Isotopic signatures (δ18O and δ13C) of bivalve shells from cold seeps and hydrothermal vents

Geobios 42 (2009) 209–219

Original article 18

Isotopic signatures (d O and d13C) of bivalve shells from cold seeps and hydrothermal vents§ Signature isotopique (d18O et d13C) de coquilles de bivalves de suintements froids et de sources hydrothermales Cécile Lietard *, Catherine Pierre UMR 7159, laboratoire d’océanographie et du climat, expérimentation et approches numériques (LOCEAN), université Pierre-et-Marie-Curie, case 100, 4, place Jussieu, 75252 Paris cedex 05, France Received 25 April 2008; accepted 4 December 2008 Available online 6 February 2009

Abstract The oxygen and carbon isotopic compositions of 108 modern shells of various bivalve species collected from cold seeps and hydrothermal vents were investigated in order to evaluate whether these parameters can provide information on environmental geochemical variability as well as on bivalve species and on the type of symbiotic bacteria present in their gills. The results show that the carbonate of bivalve shells from hydrothermal vents is characterized by abnormal positive d13C values due to kinetic isotope effects, whereas the carbonate of bivalve shells from cold seeps exhibits positive as well as negative d13C values suggesting that oxidized methane emitted by the seeping fluids may be incorporated in the shell. Comparison of the d18O and d13C values of bivalve shells hosting different chemosymbiotic bacteria suggests that each type of symbiosis is associated with a specific environment and bivalve species, indicating that there is a strong physiological/metabolic control on the incorporation of stable isotopes during the biomineralization process. # 2009 Elsevier Masson SAS. All rights reserved. Keywords: Oxygen; Carbon; Stable isotopes; Bivalve shells; Cold seeps; Hydrothermal vents

Résumé Les compositions isotopiques de l’oxygène et du carbone de 108 coquilles de bivalves vivants d’espèces variées, prélevées au niveau de sites de suintements froids et au niveau de sources hydrothermales, ont été analysées dans le but d’évaluer si ces paramètres pouvaient fournir des informations sur la variabilité géochimique de l’environnement ainsi que sur l’espèce de bivalve et le type de bactéries symbiotiques présent sur leurs branchies. Cette étude montre que le carbonate des coquilles de bivalves provenant des sources hydrothermales est caractérisé par des valeurs de d13C anormalement positives dues à des effets cinétiques, tandis que le carbonate des coquilles de bivalves provenant des sites de suintements froids montre aussi bien des valeurs de d13C positives que négatives ce qui suggère que le méthane oxydé issu des fluides qui sont émis au niveau du fond marin peut être incorporé dans la coquille. La comparaison des analyses de d18O et de d13C de coquilles de bivalves portant des bactéries chimiosymbiotiques différentes permet de suggérer que chaque type de symbiose est associé à un environnement et à une espèce de bivalve spécifique, ce qui indique un fort contrôle physiologique/métabolique sur l’incorporation des isotopes stables au cours du processus de biominéralisation. # 2009 Elsevier Masson SAS. Tous droits réservés. Mots clés : Isotopes stables ; Oxygène ; Carbone ; Coquilles de bivalves ; Suintements froids ; Sources hydrothermales

1. Introduction §

Corresponding editor: Gilles Escarguel. * Corresponding author. 13, rue du Chemin-Vert, 78610 Les Bréviaires, France. E-mail address: [email protected] (C. Lietard).

Bivalves are prominent members of the benthic communities that inhabit cold seeps and hydrothermal vents. They live close to venting fluids and their survival is based on symbiosis with chemosynthetic bacteria (Distel and Felbeck, 1987;

0016-6995/$ – see front matter # 2009 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.geobios.2008.12.001

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Fiala-Médioni, 1984; Fiala-Médioni and Felbeck, 1990). Bivalve shells are precipitated from marine bottom waters, the temperature and geochemistry of which may be locally and strongly modified by the seeping fluids. The carbonate composition of bivalve shell is thus able to register modification of the deep sea parameters such as the isotopic characteristics of their surrounding environment (Killingley and Berger, 1979; Schöne and Giere, 2005). The present study investigates the oxygen and carbon isotopic compositions (d18O, d13C) of a total of 108 modern specimens of bivalve shells, collected using submersibles at various cold seeps and hydrothermal vents in the Atlantic Ocean, the Pacific Ocean and the Mediterranean Sea (Fig. 1). The oxygen isotopic composition of a carbonate shell is mainly controlled by the ambient temperature and d18O composition of the seawater in which precipitation takes place (Epstein et al., 1953). The carbon isotopic composition of a carbonate shell depends on seawater dissolved inorganic carbon, metabolic dissolved inorganic carbon and, in some cases, of carbone derived from oxidation of methane (Hein et al., 2006; Lorrain et al., 2004; Romanek et al., 1992). Today, there is no simple and reliable model to interpret the d18O and d13C variations observed in carbonate shells. Several previous studies have been undertaken on bivalve shells from cold seeps and hydrothermal vents (Rio et al., 1988, 1992; Schöne and Giere, 2005; Hein et al., 2006), but no comparisons were realized between these two environments or between bivalve species. In this study, we present such a comparison for the first time, focusing on the nature of venting (i.e. cold seeps versus hydrothermal vents), the calcium carbonate mineralogy (i.e. calcite versus aragonite), the type of symbiotic bacteria present in bivalve gills (methanotrophic and/or sulfideoxidizing bacteria), the bivalve genus and the site location. The principal objective is to examine the d18O and d13C data set from these bivalve shells in order to extract information on the geochemical environmental variability of cold seeps and

hydrothermal vents, as well as on biological deep-sea bivalve characteristics. This first attempt to calibrate the ‘‘bivalve shell tool’’ on modern specimens is also important for its increasing use on fossil systems. A large number of ancient deep-sea cold seep sites have already been identified (Campbell, 1992; Campbell and Bottjer, 1995; Taviani, 2001; Peckmann et al., 2002). The use of the isotopic composition of carbon to identify such fossil ecosystems is so already established, based on the presence of 13C-depleted authigenic carbonates (Majima et al., 2005; Mae et al., 2007). Through our study, we hope to access to more environmental, chemical or biological information concerning these ecosystems. 2. Materials and methods One hundred and eight bivalve shells were collected alive or recently dead directly on the seafloor using submersibles, during 18 oceanographic cruises at 15 cold seeps sites and 12 hydrothermal sites (Fig. 1; Tables 1 and 2; Appendix A). Four bivalve genera, Bathymodiolus, Calyptogena, Vesicomya and Lucina, were studied as they represent the most common bivalves from the deep sea megafauna found in hydrothermal and cold seep sites (Fig. 2; Tables 1 and 2; Appendix A). Lucina, Calyptogena and Vesicomya harbor sulfide-oxidizing bacteria, whereas Bathymodiolus harbors methanotrophic and/or sulfide-oxidizing bacteria (Bergquist et al., 2004; Dubilier et al., 1998; Duperron et al., 2005; Fiala-Médioni et al., 1986, 1994, 2002; Olu et al., 1996; Pond et al., 1998; Van Dover, 2000; Von Cosel et al., 1994; Von Cosel and Olu, 1998, Table 3). Sample preparation: All shells were cleaned with H2O2 in a neutral pH solution in order to remove organic matter, commonly called periostracum. In the median part of the shell (in the length interval of 1–2 cm from the umbo to 1–2 cm from the ventral margin) and only in the outer layer of the shell, an aliquot of 50 mg of carbonate powder was removed with a dental drill (Fig. 2). The carbonate powder was analyzed by XRD to determine the mineralogy of the carbonate shells. Calyptogena and Lucina genera are mostly composed of aragonite, whereas Vesicomya and Bathymodiolus are calcitic (Blanc-Valleron, personal communication, Table 3). Stable isotope compositions of carbonate samples were measured on the CO2 obtained by conventional acid digestion with 100% orthophosphoric acid at 25 8C. The CO2 was analyzed by means of a dual inlet-triple collector mass spectrometer VG-SIRA 9. The oxygen and carbon isotopic compositions (d18O and 13 d C) are expressed in the conventional d notation and reported in % relative to the international reference V-PDB (Craig, 1957): d% V-PDB ¼

Fig. 1. Location of the studied sites. Empty circles: cold seeps; filled circles: hydrothermal vents. Localisation des sites étudiés. Cercles vides : suintements froids ; cercles pleins : sources hydrothermales.

ðR sample  R referenceÞ  1000; ðR referenceÞ

where R is the isotopic ratio of heavy to light oxygen and carbon isotopes: 18O/16O and 13C/12C. The analytical precision (2s) is  0.083% for d18O and  0.059% for d13C.

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Table 1 Information on studied samples of bivalves from cold seeps: locations, oceanographic cruises, date of collection, species, oxygen and carbon isotope compositions (see Appendix A1 for sample details). Localisation des e´chantillons, campagnes oce´anographiques, date de collecte, espe`ce de bivalve, compositions isotopiques de l’oxyge`ne et du carbone et nombres d’e´chantillons e´tudie´s pour les sites de suintements froids (voir annexe A1 pour les de´tails). Oceanographic cruise

Sample location

Sites

Bivalve species

Number of specimens

d18O (%) min–max

d13C (%) min–max

Diapisub 1992–1993

Barbados

Orenoque A Orenoque B El Pilar

Bathymodiolus boomerang Bathymodiolus sp. Vesicomya sp.

17

3.5 to 4.5

9.4 to 2.7

Manon 1992

Barbados

Manon Mount Atalante volcano

Calyptogena sp.

2

3.6 to 3.7

0.2 to 0.3

Kaiko Nankai 1989

Nankai Trough

Japan Trough Yuki Ridge S

Calyptogena sp. Calyptogena laubieri

2

3.4 to 4.0

0.6 to 0.8

Nautiperc 1991

Peru Trough

Paita site no. 8 Paita site no. 13

Calyptogena sp.

5

3.3 to 4.0

0.3 to 1.6

Gulf of Mexico 1995

Gulf of Mexico

GC 272 site Brine Pool

Bathymodiolus childressi Vesicomya sp.

2.6 to 4

7.3 to 3

Biozaire 2003–2004

Gulf of Guinea

R8 station/Regab

Calyptogena sp.

4

3.8 to 4.0

0.7 to 1.2

Medinaut 1998

Mediterranean Sea

Kazan mud volcano

Myrtea aff. amorpha

8

2.0 to 3.4

10.2 to 1.9

Nautinil 2003

Mediterranean Sea

Amon mud volcano Pockmark province

Myrtea aff. amorpha

11

1.8 to 2.6

1.9 to 2.5

Bionil 2006

Mediterranean Sea

Amon mud volcano

Myrtea aff. amorpha

4

2 to 3.2

0.7 to 3.5

17

Table 2 Information on studied samples of bivalves from hydrothermal vents: locations, oceanographic cruises, date of collection, species, oxygen and carbon isotope compositions (Appendix A2 for sample details). Localisation des e´chantillons, campagnes oce´anographiques, date de collecte, espe`ce de bivalve, compositions isotopiques de l’oxyge`ne et du carbone et nombres d’e´chantillons e´tudie´s pour les sources hydrothermales (annexe A2 pour les de´tails). Oceanographic cruises

Sample location

Sites

Bivalve species

Galápagos 1988

Galápagos

Rose Garden

Bathymodiolus thermophilus Calyptogena magnifica

Hot 1996

98N Pacific

Biovent

Bathymodiolus thermophilus

d18O (%) min–max

d13C (%) min–max

2

3.4

2.2 to 2.9

6

4 to 4.4

2.1 to 3.9

Number of specimens

Hope 1999

98N Pacific

Biovent

Bathymodiolus thermophilus

1

4.1

4

Oasis 1982

EPR 218N

218N

Calyptogena magnifica

2

3

1.9 to 3.7

Biolau 1989

Lau Basin/Fiji Isles

Hine Hina Vaillili Field

Bathymodiolus brevior

2

3.7 to 3.8

3.4 to 3.6

Bioaccess 1996

Manus Back-Arc Basin

Desmos

Bathymodiolus brevior

7

3.8 to 4.6

2.8 to 3.4

Yokosuka 1991

South western Pacific

Sunset

Bathymodiolus brevior

3

2.8 to 3.7

2.1 to 3.7

White Lady

Bathymodiolus elongatus

Diva 1994

Mid-Atlantic Ridge

Lucky-Strike (Tour Eiffel) Lucky-Strike (Elisabeth) Menez Gwen

Bathymodiolus azoricus

4

2.7 to 3.6

3.4 to 4.2

Marvel 1997

Mid-Atlantic Ridge

Menez-Gwen (PP32) Lucky-Strike (PP24) Lucky-Strike (Elisabeth)

Bathymodiolus azoricus

11

2.9 to 3.6

3 to 4.4

Environmental data (temperature, d18O and d13C of bottom seawater) available from the literature (Table 4) were used to determine the theoretical d18O and d13C values of the carbonate precipitated in isotopic equilibrium with the ambient seawater.

The calcite paleotemperature equation of O’Neil et al. (1969) was used to estimate the model d18O values of calcitic bivalve shells: 1000 lns ¼ 2:78 ð106 T 2 Þ  3:39;

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Fig. 2. Photographs of some of the bivalve shell collected from cold seeps and hydrothermal vents. The scale bar is 1 cm. Photographies de quelques coquilles de bivalves provenant de sites de suintements froids et de sources hydrothermales. La barre d’échelle représente 1 cm.

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Table 3 Mineralogy, environment and symbiotic bacteria of each bivalve genus. Mine´ralogie, environnement et bacte´ries symbiotiques de chaque genre de bivalve. Genus

Species

% aragonite

Lucina

Myrtea aff. amorpha

96

Calyptogena

Calyptogena sp.

% calcite

Chemosymbiotic bacteria

Environment

4

Sulfide-oxidizing bacteria

Cold seeps

75

25

Sulfide-oxidizing bacteria

Cold seeps

Vesicomya

Vesicomya sp.

0

100

Sulfide-oxidizing bacteria

Cold seeps

Bathymodiolus

Bathymodiolus boomerang Bathymodiolus sp.

0

100

Sulfide-oxidizing bacteria and methanotrophic bacteria

Cold seeps

Bathymodiolus

Bathymodiolus childressi

0

100

Methanotrophic bacteria

Cold seeps

Calyptogena

Calyptogena magnifica

75

25

Sulfide-oxidizing bacteria

Hydrothermal vents

Bathymodiolus

Bathymodiolus azoricus

0

100

Sulfide-oxidizing bacteria and methanotropic bacteria

Hydrothermal vents

Bathymodiolus

Bathymodiolus thermophilus Bathymodiolus brevior Bathymodiolus elongatus

0

100

Sulfide-oxidizing bacteria

Hydrothermal vents

Table 4 Environmental data set from cold seeps and hydrothermal vent sites. Donne´es environnementales des sites de suintements froids et des sources hydrothermales. d18O bottom seawater % SMOW

d13C bottom seawater % PDB

Barbados

–0.15

1

Japan Trough Peru Trough Gulf of Mexico Gulf of Guinea Mediterranean Sea EPR 218N

Estimated  0 0.16 1.7 0.2 1.50 0

0 – 0.63 0.7 1.15 0

EPR 89N Galapagos rift Lau Basin

Estimated  0 Estimated  0 0–0.7

Estimated  0 Estimated  0 Estimated  0

1.8 1 2

8.7 a 1 to 6a 2 to 19

Fiji Basin Atlantic rise

0.45 0.2

Estimated  0 1

2.2 3

2.5 to 4.4a 6 to 30

a

Bottom seawater temperature 8C 2.1 1.3 to 1.8 2 6.3 2.6 13 2

Seawater temperature close to bivalve colony 8C

References

2.4 to 20.4

Craig and Gordon, 1965; Kroopnick, 1985; Le Pichon et al., 1990; Godon et al., 2004 Sakai et al., 1992; Tsunogai et al., 2002 Suess et al., 1988; Aquilina et al., 1997 Aharon et al., 1992; Hackworth, 2005 Pierre and Fouquet, 2007; Pierre pers. com. Pierre, 1999 Lloyd, 1967; Rio et al., 1992; Kennish and Lutz, 1999; Van Dover, 2000 Mills et al., 2007 Cruise report Lécuyer et al., 1999; Desbruyères et al., 1994; Hardivillier, 2005 Koschinsky et al., 2002; Schöne and Giere, 2005 Craig and Gordon, 1965; Kroopnick, 1985; Von Cosel et al., 1999

1.19 to 1.8 Above 2 6.3 to 6.9a Above 2.6 Up to 70 8C in venta 2 to 14.5

Seawater temperature measured during cruises (cruise report).aTempérature de l’eau de mer mesurée au cours des campagnes océanographiques.

where T is the seawater temperature expressed in ˚K and a is the isotope fractionation factor between calcite and water. The aragonite paleotemperature equation of Grossman and Ku (1986) was used to estimate the model d18O values of aragonite bivalve shells: tð CÞ ¼ 21:8  4:69ðd18 Oaragonite  d18 Owater Þ; where t is the seawater temperature expressed in 8C, d18Oaragonite is expressed relative to V-PDB and d18Owater is expressed relative to V-PDB (with SMOW versus PDB = 0.20%). Romanek et al. (1992) showed a 13C enrichment between calcite and aragonite relative to bicarbonate (HCO3–) of about

1% and 2.7%, respectively and essentially independent of temperature (over the range 10–40 8C). The resulting carbon isotope fractionation between calcite and aragonite is thus estimated to be 1.7% (Romanek et al., 1992). d18O and d13C values of carbonate of the studied bivalve shells were compared using three statistical methods to identify parameters that may influence the incorporation of 18O and 13C in the carbonate. The k-means method is an algorithm used to cluster data sets and which can be used to confirm differences between already identified groups. Kolmogorov–Smirnov test (KS-test) and Kruskal–Wallis test (KW-test) are nonparametric statistical tests, the former frequently used to determine if distributions of two populations significantly differ or not, the latter used to compare the mean values of two populations.

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3. Results 3.1. Distribution of d18O and d13C values of carbonate of bivalve shells from cold seeps and hydrothermal vents The oxygen and carbon isotope compositions of bivalve shells were compared according to the nature of the venting fluids, i.e. cold seeps versus hydrothermal vents (Fig. 3). The ranges of d values for cold seep bivalve shells (n = 70) (1.81 < d18O < 4.53; –10.23 < d13C < 3.04) and for hydrothermal vent bivalve shells (n = 38) (2.78 < d18O < 4.56; 1.96 < d13C < 4.68) are significantly different (KS-test, p < 0.05). The mean d13C values are also significantly different (KW-test, p < 0.05), with values of –1.48  3.50% for cold seep shells and 3.42  0.67% for hydrothermal vent shells. However, the mean d18O values are similar (KW-test, p > 0.05), with values of 3.30  0.75% for cold seep shells and 3.62  0.53% for hydrothermal vent shells. With the exception of six outliers, the k-means clustering method gives three distinct groups, two cold seep groups and one hydrothermal vent group (Fig. 3).

Fig. 4. Distribution of oxygen and carbon isotope compositions according to calcium carbonate mineralogy. Circles: aragonite shells; triangles: calcite shells. The empty circles indicate aragonite shells that were determined by the k-means method as calcite shells; empty triangles indicate calcite shells that were determined by the k-means method as aragonite shells. Distribution des compositions isotopiques de l’oxygène et du carbone en fonction de la minéralogie du carbonate. Cercles : coquilles en aragonite ; triangles : coquilles en calcite. Les cercles vides correspondent aux coquilles aragonitiques déterminées comme calcitiques par la méthode des k-moyennes, les triangles vides correspondent aux coquilles calcitiques déterminées comme aragonitiques par la méthode des k-moyennes.

The distribution of the d18O and d13C values of the bivalve shells was examined according to the calcium carbonate mineralogy of the shells without distinction of species and locality (Fig. 4). The aragonite shells (n = 39) and calcite shells (n = 63) display similar ranges of d18O and d13C values

(respectively 1.8 < d18O < 4; –10.23 < d13C < 3.86 and 2.62 < d18O < 4.56; –9.41 < d13C < 4.68). Nevertheless, kmeans clustering differentiates four groups, two for calcite groups and two for aragonite (Fig. 4). Moreover, statistical tests indicate a different distribution of d18O and d13C values between aragonite and calcite shells (KS-test, p < 0.05) that supports the hypothesis of a difference in d18O and d13C values according to shell mineralogy.

Fig. 3. Oxygen and carbon isotope compositions of shells of various bivalve species from cold seeps and hydrothermal vents. Circles: cold seeps; triangles: hydrothermal vents. The different colors denote the different groups determined by the k-means clustering method. The empty circles indicate samples from cold seeps that were determined by the k-means method to belong to hydrothermal vents, the empty triangles indicate samples from hydrothermal vents that were determined by the k-means method to belong to cold seeps. For interpretation of references to colours, see the web version of this article. Compositions isotopiques de l’oxygène et du carbone de coquilles de différentes espèces de bivalves provenant de sites de suintements froids et de sources hydrothermales. Cercles : suintements froids ; triangles : sources hydrothermales. Les différentes couleurs indiquent les différents groupes déterminés par la méthode des k-moyennes. Les cercles vides correspondent aux échantillons de suintements froids déterminés par la méthode des k-moyennes comme étant des échantillons de sources hydrothermales, les triangles vides correspondent aux échantillons de sources hydrothermales déterminés par la méthode des k-moyennes comme étant des échantillons de suintements froids. Pour l’interprétation des couleurs, voir la version électronique de cet article.

Fig. 5. Distribution of oxygen and carbon isotope compositions according to the type of symbiotic bacteria present in bivalve gills. Each symbol and each color corresponds to a specific group determined by the k-means method. Red, orange and yellow symbols: the five groups of bivalves harboring only sulfideoxidizing bacteria; blue symbols: the two groups of bivalves harboring sulfideoxidizing and methanotrophic bacteria; green triangles: bivalves harboring only methanotrophic bacteria. For interpretation of references to colours, see the web version of this article. Distribution des compositions isotopiques de l’oxygène et du carbone en fonction du type de bactéries symbiotiques présent dans les branchies des organismes. Chaque symbole et chaque couleur correspondent à un groupe spécifique déterminé par la méthode des k-moyennes. Les symboles rouges, oranges et jaunes correspondent aux bivalves portant uniquement des bactéries sulfooxydantes (cinq groupes), les symboles bleus correspondent aux bivalves portant des bactéries sulfooxydantes et méthanotrophes (deux groupes) et les symboles verts correspondent aux bivalves portant uniquement des bactéries méthanotrophes (un groupe). Pour l’interprétation des couleurs, voir la version électronique de cet article.

3.2. d18O and d13C distribution according to calcium carbonate mineralogy

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Fig. 6. Oxygen and carbon isotope compositions of cold seep bivalve shells according to genus and site location. Circles: Lucina, squares: Calyptogena, diamonds: Vesicomya, triangles: Bathymodiolus. Compositions isotopiques de l’oxygène et du carbone des coquilles de suintements froids en fonction du genre de bivalve et de la localisation des sites. Cercles : Lucina, carrés : Calyptogena, losange : Vesicomya, triangles : Bathymodiolus.

3.3. d18O and d13C distribution according to symbiotic bacteria We examined the distribution of the oxygen and carbon isotope composition of bivalve shells according to the type of symbiotic bacteria hosted in their gills (Fig. 5 and Table 3). For the species (Bathymodiolus childressi) which harbors only methanotrophic bacteria (n = 11), the isotopic compositions are grouped in a small range, 3.29 < d18O < 3.97 and 7.3 < d13C < 3.57. Numerous species belonging to Lucina, Calyptogena, Bathymodiolus and Vesicomya genera harbor only sulfide-oxidizing bacteria (n = 68); within this group, the isotopic compositions exhibit wide ranges (1.81 < d18O < 4.56 and –10.23 < d13C < 4.00). Three Bathymodiolus species harbor both methanotrophic and sulfide-oxidizing bacteria (n = 29); for this third group, the isotopic compositions are also widely distributed (2.78 < d18O < 4.53 and –9.41 < d13C < 4.68). Seven groups were determined by k-means clustering: five groups correspond to bivalves harboring only sulfide-oxidizing bacteria, one group corresponds to bivalves harboring sulfideoxidizing and methanotrophic bacteria and one group corresponds to a mixture of bivalves harboring sulfideoxidizing and methanotrophic bacteria and of bivalves harboring only methanotrophic bacteria (Fig. 5). This method does not differentiate bivalves harboring only methanotrophic bacteria from those harboring both sulfide-oxidizing and methanotrophic bacteria. Nonetheless, nonparametric statistical tests indicate that the clusters of d18O and d13C values are different and thus specific to each kind of symbiosis (KS-test, p < 0.13). 3.4. Distribution of d18O and d13C values according to genus and site location With the exception of three specimens, all organisms from hydrothermal vents belong to Bathymodiolus genus, and there

is no specific distribution of d18O and d13C values according to site location. For cold seeps, we studied several cold seep vents in each region; for example, in the Barbados region we studied five cold seep vents. Within a single cold seep (the Kazan mud volcano), d18O values may vary by up to 1.35% and d13C values by up to 12.13%. The isotopic compositions of the shells from the six studied regions exhibit the following values (Fig. 6):  Barbados (n = 19): 3.5 < d18O < 4.5; 9.4 < d13C < 2.7;  Peru Trough (n = 5): 3.3 < d18O < 4.0; 0.3 < d13C < 1.6;  Gulf of Mexico (n = 17): 2.6 < d18O < 3.9; 7.3 < d13C < 3.0;  Japan Trough (n = 2): 3.5 < d18O < 4.0; 0.61 < d13C < 0.8;  Mediterranean Sea (n = 23): 1.8 < d18O < 3.4; 10.2 < d13C < 3.0;  Gulf of Guinea (n = 4): 3.8 < d18O < 4.0; 0.5 < d13C < 1.2. The k-means clustering method does not differentiate groups according to site location. With regard to bivalve genus, d13C values are higher for Calyptogena, Lucina and Vesicomya than for Bathymodiolus. Except for nine outliers, the k-means method confirms the difference between the group of Calyptogena, Lucina and Vesicomya genera and that of Bathymodiolus genus. 4. Discussion and conclusion With the exception of six outliers, we can clearly differentiate bivalve specimens from cold seeps and hydrothermal vents according to their oxygen and carbon isotopic compositions (Fig. 3). Differences in oxygen and carbon isotope compositions observed between these two deep-sea environments could be explained by several parameters: the carbonate mineralogy of the shell, the presence in the bivalve gills of various symbiotic

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bacteria, or varying fluid compositions. Fluids from cold seep environments are characterized by low d13C values of dissolved inorganic carbon due to anaerobic and aerobic oxidation of methane contained in the venting fluids (Brooks et al., 1984; Charlou et al., 2003). Hydrothermal fluids are characterized by high temperatures of up to 350 8C (Van Dover, 2000). However, organisms are not able to live in such warm conditions and instead develop around emission areas, at the interface between fluids and ambient seawater, at maximum temperatures of 30– 40 8C and thus away from fluid vents (Desbruyères et al., 1982). In the case of cold seeps, fluids may reach temperatures of 60 8C at most and bivalve shells often live very close to fluid vents. The oxygen and carbon isotope compositions of bivalve shells show that each type of symbiosis is associated with a specific environment (Fig. 5). Excepted for the methanotrophic symbiosis which was observed only for bivalves of cold seep environments, symbiosis with both methanotrophic and sulfideoxidizing bacteria and symbiosis with only sulfide-oxidizing bacteria occur in cold seeps as well as in hydrothermal vents. Specimens harboring only sulfide-oxidizing bacteria are able to live at high methane concentrations as well as at high sulfide concentrations (with a preference for moderate methane concentration) as postulated by Temara et al. (1992); this suggests that the main role of sulfide-oxidizing bacteria is to oxidize hydrogen sulfide and thus to detoxify the host organism’s environment. In our study, we have shown that the carbonate shells of bivalves associated with methanotrophic symbiosis exhibit very low d13C values, which proves that these species prefer methane-rich environments. The faculty of these organisms to live in hydrogen sulfide-rich environments seems to confirm the hypothesis that in some environments, Bathymodiolus do not need sulfide-oxidizing bacteria because they are able to detoxify their environment by themselves (Geret et al., 1998; Larsen et al., 1997; Rousse et al., 1998). In deep-sea hydrothermal and cold seep environments, the association of methanotrophic and sulfide-oxidizing bacteria in bivalve gills allows these species to live in a variety of environments where nutrient resources provided by venting fluids are variable. The theoretical d13C values of aragonite and calcite shells were calculated for the different cold seeps (2.7 to 3.8 for aragonite; 1.6 to 2.0 for calcite) and hydrothermal vents (2.7 for aragonite; 1.0 to 2.0 for calcite). With the exception of three outliers, all the d13C values measured in cold seep shells are 13C-depleted by 0.1 to 14%, compared to the theoretical d13C values. This 13C-depletion has been interpreted to indicate an additional source of carbon in the seawater dissolved inorganic carbon that originates from oxidized methane (Lietard and Pierre, 2008; Schöne and Giere, 2005). In contrast, hydrothermal bivalve shells display 13Cenrichments by 0.26 to 3% compared to the theoretical d13C values. Rio et al. (1992) and Schöne and Giere (2005) also noticed 13C-enrichments in carbonate shells from hydrothermal vents of Calyptogena magnifica, Bathymodiolus thermophilus and Bathymodiolus brevior that harbor sulfide-oxidizing bacteria. Rio et al. (1992) interpreted this 13C-enrichment by

postulating that sulfide-oxidizing bacteria should uptake part of the dissolved inorganic carbon contained in the extrapallial liquid to realize the biosynthesis; they suggested that isotopic fractionation concentrates 13C in the extrapallial liquid (solely if seawater bicarbonate migration through the mantle is slower than the metabolic extraction) and thus induce the 13Cenrichment in the carbonate of bivalve shells. Turner (1982) had shown that kinetic isotope fractionation during calcium carbonate precipitation was rate-dependent, but Romanek et al. (1992) dismissed this result. Recently, Groot (2007) suggested that any precipitation process that does not reach isotopic equilibrium is affected by kinetic isotope fractionation, which might explain 13C-enrichment. If we consider only bivalves from cold seep environments, the d13C differences observed between Calyptogena, Lucina and Vesicomya genera compared with Bathymodiolus genus can be explained by difference of the organism positions within the sediment, Bathymodiolus living burier in sediment and closer to venting fluids than Calyptogena, Lucina and Vesicomya. The theoretical model d18O values of bivalve shells from cold seeps were calculated for each site and according to calcium carbonate mineralogy: Mediterranean Sea/aragonite: 3.2%, Gulf of Guinea/aragonite: 4.1%, Gulf of Mexico/calcite: 3.6%, Japan Trough/aragonite: 3.2%, Peru Trough/aragonite: 3.9% and Barbados/calcite: 2.8%. Bivalve shells from Mediterranean Sea (with the exception of one outlier) are 18O-depleted by up to 1.4% compared to the d18O value of carbonate precipitated in isotopic equilibrium with the bottom seawater (Fig. 6). This 18O-depletion suggests either a contribution of 18O-poor water or an increase of ambient seawater temperature produced by warm seeping fluids. The theoretical model temperatures calculated for the Eastern Mediterranean bivalve shells range between 12– 19.4 8C, which is in good agreement with the hypothesis of an increase of ambient seawater temperatures produced by contributions of warm fluids. In contrast, bivalve shells from the Japan Trough and Barbados show 18O-enrichments, which suggest a contribution of 18O-rich water. Two processes might produce 18O-rich water, either the decomposition of gas hydrates (Hesse and Harrison, 1981; Jenden and Gieskes, 1983) which are abundant at these two sites (Martin et al., 1996; Saito and Suzuki, 2007), or dehydration of clays at greater depths (Koster Van Groos and Guggenheim, 1984; Savin and Epstein, 1970). For the Gulf of Mexico and Peru Trough, bivalve shells display both 18O-depletions and 18Oenrichments that suggest a mixing of the different processes mentioned above. Another possible mechanism to explain the difference between measured and modeled d18O values is temperaturedependent shell growth, which is assumed in this study to be similar among mollusc species (molluscs with the same mineralogy). However, species-specific as well as site-specific fractionations have previously been suggested for the marine aragonitic bivalve Mesodesma donacium (Carré et al., 2005), observed for different freshwater aragonitic gastropods (Shanahan et al., 2005) and suggested for deep-sea bivalve shells (Schöne and Giere, 2005).

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In conclusion, the study of the d18O and d13C values of deepsea bivalve shells provides interesting environmental information. We were able to distinguish bivalve shells from cold seeps and those from hydrothermal vents. This study has shown that the symbiotic bacteria living in bivalve gills have an important physiological control on the d18O and d13C distributions. Moreover, we can identify subgroups that correspond to the different site locations of the venting fluids. This study is a first step towards obtaining environmental information as the nature of venting fluids (cold seeps or hydrothermal vent) and the variability of methane and hydrogen sulfide concentration, as well as biological information, as the type of symbiotic bacteria present in bivalve gills. Even if such information could be of use in the future for investigations of fossil cold seeps, more investigations are still needed to calibrate this tool. A project called ESONET/EMSO, coordinated by IFREMER, plans to deploy deep seafloor observatories at five specific sites including a cold seep site (Hakon Mosby Mud Volcano). This project will allow continuous monitoring of deep-sea floor environments (pollution, venting fluids, earthquakes, turbidity currents...) and will allow us to better calibrate this bivalve tool. Acknowledgements We thank Aline Fiala-Médioni (laboratoire Arago, Banyulssur-mer) for providing most of the bivalve shells. This research was supported by the GDR-Marges INSU program, the ESF Mediflux project, and the sixth PCRD EC-Hermes project. The manuscript benefited from the helpful comments of Daniel Praeg, Christophe Lécuyer and Gilles Escarguel who are warmfully acknowledged for their collaboration. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.geobios.2008.12.001. References Aharon, P., Graber, E.R., Robert, H.H., 1992. Dissolved carbon and d13C anomalies in the water column caused by hydrocarbon seeps on the northwestern Gulf of Mexico slope. Geo-Marine Letters 12, 33–40. Aquilina, L., Dia, A.N., Boulègue, J., Bourgois, J., Fouillac, A.M., 1997. Massive barite deposits in the convergent margin off Peru: Implications for fluid circulation within subduction zones. Geochimica et Cosmochimica Acta 61, 1233–1245. Bergquist, D.C., Fleckenstein, C., Szalai, E.B., Knisel, J., Fisher, C.R., 2004. Environment dives physiological variability in the cold seep mussel Bathymodiolus childressi. Limnology and Oceanography 49, 706–715. Brooks, J.M., Kennicutt II, M.C., Fay, R.R., McDonald, T.J., Sassen, R., 1984. Thermogenic gas hydrates in the Gulf of Mexico. Science 226, 965–967. Campbell, K.A., 1992. Recognition of a Mio–Pliocene cold seep setting from the northeast Pacific convergent margin, Washington, USA. Palaios 7, 422–433. Campbell, K.A., Bottjer, D.J., 1995. Peregrinella: an early Cretaceous coldseep-restricted brachiopod. Paleobiology 21, 463–478. Carré, M., Bentaleb, I., Blamart, D., Ogle, N., Cardenas, F., Zevallos, S., Kalin, R.M., Ortlieb, L., Fontugne, M., 2005. Stable isotopes and sclerochronology

217

of the bivalve Mesodesma donacium: Potential application to Peruvian paleoceanographic reconstructions. Palaeogeography, Palaeoclimatology, Palaeoecology 228, 4–25. Charlou, J.L., Donval, J.P., Zitter, T., Roy, N., Jean-Baptiste, P., Foucher, J.P., Woodside, J., 2003. Medinaut Scientific Party. Evidence of methane venting and geochemistry of brines on mud volcanoes of the eastern Mediterranean Sea. Deep-Sea Research 1 50, 941–958. Craig, H., 1957. Isotope standards for carbon and oxygen and correction factors for mass spectrometric analysis of carbon dioxide. Geochimica et Cosmochimica Acta 12, 133–149. Craig, H., Gordon, L.I., 1965. Deuterium and oxygen-18 variations in the ocean and the marine atmosphere. In: Tongiorgi, E. (Ed.), Proceedings of a Conference on Stable Isotopes in Oceanographic Studies and Paleo-temperatures. Lischi and Figli, Pisa, pp. 9–130. Desbruyères, D., Alayse-Danet, A.-M., Ohta, S., Scientific parties of BIOLAU and STARMER Cruises, 1994. Deep-sea hydrothermal communities in southwestern Pacific back-arc basins (the North Fiji and Lau Basins): Composition, microdistribution and food web. Marine Geology 116, pp. 227–242. Desbruyères, D., Crassous, P., Grassle, J., Khipounoff, A., Reyss, D., Rio, M., Van Praet, M., 1982. Données écologiques sur un nouveau site d’hydrothermalisme actif de la ride du Pacifique oriental. Comptes Rendus de l’Académie des Sciences de Paris 295, 489–494. Distel, D., Felbeck, H., 1987. Bacteria-bearing tissues in the lucinid clams Lucinoma aequizonata, Lucinoma annulata and Lucina floridana: the functional morphology of an endosymbiotic bacteria. Marine Biology 96, 79–86. Dubilier, N., Windoffer, R., Giere, O., 1998. Ultrastructure and stable carbon isotope composition of the hydrothermal vent mussels Bathymodiolus brevior and Bathymodiolus sp. affinis brevior from the North Fiji Basin, western Pacific. Marine Ecology Progress Series 165, 187–193. Duperron, S., Nadalig, T., Caprais, J.-C., Sibuet, M., Fiala-Médioni, A., Amann, R., Dubilier, N., 2005. Dual symbiosis in a Bathymodiolus sp. mussel from a methane seep on the Gabon Continental Margin (Southeast Atlantic): 16S rRNA phylogeny and distribution of the symbionts in gills. Applied and Environmental Microbiology 71, 1694–1700. Epstein, S., Buchsbaum, R., Lowenstam, H., Urey, H.C., 1953. Revised carbonate water isotopic temperature scale. Geological Society of America Bulletin 64, 1315–1326. Fiala-Médioni, A., 1984. Mise en évidence par microscopie électronique à transmission de l’abondance de bactéries symbiotiques dans la branchie de mollusques bivalves de sources hydrothermales profondes. Comptes Rendus de l’Académie des Sciences de Paris 298, 487–492. Fiala-Médioni, A., Felbeck, H., 1990. Autotrophic processes in invertebrate nutrition: bacterial symbiosis in bivalve molluscs. Comparative Physiology 5, 49–69. Fiala-Médioni, A., MacKiness, Z.P., Dando, P., Boulegue, J., Mariotti, A., Alayse-Danet, A.M., Robinson, J.J., Cavanaugh, C.M., 2002. Ultrastructural, biochemical, and immunological characterization of two populations of the mytilid mussel Bathymodiolus azoricus from the Mid-Atlantic Ridge: evidence for a dual symbiosis. Marine Biology 141, 1035–1043. Fiala-Médioni, A., Metivier, C., Herry, A., Lepennec, M., 1986. Ultrastructure of the gill of the hydrothermal-vent Mytilid Bathymodiolus sp. Marine Biology 92, 65–72. Fiala-Médioni, A., Michalski, J.C., Jolles, J., Alonso, C., Montreuil, J., 1994. Lysosomic and lysozyme activities in the gill of bivalves from deep hydrothermal vents. Comptes Rendus de l’Académie des Sciences de Paris 317, 239–244. Geret, F., Rousse, N., Riso, R., Sarradin, P.M., Cosson, R., 1998. Metal compartmentalization and metallothionein isoforms in mussels from the Mid-Atlantic Ridge: preliminary approach to the fluid–organism relationship. Cahier de Biologie Marine 39, 291–293. Godon, A., Jendrzejewski, N., Castrec-Rouelle, M., Dia, A., Pineau, F., Boulègue, J., Javoy, M., 2004. Origin and evolution of fluids from mud volcanoes in the Barbados accretionary complex. Geochimica et Cosmochimica Acta 68, 2153–2165. Groot, P. de, 2007. Kinetic isotope fractionation: Magic or logic? Geophysics Research (abstract).

218

C. Lietard, C. Pierre / Geobios 42 (2009) 209–219

Grossman, E.L., Ku, T.L., 1986. Oxygen and carbon isotope fractionation in biogenic aragonite: Temperature effects. Chemical Geology 59, 59–74. Hackworth, M.S., 2005. Carbonate records of submarine hydrocarbon venting: northern Gulf of Mexico. Thesis of University of Virginia, Virginia. Hardivillier, 2005. Caractérisation et expression des gènes de métallothionéines chez deux modioles hydrothermales : Bathymodiolus thermophilus et Bathymodiolus azoricus. Thèse de doctorat, université du Maine, Le Mans. Hein, J.R., Normark, W.R., McIntyre, B.R., Lorenson, T.D., Powell II, C.L., 2006. Methanogenic calcite, 13C-depleted bivalve shells, and gas hydrate from a mud volcano offshore southern California. Geology 34, 109–112. Hesse, R., Harrison, W., 1981. Gas hydrates (clathrates) causing pore-water freshening and oxygen isotope fractionation in deep water sedimentary sections of terrigenous continental margins. Earth and Planetary Science Letters 55, 453–462. Jenden, P.D., Gieskes, J.M., 1983. Chemical and isotopic composition of interstitial water from Deep Sea Drilling Project Sites 533 and 534. In: Sheridan, R.E., Gradstein, F.M. et al. (Eds.), Initial Reports of the Deep Sea Drilling Project 76, U.S. Government Printing Office, Washington, pp. 453–461. Kennish, M.J., Lutz, R.A., 1999. Calcium carbonate dissolution rates in deepsea bivalve shells on the East Pacific Rise at 218N: results of an 8-year in situ experiment. Palaeogeography, Palaeoclimatology, Palaeoecology 154, 293–299. Killingley, J.S., Berger, W.H., 1979. Stable isotopes in a mollusk shell: detection of upwelling events. Science 205, 186–188. Koschinsky, A., Seifert, R., Halbach, P., Bau, M., Brasse, S., Carvalho, L.M., de Fonseca, N.M., 2002. Geochemistry of diffuse low-temperature hydrothermal fluids in the North Fiji Basin. Geochimica et Cosmochimica Acta 66, 1409–1427. Koster Van Groos, A.F., Guggenheim, S., 1984. The effect of pressure on the dehydration reaction of interlayer water in Na-montmorillonite (SWy-1). American Mineralogist 69, 872–879. Kroopnick, P.M., 1985. The distribution of 13C of SCO2 in the world oceans. Deep-Sea Research, Part A, Oceanographic research papers 32, 57–84. Larsen, E.H., Quétel, C.R., Munoz, R., Fiala-Médioni, A., Donard, O.F.X., 1997. Arsenic speciation in shrimp and mussel from the Mid-Atlantic hydrothermal vents. Marine Chemistry 57, 341–346. Lécuyer, C., Dubois, M., Marignac, Ch., Gruau, G., Fouquet, Y., Ramboz, C., 1999. Phase separation and fluid mixing in subseafloor back arc hydrothermal systems: A microthermometric and oxygen isotope study of fluid inclusions in the barite-sulfide chimneys of the Lau basin. Journal of Geophysical Research 104, 17911–17927. Le Pichon, X., Henry, P., Lallemant, S., 1990. Water flow in the Barbados accretionary complex. Journal of Geophysical Research 95, 8945–8967. Lietard, C., Pierre, C., 2008. High-resolution isotopic records (d18O and d13C) and cathodoluminescence study of lucinid shells from methane seeps of the Eastern Mediterranean. Geo-Marine Letters 28, 195–203. Lloyd, R.M., 1967. Oxygen-18 composition of oceanic sulfate. Science 156, 1228–1231. Lorrain, A., Paulet, Y.-M., Chauvaud, L., Dunbar, R., Mucciarone, D., Fontugne, M., 2004. d13C variation in scallop shells: Increasing metabolic carbon contribution with body size? Geochimica et Cosmochimica Acta 68, 3509–3519. Mae, A., Yamanaka, T., Shimoyama, S., 2007. Stable isotope evidence for identification of chemosynthesis-based fossil bivalves associated with cold-seepages. Palaeogeography, Palaeoclimatology, Palaeoecology 245, 411–420. Majima, R., Nobuhara, T., Kitazaki, T., 2005. Review of fossil chemosynthetic assemblages in Japan. Palaeogeography, Palaeoclimatology. Palaeoecology 227, 86–123. Martin, J.B., Kastner, M., Henry, P., Le Pichon, X., Lallement, S., 1996. Chemical and isotopic evidence for sources of fluids in a mud volcano field seaward of the Barbados accretionary wedge. Journal of Geophysical Research 101, 20325–20345. Mills, S.W., Mullineaux, L.S., Tyler, P.A., 2007. Habitat association in gastropod species at East Pacific Rise hydrothermal vents (98500 N). Biological Bulletin 212, 185–194. Olu, K., Sibuet, M., Harmegnies, F., Foucher, J.-P., Fiala-Médioni, A., 1996. Spatial distribution of diverse cold seep communities living on various

diapiric structures of the southern Barbados prism. Progress in Oceanography 38, 347–376. O’Neil, J.R., Clayton, R.N., Mayeda, T.K., 1969. Oxygen isotope fractionation in divalent metal carbonates. Journal of Chemical Physics 51, 5547– 5558. Peckmann, J., Goedert, J.L., Thiel, V., Michaelis, W., Reitner, J., 2002. A comprehensive approach to the study of methane-seep deposits from the Lincoln Creek formation, western Washington State USA. Sedimentology 49, 855–873. Pierre, C., 1999. The oxygen and carbon isotope distribution in the Mediterranean water masses. Marine Geology 153, 41–55. Pierre, C., Fouquet, Y., 2007. Authigenic carbonates from methane seeps of the Congo deep-sea fan. Geo-Marine Letters 27, 249–257. Pond, D.W., Bell, M.V., Dixon, D.R., Fallick, A.E., Segonzac, M., Sargent, J.R., 1998. Stable-carbon isotope composition of fatty acids in hydrothermal vent mussels containing methanotrophic and thiotrophic bacterial endosymbionts. Applied and Environmental Microbiology 64, 370–375. Rio, M., Renard, M., Roux, M., Clauser, S., Davanzo, F., Herrera Duvault, Y., 1988. Composition chimique et isotopique des tests de bivalves des sources hydrothermales océaniques. Bulletin de la Société géologique de France 8, 151–159. Rio, M., Roux, M., Renard, M., Schein, E., 1992. Chemical and isotopic features of present-day bivalve shells from hydrothermal vents or cold seeps. Palaios 7, 351–360. Romanek, C.S., Grossman, E.L., Morse, J.W., 1992. Carbon isotopic fractionation in synthetic aragonite and calcite: effects of temperature and precipitation rate. Geochimica et Cosmochimica Acta 56, 419–430. Rousse, N., Boulègue, J., Cosson, R., Fiala-Médioni, A., 1998. Bioaccumulation of metal within the hydrothermal mytilidae Bathymodiolus sp, from the Mid-Atlantic Ridge. Oceanologica Acta 21, 597–607. Saito, H., Suzuki, N., 2007. Terrestrial organic matter controlling gas hydrate formation in the Nankai Trough accretionary prism, offshore Shikoku, Japan. Journal of Geochemical Exploration 95, 88–100. Sakai, H., Gamo, T., Ogama, Y., Boulègue, J., 1992. Stable isotopic ratios and origins of the carbonates associated with cold seepage at the eastern Nankai Trough. Earth and Planetary Science Letters 109, 391–404. Savin, S.M., Epstein, S., 1970. The oxygen and hydrogen isotope geochemistry of clay minerals. Geochimica et Cosmochimica Acta 34, 25–42. Schöne, B.R., Giere, O., 2005. Growth increments and stable isotope variation in shells of the deep-sea hydrothermal vent bivalve mollusk Bathymodiolus brevior from the North Fiji Basin. Pacific Ocean. Deep-Sea Research 52, 1896–1910. Shanahan, T.M., Pigati, J.S., Dettman, D.L., Quade, J., 2005. Isotopic variability in the aragonite shells of freshwater gastropods living in springs with nearly constant temperature and isotopic composition. Geochimica et Cosmochimica Acta 69, 3949–3966. Suess, E., von Huene, R., Emeis, K.C., Bourgois, J., del C. Cruzado, J., De Wever, P., Eglington, G., Garrison, R., Greenberg, M., Herrera, E., Hill, P., Ibaraki, M., Kastner, M., Kemp, A.E.S., Kvenvolden, K., Langridge, R., Lindsey-Griffin, N., Marsters, J., Martini, E., McCabe, R., Ocola, L., Resig, J., Wilfredo, A., Schrader, H., Thornburg, T.M., Wefer, G., Yamano, M., 1988. Introduction, objectives, and principal results, Leg 112, Peru Continental Margin. Proceedings ODP, Initial Reports, 112, College Station, TX (Ocean Drilling Program), pp. 1–1015. Taviani, M., 2001. Fluid venting and associated processes. In: Vai, G.B., Martini, I.P. (Eds.), Anatomy of an Orogen. The Apennines and Adjacent Mediterranean Basins. Kluwer Academic Publisher, Dordrecht, pp. 351– 366. Temara, A., Ridder, C., de Kuenen, J.G., Robertson, L.A., 1992. Sulfideoxidizing bacteria in the burrowing echinoid. Echinocardium cordatum (Echinodermata). Marine Biology 115, 1432–1793. Tsunogai, U., Yoshida, N., Gamo, T., 2002. Carbon isotopic evidence of methane oxidation through sulfate reduction in sediment beneath cold seep vents on the seafloor at Nankai Trough. Marine Geology 187, 145– 160. Turner, J.V., 1982. Kinetic fractionation of carbon-13 during calcium carbonate precipitation. Geochimica et Cosmochimica Acta 46, 1183–1191.

C. Lietard, C. Pierre / Geobios 42 (2009) 209–219 Van Dover, C.L., 2000. The Ecology of Deep-Sea Hydrothermal Vents. Princeton University Press, Princeton. Von Cosel, R., Metivier, B., Hashimoto, J., 1994. Three new species of Bathymodiolus (Bivalvia Mytilidae) from hydrothermal vents in the Lau Basin and the North Fiji Basin, western Pacific, and the Snake Pit area, MidAtlantic Ridge. The Veliger 37, 374–392.

219

Von Cosel, R., Olu, K., 1998. Gigantism in Mytilidae. A new Bathymodiolus from cold seep areas on the Barbados accretionary prism. Comptes Rendus de l’Académie des Sciences de Paris 321, 655–663. Von Cosel, R., Comtet, T., Krylova, E.M., 1999. Bathymodiolus (Bivalvia Mytilidae) from hydrothermal vents on the azores triple junction and the Logatchev hydrothermal field, Mid-Atlantic Ridge. The Veliger 42, 218–248.