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Stable isotope evidence for chemosynthesis in an abyssal community
... Due to their ubiquity and dominance in cold seep ecosystems, chemosymbiotic bivalves-in particular bathymodiolin mussels and vesicomyid clams-have attracted the attention of researchers since the discoveries of these ecosystems. They were first investigated in the Gulf of Mexico with respect to their biogeochemical behavior (Paull et al. 1985;Childress et al. 1986;Cordes et al. 2009) and were subsequently found and studied at virtually all active cold seeps worldwide (Nankai Encouraging progress has also been made in discovering and understanding seepinhabiting bivalves in the South China Sea (SCS) in the last 20 years through a large amount of investment in capital and technology. To date, three active cold seep regions (Site F, Haima and Yam) with seabed manifestations of significant gas seepage and active biological activity have been identified in the SCS, and bivalves represent the dominant macrofauna at these sites. ...
... It is well recognized that measuring the carbon, nitrogen, and sulfur isotope compositions of the macrofauna inhabiting cold seeps is one of the most powerful approaches to identifying their food and energy sources, as well as the determination of complex trophic interactions, including symbiosis and heterotrophy (Paull et al. 1985;Childress et al. 1986;Brooks et al. 1987;Carlier et al. 2010;Decker and Olu 2012;Demopoulos et al. 2019;Ke et al. 2022). Indeed, it is possible to distinguish consumers that assimilate carbon through chemosynthesis (more 13 C-and 15 Ndepleted) from those that rely on photosynthetic primary production (Paull et al. 1985;Brooks et al. 1987). ...
... It is well recognized that measuring the carbon, nitrogen, and sulfur isotope compositions of the macrofauna inhabiting cold seeps is one of the most powerful approaches to identifying their food and energy sources, as well as the determination of complex trophic interactions, including symbiosis and heterotrophy (Paull et al. 1985;Childress et al. 1986;Brooks et al. 1987;Carlier et al. 2010;Decker and Olu 2012;Demopoulos et al. 2019;Ke et al. 2022). Indeed, it is possible to distinguish consumers that assimilate carbon through chemosynthesis (more 13 C-and 15 Ndepleted) from those that rely on photosynthetic primary production (Paull et al. 1985;Brooks et al. 1987). This is because methane is much more 13 C-depleted (usually δ 13 C CH4 < −40‰; Whiticar 1999) than dissolved inorganic carbon (DIC) Wang et al. 2022a) in the water column (δ 13 C DIC ≈ 0‰), and methane is assimilated by bacteria with only a small carbon isotopic fractionation (Alperin et al. 1988). ...
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Presents first-time synthetic knowledge of the marine seeps across the continental slope of the South China Sea
Provides distinctive seafloor images that have not been viewed before by most readers
Summarizes results from different aspects of seep systems including geology, geophysics, geochemistry, and ecology
... Due to their ubiquity and dominance in cold seep ecosystems, chemosymbiotic bivalves-in particular bathymodiolin mussels and vesicomyid clams-have attracted the attention of researchers since the discoveries of these ecosystems. They were first investigated in the Gulf of Mexico with respect to their biogeochemical behavior (Paull et al. 1985;Childress et al. 1986;Cordes et al. 2009) and were subsequently found and studied at virtually all active cold seeps worldwide (Nankai accretionary wedge: Fiala-Médioni et al. 1993; Håkon Mosby mud volcano: Gebruk et al. 2003; pockmarks on the West African margin: Olu-Le Roy et al. 2007; Concepción methane seep area off Chile: Sellanes et al. 2008;New Zealand: Thurber et al. 2010;Marmara Sea: Ritt et al. 2012;North Atlantic and Mediterranean Sea: Duperron et al. 2013; Gulf of Cadiz: Rodrigues et al. 2013; Pacific coast of Costa Rica: Levin et al. 2015;Guaymas Basin: Portail et al. 2015;Arctic: Åström et al. 2019;Krishna-Godavari Basin: Peketi et al. 2022). After nearly 40 years of research, the understanding of the unique symbiotic relationships between seep-inhabiting bivalves and chemotrophic bacteria and the related biogeochemical processes has grown considerably (Fisher 1995;Dubilier et al. 2008;Petersen and Dubilier 2009;Lorion et al. 2013;Decker et al. 2014;Petersen et al. 2016). ...
... It is well recognized that measuring the carbon, nitrogen, and sulfur isotope compositions of the macrofauna inhabiting cold seeps is one of the most powerful approaches to identifying their food and energy sources, as well as the determination of complex trophic interactions, including symbiosis and heterotrophy (Paull et al. 1985;Childress et al. 1986;Brooks et al. 1987;Carlier et al. 2010;Decker and Olu 2012;Demopoulos et al. 2019;Ke et al. 2022). Indeed, it is possible to distinguish consumers that assimilate carbon through chemosynthesis (more 13 C-and 15 Ndepleted) from those that rely on photosynthetic primary production (Paull et al. 1985;Brooks et al. 1987). ...
... It is well recognized that measuring the carbon, nitrogen, and sulfur isotope compositions of the macrofauna inhabiting cold seeps is one of the most powerful approaches to identifying their food and energy sources, as well as the determination of complex trophic interactions, including symbiosis and heterotrophy (Paull et al. 1985;Childress et al. 1986;Brooks et al. 1987;Carlier et al. 2010;Decker and Olu 2012;Demopoulos et al. 2019;Ke et al. 2022). Indeed, it is possible to distinguish consumers that assimilate carbon through chemosynthesis (more 13 C-and 15 Ndepleted) from those that rely on photosynthetic primary production (Paull et al. 1985;Brooks et al. 1987). This is because methane is much more 13 C-depleted (usually δ 13 C CH4 < −40‰; Whiticar 1999) than dissolved inorganic carbon (DIC) Wang et al. 2022a) in the water column (δ 13 C DIC ≈ 0‰), and methane is assimilated by bacteria with only a small carbon isotopic fractionation (Alperin et al. 1988). ...
Reduced compounds dissolved in seeping fluids, such as methane and hydrogen sulfide, are the main energy sources in submarine cold seep systems, where they nourish the unique chemosynthesis-based ecosystems. Chemosymbi-otic bivalves are the dominant macrofauna in many of these ecosystems and have been extensively studied due to their large biomass (hundreds of individuals per square meter), their symbiotic relationships with chemotrophic bacteria (methan-otrophic bivalves: methane-oxidizing bacteria; thiotrophic bivalves: sulfur-oxidizing bacteria), and because they are unique archives of biogeochemical processes. In this chapter, we briefly introduce the advancements in seep bivalve research worldwide and then summarize the trophic modes and geographic distribution of seep bivalves in the South China Sea. Thereafter, the biogeochemical processes, such as the enzy-matic strategy and energy transfer of seep bivalves, are generalized by integrating the trace elements and stable isotope data of the soft tissues and their corresponding calcareous shells of seep bivalves. Overall, we highlight the past contributions and current knowledge in this field and outline opportunities and future directions to expand this area of research.
... Due to their ubiquity and dominance in cold seep ecosystems, chemosymbiotic bivalves-in particular bathymodiolin mussels and vesicomyid clams-have attracted the attention of researchers since the discoveries of these ecosystems. They were first investigated in the Gulf of Mexico with respect to their biogeochemical behavior (Paull et al. 1985;Childress et al. 1986;Cordes et al. 2009) and were subsequently found and studied at virtually all active cold seeps worldwide (Nankai Encouraging progress has also been made in discovering and understanding seepinhabiting bivalves in the South China Sea (SCS) in the last 20 years through a large amount of investment in capital and technology. To date, three active cold seep regions (Site F, Haima and Yam) with seabed manifestations of significant gas seepage and active biological activity have been identified in the SCS, and bivalves represent the dominant macrofauna at these sites. ...
... It is well recognized that measuring the carbon, nitrogen, and sulfur isotope compositions of the macrofauna inhabiting cold seeps is one of the most powerful approaches to identifying their food and energy sources, as well as the determination of complex trophic interactions, including symbiosis and heterotrophy (Paull et al. 1985;Childress et al. 1986;Brooks et al. 1987;Carlier et al. 2010;Decker and Olu 2012;Demopoulos et al. 2019;Ke et al. 2022). Indeed, it is possible to distinguish consumers that assimilate carbon through chemosynthesis (more 13 C-and 15 Ndepleted) from those that rely on photosynthetic primary production (Paull et al. 1985;Brooks et al. 1987). ...
... It is well recognized that measuring the carbon, nitrogen, and sulfur isotope compositions of the macrofauna inhabiting cold seeps is one of the most powerful approaches to identifying their food and energy sources, as well as the determination of complex trophic interactions, including symbiosis and heterotrophy (Paull et al. 1985;Childress et al. 1986;Brooks et al. 1987;Carlier et al. 2010;Decker and Olu 2012;Demopoulos et al. 2019;Ke et al. 2022). Indeed, it is possible to distinguish consumers that assimilate carbon through chemosynthesis (more 13 C-and 15 Ndepleted) from those that rely on photosynthetic primary production (Paull et al. 1985;Brooks et al. 1987). This is because methane is much more 13 C-depleted (usually δ 13 C CH4 < −40‰; Whiticar 1999) than dissolved inorganic carbon (DIC) Wang et al. 2022a) in the water column (δ 13 C DIC ≈ 0‰), and methane is assimilated by bacteria with only a small carbon isotopic fractionation (Alperin et al. 1988). ...
Extensive submarine cold seep areas, i.e., the Beikang Basin and the Nansha Trough, were discovered on the southern continental slope of the South China Sea. Bottom-simulating reflections are widespread in these areas and show a close relationship to the cold seep system. High-resolution 2-D seismic data and multibeam bathymetry data have confirmed the existence of deep-routed conduits−mud volcanoes, diapirs, and gas chimneys. The geochemical characteristics of seep carbonates and headspace gas indicate that the fluid was mainly sourced from biogenic gas, with contributions from deep-rooted thermogenic gases. Additionally, negative pore water chloride anomalies and positive δ18O values (3.7‰ < δ18O < 5.0‰) of the seep carbonates provided indicators of hydrate water addition during carbonate precipitation. The negative δ13C excursion of planktonic foraminifera from the Nansha Trough indicated two methane release events, which occurred approximately 29–32 ka and 38–42 ka before present, and the driving mechanism for methane seepage in this area is possibly related to overpressure from the large sediment accumulation that occurred during sea level lowstands.
... Among the dominant animals at seeps are bathymodiolin mussels and vesicomyid clams, which live in symbiosis with thiotrophic and/or methanotrophic symbionts and derive the vast majority of their nutrition from their endosymbionts (e.g. Paull et al., 1985;Childress et al., 1986;Cordes et al., 2009;Duperron, 2010;Becker et al., 2010). ...
... The nitrogen sources of chemosymbiotic animals are not well constrained because of the lack of δ 15 N signals of nitrate, nitrite, and ammonium from the environment. However, a local nitrogen origin has been hypothesized by a few studies (Paull et al., 1985;Kennicutt et al., 1992;Becker et al., 2010;Feng et al., 2015;Yamanaka et al., 2015). Furthermore, the combination of tissue δ 13 C, δ 15 N, and δ 34 S values are useful to elucidate processes that affect the chemical and isotopic compositions of seeping fluids as well as seepage dynamics (Becker et al., 2010(Becker et al., , 2013(Becker et al., , 2014Rodrigues et al., 2013;Feng et al., 2015). ...
... Case studies of modern seep bivalves reveal that the carbon isotopic composition of shell carbonate largely reflects the isotopic composition of dissolved inorganic carbon of ambient seawater (e.g. Paull et al., 1985;Feng et al., 2009). Because the organic matrix is secreted from the organism's mantle (Barnes, 1987), the isotopic composition of the mantle should be archived in the shell organic matrix (SOM), and such information is expected to be retained during depositional processes (Degens, 1969;O'Donnell et al., 2003;Mae et al., 2007;Dreier et al., 2012Dreier et al., , 2014. ...
Chemosymbiotic bivalves harboring endosymbiotic, chemotrophic bacteria have been investigated from a variety of hydrocarbon seeps worldwide. It has been shown that carbon, nitrogen, and sulfur isotopic compositions of the animal soft body parts are excellent indicators for evaluating energy transfer and food sources for the respective deep-sea habitats. However, recognition of chemosymbiosis has proven to be difficult for bivalves that dwelled at ancient seeps due to the lack of soft tissue. Here, we investigated δ13C, δ15N, and δ34S signatures of the tissue (mantle) and the shell organic matrix (SOM) of the same specimens of three bathymodiolin mussel species with different chemotrophic symbionts (methanotrophs in Bathymodiolus platifrons and B. childressi and thiotrophs in B. aduloides) and one vesicomyid clam (Calyptogena sp.) from a variety of hydrocarbon seeps from the South China Sea and the Gulf of Mexico. The data obtained demonstrate that all seep bivalves regardless of species or locations reveal overall small differences in δ13C (≤+4‰), δ15N (≤+1‰), and δ34S (≤+5‰) values between SOM and mantle (∆SOM-mantle) of the specimens. Relatively larger ∆SOM-mantle for δ13C values (as high as +10‰) in B. platifrons and larger ∆SOM-mantle for δ34S values (up to 16‰) in B. aduloides and Calyptogena sp. might be due to different symbionts in their gills. Since SOM can be extracted from fossil bivalve shells, the proxy can be used as a fingerprint of chemosynthesis-based food chains, although its utility will depend on the quality of preservation of the shell organic matter. Despite this uncertainty, the new proxy has great potential to reconstruct energy flow through different types of chemosynthesis-based ecosystems.
... passives. Il s'agit des suintements dits « froids », car leur température, qui dépasse rarement 20°C, est plus modérée que celle des fluides hydrothermaux, qui peuvent s'élever à 400°C (Paull et al., 1985 ;Olu et al., 1997 ;Tunnicliffe et al., 2003). Le premier suintement froid a été découvert sur la faille active de San Clemente au large de la Californie, à 1 800 m de profondeur (Lonsdale,1979). ...
... Le premier suintement froid a été découvert sur la faille active de San Clemente au large de la Californie, à 1 800 m de profondeur (Lonsdale,1979). Les caractéristiques principales des suintements froids sont leur teneur élevée en méthane, mais des hydrocarbures plus lourds peuvent également prédominer (Davis et Spies, 1980 ;Paull et al., 1985 ;Roberts et Aharon, 1994), ainsi que des sulfures. ...
... Les suintements froids sont quant à eux constitués d'écoulements de saumures (Paull et al., 1985 ;Carney, 1994) et de fluides dits « froids », par opposition aux fluides hydrothermaux précités, car leur température reste inférieure à 20°C (Olu et al., 1997 ;Tunnicliffe et al., 2003). Ces fluides sont riches en méthane, en sulfures et en hydrocarbures (De Lange, 1990 ;Levin, 2005). ...
This work presents the copper speciation in the deep ocean and the exchanges existing between different size fractions : particulate, dissolved and colloidal. It focus on the mixing zone between deep sources and seawater. The enhancement of our knowledge and the optimization of instrumentation make possible the development of sampling and analysis strategies accorded with the nature and the accessibility of these extreme environments. A part of this work consisted in the development of effective analysis methods for the quantification of copper and copper's ligands. Our results showed that physical speciation seems to be essentially controlled by the variations of pH and oxydoreductive caracteristics during the dilution of the hydrothermal fluid by seawater. The chemical speciation of copper seems essentially controlled by sulfide ligands and the oxydative caracteristics of the environment. The environment is generally more complexing on Lucky Strike vent field than in Guaymas Basin. Around each vent, pseudopolarography and complexing capacities showed that the environment is more complexing in the anoxic zone, near the source, than in the oxic zone. In the oxic zone, copper is generally labile and its concentrations (they can reach 100 nM) exceed the ligands concentrations. In the oxic zone, around 27% of the complexes are dissociated, whereas around 73% remains stabilised.
... tube sections and worms) ranged from −57.1 ± 1.2 to −49.9 ± 2.6 ‰ (Fig. 2), mostly overlapping for the given samples, except for the top of the tube sections. Among them, the bulk δ 13 C values of worms were the most 13 C de pleted compared to organic sources (−10 to −35 ‰) derived from photosynthetic origin or dissolved chemical species in sea- (Paull et al. 1985, Thurber et al. 2010, Feng et al. 2015. This may be partially attributable to methane oxidizers (below ca. ...
... This may be partially attributable to methane oxidizers (below ca. −66 ‰) using a carbon source highly depleted in 13 C such as biogenic methane (Paull et al. 1985, MacAvoy et al. 2002, Thurber et al. 2010). However, sulfur oxidizers can also have similar iso topic values (δ 13 C ≈ −72 ‰) by incorporating 13 C-depleted DIC derived from anaerobic oxidation of methane (AOM) and by further fractionation in autotrophic assimilation pathways (Nelson & Fisher 1995, Boetius et al. 2000, Lösekann et al. 2008, Thurber et al. 2010. ...
Siboglinid tubeworms of the genus Oligobrachia that thrive in obligatory association with endosymbionts have been predominantly observed in Arctic and high-latitude Atlantic cold seeps. Metabolic features of endosymbionts provide fundamental understanding for the survival strategy of tubeworms in cold seeps. However, no information on the bacterial endosymbionts of tubeworms from the Canadian Beaufort Sea has been available until now. In this study, we investigated the phylogeny and metabolic potential of a bacterial endosymbiont of siboglinid tubeworms from an active mud volcano in the Canadian Beaufort Sea using Illumina MiSeq sequencing of 16S rRNA gene amplicons. The siboglinid tubeworm shared 99.9% 18S rRNA gene sequence similarity with Oligobrachia haakonmosbiensis and 99.7–99.8% mitochondrial cytochrome C oxidase subunit I gene similarity with members of Oligobrachia sp. CPL-clade and was designated ‘Oligobrachia sp. BS1.’ The endosymbiont of Oligobrachia sp. BS1, which belongs to the Gammaproteobacteria, was most closely related to endosymbionts of Oligobrachia sp. CPL-clade, revealing the close relationships between the endosymbionts and their hosts. The bacterial endosymbiont of Oligobrachia sp. BS1 contained the key gene required for sulfur oxidation, aprA gene encoding the α-subunit of adenosine 1,5-phosphosulfate reductase, suggesting that this endosymbiont is capable of using sulfide as an energy source. The bacterial endosymbiont of an Oligobrachia species from an active mud volcano in the Canadian Beaufort Sea presented here expands our knowledge of the identities and thiotrophic metabolism of endosymbionts that are associated with hosts that dominate a wide range of methane seep habitats in the Arctic.
... tube sections and worms) ranged from −57.1 ± 1.2 to −49.9 ± 2.6 ‰ (Fig. 2), mostly overlapping for the given samples, except for the top of the tube sections. Among them, the bulk δ 13 C values of worms were the most 13 C de pleted compared to organic sources (−10 to −35 ‰) derived from photosynthetic origin or dissolved chemical species in sea- (Paull et al. 1985, Thurber et al. 2010, Feng et al. 2015. This may be partially attributable to methane oxidizers (below ca. ...
... This may be partially attributable to methane oxidizers (below ca. −66 ‰) using a carbon source highly depleted in 13 C such as biogenic methane (Paull et al. 1985, MacAvoy et al. 2002, Thurber et al. 2010). However, sulfur oxidizers can also have similar iso topic values (δ 13 C ≈ −72 ‰) by incorporating 13 C-depleted DIC derived from anaerobic oxidation of methane (AOM) and by further fractionation in autotrophic assimilation pathways (Nelson & Fisher 1995, Boetius et al. 2000, Lösekann et al. 2008, Thurber et al. 2010. ...
... Air-to-seawater transport prefers lighter 12 CO 2 to heavier 13 CO 2 and thus decreases its δ 13 C by 2‰ (Δ 13 C of −2‰, Table 2) [12]. Part of Methane seeps [23,24,26,144] Brine seep at Florida Escarpment [27,28] 5 CO 2 Interstitial water -50.0 to -5.00 (DIC) -38.0 to +11.0 (DIC) -21.0 to +1.00 (CO 2 ) Reductive TCA cycle [152,153] Biomineralization (shell formation) A few; +10.0 To DIC; to food [154] Table 2. Stable carbon isotope fractionation, Δ 13 C (‰), during geo-biological processes of carbon dynamics associated with methane seepage. ...
... Almost the same δ 13 C values, −22.0 to −30.0‰, of sedimentary organic matter from methane seepstwere reported [23][24][25][26]. However, very depleted δ 13 C values, as low as −47.0 to −80.0‰, of sedimentary organic matter were also reported from the methane seep at the base of Florida Escarpment in the Gulf of Mexico [27,28], which may be asso- ciated with "brine" seepage from very old organics or organics of non-photosynthetic origins. ...
... Both skeletal and authigenic non-skeletal carbonates in present-day as well as in fossil cold seeps can display a wide range of δ 13 C values, from normal marine to very negative (Paull et al., 1985(Paull et al., , 1989(Paull et al., , 1992Kulm et al., 1986;Rio et al., 1986Rio et al., , 1992Campbell, 1992Campbell, , 2006Gaillard et al., 1992;CoBabe, 1998;Hein et al., 2006;Lietard and Pierre, 2009). We have analyzed isotopes in bulk samples as well as carbonate shells of bivalves (small mytilids, Neopycnodonte, and pectinids), tubes of Ditrupa and benthic foraminiferal tests. ...
... Nonetheless, there are two exceptions, i.e. samples CARANT-A and CARPARQ-2A, in which the isotopic signal seems to be unaltered (Table 2). Sample CARANT-A has δ 13 C and δ 18 O values of normal marine waters whereas sample CARPARQ-2A has carbon and oxygen values within the range of values reported by Paull et al. (1985Paull et al. ( , 1989Paull et al. ( , 1992 for cold-seep mussels from the Florida Escarpment (N Gulf of Mexico). ...
Upper Miocene heterozoan carbonates crop out extensively in a NE–SW-trending belt (42 km long and 1.5–8 km wide) along the so-called El Alcor topographic high, from Carmona to Dos Hermanas (Seville, S Spain). These carbonates formed at the southern active margin of the Guadalquivir Basin, the foreland basin of the Betic Cordillera. They change to marls basinward (NE) and to sands landward (SE and SW). Therefore, carbonate production was constrained to a limited area in an otherwise siliciclastic shelf. The carbonates (up to 40 m thick) overlie a gradually coarsening-upward succession of marls followed by silts and sandstones. The carbonate sequence can be divided into three subunits corresponding, from bottom to top, to lowstand, transgressive, and highstand system tract deposits. The lower subunit, exhibiting extensive trough cross-bedding, is interpreted as a shallow-water bar deposit. The intermediate subunit onlaps underlying sediments and was deposited in deeper, low-turbulence conditions. The upper subunit deposits accumulated in a well-oxygenated outer platform based on benthic foraminiferal assemblages. The presence of hummocky and swaley cross-stratification in these latter deposits suggests that they were affected by storms. Pervasive fluid-escape structures are also observed throughout the carbonates.
... We tested this hypothesis by comparing the stable isotope compositions of alvinocarid shrimp from shallow and deep vestimentiferan communities to determine whether there is isotopic evidence of greater usage of seep-derived nutrition at greater depths. Organic matter from the photic zone has δ 13 C values between -23 and -19‰ [11], and carbon fixed by chemoautotrophy ranges from -75 to -28‰ [12,13], with the more negative values in this range indicating carbon derived Ocean Energy Management (BOEM) lease block designations and consist of a two-letter abbreviation, which stands for the region (AC=Alaminos Canyon, for example), followed by a three-digit number. The yellow text gives the name for the region, while the white points and text signify the specific study sites. ...
... We tested this hypothesis by comparing the stable isotope compositions of alvinocarid shrimp from shallow and deep vestimentiferan communities to determine whether there is isotopic evidence of greater usage of seep-derived nutrition at greater depths. Organic matter from the photic zone has δ 13 C values between-23 and-19‰[11], and carbon fixed by chemoautotrophy ranges from-75 to-28‰[12,13], with the more negative values in this range indicating carbon derivedThe site names are based on Bureau of Ocean Energy Management (BOEM) lease block designations and consist of a two-letter abbreviation, which stands for the region (AC=Alaminos Canyon, for example), followed by a three-digit number. The yellow text gives the name for the region, while the white points and text signify the specific study sites. ...
We analyzed the tissue carbon, nitrogen, and sulfur stable isotope contents of macrofaunal communities associated with vestimentiferan tubeworms and bathymodiolin mussels from the Gulf of Mexico lower continental slope (970-2800 m). Shrimp in the genus Alvinocaris associated with vestimentiferans from shallow (530 m) and deep (1400-2800 m) sites were used to test the hypothesis that seep animals derive a greater proportion of their nutrition from seeps (i.e. a lower proportion from the surface) at greater depths. To account for spatial variability in the inorganic source pool, we used the differences between the mean tissue δ(13)C and δ(15)N of the shrimp in each collection and the mean δ (13)C and δ(15)N values of the vestimentiferans from the same collection, since vestimentiferans are functionally autotrophic and serve as a baseline for environmental isotopic variation. There was a significant negative relationship between this difference and depth for both δ(13)C and δ(15)N (p=0.02 and 0.007, respectively), which supports the hypothesis of higher dependence on seep nutrition with depth. The small polychaete worm Protomystides sp. was hypothesized to be a blood parasite of the vestimentiferan Escarpialaminata. There was a highly significant linear relationship between the δ(13)C values of Protomystides sp. and the E. laminata individuals to which they were attached across all collections (p < 0.001) and within a single collection (p = 0.01), although this relationship was not significant for δ(15)N and δ(34)S. We made several other qualitative inferences with respect to the feeding biology of the taxa occurring in these lower slope seeps, some of which have not been described prior to this study.
... and thus extremely 13 C-depleted in comparison to organic matter in regular, recent marine sediments (210 to 235%), which are usually of photosynthetic origin (Calvin Benson Cycle) [33]. In eukaryotes, such negative carbon isotope signatures are typically attributed to a methanotrophic food chain [30,36,909192. However, also sulfate reducing bacteria and thiotrophs may show similar signatures by incorporating isotopically depleted CO 2 derived from methane oxidation and by further fractionation in autotrophic assimilation pathways [93,94]. ...
... A second source of steroids could be symbiotic megafauna such as Bathymodiolus sp. and Lamellibrachia sp, which are also a potential food source for heterotrophic megafauna [36,99]. We did not measure d 13 C-values of these organisms at Md. 12, but it is reasonable to assume that the bathymodiolin biomass is strongly 13 C-depleted just as has been found at other cold seeps [22,90,92], so that Bathymodiolus sp. could be a source of the crab's 13 C-depleted steroid pool. Lamellibrachia sp., on the other hand, is often not 13 C-depleted [92,100101102. ...
Cold seep ecosystems can support enormous biomasses of free-living and symbiotic chemoautotrophic organisms that get their energy from the oxidation of methane or sulfide. Most of this biomass derives from animals that are associated with bacterial symbionts, which are able to metabolize the chemical resources provided by the seeping fluids. Often these systems also harbor dense accumulations of non-symbiotic megafauna, which can be relevant in exporting chemosynthetically fixed carbon from seeps to the surrounding deep sea. Here we investigated the carbon sources of lithodid crabs (Paralomis sp.) feeding on thiotrophic bacterial mats at an active mud volcano at the Costa Rica subduction zone. To evaluate the dietary carbon source of the crabs, we compared the microbial community in stomach contents with surface sediments covered by microbial mats. The stomach content analyses revealed a dominance of epsilonproteobacterial 16S rRNA gene sequences related to the free-living and epibiotic sulfur oxidiser Sulfurovum sp. We also found Sulfurovum sp. as well as members of the genera Arcobacter and Sulfurimonas in mat-covered surface sediments where Epsilonproteobacteria were highly abundant constituting 10% of total cells. Furthermore, we detected substantial amounts of bacterial fatty acids such as i-C15∶0 and C17∶1ω6c with stable carbon isotope compositions as low as -53‰ in the stomach and muscle tissue. These results indicate that the white microbial mats at Mound 12 are comprised of Epsilonproteobacteria and that microbial mat-derived carbon provides an important contribution to the crab's nutrition. In addition, our lipid analyses also suggest that the crabs feed on other (13)C-depleted organic matter sources, possibly symbiotic megafauna as well as on photosynthetic carbon sources such as sedimentary detritus.
... Methane seeps along continental margins harbor lush faunal communities composed mainly of animals living in symbiosis with chemotrophic bacteria, from which they derive their nutrition (Paull et al. 1985, Dubilier et al. 2008). Due to this in situ food source, these faunas are believed to have a unique evolutionary history, closely linked to that of similar faunal communities living at hydrothermal vents (McArthur and Tunnicliffe 1998;Vrijenhoek 2013). ...
Ancient hydrocarbon-seep sites known as "Calcari a Lucina" are common in Miocene strata of northern Italy and typically consist of carbonate deposits dominated by large luci-nid, bathymodiolin, and vesicomyid bivalves. Here we report two new sites found in Upper Miocene strata at Monte Mauro near Brisighella in the Emilia-Romagna province. One is unusual by being embedded in unconsolidated silt-stone without any carbonate, but yet, consisting of the typical , seep-restricted bivalves Bathymodiolus moroniae and Archivesica aharoni vesicomyid clams and bathymodiolin mussels. The second deposit is dominated by the lucinid Megaxinus bellardianus, which has never been reported from a Miocene seep deposit in this region, despite being common in coeval siliciclastic sediments nearby. This species emphasizes biogeographic relationships between Upper Miocene seep faunas in the Mediterranean region and the tropic Indo-West Pacific Ocean.
... The Gulf of Mexico seeps (Brine Pool, Bush Hill, and West Florida Escarpment) have been extensively studied both geologically and biologically (Paull et al., 1984(Paull et al., , 1985Martens et al., 1991;Chanton et al., 1993), and were the basis for seminal observations on chemoautrophic life, including the demonstration of methane-based symbiosis between animals and intracellular bacteria (Childress et al., 1986). The mussels of these sites are particularly well characterized, and the reader is referred to the numerous papers concerning in particular their symbionts or their isotopic compositions allowing analysis of their diet (e.g., Fig. 1. ...
We report on the abundances of REE in a comprehensive suite of shells of deep-sea chemosynthetic mussels from hydrothermal vents and cold seeps. Except for mussel shells from oceanic hydrothermal sites that often show extremely pronounced Eu anomalies ((Eu/Sm)sn = 2–200), and abundances for this element that can occasionally exceed 200 ng/g, REE concentrations are usually low and typically between 10⁻⁴ and 10⁻³ times the shale reference.
In addition to exhibiting commonly high Eu anomalies, mussel shells from hydrothermal vents are depleted in light-REE and heavy-REE compared to reference shales (e.g., Pr/Sm)sn < 1, (Tb/Yb)sn = 1–6). These features are inherited from hydrothermal fluids. Mussel shells from cold seeps have very different REE concentrations, which also reflect the compositions of the waters they filter: their (Eu/Sm)sn ratios are much lower (<2) and are much less heavy-REE fractionated ((Tb/Yb)sn = 0.5–2.7). Furthermore, the REE distributions show a clear dichotomy between thiotrophic and methanotrophic mussels. The latter show marked enrichments in light-REE and even sometimes La enrichments much larger than those classically observed in deep-sea waters, leading to huge positive La anomalies (La/La* > 10). These light-REE enrichments are likely related to REE-dependent methanol dehydrogenase enzymes used by the symbionts that these mussels host in their gills. These data show that REE chemistry is a promising tool to study chemosynthetic faunas living near hydrothermal vents or cold seeps. Furthermore, REE chemistry, coupled with stable isotopes, should reveal the footprint of aerobic methanotrophy in carbonates formed in cold seeps, but also potentially in ancient sediments.
... Chemosynthetic carbonate accumulations near hydrocarbon seepage attest to the presence of nonphotosynthetic life (Paull et al., 1985) and to hydrocarbon presence in various tectonic settings (Campbell, 2006). The isotopic analyses of seep carbonates brings key information regarding conditions in sub-seafloor conduits and methane seep settings (Nelson et al., 2019). ...
Recent studies using the CO2 carbonate clumped isotope (¹³C-¹⁸O-¹⁶O, i.e., Δ47) paleothermometer and bulk isotopes (δ¹³C, δ¹⁸O) have brought new insights into the prevailing conditions during carbonate formation around marine methane seeps. These studies mostly revealed δ¹⁸O or paired δ¹⁸O and Δ47 disequilibria between precipitating minerals, water and DIC species. Here, we have sampled bivalves and cements from two modern, slow-release methane seeps located in the St. Lawrence Estuary. The bivalve shells have marine isotopic signals, whereas the cements show wide Δ47 (up to +0.05‰) and minor δ¹⁸O (+0.8‰) positive offsets relative to marine equilibrium, with a narrow δ¹³C range (-33.5 to -31.1‰). The observed isotopic trends show that, unlike in previous studies, the aragonite shells precipitated at full isotopic equilibrium, whilst the cements suggest differential disequilibrium precipitation. We propose that the suite of results were generated by distinct Δ47 and δ¹⁸O pathways, as supported by DIC-water isotopic exchange numerical experiments. The observed trends typify slow rates of methane oxidation and carbonate precipitation from residual gas with high-δ¹⁸O and low-Δ47 values after methane-derived CO2 diffusion. Overall, we suggest that the shells represent potential archives of seep conditions, and that the seep cements define a new Δ47 and δ¹⁸O domain widening the known spectrum of marine conditions producing natural carbonates. Our results, compiled with literature data, help refine the basis for interpreting carbonate precipitation mechanisms in ancient seeps or other geological settings.
... Although hydrocarbon-seep carbonates do not form regional-scale rock formations, they are abundant in ocean margin sediments, and seeps represent hotspots of benthic microbial activity (Sibuet and Olu, 1998;Boetius and Wenzhöfer, 2013;Suess, 2014). Seeps harbor unique oases of life independent of sunlight that are fueled by persistent flux of reduced fluids from seafloor sediments (Kennicutt II et al., 1985;Paull et al., 1984Paull et al., , 1985Brooks et al., 1987). Seep carbonates precipitate in dynamic environments as a consequence of sulfate-driven anaerobic oxidation of methane (SD-AOM; Boetius et al., 2000). ...
Marine authigenic carbonates form shallow-water microbialites, mud mounds, and hydrocarbon-seep deposits and contain appreciable amounts of trace elements that yield information on paleoenvironments. Element patterns of some of these carbonates archive metabolic processes through geologic time since many trace elements are redox-sensitive and participate in biological cycling. Trace element distributions in microbial carbonates not only yield information on the redox state of ancient oceans, but also on the chemical evolution of Earth’s hydrosphere and atmosphere. Trace element patterns can be used to distinguish marine from freshwater sources, to estimate water depth, and can help identify microbial metabolisms through time. A major issue concerning the use of marine carbonates as a paleoenvironmental archive is assessing the degree of early and late diagenetic alteration, which can modify or even reset the original content and distribution of trace elements. The degree and effect of early and late diagenetic alteration can be evaluated by comparing element contents to organic and other inorganic geochemical proxies. Authigenic hydrocarbon-seep carbonates forming in seafloor sediments are the product of microbial oxidation of methane and other hydrocarbon compounds. Seep carbonates are excellent archives, whose trace element contents yield information on sedimentary redox processes, as well as information on seepage intensity and fluid composition. Trace elements serve as proxies in these highly dynamic environments shaped by fluid seepage and chemosynthesis, and can help to reconstruct the evolution of chemosynthesis-based life at seeps through the Phanerozoic.
... Among marine organisms, δ 15 N of phytoplankton ranges from +2‰ to +8‰, that of zooplankton ranges from +8‰ to +15‰, and that of fishes ranges from +7‰ to +20‰ (Paull et al., 1985). The δ 15 N value of TN in accumulated seafloor sediments is approximately +7‰ on average, reflecting the δ 15 N of organic matter produced in the water column and eventually settling to the seafloor (e.g., Sweeney et al., 1978). ...
The Fukuzaki Limestone is a small limestone lens embedded in siliciclastic Taishu Group rocks on Tsushima Island in the southwestern Japan Sea. A fossil assemblage in this limestone consisting of the bivalve mollusc Bathymodiolus sp. (Bathymodiolinae) was previously inferred, on the basis of the limestone's isolated lenticular occurrence and the chemosynthetic nature of modern Bathymodiolinae, to rely on chemosynthetic production, but conclusive evidence was not provided. Carbon, nitrogen, oxygen, and sulfur isotope ratios in the limestone and its host rock mudstone were measured to clarify the paleoecology of the fossil assemblage and the formation environment of the limestone. The low δ¹³C (−39.8‰ to −31.7‰) and δ¹⁸O (−13.8‰ to −11.9‰) values of carbonate of the limestone lens strongly suggest that the limestone is composed of authigenic carbonate rock precipitated from bicarbonate derived from anaerobic oxidation of biogenic or thermogenic methane. The fossil assemblage in the limestone lens is consistent with a chemosynthesis-based animal assemblage harboring thioautotrophic (sulfur-oxidizing) symbionts, and the low δ¹³C and δ³⁴S values of total organic carbon and sulfide sulfur, respectively, in the limestone lens and mud layers suggest that they reflect chemosynthetic production using hydrogen sulfide derived from anaerobic methane oxidation by microbes. Furthermore, the stratigraphic position of the lens in the upper part of the Lower Unit of the Taishu Group indicates that it was precipitated at a water depth >800 m (deeper than the lower middle bathyal zone). These findings indicate that a deep-sea basin locally supplied with methane had already formed in the southwestern Japan Sea by rapid subsidence during the opening stage of the Japan Sea (16–17 Ma).
... A small brine pool, called NR-1, in the Gulf of Mexico is even surrounded by dense beds of Bathymodiolus mussels, which house chemolithoautotrophic bacteria presumably fed by sulfide or methane from the anoxic brine lake (MacDonald et al. 1990). In sediments fed by a sulfate-depleted hypersaline brine seep, Paull et al. (1985) found that the carbon in mussel tissue was isotopically light and hence presumably derived (via endosymbiotic methanotrophs) from brine-derived methane. Therefore, there is good evidence that food webs are stimulated by reduced compounds derived from microbial activity in hypersaline brines analogous to hydrothermal vent communities (Martens et al. 1991). ...
... Mean POC flux (g C m −2 y −1 ± S.D.) Y. Xu et al. Deep-Sea Research Part II 155 (2018) 19-26 Fourqurean, 2003), and -44‰ to -77‰ for organic matter from chemosynthesis at hydrothermal vents (Paull et al., 1985). Richardson et al. (1995) reported a C/N ratio of 6 for surface sediments from the Puerto Rico Trench, suggesting a predominant marine origin for sedimentary organic matter. ...
... Marine cold seeps are hotspots of life on the seafloor where chemical energy is converted into biomass by chemosynthetic microorganisms (Paull et al., 1985). This chemical energy is delivered by the seepage of methane that is consumed by a consortium of methanotrophic archaea and associated sulfate-reducing bacteria mediating the sulfate-driven anaerobic oxidation of methane (SD-AOM; Boetius et al., 2000). ...
Ancient methane-seep carbonates are geological archives of environmental conditions and record past microbial activity. To better understand the information stored in this archive, a comparison was made of phase-specific major, trace, and rare earth element (REE) patterns, mineralogies, and textures of two early diagenetic carbonate phases in five ancient methane-seep deposits including Oligocene limestones from the Satsop and Canyon rivers (Washington State), the Cretaceous Tepee Buttes (Colorado), and the Carboniferous Ganigobis limestones (Namibia). (1) Cryptocrystalline, yellow aragonite and (2) banded and botryoidal aggregates of clear, fibrous aragonite typify many Phanerozoic seep limestones, and are common features of authigenic seep carbonates forming close to the sediment-water interface today. Light REE enrichment in yellow aragonite is observed together with high organic matter contents, indicated by intense autofluorescence of yellow aragonite, and occurs in combination with low Mg/Sr ratios. Conversely, heavy REE enrichment is observed in neomorphic yellow calcite spar typified by high Mg/Sr ratios, indicating progressive diagenetic alteration during early diagenesis in marine pore waters affected by a succession of biogeochemical reactions. These observations suggest that REE contents and patterns of early diagenetic carbonate phases are a function of the quality of preservation. Transformation of primary aragonite to calcite resulting from changing pore water compositions during later-stage early diagenesis is apparently capable to significantly modify elemental composition. The new results reveal that rare earth elements do not necessarily behave conservatively if early diagenesis is controlled to a large extent by evolving pore water compositions in environments strongly affected by biogeochemical processes. For such settings a careful assessment of diagenetic alteration is consequently required before calcite resulting from aragonite transformation can be used for reliable paleoenvironment reconstruction.
... Another type of reduced biotopes is cold methane seeps (Paull, Jull, Toolin, & Linick, 1985), which are interesting and unique from the viewpoint of ecology of the benthic fauna, the last functions by means of bacterial chemosynthesis. Bioaccumulation remains a poorly understood aspect of these processes. ...
A comparative study of the bioaccumulation of trace elements in benthic organisms inhabiting the area of methane seeps in the Deryugin Basin and nearby the Paramushir Island (Sea of Okhotsk) has been performed. The data pertain to both essential elements (Fe, Mn, Ni, Co, Cr, and Cu), which are necessary in certain concentrations for the metabolism of organisms, and nonessential heavy metals (Cd, Pb, and Hg), as well as As, a toxic metalloid. Dominating representatives of the bottom fauna from the Deryugin Basin (sea anemones, clams) were characterized by high bioaccumulation coefficients of most of the elements (≥ n103), regardless of their biochemical properties. The use of the coefficient K, which characterizes the accumulation of trace elements in the soft tissues of bivalves relative to their shells, allowed us to detect differences in the bioaccumulation character. Symbiotrophic bivalves of the family Vesicomyidae from the Deryugin Basin were characterized by the accumulation of all of the trace elements mostly in soft tissues (gills, primarily) compared to the carbonate shells (coefficient K > 1). We suppose that different effect of abiotic (biological availability of elements and water turbidity) and biotic (throphic strategy) factors of the habitats may probably be a reason of such phenomenon.
... Hydrocarbon seeps are places on the seafloor where fluids rich in methane and hydrogen sulfide reach the seabed (Suess 2014). These sites are often inhabited by a highly specialized macrofauna of low diversity but high biomass, which takes advantage of nutrients provided by chemoautotrophic bacteria that use methane and sulfide to synthesize organic matter (Paull et al. 1985;Childress et al. 1986;Sibuet and Olu 1998). The fauna inhabiting hydrocarbon-seeps in the Mediterranean Sea has an impoverished character (Olu et al. 2004;Ritt et al. 2010Ritt et al. , 2011Taviani 2011; compared to those known from the continental margins of the Atlantic Ocean proper or from the Indian and Pacific oceans (Van Dover et al. 2002). ...
M. 2018. Chemosymbiotic bivalves from the late Pliocene Stirone River hydrocarbon seep complex in northern Italy. Acta Palaeontologica Polonica 63: xxx-xxx. Seven species of chemosymbiotic bivalves are described from the late Pliocene Stirone River hydrocarbon seep complex in northern Italy, including one new species and two in open nomenclature. The known species are the solemyid Acharax doderleini, the lucinids Lucinoma persolida and Megaxinus ellipticus, and the vesicomyid Isorropodon aff. perplexum; in open nomenclature we report two lucinids, including the largest species of Lucinoma known from the Italian Pliocene to date, and a strongly inflated, large Anodontia sp. The most abundant species at the Stirone seep complex is the lucinid Megaxinus stironensis sp. nov. This Pliocene seep fauna differs from that of the well-known Miocene "Calcari a Lucina" seep deposits by lacking large bathymodiolin mussels and vesicomyid clams; instead, the dominance of the lucinid Megaxinus stironensis gives this fauna a unique character. We speculate that at the Stirone seep complex, Megaxinus had occupied the ecological niche that Meganodontia occupied at the Miocene "Calcari a Lucina" seep sites in the Mediterranean basin, and that the dominance of Megaxinus could be a widespread feature of Pliocene chemosyn-thesis-based ecosystems in Mediterranean Pliocene.
... A small brine pool, called NR-1, in the Gulf of Mexico is even surrounded by dense beds of Bathymodiolus mussels, which house chemolithoautotrophic bacteria presumably fed by sulfide or methane from the anoxic brine lake (MacDonald et al. 1990). In sediments fed by a sulfate-depleted hypersaline brine seep, Paull et al. (1985) found that the carbon in mussel tissue was isotopically light and hence presumably derived (via endosymbiotic methanotrophs) from brine-derived methane. Therefore, there is good evidence that food webs are stimulated by reduced compounds derived from microbial activity in hypersaline brines analogous to hydrothermal vent communities (Martens et al. 1991). ...
... A comparison of the 13 C values obtained from our brachiopod shell material reveals that they are either slightly lighter than or similar to those derived from shell calcite of Late Triassic or Jurassic brachiopods from typical marine environments (e.g., Veizer et al. 1999;Korte et al. 2005), suggesting near equilibrium with the contemporaneous seawater. Paull et al. (1985Paull et al. ( , 1989) and Rio et al. (1992) studied bivalves from modern habitats around hydrothermal vents, containing different chemosynthetic symbionts. The first two groups of bivalves harbored methane-oxidizing bacteria, whereas the third group contained sulfide-oxidizing bacteria. ...
Cold seeps, where seepage of hydrocarbon-rich fluids occurs in the sea floor, are sites which harbor highly specialized ecosystems associated with distinctive carbonate sediments. Although their Mesozoic record is scarce and patchy, it commonly includes dimerelloid rhynchonellide brachiopods. Here we report a monospecific assemblage of Anarhynchia from a limestone boulder of Early Pliensbachian (Early Jurassic) age in the Inklin Formation of the Whitehorse Trough in the Stikine terrane, from a locality at Atlin Lake in northern British Columbia. Specimens are among the largest known Mesozoic brachiopods, up to 9 cm in length, and described here as Anarhynchia smithi n. sp. Early precipitated carbonate cement phases of the limestone have carbon isotopic composition highly depleted in 13C, indicative of the influence of microbial oxidation of methane derived from a cold seep. Carbonate petrography of the banded-fibrous cement and other characteristic components supports this paleoenvironmental inference. Volcanogenic detrital grains in the matrix are indistinguishable from those in the sandstone layers in the siliciclastic sequence, suggesting that the seep carbonate is broadly coeval with the enclosing conglomerate. The new record extends the geographic range and species-level diversity of the genus, but supports its endemism to the East Pacific and membership in chemosynthesis-based ecosystems. The distribution of three distinct but congeneric species suggests that allopatric speciation occurred at separate sites along the active margin of western North America, and Anarhynchia was restricted to seep and vent habitats in the Early Jurassic.
... All of the fishes were enriched in 13 C (−23.2‰ to −16.4‰) relative to chemosynthetically derived organic matter (e.g. −75‰ to −28‰, Paull et al., 1985;Brooks et al., 1987;Kennicutt et al., 1992), with values more consistent with assimilating photosynthetically based organic material. ...
... The discoveries of diverse chemolithic bioenergetic pathways contributed greatly to the understanding of the complexity of energy flow in Earth ecosystems and the interdependency of the biogeochemical cycles involving carbon, nitrogen, sulfur, iron, and other bioessential elements ( Table 1). The discoveries of chemosynthetic ecosystems in the deep-sea hydrothermal vent and cold-seep environments as "oases" in the vast deep ocean "deserts" were true scientific thrills in the 70s and 80s of the 20th century, spotlighting the cornerstone species role in community structure and the primary producer role in trophic transfer the chemoautotrophic bacteria and archaea play in these sunlight-independent marine ecosystems (Felbeck and Somero, 1982;Paull et al., 1985;J?rgensen and Boetius, 2007). ...
Transformation and mobilization of bioessential elements in the biosphere, lithosphere, atmosphere, and hydrosphere constitute the Earth’s biogeochemical cycles, which are driven mainly by microorganisms through their energy and material metabolic processes. Without microbial energy harvesting from sources of light and inorganic chemical bonds for autotrophic fixation of inorganic carbon, there would not be sustainable ecosystems in the vast ocean. Although ecological energetics (eco-energetics) has been emphasized as a core aspect of ecosystem analyses and microorganisms largely control the flow of matter and energy in marine ecosystems, marine microbial communities are rarely studied from the eco-energetic perspective. The diverse bioenergetic pathways and eco-energetic strategies of the microorganisms are essentially the outcome of biosphere-geosphere interactions over evolutionary times. The biogeochemical cycles are intimately interconnected with energy fluxes across the biosphere and the capacity of the ocean to fix inorganic carbon is generally constrained by the availability of nutrients and energy. The understanding of how microbial eco-energetic processes influence the structure and function of marine ecosystems and how they interact with the changing environment is thus fundamental to a mechanistic and predictive understanding of the marine carbon and nitrogen cycles and the trends in global change. By using major groups of chemolithoautotrophic microorganisms that participate in the marine nitrogen cycle as examples, this article examines their eco-energetic strategies, contributions to carbon cycling, and putative responses to and impacts on the various global change processes associated with global warming, ocean acidification, eutrophication, deoxygenation, and pollution. We conclude that knowledge gaps remain despite decades of tremendous research efforts. The advent of new techniques may bring the dawn to scientific breakthroughs that necessitate the multidisciplinary combination of eco-energetic, biogeochemical and “omics” studies in this field.
... The biological conversion of one or more carbon molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic molecules (e.g., hydrogen gas, hydrogen sulfide) or methane as a source of energy is known as chemosynthesis. Shortly after these deep-sea discoveries, similar assemblages of organisms were recovered on the continental slope of the north-central Gulf of Mexico at a petroleum seep and at a brine seep at the base of the escarpment off the shore of western Florida (Kennicutt et al. 1985;Paull et al. 1984Paull et al. , 1985Brooks et al. 1987a, b;Brooks et al. 1989). These unique biological assemblages have become known as cold-seep communities as contrasted to hydrothermal-vent communities. ...
Oil and gas seeps are common worldwide; occur on land and beneath the ocean; are numerous in the Gulf of Mexico; and are biogenic, thermogenic, or mixed in origin. Seeps occur as gases, liquids, asphalts, and tars. Seeps are estimated to account for about 95 % of oil annually discharged to the Gulf of Mexico waters. Biogenic gas seeps have a microbial metabolic origin. Thermogenic hydrocarbons rise to the surface from more deeply buried source rock horizons or accumulations. The seepage of oil and gas into marine sediments initiates a complex biogeochemical cycle. A unique ecology has evolved in association with oil and gas seeps based on chemosynthesis and symbioses. Consortia of microbial species mediate the geological and biogeochemical processes that are essential for supporting what are commonly referred to as cold-seep communities. At these locations, bacteria oxidize hydrocarbons to carbon dioxide or bicarbonate ions, which favor the formation of hard ground substrate in otherwise mostly muddy environments. Thermogenic oil and gas seeps and biogenic gas seeps are pervasive and intrinsic features of the Gulf of Mexico. Thermogenic seeps will persist as long as oil and gas continue to migrate to the seafloor.
... In the Guaymas Basin, photosynthesis-derived matter degraded in the water column is enriched in δ 15 N ( Table 2). While lacking the δ 15 N of chemosynthetic producers, these are usually associated with low or even negative values, characteristic of local inorganic nitrogen sources (NO 3 -, NH 4 + , N 2 ) [45,62,72]. Although stable isotope mixing models are increasingly used to quantify consumer diets, their use was not possible in our study owing to the presence of a large number of potential sources and the lack of δ 15 N values for chemosynthetic producers. ...
In the Guaymas Basin, the presence of cold seeps and hydrothermal vents in close proximity, similar sedimentary settings and comparable depths offers a unique opportunity to assess and compare the functioning of these deep-sea chemosynthetic ecosystems. The food webs of five seep and four vent assemblages were studied using stable carbon and nitrogen isotope analyses. Although the two ecosystems shared similar potential basal sources, their food webs differed: seeps relied predominantly on methanotrophy and thiotrophy via the Calvin-Benson-Bassham (CBB) cycle and vents on petroleum-derived organic matter and thiotrophy via the CBB and reductive tricarboxylic acid (rTCA) cycles. In contrast to symbiotic species, the heterotrophic fauna exhibited high trophic flexibility among assemblages, suggesting weak trophic links to the metabolic diversity of chemosynthetic primary producers. At both ecosystems, food webs did not appear to be organised through predator-prey links but rather through weak trophic relationships among co-occurring species. Examples of trophic or spatial niche differentiation highlighted the importance of species-sorting processes within chemo-synthetic ecosystems. Variability in food web structure, addressed through Bayesian metrics, revealed consistent trends across ecosystems. Food-web complexity significantly decreased with increasing methane concentrations, a common proxy for the intensity of seep and vent fluid fluxes. Although high fluid-fluxes have the potential to enhance primary productivity, they generate environmental constraints that may limit microbial diversity, colonisation of consumers and the structuring role of competitive interactions, leading to an overall reduction of food-web complexity and an increase in trophic redundancy. Heterogeneity provided by foundation species was identified as an additional structuring factor. According to their biological activities , foundation species may have the potential to partly release the competitive pressure within communities of low fluid-flux habitats. Finally, ecosystem functioning in vents and seeps was highly similar despite environmental differences (e.g. physico-chemistry, dominant basal sources) suggesting that ecological niches are not specifically linked to the nature of fluids. This comparison of seep and vent functioning in the Guaymas basin thus provides further supports to the hypothesis of continuity among deep-sea chemosynthetic ecosystems.
... [4] The stable N isotope composition of vent organisms has previously been measured to study feeding ecology and trophic structure in HV systems. In earlier work, very low d 15 N (for definition see section 2) values ($À10 to +4‰) of HV organisms, for example, have been attributed to strong N isotope fractionation during chemosynthetic assimilation of ammonium or the local supply of 15 N-depleted ammonium [Rau, 1981;Paull et al., 1985;Van Dover and Fry, 1994;Kennicutt and Burke, 1992;Van Dover, 2002]. ...
Little is known about nitrogen (N) transformations in general, and the elimination of N in particular, at diffuse vents where anoxic hydrothermal fluids have mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N-loss pathways (denitrification, anammox) and dissimilative nitrate reduction to ammonium (DNRA) in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e. temperature, pH, nutrients, H2S and N2O concentrations) as well as the biodiversity and abundance of chemolithotrophic nitrate-reducing, sulfur-oxidizing γ-proteobacteria (SUP05 cluster) using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA) genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR) assays. Denitrification was the dominant N-loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l−1 day−1. In comparison, anammox rates were always
... Research cruises in recent years have discovered new vent habitats in the Southern [52], Indian [67], and Arctic [68] Oceans, with expectations of more vent habitats to come [36]. The discovery of seeps and their chemosynthetic communities [69] some 30 years ago was thought to represent a habitat extension of hydrothermal vents, but we now recognize seeps, which may include methane, natural gas, or hydrocarbon emissions, as quite distinct habitats with little species overlap with vents [66] and high rates of endemism [70]. Although we know that seeps, and the mud volcanoes that characterize some seep environments, occur widely in all oceans [71], new discoveries continue, such as the first report of an Antarctic seep just a decade ago [72]. ...
The 70 % of Earth's surface covered by oceans supports significant biological diversity and immense untapped potential for marine bioproducts. The recently completed international Census of Marine Life (2000-2010) invested heavily in evaluating the diversity, abundance, and distribution of life in the ocean but concluded that at least 50 % and potentially > 90 % of marine species remain undescribed by science. Despite this potential, and numerous successes spanning pharmaceuticals, nutraceuticals, anti-foulants and adhesives, biofuels, biocatalysts (enzymes), and cosmetics, several impediments have slowed marine bioproduct development. First, the sheer size of the ocean constrains comprehensive exploration. Second, marine taxonomists and ecologists generally do not focus on the most promising groups for bioproduct development. Third, the geographic mismatch between (often remote) biodiversity hotspots and science capacity limit discovery. Despite these challenges, new ocean sampling tools (digital imaging, remote vehicles, genetic approaches, in situ samplers), many developed or improved during the Census of Marine Life, should enhance future marine biodiversity and thus marine bioproduct discovery.
Georg Thieme Verlag KG Stuttgart · New York.
... To date the MOB symbionts have been either coccoid or rod-shaped cells with type I internal membranes (Fig. 2) and an active hexulose phosphate synthase pathway for carbon assimilation; thus far, type II organisms have not been observed (e.g., Cavanaugh et at., 1987;Wood and Kelly, 1989;Schmaljohann et at., 1990). Regardless of the taxonomic affinities of the MOB, these symbioses accounted for a large fraction of host carbon and energy requirements (e.g., Cary et at., 1988; and apparently contributed to dramatic, productive benthic communities isolated from significant phytoplanktonic organic inputs (e.g., Paull et at., 1984Paull et at., , 1985Kennicutt et at., 1985Kennicutt et at., , 1989Hovland and Thomsen, 1989;MacDonald et at., 1990;Dando et at., 1991). ...
Methane oxidation became a subject of scientific inquiry when Alessandro Volta observed in 1776 that gas bubbles collected from a pond were combustible. Methane was subsequently exploited as a source of heat and light. However, in spite of its commercial significance, the biological and ecological aspects of methane oxidation were largely ignored until the pioneering work of Söhngen (1906), who first isolated methane-oxidizing bacteria (MOB). [Quayle (1987) notes that Lowe probably isolated the first MOB in 1892 without recognizing their ability to oxidize methane.] Little additional progress was made until the 1960s, at which time the systematic efforts of several groups provided methodological tools and details on the taxonomy, physiology, and biochemistry of C1 metabolism. Aside from purely academic motivations, this work was stimulated by: (1) the potential use of methanotrophic bacteria as sources of “single cell protein”; (2) the role of methylotrophic bacteria in food spoilage; (3) the possible use of methanotrophs in the bioremediation of certain halogenated organic pollutants or as agents for commercial biotransformations (Higgins et al., 1980). Ecological studies were slower in development, but a number of important observations established the ubiquity of methanotrophs, the impact of methane oxidation in freshwater and some marine systems, and the potential for anaerobic as well as aerobic methane oxidation (see Hanson, 1980, and Rudd and Taylor, 1980, for earlier reviews).
... It is unknown whether thermogenic or biogenic sources were tapped, or if mixing with other carbon reservoirs affected the isotopic signal. For example, typical carbon sources for most deepsea settings include: total dissolved inorganic carbon in seawater (0%o); marine organic carbon, particulate and dissolved ( 20 to -25%o); terrestrial plant material ( 10 to -30%o); thermogenic methane (+ values to -40%o); and biogenic methane ( 50 to <-80%o) (Paull et al., 1985, and references therein). Oxygen isotopic signatures of the cement are consistent with seawater values and indicate that there was no significant change in ambient temperature of formation. ...
... PDB) of their tissue carbon, which is 28.4& more depleted than the organic carbon (226.4 6 0.6& PDB) found in the surrounding sediments. This value is atypical of organisms that are solely supported by photosynthetic ecosystems, and more consistent with a highly depleted 13 C carbon source such as methane [Paull et al., 1985]. Where the sulfate from the overlying seawater is mixed with the escaping methane-bearing pore fluids near the seafloor, anaerobic methane oxidation produces sulfide, which supports microbial primary production [e.g., Boetius et al., 2000]. ...
Morphologic features, 600-1100 m across and elevated up to 30 m above the surrounding seafloor, interpreted to be mud volcanoes were investigated on the continental slope in the Beaufort Sea in the Canadian Arctic. Sediment cores, detailed mapping with an autonomous underwater vehicle, and exploration with a remotely operated vehicle show that these are young and actively forming features experiencing ongoing eruptions. Biogenic methane and low-chloride, sodium-bicarbonate-rich waters are extruded with warm sediment that accumulates to form cones and low-relief circular plateaus. The chemical and isotopic compositions of the ascending water indicate that a mixture of meteoric water, seawater, and water from clay dehydration has played a significant role in the evolution of these fluids. The venting methane supports extensive siboglinid tubeworms communities and forms some gas hydrates within the near seafloor. We believe that these are the first documented living chemosynthetic biological communities in the continental slope of the western Arctic Ocean.
... Methane seeps on the deep-sea floor harbor dense faunal communities whose dominant members rely on chemosynthetic bacteria for nutrition [1,2]. First discovered in the Gulf of Mexico in the 1980s, they are now recognized at virtually all continental margins worldwide [3,4]. ...
We report new examples of Cenozoic cold-seep communities from Colombia, Cuba, the Dominican Republic, Trinidad, and Venezuela, and attempt to improve the stratigraphic dating of Cenozoic Caribbean seep communities using strontium isotope stratigraphy. Two seep faunas are distinguished in Barbados: the late Eocene mudstone-hosted 'Joes River fauna' consists mainly of large lucinid bivalves and tall abyssochrysoid gastropods, and the early Miocene carbonate-hosted 'Bath Cliffs fauna' containing the vesicomyid Pleuro-phopsis, the mytilid Bathymodiolus and small gastropods. Two new Oligocene seep communities from the Sinú River basin in Colombia consist of lucinid bivalves including Elongatolucina, thyasirid and solemyid bivalves, and Pleurophopsis. A new early Miocene seep community from Cuba includes Pleurophopsis and the large lucinid Meganodontia. Strontium isotope stratigraphy suggests an Eocene age for the Cuban Elmira asphalt mine seep community, making it the oldest in the Caribbean region. A new basal Pliocene seep fauna from the Dominican Republic is characterized by the large lucinid Anodontia (Pego-physema). In Trinidad we distinguish two types of seep faunas: the mudstone-hosted Godi-neau River fauna consisting mainly of lucinid bivalves, and the limestone-hosted Freeman's Bay fauna consisting chiefly of Pleurophopsis, Bathymodiolus, and small gastropods; they are all dated as late Miocene. Four new seep communities of Oligocene to Miocene age are reported from Venezuela. They consist mainly of large globular lucinid bivalves including Meganodontia, and moderately sized vesicomyid bivalves. After the late Miocene many large and typical 'Cenozoic' lucinid genera disappeared from the Caribbean seeps and are today known only from the central Indo-Pacific Ocean. We speculate that the increasingly oligotrophic conditions in the Caribbean Sea after the closure of the Isthmus of Panama in the Pliocene may have been unfavorable for such large lucinids because they are only fac-ultative chemosymbiotic and need to derive a significant proportion of their nutrition from suspended organic matter.
... Among the dominant animals are bathymodiolin mussels, which live in symbiosis with thiotrophic and/or methanotrophic symbionts and derive the vast majority of their nutrition from these symbionts (e.g. Paull et al., 1985;Childress et al., 1986;Cordes et al., 2009;Duperron, 2010). The carbon source for the methanotrophic and thiotrophic bacteria is methane and dissolved inorganic carbon (DIC), respectively (Fisher, 1990;Conway et al., 1994). ...
... In modern marine environments, active cold seeps are commonly associated with the occurrences of pockmarkers on the seafloor, BSRs in seismic profiles, shallow SMI in sediment columns and high concentration of dissolved methane in bottom water (Borowski et al. 1999;Gay et al. 2006). However, there are other geological and biological features associated with methane expulsions: 1) the occurrence of chemosynthetic community including mollusks and tubeworms (Paull et al. 1985;Sibuet and Olu 1998); 2) the existence of authigenic pyrites in the sediments (Kohn et al. 1998;Hill et al. 2004;Riedel et al. 2006); and 3) the occurrence of chemically precipitated authigenic carbonates with depleted carbon isotope values (Hathaway and Degens 1969;Kulm et al. 1986;Paull et al. 1992;Lein 2004). ...
Pogonophoran tube worms, elongated pyrite tubes and authigenic carbonate nodules are used to evaluate the occurrence of potential cold seeps in the syn-collision accretionary prism Kaoping Slope off SW Taiwan. At least two species of pogonophoran tubeworms were found in surface and core sediments. Pyrites occur in three different forms: fillings inside foraminiferal chambers, cements between calcareous microfossils, and elongated tubes. The bottom water off SW Taiwan is aerobic, but authigenic pyrites are found in the surface sediments at several sites, suggesting the existence of local reducing environments enabling the formation of pyrites. These environments are most likely caused by the occurrence of active cold seeps where methane expulses. Authigenic carbonates with highly depleted carbon isotope values (-54 to -43‰) were found at more than 5 locations, in agreement with a methane-derived source for the carbon. Integrating these geological and biological results, this study demonstrates that there are active cold seeps with methane expulsions in several anticline hinge zones east of the associated thrust faults in water depths of 800-1500 m of the frontal syn-collision accretionary prism Kaoping Slope. The existence of these high potential active cold seep sites is also supported by the occurrences of distinct bottom simulating reflectors (BSRs), shallow sulfate-methane interface and high concentrations of dissolved methane in bottom water.
... Cold seeps have been recognized on both passive and active continental margins [e.g., Paull et al., 1985;Hovland and Judd, 1988;Silver et al., 2000;Boetius and Wenzhofer, 2013]. Cold seeps located in the deep sea along these margins provide the foundation for diverse chemosynthetic ecosystems, which can contain more biomass and utilize more oxygen than the surrounding deep-sea communities by orders of magnitude [Levin, 2005;Boetius and Wenzhofer, 2013]. ...
The importance of tectonics and fluid flow in controlling cold seep habitats has long been appreciated at convergent margins, but remains poorly understood in strike-slip systems. Here, we present geophysical, geochemical and biological data from an active methane seep offshore from Del Mar, California in the inner California borderlands (ICB). The location of this seep appears controlled by localized transpression associated with a step in the San Diego Trough fault zone, and provides an opportunity to examine the interplay between fluid expulsion and restraining step-overs along strike-slip fault systems. These segment boundaries may have important controls on seep locations in the ICB and other margins characterized by strike-slip faulting (e.g., Greece, Sea of Marmara, and Caribbean). The strike-slip fault systems offshore southern California appear to have a limited distribution of seep sites compared to a wider distribution at convergent plate boundaries, which may influence seep habitat diversity and connectivity.
... yokosukensis). Such an association dominated by vesicomyid bivalves is typical for extant cold seep communities (Paull et al. 1985;Levin 2005;Majima et al. 2005;Campbell, 2006) and suggests that the Kii Oshima fauna might have lived at an ancient cold seep. Predatory gastropods such as the naticid Euspira meisensis found along with the chemosymbiotic bivalves are common in soft sediments in many marine environments, but they are also frequently found at ancient cold-seep communities, especially in the North Pacific realm Kiel, 2010b). ...
A fossil association of potentially chemosymbiotic bivalves is reported from the lower Miocene Shikiya Formation in Kii Oshima Island, Wakayama Prefecture, Japan. The association is dominated by the elongate vesicomyid species Adulomya uchimuraensis (Kuroda, 1931); a second vesicomyid of lower abundance is here described as Archivesica sakoi new species. It represents the oldest species of the genus Archivesica and has a similar hinge structure as " Calyptogena " laubieri (Okutani and Mé tivier, 1986). Additional faunal elements include chemosymbiotic bivalves, namely the solemyid Acharax cf. yokosukensis Kanie and Kuramochi, 1995, and the lucinids Lucinoma? sp. and Poumea? sp., as well as the naticid gastropod Euspira meisensis (Makiyama, 1926). This association of fossil bivalves all with well-known chemosymbiotic living relatives suggests that these specimens lived at an ancient cold seep, and their mode of occurrence as mostly articulated shells parallel to the bedding plane indicates that were transported a short distance and then quickly buried.
... -15 to -10 ‰) (Hügler & Sievert 2011). Moreover, symbiotic or free-living chemoauto trophic microbes typically fix local nitrogen resulting in expression of light or negative δ 15 N signatures in consu mer tissues around chemo synthetic habitats (Paull et al. 1985, Kennicutt et al. 1992. ...
We explore the trophic ecology of heterotrophic fauna associated with a high temperature (HT) vent, 2 low temperature vents, a 'near-HT vent' habitat and a non-vent site situated at upper bathyal depths on the southern Mohn's Ridge in the Arctic Ocean. Only a single taxon (the gastropod Pseudosetia griegi) was found at the high temperature vent habitat. Their mean delta C-13 values were significantly lighter than conspecifics from a low temperature vent habitat within the same vent field, reflecting the incorporation of sulfide oxidizing bacteria into the biomass of the animals. The majority of fauna from the low temperature, near-HT, and non-vent habitats had isotopic signatures indicative of assimilation of photosynthetic material. However, we found remarkably diverse isotopic compositions among the fauna sampled here, with a small sub-set of fauna at each site possessing C and N isotopic signatures indicative of incorporation of chemo synthetic production. Moreover, when isotopic signatures of similar taxa were compared from the same sample, delta C-13 signatures suggested a high degree of trophic complexity can exist over relatively small spatial scales at vent habitats on the southern Mohn's Ridge. The high contribution of photosynthetic food material to faunal diets and variability in food types may result from the upper bathyal venting depth and sedimentary nature of the vents. We hypothesize that the upper bathyal depth of active venting may lead to iron enhancement of surface photosynthetic production, especially in high nutrient areas, which ultimately sinks to the seabed where it is incorporated by fauna around the vents.
... For OCS ecosystems, the only carbon source ubiquitously and continuously available is phytoplankton, classically considered the sole oceanic carbon source (Thayer et al. 1983;Fry and Sherr 1984;Dauby 1989), excluding local primary production from seafloor chemosynthesis (Kennicutt et al. 1985;Paull et al. 1985;Brooks et al. 1987). At high latitudes, sea ice algae may be an important supplementary carbon source (Hobson et al. 1995(Hobson et al. , 2002. ...
The hypothesis that phytoplankton is the sole carbon source for the OCS deep-reef community (>60 m) was tested. Trophic structure for NE Gulf of Mexico deep reefs was analyzed via carbon and nitrogen stable isotopes. Carbon signatures for 114 entities (carbon sources, sediment, fishes, and invertebrates) supported surface phytoplankton as the primary fuel for the deep reef. However, a second carbon source, the macroalga Sargassum, with its epiphytic macroalgal associate, Cladophora liniformis, was also identified. Macroalgal carbon signatures were detected among 23 consumer entities. Most notably, macroalgae contributed 45 % of total carbon to the 13C isotopic spectrum of the particulate-feeding reef-crest gorgonian Nicella. The discontinuous spatial distribution of some sessile deep-reef invertebrates utilizing pelagic macroalgal carbon may be trophically tied to the contagious distribution of Sargassum biomass along major ocean surface features.
... Methane-seep faunas were first discovered in the early 1980s in the Gulf of Mexico and are now †Author for correspondence: joern.peckmann@univie.ac.at recognized at most continental margins (Paull et al. 1984;Baker et al. 2010). Their highly specialized taxa are closely related to those at deep-sea hydrothermal vents and many rely on chemotrophic symbionts for nutrition (Paull et al. 1985). Although the rise of the modern, mollusc-dominated vent and seep fauna began during the Cretaceous Period, the main players at present-day vents and seeps appeared in early Cenozoic time (Campbell & Bottjer, 1995;Kiel & Little, 2006;Kiel, 2010;Vrijenhoek, 2013). ...
Three isolated limestone deposits and their fauna are described from a middle Eocene
Flysch succession in northwestern Istria, Croatia. The limestones are identified as ancient methaneseep
deposits based on fabrics and characteristic mineral phases, δ13Ccarbonate values as low as −42.2‰
and 13C-depleted lipid biomarkers indicative of methane-oxidizing archaea. The faint bedding of the
largest seep deposit, the great dominance of authigenic micrite over early diagenetic fibrous cement,
as well as biomarker patterns indicate that seepage was diffusive rather than advective. Apart from
methanotrophic archaea, aerobic methanotrophic bacteria were present at the Eocene seeps as revealed
by 13C-depleted lanostanes and hopanoids. The observed corrosion surfaces in the limestones probably
reflect carbonate dissolution caused by aerobic methanotrophy. The macrofauna consists mainly of
chemosymbiotic bivalves such as solemyids (Acharax), thyasirids (Thyasira) and lucinids (Amanocina).
The middle Eocene marks the rise of the modern seep fauna, but so far the fossil record of seeps of this
age is restricted to the North Pacific region. The taxa found at Buje originated during the Cretaceous
Period, whereas taxa typical of the modern seep fauna such as bathymodiolin mussels and vesicomyid
clams are absent. Although this is only a first palaeontological glimpse into the biogeography during
the rise of the modern seep fauna, it agrees with biogeographic investigations based on the modern
vent fauna indicating that the dominant taxa of the modern seep fauna first appeared in the Pacific
Ocean.
... Furthermore, tissues were shown to be more depleted in 13 C relatively to 12 C in cold seep environments (e.g. − 42 to − 77‰ for Bathymodiolus heckerae) dominated by methanotrophy due to the extremely light composition of methane in these environments whereas the reliance on sulfide-oxidation dominating in hydrothermal vent system is reflected in higher δ 13 C of tissues (e.g., − 23 to − 34‰ for Bathymodiolus thermophilus) as the carbon source (CO 2 ) is less 13 C depleted in this case (Rau and Hedges, 1979;Paull et al., 1985;Colaço et al., 2002). The signature of the two pathways was also suspected for species that rely on dual symbiosis, methanotrophy and sulfide-oxidizing, even at hydrothermal vents where methane is much less depleted in 13 C than at cold seeps . ...
... Although the 'heroic age' of deep-sea exploration established universal occurrence of a metazoan deep-sea fauna, high biodiversity was only recognized and quantified in the 1960s, first using semiquantitative anchor dredges and epibenthic sledges [3], and subsequently using box corers [4]. The application of submersibles to scientific and biological investigations enabled the discovery of hydrothermal vents [5] and seeps [6], the first manipulative experiments, the testing of ecological hypothesis in the deep sea [7], the use of videos and still imagery to document life in trenches, along with other advances aided by hybrid remotely operated vehicles (ROVs), bottom crawlers, and landers (Table 1). ...
Deep-sea ecosystems represent Earth's major ecological research frontier. Focusing on seafloor ecosystems, we demonstrate how new technologies underpin discoveries that challenge major ecological hypotheses and paradigms, illuminating new deep-sea geosphere-biosphere interactions. We now recognize greater habitat complexity, new ecological interactions and the importance of 'dark energy', and chemosynthetic production in fuelling biodiversity. We also acknowledge functional hotspots that contradict a food-poor, metabolically inactive, and minor component of global carbon cycles. Symbioses appear widespread, revealing novel adaptations. Populations show complex spatial structure and evolutionary histories. These new findings redefine deep-sea ecology and the role of Earth's largest biome in global biosphere functioning. Indeed, deep-sea exploration can open new perspectives in ecological research to help mitigate exploitation impacts.
... The discovery of a rich biological community along the passive Florida Escarpment with organisms similar to those living at active hydrothermal vents, now almost 30 years ago, led to the first description of "cold seeps" by Paull et al. (1984Paull et al. ( , 1985. Although cold seeps and hydrothermal vent ecosystems share commonalitiesboth depend on chemosynthesis instead of photosynthesisthey also show many pertinent differences. ...
... Methane seeps in the deep sea are inhabited by unusual faunal communities that are dominated by taxa living in symbiosis with chemoautotrophic bacteria (Paull et al., 1985; Levin, 2005). The most intensely studied groups of chemosymbiotic bivalves are the epifaunal bathymodiolines and the semiinfaunal vesicomyids. ...
Twelve species of lucinid bivalves are reported from late Jurassic to late Miocene methane-seep deposits worldwide. Among them, eight species and two genera are new. Amanocina n. gen. includes Nipponothracia yezoensis from the Cenomanian of Japan as type species, Cryptolucina kuhnpassetensis Kelly, 2000 from the Berriasian of Greenland, A. raukumara n. sp. from the Albian of New Zealand and A. colombiana n. sp. from the Oligocene of Colombia. Tehamatea n. gen. includes Lucina ovalis Stanton, 1895 and Lucina colusaensis Stanton, 1895 from the late Jurassic to early Cretaceous of California, T. vocontiana n. sp. from the Hauterivian of southern Europe and T. agirrezabalai n. sp. from the Albian of northern Spain. The new species are: Cubatea awanuiensis from the Albian and Cenomanian of New Zealand, Nymphalucina panochensis from the early Palaeocene of California, Elliptiolucina washingtonia from the late Oligocene of Washington State, USA, and Elongatolucina peckmanni from the Oligocene of Colombia. New combinations are provided for Nipponothracia lomitensis (Olsson, 1931) from the Oligocene of Peru and Elliptiolucina hetzeli (Martin, 1933) from the late Miocene of Indonesia. The an-terior adductor muscle scar of Beauvoisina carinata is documented for the first time. The lucinids found at Jurassic and Cretaceous deep-water methane seeps belong to the subfamily Myrteinae and within this to genera that are restricted to the seep environment (Beauvoisina, Tehamatea, Amanocina and Cubatea); shallow-water seeps were inhabited by the codakiine genus Nymphalucina, which is not seep-restricted. Amanocina, Cubatea and Nymphalucina survived into the Cenozoic. Genera that newly colonized deep-water seeps during the Cenozoic include members of both Myrteinae (Elongatolucina, Nipponothracia and Elliptiolucina) and Codakiinae (Epilucina and Lucinoma); the latter are clearly not seep-restricted.
The Mariana Trench is the deepest oceanic region on earth, its microbial ecological exploration has become feasible with the rapid progress of submersible and metagenomic sequencing. We investigated the community compositions and metabolic functions of the core microbiome along the abyssal-hadal transition zone of the Mariana Trench, although most studies by far were focused on the pelagic zone.
Benthic animals that rely on endosymbiotic bacteria for their nutrition are ubiquitous around deep-sea hydrothermal vents and cold seeps where hydrogen sulfide together with methane is issuing. To elucidate the strategic adaptation of these animals to these environments, relevant analytical data on the carbon, nitrogen, and sulfur isotopic signatures of the soft body were compiled and evaluated in relation to those of hydrogen sulfide, methane, and ammonia in the habitat. The soft body part carbon isotopic compositions (δ13C) of pogonophorans, vesicomyid and solemyid clams, gastropods, and Bathymodiolus spp. in which sulfur-oxidizing bacteria are the sole endosymbiont, varied within a relatively narrow range of 35±5‰, which indicates catalytic fixation of dissolved bicarbonate by ribulose-1, 5-biphosphate carboxylase/oxygenase. In contrast, benthic animals habouring methanotrophic endosymbionts showed a wider variation in ranges of carbon isotopic composition, from extremely light (δ13C=-70‰) to heavy (δ13C=-19‰). The variation results from the diverse sources of the substrate methane and associated specific metabolic pathways. Soft body part sulfur isotopic composition (δ34S) of benthic animals harbouring methanotrophic bacteria showed a narrow range of+13 to+16‰, indicating incorporation and assimilation of seawater sulfate (δ34S= +21‰) under a limited kinetic, sulfur isotopic fractionation (up to 6‰). The benthic animals harbouring sulfur-oxidizing bacteria showed 34S values from light (down to -20‰) to near 0, in accordance with the biogenic and magmatic origins of the sulfur, respectively. Two samples of Bathymodiolus spp. with dual symbiosis from the South Chamorro Seamount and Gulf of Mexico showed intermediate δ34S values, which indicate use of both heavy seawater sulfate-sulfur and light sulfide-sulfur in their nutrition. Animals that rely on chemosynthesis for nutrition are characterized by their unique soft body part nitrogen isotopic signatures with fairly light values down to -10‰, values that are seldom observed in terrestrial and ordinary marine ecosystems. Such light values may be inherited from the source inorganic nitrogen or they may arise from large-scale nitrogen isotopic fractionation in the course of metabolic pathways. Data concerning the nitrogen isotopic composition of the dissolved ammonia associated with chemosynthesis-based animal community is needed.
Specimens of Siboglinum poseidon were collected by box coring and studied together with their undisturbed habitat. Occupied tubes occur in depse aggregations beneath the sediment surface directly at methane seep sites. Fertilized eggs develop into small larvae within the anterior transparent region of the tube. The oldest larvae observed in tubes measure c. 370 µm in length. It is concluded that released larvae develop in the sediment in the oxygenated top layer. Three tube types have been found: 1, the larval envelope; 2, the juvenile, transparent tube and 3, the ringed, adult tube. The smallest specimens recovered from the sediment measure c. 2 mm. They are complete with a tentacle, pyriform glands, bacteriocytes and juvenile opisthosoma. Some larvae were reared under laboratory conditions for 10 weeks. At that stage red blood becomes visible and a small tentacular bud is formed dorsally.
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