kind of analysis must be evaluatedas being a powerful tool for an assessment of the ecotoxicologicalrisk determined by inorganic contaminants in marine and transi-tional-marine environments.

The presence of nanoparticles, including Fe and S, Ba and S, andLa, Ce, Nd and S in abnormal specimens of A. tepida, is also ob-served. Iron sulphides are mainly represented by framboidal aggre-gates of pyrite. The main reason for sulphidization of foraminiferaltests has not yet been established. It can, however, be related toeither the metabolization of organic matter under anaerobic condi-tions by sulphate-reducing bacteria, or to a detoxification mecha-nism with metallothionein.

Acknowledgments

The authors warmly thank Charles Sheppard (Chief Editor) andan anonymous reviewer for their criticism and helpful suggestions,which greatly improved the manuscript. The authors are verygrateful to Prof. Myriam Del Rio (Earth Sciences Department ofthe University of Cagliari) for providing assistance in the laboratoryprocessing and for her useful discussions. The authors are, also,grateful to CINSA (Interdipartimental Center of Environmental Sci-ences – University of Cagliari) for making available its LAMP re-search laboratories and to Cooperativa Pescatori of Santa Gillalagoon to collaborative assistance during the sampling. This is Pub-lication No. 31 of the Sezione di Geobiologia of the UrbinoUniversity.

Appendix A. Supplementary material

Supplementary data associated with this article can be found, inthe online version, at doi:10.1016/j.marpolbul.2009.01.015.

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