Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 3 , M. Waeles 1 1 , L. Menot 1 ers a unique opportunity to assess the ff , J. C. Caprais , and J. Sarrazin 2 4 8498 8497 , A. Godfroy 1 , E. Escobar-Briones 1 -axis submarine volcanoes. According to their geological contexts, ff , P. M. Sarradin , K. Olu 4 1 This discussion paper is/has beenPlease under refer review to for the the corresponding journal final Biogeosciences paper (BG). in BG if available. Institut Carnot Ifremer EDROME, Centre de Bretagne, REM/EEP, Laboratoire Environnement Universidad Nacional Autónoma de México, Instituto de Ciencias del MarUniversité de y Bretagne Limnología, Occidentale, AP IUEM, Lemar UMR CNRS 6539,Laboratoire 29280 de Plouzané, Microbiologie des Environnements Extrêmes, UMR6197, IFREMER, UBO, pore-fluid pressures within sediments result in emissions of buried interstitial fluids Cold-seep ecosystems are related tofaults, active whereas and hydrothermal passive margins ventsarc and occur basins along along transform and the o deep-sea mid-ocean cold-seep ridge and systems, hydrothermal back- processes vent that ecosystems give involve rise distinct to geochemical fluid emissions from beneath the seafloor. At seeps, high role of ecosystem specific environmentalseep conditions and on four macrofaunal vent communities.common assemblages Six major were foundation studied, taxa: three vesicomyidbial bivalves, of siboglinid mats. which tubeworms Macrofaunal were and community micro- characteriseddiversity and by structure composition at patterns theabiotic were family factors primarily including level shaped methane showed bysubstratum and and that seep the hydrogen heterogeneity density, and sulphide provided vent by concentrations. foundationditional common species The structuring were factors identified type and as of their ad- rolesSurprisingly, were the found presence to of vary vent accordinghigher environmental to specificities, metal fluid with concentrations regimes. higher and temperature, lowerpatterns. pH Moreover, was Guaymas not seep significant andspecies in vent shared explaining suggesting community an frequent importantstudy connections number provides of between common further the supportand two for vent ecosystems. the ecosystems. hypothesis Finally, of this continuity among deep-sea seep 1 Introduction Abstract Understanding the ecological processes andecosystems connectivity requires of chemosynthetic comparative deep-sea studies.Mexico), In the the presence Guaymas ofcomparable Basin sedimentary seeps (Gulf settings and of and depths California, vents o in the absence of biogeographic barrier, P. Cruaud 1 Profond, 29280 Plouzané,2 France 70-305, Ciudad Universitaria,3 México France 4 CNRS, Technopôle Brest Iroise, 29280 Plouzané, France Received: 10 April 2015 – Accepted: 9Correspondence May to: 2015 M. – Portail Published: ([email protected]) 10 June 2015 Published by Copernicus Publications on behalf of the European Geosciences Union. Comparative study of vent andmacrofaunal seep communities in the Guaymas Basin M. Portail Biogeosciences Discuss., 12, 8497–8571, 2015 www.biogeosciences-discuss.net/12/8497/2015/ doi:10.5194/bgd-12-8497-2015 © Author(s) 2015. CC Attribution 3.0 License. 5 25 10 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | e et al., 2003). ff ects on associated ff e et al., 2003, 1998; Sibuet ff erences. Comparative studies have ff erent geological contexts, both ecosys- ff 8499 8500 C) on the seafloor. The fluid composition be- ◦ , thereby form various habitats that are colonised Beggiatoa e and Fowler, 1996; Sibuet and Olu, 1998; Carney, 1994). Communities also e et al., 1998; Tyler et al., 2002). Rapidly, the evidence of evolutionary and ff ff Despite these numerous homologies, comparison of seeps and vents at the macro- Although seeps and vents belong to two di environments (toxicity) and often live inand association Völkel, with 1998; symbiotic Childress bacteria and (Grieshaber Fisher,crobial 1992). mats These dominated species, by together with dense mi- by macrofaunal communities.species Across may vent have and similar autogenic seep and ecosystems, allogenic these engineering foundation e communities (Cordes et al.,nities 2010; share Govenar, a 2010). highlow Globally, level vent taxonomic of and diversity endemism, seep in(Tunnicli elevated commu- comparison macrofaunal to densities non-chemosynthetic and deep-sea relatively ecosystems share some families and generacestors, presenting with evolutionary connections many via transitions(Tunnicli common between an- vent and seep habitats over geological time faunal community level have revealed striking di mainly composed ofthermogenic hydrocarbons degradation (e.g. of methane) organiclayers, matter. produced methane As is from these oxidised fluids the bytion reach microbial biogenic by the consortia, the and upper concomitantly anaerobic sediment with oxidationemission sulphate of at reduc- methane the (AOM), water–sediment resulting interface inand (Boetius high et Olu, hydrogen al., 1998; sulphide 2000; Kojima, Valentine,water 2002; 2002; Sibuet Coleman penetrates and in Ballard, theinitiate 2001). ocean the In crust contrast, rise fissures at of and vents, hot sea- heats fluids up (up until to advection 400 processes Therefore, seeps and vents canother be hand, they considered generate as energy-rich extreme fluidsthetic that ecosystems sustain production for high in life. local On deep-sea microbial chemosyn- the ecosystems,2008). which There, are bacteria usually food-limited and (Smithdrogen archaea et sulphide, rely al., which mainly areseeps on the (McCollom the two and oxidation most of Shock,chemosynthetic common methane 1997; production reduced and and Dubilier compounds tolerance hy- et to in environmentaldominant al., vents conditions role 2008; underlie and the Fisher, of pre- 1990). fluidtherefore Reliance share input on many in ecological both homologies.that They ecosystems. are harbour These heterogeneously macrofaunal communities chemosyntheticthe distributed presence ecosystems in of a foundation species.chaetes mosaic These (vestimentiferan of tubeworms, foundation frenulate species dense and include monoliferancomyid assemblages siboglinid pogonophorans), and defined poly- vesi- bathymodiolid by bivalves,tropod alvinellid families, tube-dwelling which worms, have developed and numerous several strategies gas- to adapt to their extreme functional homologies highlightedhypothesis potential was links reinforced between bythe the the discovery two presence of additional ecosystems. of chemosynthetic seep(Smith This stepping-stones and and such as vent Baco, large shared 2003;ties organic species Smith falls at and and a by recently Kukert,seep”, discovered 1989). associated hybrid Moreover, with seep macrofaunal a and communi- harboured subducting vent seamount both ecosystem on seep called the andpothesis a convergent vent of Costa “hydrothermal continuity features, Rica among thus margin, reducing providing ecosystems additional (Levin et support al., for 2012). the hy- comes highly complex inin contact trace, with minor subsurface rocks, anddissolved with major metals enriched (Von elements, concentrations Damm, methane, 1995; hydrogen Jannasch and sulphide, Mottl, hydrogen 1985). gastems and are characterised by fluidpresence emissions that of present high unusual properties, concentrationsents such and of as significant the toxic temporal compounds, variation at steep small physico-chemical spatial gradi- scales (Tunnicli proposed that seeps exhibitand higher Olu, 1998; diversity Turnipseed et and al., 2003,thermore, lower 2004; the Levin, endemism number 2005; of than Bernardino species et vents shared al.,is on 2012). (Sibuet less a Fur- than global 10 scale % between of theand the two Olu, total ecosystems recorded 1998). species In (e.g.Ocean Tunnicli addition, also a points recent review tomunities of strong even several dissimilarities at sedimented between the sites vent in family and level the seep (up Pacific macrofaunal to com- 93 %) (Bernardino et al., 2012). These strong 5 5 10 20 25 15 20 15 10 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | er- ff use, er in ff ff ects of foun- ff e et al., 2003; ff ers a unique opportunity to ect of vent-specific environ- ff ff erent physiological stress regimes ff 8502 8501 er and which abiotic and biotic factors can best ex- ff ects (Govenar, 2010; Sarrazin et al., 1999). Overall, ff erences among communities. Despite variation in environmen- ff (Dall, 1895), with genetic exchanges among Guaymas seep and vent erences are assumed to be partly shaped by large-scale factors because seep and The Guaymas Basin is one of the only areas in the world that harbours both ecosys- Here, we compared the structure (abundance, diversity and composition) of Guay- ff tions. The following questions wereences addressed: in (1) geochemistry, what microbial are processes the and similarities potential and engineering di e tems in close proximity. Locatedthe in the Guaymas central Basin portion is of aat the young less Gulf spreading than of centre California, 60parable where km Mexico, depths hydrothermal from (around vents cold are 2000 m)1990; found seeps and Lonsdale without in et apparent a al., similar biogeographic 1980). sedimentary barrier, Therefore, setting at this (Simoneit com- study et site al., o mas seep and vent macrofaunal assemblages in relation to their environmental condi- scale factors and environmental conditionsdissimilarities on (Bernardino vent et and al., 2012). seep macrofaunal community assess and compare the role ofnal local seep communities. and Moreover, vent the environmental factors presenceArchivesica on gigas macrofau- of the samesuggest Vesicomyidae a bivalve current species, or recentunpublished connectivity data). between the two ecosystems (Arnaud-Haond, dation species within andvent between macrofaunal communities ecosystems? di (2) Does the structure of seep and that can act as “ecosystem filters”. Nevertheless, the e low fluid-flow sites thanspecific niches in may exist. more focused venting of hot fluids at vents, where vent- seeps and vents. Althoughof the reliance reduced on chemical chemical concentrationstors energy in may underlies both the lead ecosystems, central toexplain, additional role at distinct vent-specific least community fac- partly, the structurethese lower patterns diversity distinct at among environmental vents ecosystems conditions comparedlap with may and between seeps. be thus seeps Furthermore, responsible and for vents, the in low addition species to the over- di plain community structure patterns?overlap And between finally, the (3) twoditions? what ecosystems We is and test the howshow level whether does density of macrofaunal and macrofaunal it communities, diversity relateat sustained both patterns to seep by governed and environmental chemical vent by con- sites,dependent. energy, reduced and Specifically, whether we compound the test composition concentrations whether of macrofaunal macrofauna overlap is ecosystem- is larger among di di Sibuet and Olu, 1998; Herzigdriving and community Hannington, dynamics 2000). Therefore, and ecological regulating processes community structure may indeed di vent ecosystems are usuallytion separated and by subsequent long evolutionary distances. divergence,to as Their continents (and well biogeographic the as isola- resulting theportant settlement closer of role proximity background in macrofauna) of may structuring seeps playertheless, these an communities in im- (Carney, the 1994; Japan Bakerare Sea, et found in a al., close 2010). region proximity, the Nev- where28 similarity % a between (Watanabe seep total et and al., of ventto 2010; species 42 reached Sibuet large-scale seep only and factors, and Olu, contrasting 1998; venttribute Nakajima ecosystems seep to et the and al., strong 2014). vent di In environmental addition conditions may con- tal conditions in eachand type environmental of settings ecosystem, in due whichas seep to and the more vent multiplicity occur, prohibitive vents of to areanomalies, geological usually life higher contexts considered than metal seeps. concentrations,as lower Vent pH sites higher and usually outflow oxygen exhibit rates concentrations greater and as temperature well temporal instability than seeps (Tunnicli mental factors on the structurestrong of correlations macrofaunal among communities physico-chemical are factorsestimation not (Johnson well of et known al., their due 1988), respective to the preventing e key questions that remain to be addressed involve the relative influences of large 5 5 15 10 25 20 20 15 10 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | sub- C (Von (Thunell ◦ 1 ) (Bernard, − Hyalogyrina Nautile -axis reference ff kilmeri usely through the ff (syn. C or through mounds and ◦ equipped with the Phreagena soyoae L’Atalante -axis site was sampled and used as a back- ff 8504 8503 genus, (2) S_Gast characterised by W) at 1900 m depth and (3) an o 0 and a sedimentation rate of 2.7 mmy (Dall, 1895) vesicomyids that were found at the pe- 1 24 − ◦ d 2 − Beggiatoa N, 111 0 W) located at 1500 m depth (Lonsdale et al., 1980; Simoneit 00 ◦ 0 30 ◦ W) at 1550 m depth, (2) a large hydrothermal field on the Southern – a total of six seep assemblages were studied (Fig. 2). Three as- 0 Archivesica gigas 2400 mgCm 29 ∼ ◦ N, 111 0 25 ◦ N, 111 0 36 ◦ Sonora margin The Southern Trough spreading segment is characterised by magmatic intrusions The Guaymas Basin is characterised by exceptionally high sedimentation rates due The Sonora margin transform faults are located along the eroding crest of a steep sp. gastropods formingcharacterised grey by mats surrounding the microbial mats, and (3) S_VesA semblages were sampled atbial the mats Vasconcelos dominated site: by (1) the S_Mat characterised by micro- Damm et al., 1985). Fluid compositionweight is enriched organic in acids, hydrogen sulphide, petroleum-likeand low-molecular- aliphatic methane and (Kawka aromatic andmoneit, hydrocarbons, Simoneit, 1995), ammonia, but 1987, relatively 1990;unusual low Simoneit composition metal et concentrations is al., (Von linkedments Damm 1996; that to enhance et Leif metal the al., and sulphide chemicalorganic 1985). precipitation Si- matter and This interactions the (Kawka between thermocatalytic and percolation fluidshave Simoneit, of 1987). and been The sedi- described foundationLonsdale species (Soto and of and Becker, this 1985; Grassle, vent Deminathe area 1988; et associated Ruelas-Inzunza al., macrofaunal 2009), et communityHilbig, but al., (Grassle 1990). only et To 2003, few date, al., studies there 2005; and have 1985; have vent included been Soto, communities. no 2009; comparative Blake studies on and the Guaymas2.2 seep Sampling design The Biodiversity and Interactions inon the Guaymas board Basin (BIG) the cruisemersible. oceanographic was The held autonomous vessel in underwater R/V 2010 resulted vehicle in (AUV) the AsterX fine-scale explorations mappingcation of of of active the new seep area sites, and particularly ventwas on sites subsequently the and used Sonora also margin to to (Fig. identify thethe 1). and identifi- presence The sample Nautile of specific submersible foundation assemblages, species. characterisedground An by reference o site of the Guaymas Basin (G_Ref). riphery of white andwas sampled: grey (4) mats. S_VesP At characterised by Ayala, another type of Vesicomyidae assemblage 2 Materials and methods 2.1 Study area This study focused on threeof areas the in Gulf the of Guaymas Basin California(27 located (Fig. in 1): the (1) central cold portion seeps on the Sonora margin transform faults Trough depression (27 Becker, 1985; Fisherwater–sediment and interface Becker, at 1991). temperatures Vent fluids less than emanate 200 di that drive an upwardand hydrothermal maintain flux a through recharging the seawater organic-rich circulation overlying (Gieskes sediments et al., 1982; Lonsdale and carbon flux of anticline (Simoneit et al., 1990;tinental Paull shelf et pockmarks al., and 2007). havesion They been of are named methane structurally and “hydrocarbon similar higher seeps” hydrocarbon toknown due components. con- (Simoneit Their to et geochemistry the is al., emis- still 1990).this poorly Extensive area carbonate (Paull concretions et have al., beenunknown 2007). and reported only Macrofaunal in foundation communities species of have beenet the described al., Sonora (Simoneit 2007). et seep al., are 1990; mostly Paull et al., 1990; Paull et al., 2007). to the high biological productivity in surface waters which produce a particulate organic site (27 et al., 2007; VonBasin Damm is et lined al., with 1985; a1982; Dean 1–2 Calvert, km et 1966). layer al., of 2004). organic-rich, Consequently, diatomaceous the sediments Guaymas (Schrader, chimneys rising over the seafloor where temperatures can reach up 350 5 5 25 10 15 20 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | sp. Escarpia P. bactericola Beggiatoa Riftia pachyp- (Webb, 1969) siboglinid tubeworms (Dall, 1891) vesicomyids were sam- containers (2 L, Baxter) using the PEPITO erent assemblages, all sampling and mea- 8506 8505 tm ff HATF filters for further quantification of dissolved (Desbruyères and Laubier, 1982) and ® sp. microbial mats surrounded by yellow Calyptogena pacifica Lamellibrachia barhami vesicomyid. At the Mat Mound site, a siboglinid assemblage on Beggiatoa – a total of four vent assemblages were studied (Fig. 2). At the A. gigas Paralvinella grasslei C) for sub-sampling. Sediment cores (0–10 cm) were sub-sampled in 2 cm ◦ 8 (Jones, 1985) and ∼ PCR (Jones, 1981) embedded in microbial mats. Finally, at the Rebecca’s Roots site, an Data on physico-chemical factors were analysed on all habitats or only on soft- For characterising soft-sediment habitats, we took additional temperature measure- Southern Trough tors from sediment porephysico-chemical waters in factors soft were sediment separated habitats.tions, For into which both represented “interface” types fluid and ofcorresponded input to substrata, “maximum” proxies. the concentra- measurements On made hardues close substrata, to were the the selected substratum “interface” from and values blages. “maximum” all val- measurements Similarly, made soft within sedimentsummarised the as three-dimensional physico-chemical interface assem- conditions values (0–2 fromcores cm) (10 and pore cm). maximum waters values along were the depth of2.4 the Quantification of sedimentary microbial populations using quantitative At each location, a sedimentble push 1). core After was recovery collected on forroom board, microbiological ( sediment analyses cores (Ta- were immediately transferred to a cold sediment habitats. To compare allsurements habitats, on physico-chemical hard factors substratum from habitats water were mea- examined against physico-chemical fac- 2013; Russ et al.,used 2013). to characterise The the CALMAR methane benthic flux at chamber the (Caprais interface of et vesicomyid al., assemblages. 2010) was ments within the sediment layer,well using as a push-core 50 samples. cm The long porealong waters graduated cores were temperature extracted and sensor from each as analysedconcentrations 0–2 for cm following sections procedures methane, described hydrogen in sulphide, (Caprais et sulphate al., and 2010; ammonium Vigneron et al., (Salaün and van den Berg,board 2006). using pH a measurements Metrohm (NBSing glass scale) the were electrode. headspace performed technique Methane on (HSS concentrations(Perichrom 86.50, 2100, were DaniInstruments) Alpha and quantified MOS) a us- equipped gasCaprais, with chromatograph 1996). a flame-ionization detector (Sarradin and metals (Fe, Mnplasma-optical and emission spectrometry Cu). (ICP-OES)Spectrométrie Fe (Ultima Océan), 2, and whereas Horiba Cu Mn Jobin was Yvon, were measured Pôle using determined a using gold microwire inductively electrode coupled 1974). Some specimens of pled in qualitative peripheralthe samples Juarez site, at two the assemblages Ayala were and sampled: (5) Vasconcelos S_Sib sites. characterised Finally, by at spicata established on carbonate concretions andof (6) reduced S_Sib_P sediments corresponding in to the the immediate presence periphery of S_Sib. Mega Mat site, a microbialthe mat presence assemblage of was white sampled: (1) V_Mat, characterised by sampler implemented ona the titanium-Tygon Nautile inlet associated submersible. withter The the submersible samples Nautile recovery, temperature were the probe.tered pumped containers Immediately through af- with were 0.45 brought µm to Millipore a clean laboratory and fil- (Desbruyères and Segonzac, 1997). 2.3 Characterisation of physico-chemical conditions To characterise thesurements habitats were of performed thetemperatures in were di close recordedwere proximity using collected to the in the Fenwal Nautile Transfer organisms Pack temperature (Table probe. 1). Water Habitat samples a 3–4 m high sulphide mound was sampled: (3) V_Sib characterised by mats. At the Morelos site, aacterised Vesicomyidae assemblage by was sampled: (2) V_VesA char- tila alvinellid assemblage was sampled onpresence the 13 of m edifice: (4) V_Alv characterised by the 5 5 20 15 25 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | – 5 cients ffi Desulfococcus / cult to carry out ffi ects across assem- ff Desulfosarcina ) were used to collect the macrofauna 2 8508 8507 Green SuperMix ROX (Quanta Bioscience), 1 ng erently on soft and hard substrata (Table 1). For ® C for subsequent total nucleic acid extraction. For ff ◦ 80 − SYBR group) and SEEP-SRB2 (Vigneron et al., 2014) were es- ects on the structure of macrofaunal communities (Gove- ® ff ciencies of the reactions were above 85 % and coe ffi ect. qPCR results were cumulated along the entire length of ff ) of standard curves were close to 0.99. Samples were diluted 2 250 µm) sensu stricto (i.e. excluding meiofaunal taxa) (Hessler and R > ) of plasmids containing environmental 16S rRNA genes of selected 1 Desulfobulbus − ered formaldehyde for 24 h then preserved in 70 % alcohol. In the laboratory, ff copiesµL 9 valve identifications were made in collaboration with Elena Krylova (Shirshov Institute 2.5.2 Macrofaunal communities Sediment macrofaunal samples wereAll sliced sediment into sub-samples layers and (0–1, hardfour 1–3, sieves substrata of 3–5 samples decreasing and mesh were sizes 5–10 then (1,in cm). sieved 0.5, 4 on 0.3 % and bu a 0.25 stack mm). The of samples were fixed Jumars, 1974; Dinet et al., 1985)done were sorted, to counted the and lowest identified.taxa. Identification taxonomic was level Polychaete possible morphological with identifications particularatically at attention reached paid the due to species to dominant level the were sieving process not which system- often damages the organisms. Bi- blages, we used biomass (ash-free drywithout weight (AFDW) shells without for tubes vesicomyids for siboglinids andproxies and gastropods) for and their densities biological of activity foundation and species habitat as provision. only macrofauna ( Software (see protocol in Sarrazinanalysed five et times al., to 1997). estimate Eachmates mean the sampled surface sampled area values. surfaces This was due method outlinednal to probably and coverage, the underesti- inducing omission a of bias reliefto in or quantitatively density thickness sample estimates of the but the macrofau- noet macrofauna other al., on method 2010). hard is substrata yet available in the deep2.5.1 sea (Gauthier Foundation species The distribution of foundationtherefore excluded species them was from usedcan the have a community both priori level allogenic (e.g. study. to bioturbation, Furthermore,tat sulphide define provision) these pumping) engineering assemblages; species and e autogenic we (e.g.nar, habi- 2010). For consistent approximation of potential engineering e thick layers and then frozen at timated. Standard curves were obtained in triplicate withmicrobial 10-fold lineages. serial The dilutions e (10 group), DBB ( 10 found within the sediment layer.grab On sampling with hard the substrata, ROV arm suctionplaced was sampling used in to before individual collect and isothermal the after macrofauna boxes.communities and Although samples is quantitative were sampling straightforward of withon soft-sediment box-corers, hard it substrata. is VideoNumerical much imagery images more taken is di before therefore and used after to sampling were assess analysed the using sampled the surface. Image J until the crossing point decreasedsence log-linearly of with an sample inhibition dilutions, e indicating the ab- Macrofaunal sampling was done di each sample, total nucleicet acids al., were 1996) extracted and using detailedwere a in then method (Cruaud estimated et modified by al., from quantitativea 2014). PCR (Zhou Step Archaeal (qPCR). One and Amplifications Plus bacterial were instrument abundances ume performed (Life of with Technologies, 25 Gaithersburg, µL using MD, PerfeCTa USA) in a final vol- of determination ( the sediment core and expressed in copy number per2.5 gram of sediment. Macrofaunal community characterisation soft substrata, blade corers (180 or 360 cm of crude nucleic acid extract (template)cording and to primers the with manufacturer’s appropriate instructions. concentrations The ac- groups primers potentially used involved targeted in specific AOM. microbial Relativemethane-oxidizers abundances (archaeal of known anaerobic clades methanotrophs of ANME-1, anaerobic et -2 al., and 2013) -3) and (Vigneron their potential bacterial partners DSS ( 5 5 25 15 20 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | axes of the CIA). These x erences in sampling strategies be- ff 8510 8509 ects of foundation species. For all RDA analyses, forward value of 0.1 was used to sort the significant explanatory ff p varied between 1 and 4, Table 5) and di n All analyses were performed in the R environment (R Development Core Team, At the ecosystem level and among the three vesicomyid assemblages for which Community composition analyses were based on Hellinger-transformed family den- substrata qualitative variable asfoundation species well descriptors. as On softried normalised substrata, out physico-chemical a first co-inertia variables on analysisgroups and normalised (CIA) potentially was physico-chemical involved car- factors in andtween AOM. the physico-chemical The abundance variables CIA of and summarisetats microbial microbial most into processes of a across limited the number sedimentary co-variance of habi- be- independent variables (the first new variables, which can beeach considered habitat, to were depictproxies then the of biogeochemical used the environment engineering as of e explanatory variables in a RDA, together with the 2014). Multivariate analyses weresanen carried et out al., using 2015),2012) rdaTest ade4 function packages. (Dray and and vegan Dufour, (Ok- 2007) and betapart (Baselga and Orme, selection with a threshold Torrie, 1997). The Sorensen index was usedof to the estimate seep and compare and the ventilarity beta ecosystems diversity was based decomposed on presence/absence according data.antithetic to Sorensen processes, turnover namely dissim- and species nestedness, replacement and which species result loss from (Baselga, two 2010). comparisons were possible, meanKruskal–Wallis comparisons test, were followed done by using a the LSD non-parametric rank test for pairwise comparisons (Steel and tance gives a loweras weight an to indicator dominant of similarity taxaical between and redundancy samples avoids (Legendre analyses and considering (RDA), Gallagher, considering double 2001). all absence Canon- assemblages, included hard and soft variables. The significance ofendre CIA and and Legendre, RDA 2012). were tested with permutation tests (Leg- sities to conserve Hellinger, rather than Euclidian, distances in PCA. The Hellinger dis- of Oceanology, Russia), although athe large species number level. of Gastropods juveniles were could exhaustivelyders characterised not Warén in be (Swedish collaboration identified Museum with to of An- Naturalpossible History, to Sweden). determine Because to it the waswere species not done level, always at comparisons the of the familynal level, macrofaunal except community densities, for some such taxa asTanaidacea with and low Aplacophora, Amphipoda. contributions Sipuncula, to macrofau- Scaphopoda, Nemertina, Cumacea, 2.6 Data analyses At the assemblage scale,blages considering ( the low leveltween of soft replication and within hard some substrata,Rarefaction assem- data curves analyses and mainly Hurlbert’s relied ES(n)diversity upon diversity R descriptive index package were statistics. (Kindt computed andon using Coe, the pooled 2005) Bio- abundances and thebecause per functions this assemblage. in index The Gauthier isand et ES(n) the al. Heip, measure most (2010) 1990). of suitable Spearmanables, for diversity rank foundation non-standardised correlations was species sample were descriptors used sizes carried andand (Soetaert associated on ES(n) macrofaunal physico-chemical diversity. community vari- Two density levelsblages of sampled analysis (hard wereblages, and applied: thereby allowing one soft) the considering addition and ofthe all supplementary abundance a assem- physico-chemical of variables subset microbes and potentially focusingwere involved in tested on AOM. for Parametric soft-substratum regression ES(n) models tions and assem- to macrofaunal compare density our in data with relation previous to studies. physico-chemical condi- 5 5 20 15 25 10 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 0.7, 1 to C at ◦ : 0.9, : 0.9, ∼ R R 56 R > ∼ 30 000 µM, 30 000 µM). 50µM) found ∼ ∼ ∼ 1 to 800 µM, sep- ∼ 0.05). Thus, only maximal C at V_Sib and ◦ at S_VesA and S_VesP and p < 1 30 − ∼ d 2 0.7, − 15 000 µM) and S_Mat ( R > 0.05). Maximum ammonium concentra- ∼ p < 2 mmolm C at V_Alv, 8512 8511 ◦ 300 to 900 µM) at V_Sib, V_Alv and the high- 56 µM, close to the G_Ref reference site val- ∼ 0.01) while sulphate concentrations were neg- 900 µM with low concentrations ( ∼ ∼ 0.8, 20 ∼ ∼ p < R > 26 to 50 to – in soft-sediment assemblages, hydrogen sulphide, sul- 0.8, ∼ ∼ R > 9000 µm, with the lowest concentration found at V_VesA and ∼ C at V_VesA, ◦ at V_VesA (Table 2b). 7 – temperature and methane concentrations were the only two physico- 1 ∼ − 1700 to d 2 ∼ 0.05): vent sites often showed high methane concentrations whereas seep − p < C in the Guaymas Basin) were found in seep sites, neither on hard substrata, nor 0.05). Hydrogen sulphide was not detected at the reference site G_ref. At seeps, 0.001). Thus, only maximal values are presented herein. 0.05). ◦ ered. The seep siboglinid site was characterised by lower fluid input than the vent 1 µM). At seeps, maximum methane concentrations ranged from 700 to 800 µM), represented by S_Gast and S_Mat. At vents, maximum methane : 0.5, As expected, hydrogen sulphide concentrations were positively correlated with Soft sediment assemblages No temperature anomalies in comparison to ambient bottom seawater (which is at Maximum methane concentrations at the Guaymas reference site (G_Ref) were low Methane concentrations were positively correlated with temperature anomalies Maximum ammonium concentrations were positively correlated to temperature, be- Overall, seep and vent assemblages were classified into two habitat groups accord- 9 mmolm ff ∼ ∼ R methane concentrations ( values are presented herein. atively correlated with bothp hydrogen < sulphide and methanemaximum concentrations hydrogen ( sulphide concentrations ranged from undetected to the highest at V_Mat. ing higher at ventstions than at seeps seeps ( ranged from siboglinid site. Although methane and hydrogen sulphide showed comparable concen- phates and ammonium concentrations were alsoand compared maximum (Table 2a). values Again, were interface always correlated ( with no detection throughout the 10 cmHigh sediment concentrations core at were S_VesP,S_VesA and S_Sib_P. foundAt at vents, S_Gast maximum ( hydrogenranged sulphide from concentrations in the two soft-sediment sites ues (13 µM). Vent maximum(384 ammonium µM) and concentrations V_Mat were (1800 much µM). higher at V_VesA ing to the concentrationshigher of fluid reduced inputs compounds,V_Alv at regardless and V_Mat), two of whereas seep the fourone seep ecosystem, sites vent sites (V_VesA) (S_Sib, with site (S_Gast, S_SibP, S_VesA showed and lower S_Mat) fluid S_VesP)reference and inputs, site and closer (G_Ref). to three Despite those some found ventV_Mat) at variations, and the sites seep Guaymas vesicomyid and (V_Sib, (S_VesA, S_VesP, vent V_VesA) habitats microbialspective belonged groups, mat whereas to (S_Mat, seep the and same ventdi re- siboglinid (S_Sib and V_Sib) habitats strongly 3 Results 3.1 Environmental description 3.1.1 Physico-chemical conditions All assemblages chemical variables that were measured acrosssubstrata all assemblages, (Table including 2a). hard and Interface soft and maximum values were always correlated ( p < temperature of 2.9 within the sediments. At vents, all sites showed temperature anomalies with maximum ( V_Mat. Thus, temperature anomalies were specific to vents. arating assemblages into two habitat groups, one showing low concentrations ( 30 µM), i.e. S_VesA, S_Sib_P, S_VesP( and S_Sib, and the other, high concentrations concentrations ranged from at V_VesA and high concentrations ( est concentrations found atcally, V_Mat. methane flux While was fluid null fluxes at were G_Ref, not measured systemati- p < ( ∼ sites generally had low methanesites, concentrations. vent Furthermore, methane after concentrations exclusion and of temperatures seep were highly correlated ( 5 5 15 10 25 20 10 15 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | . 2 2 ± 2 − − − sp. alvinellids . 25 000 indm 2 Hyalogyrina − ∼ and a biomass of 2 erences reflect the species at S_VesP − ff and biomass of 262 P.bactericola , respectively. Macrofau- 2 2 − − 0.01). According to the first and and a biomass of 457 gm but harboured a low amount 50 indm in S_Mat to 2 2 P. soyoae = ± in S_VesA. At vents, densities 2 0.05) while mean pH was sig- − − and a biomass of 6630 gm − 2 p − 2 in V_Sib, with V_VesA and V_Alv 70 indm . − p < 2 2 0.05). These di ± − − P.grasslei siboglinids at S_Sib were characterised p < and a biomass of 31.2 gm and within the S_Sib assemblage with 2 erences were found between Guaymas ref- − ff 8514 8513 2 erences between seeps and vents. For exam- − 42 and 74 ff siboglinids at V_Sib were characterised by long ± E. spicata concentrations at V_Mat, where a higher frequency 4 and 0.05), whereas at vents, density was not significantly p < vesicomyid at S_VesA and (Decker et al. unpublished data). The small in V_Mat to 94 400 indm 2 R. pachyptila 2 . − − 2 – L. barhami − 0.03). Significant di in S_VesP, and up to 11 000 indm – A. gigas = 2 − p 358 gm . The two vesicomyid assemblages showed highly contrasting densities, (Decker et al., unpublished data). 2 ± 2 − − erent ( ff vesicomyids at V_VesA reached a density of 56 1400 indm ∼ 107 gm erent with a high heterogeneity between replicates. erent either from seeps, or from the Guaymas reference site. Relatively compa- ± Siboglinid density and biomass were much higher at vents than at seeps while Densities at the Guaymas reference site, the seep sites and vent sites were signif- Vent assemblages 8000 indm ff ff at V_Alv reached a density of 1070 indm among the three vesicomyiddi assemblages, density and biomass were not statistically 3.2 Macrofaunal community structure 3.2.1 Density patterns At seeps, macrofaunal densities rangedin from 880 indm S_Gastperiphery (Table 5). (S_Sib_P) Densities∼ with were 4650 indm intermediatewith atranged the from 710 siboglinid indm showing assemblage intermediate density values of 1670 and 2610 indm nal density at G_ref was the lowest with 570 indm A. gigas 81 icantly di erence and seep densitiesdi ( rable density ranges were observed across ecosystems for microbial mats (S_Mat, 119 and 405 wide tubes. They reached a density of 1280 indm of biomass of 2.4 gm gastropods at S_Gast reached densities of 10 200 indm showed respective densities of 102 specific input of hydrothermal fluid in those assemblages. 3.1.2 Microbial populations with respect toMicrobial the populations physico-chemical conditions potentially involvedchemical in conditions AOM in processes theble CIA co-varied 3). performed with The on physico- relationships soft-sediment were assemblages statistically (Fig. significant 3, ( Ta- by long thin tubes. They(AFDW) reached (Table a 4). density of 720 indm ple, the patterns ofthan pH habitats across and ecosystems Mn (Table 2b). Mean concentrationshigher Mn discriminated at concentrations were vents vents significantly from than seeps at rather seeps (Kruskal–Wallis test, axis, which contributed toconcentrations 85 % and low of sulphate the concentrations were variance,of associated high with ANMEs high methane abundances 1 and and hydrogenblages. 2 sulphide The second at axis, one which accountedperature end, for anomalies corresponding 15 and % to of high S_Mat, the NH of variance, V_Mat was ANME1 and driven by and S_Gast tem- S_Mat assem- a and S_Gast. lower The first frequency CIAthetic of axis processes thus ANME2 summarised and the can and varianceecosystems, due be DSS to whereas considered chemosyn- were the a second found proxytions that axis for compared are fluid of with specific input the to across vents. CIA vent summarised and3.1.3 environmental seep condi- Foundation species descriptors Seep assemblages tration ranges among seep andnium concentrations vent were ecosystems, specific temperature to anomaliesfor vents. and all In ammo- addition, assemblages other suggest compounds further not di available nificantly lower at vents (Kruskal–Wallis test, 5 5 10 15 20 25 10 25 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | at did 0.8, 41 erent 41 = ff R A. gigas P. soyoae P. soyoae cient sampling ffi values were observed and methane concentra- 41 41 assemblage (V_VesA) was and maximum methane con- and temperature anomalies erences in siboglinid assem- (V_VesA) and seep ff 0.05). In addition, a logarithmic 41 41 p < on soft-sediment assemblages was 0.001) and traduced a diversity de- A. gigas 41 A. gigas 0.7, erences were close to being significant p < ff R > ered strongly, being higher at vents. Among ff 8516 8515 0.78, 0.01). ES = 2 p < R 0.8, 0.05), with the latter assemblages showing comparable assemblage (S_VesA) compared with the seep R > p < erences were found with higher densities at the seep ff ort at V_Mat and G_ref (2 LBC and 4 SBS respectively) was ff A. gigas 0.05), reflecting that three of the four vent assemblages showed a rel- p < ciently characterised, but appeared intermediate between S_VesA and S_VesP ffi 0.6, 0.07). Significant di 0.05). = ort. The sampling e A negative correlation was observed between ES Alpha diversity appeared maximal at the Guaymas reference assemblage (G_Ref) ES(n) alpha diversity was estimated for each assemblage based on 41 individuals, Macrofaunal densities did not show any significant correlation with physico-chemical ff R > p ( atively low diversity, whereas fourversity. A of strong the negative correlation six was seep foundtions between for assemblages ES all had assemblages relatively ( high di- blages (S_Sib, V_Sib), with lower diversity at the vent assemblage. Although ES positively correlated with sulphate concentrations andgen negatively sulphide correlated and with methane hydro- concentrations ( regression model was fit to the relationship between ES ones (Fig. 5). not su centrations among all assemblagesregression to was compare highly our significant data ( with previous studies. This in microbial matV_VesA) (S_Mat, assemblages, V_Mat) whereas they and showed vesicomyid strong vent di andnot seep separate (S_VesP, the S_VesA, three vesicomyiddiversity assemblages, in the the rarefaction seep curves showedassemblage higher (S_VesP). The diversity in the vent crease along a fluidwere underestimated input at gradient seep (Fig. and 6). vent Diversity microbial values mats predicted (S_Mat, by V_Mat) the assemblages model among seep and vent ecosystems. Relatively comparable ES (as observed with ES(n) and the rarefaction curve) and was not significantly di seeps ranged from 2 (S_Gast)ilies to (V_VesA) 13 at families vents (S_Sib_P), while and the from reference 2 site (V_Sib) G_ref to included 10 14 fam- families (Table 5). corresponding to the minimum number of individuals observed at any one site. ES indeed relatively lower thanbut not at at assemblages the where V_VesA and diversity S_Mat was sites (3 well-characterised, LBC and 3 LBC respectively) (Table 1). V_Mat) and vesicomyid assemblagessiboglinid (S_VesA, assemblages S_VesA, (S_Sib, V_VesA), V_Sib) whereas di those of the three vesicomyid assemblages, density di (S_VesP) assemblages ( ( assemblage (S_VesA) compared with the vent densities. factors. However, log-transformed densitiesmethane showed that concentrations, along densities the appearedvesicomyid range assemblages to of (S_VesP, be S_VesA, maximal V_VesA)(S_Sib) first together and enhanced with their at periphery seephighest seep (S_Sib_P) methane siboglinids and concentrations compared at vent to seep andrelated the vent to reference microbial minimum mats site densities (S_Mat, (G_Ref) of V_Mat)high were while all density chemosynthetic fluctuations assemblages were (Fig.(V_Sib) found 4). assemblages, among despite In vent relatively between, alvinellid comparable maximal (V_Alv)A methane and concentrations. similar vent siboglinid patternpared was with found seep andrelationship between between vent seep macrofaunal microbial community gastropod matswas density assemblage (S_Mat, found and V_Mat). with foundation (S_Gast) species S_Gast Infoundation com- density and addition, species and V_Sib a associated assemblages polynomial communities harbouring than the higher other densities assemblages ( of both p < 3.2.2 Alpha diversity patterns As seen on rarefaction curves, theon diversity was the relatively assemblage. well Four characterised depending curves,assemblages, corresponding did to not G_ref, reach V_VesA,e an V_Mat asymptote and (Fig. S_Mat 5), indicating an insu 5 5 20 15 25 10 10 15 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | erentiating in particular the S_Sib assem- ff 5 % of the community composition at S_VesP 8518 8517 > Macrofaunal community composition at the family level was analysed using Overall, although the heterogeneity between macrofaunal communities appeared At seeps, macrofaunal composition was dominated by Polychaeta (from 57.3 to At vents, similar to what was observed at seeps, Polychaeta dominated the macro- of S_VesA and V_VesA in whichPCA there accounted was for a 27 slight % overlap ofthe (Fig. the G_ref 8). variability and The in first S_Sib_P community axis composition, assemblagesonidae of mostly dominated polychaetes the separating by from Cirratulidae, the Paraonidaecharacterised V_Sib, and by V_Mat, Spi- higher V_Alv, frequencies S_Gast of Dorvilleidaetermediate and and S_Mat compositions Ampharetidae assemblages, polychaetes. were In- foundsecond at axis S_Sib_P, S_VesP, accounted S_VesA and fortion. 14 V_VesA. It % The was of mainly influenced the byaxis the variance accounted dominance in of for Bathyspinulidae macrofaunal 10 at % community S_VesP.The of third composi- the variance, di a between-groups PCA, aance particular between case assemblages. of Together, thetotal RDA variance three that in first tests community axes and compositionwas accounted maximises (Fig. relatively for the 8). high, 51 The vari- but % intra-assemblage lower of heterogeneity than the the inter-assemblage variability, with the exception higher at seepsassemblages than (Fig. at 8). Community vents, compositions there across seep was and no vent common discrimination micro- between vent and seep at V_VesA where they formedcophora respectively 19.4, represented 15 less and that 7.2dominated % 5 % of at the of all community. the Apla- sites,lowed abundance. by with At V_Mat the maximum (75 %), family relative V_Alvfound level, abundance in (59 Dorvilleidae %) all found and assemblages, at V_VesA with (40(9 highest %) V_Sib %), abundances (Fig. (91 V_VesA in 7). %) V_Mat Ampharetidae (8 fol- %) (16 were of %) and Polynoidae followed by (37 V_Alv %). V_Sib (3 At %).sionidae V_Mat, were V_Alv some found Nereididae, was but Thyasiridae, characterisedV_VesA Provannidae they had by and collectively a He- high accounted higher abundance frequency forulidae of (16 only %), Provannidae 10 Amphipoda % (9 %) (7 %), of and Neomphaloidae the of (6 %) abundance. taxa and such Cirratulidae as (4 Bathyspin- %). blage, characterised by the presenceSerpulidae of and Polynoidae, Nereididae. Lepetodrilidae, Neolepetopsidae, all assemblages, Gastropoda representedS_Sib less and than S_VesP, were 5 % theyrespectively). of reached Ophiuroidae represented the higher relative specimens, abundances except (38.2 at and 16.9 %, 99.8 %) with the exception of S_VesP where Bivalvia dominated (53.9 %) (Fig. 7). In faunal composition in alltropoda and assemblages Malacostraca (from abundances were 56.7 found at to frequencies 99.9 higher %) than 5 (Fig. % only 7). Bivalvia, Gas- and overestimated at threevisible assemblages discrimination (S_Gast, between seep V_Sib and and vent ecosystems. V_Alv). There3.2.3 was no Community composition patterns At the reference sitevalvia, (G_Ref), Aplacophora Polychaeta and dominated Cnidaria the representing lessIn community than terms (90.2 5 %) of % with of families, the Bi- G_Refdae community and was (Fig. Paraonidae dominated 7). (each by 12 %), Cirratulidaetaxa Ampharetidae (29 accounting %) (10 for %) followed less and by than Spionidae Nereidi- 5 (7 % %), of the other the abundance. (7.1 %) and S_VesAall (6 %). assemblages except Aplacophora for formedSipunculida, S_VesA, where Scaphopoda less it and than reached Nemertina 5Macrofaunal 7.2 never % %. composition exceeded of Malacostraca, at 5 % Cnidaria, the the ofof family community relative level the discriminated abundance. in other S_Mat assemblages andrespectively due S_Gast represented to from 32 their all and relativelyand 69 high % S_VesA proportion shared of of dominance the Ampharetidaeassemblages of abundance. can that Dorvilleidae In be (39, addition, distinguished 31 by S_Mat,the and the S_Gast highest dominance 40 % of frequency respectively). specific(8 Other of families: %), S_VesP S_Sib Nuculanidae had showed a bivalves highSerpulidae (52 frequency %) (18 of %) Lepetodrilidae and and (26 S_Sib_P %), ProvannidaeLumbrineridae had Polynoidae gastropods (11 (20 a %), %) relatively Cossuridae and high (10 %), frequency Paraonidae of (9 %) Cirratulidae and (19 %), Thysaridae (6 %). 5 5 20 15 10 25 10 15 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 0.01), A. gigas p < 0.08) of the variabil- = nities with assemblages at S_VesP, compared to p ffi P. soyoae 0.01) and 13 % ( , 0.25) (Fig. 9). The first axis was mostly ects of 2 0.06) of the variability in macrofaunal com- = ff R = – the forward selection test showed that the p 8520 8519 p species in seeps (S_VesP). ered according to the ecosystem they belonged to ff at seeps and vents (S_VesA, V_VesA) were more similar P. soyoae 0.31) (Fig. 10). According to the first axis, higher fluid inputs 0.03) and 20 % ( = = nities with assemblages characterised by high methane concen- 2 A. gigas ffi p R erences in the engineering e ff values of 0.01 and 0.07, respectively). The relationship with the first axis of the , at S_VesA and V_VesA. p Relationships with site characteristics Focusing on soft sediment assemblages, the forward selection test showed that variation of macrofaunal community composition amonginfluenced assemblages by was maximum significantly methane concentrations andwhereas the type temperature of anomalies substratum ( andwere the not biomass significant. and The(RDA) density first accounted of two for foundation respectively components species 27 of % the ( canonical redundancy analysis ity in macrofaunal compositiondriven (adjusted by maximum methane concentrations.S_Gast, The V_Sib, high V_Mat, methane V_Alv concentrations andinance at S_Mat of the sites dorvilleids were mainlymethane and associated concentrations ampharetids with at the and dom- ratulids, all to bathyspinulids, other a paranoids, lumbrinerids, lesser sitesand aplacophorans, extent were neolepetopsids. ophiurids, to linked Nevertheless, hesionids polynoids. to insitions The this higher had low latter more abundances group, a oftrations. S_VesA cir- The and V_VesA second compo- RDAalso axis by was higher driven methaneend, by concentrations hard the in substrata type V_Mat,tion, of mainly S_Mat with substratum the contributed and presence (hard/soft) S_Gast to ofand but sites. polynoids neolepetopsids S_Sib at On at V_Alv and S_Sib. one coupled OnV_Mat, V_Alv to the S_Mat that other and macrofaunal of end, S_Gast composi- lepetodrilids, mainly thewhereas accounted serpulids higher soft for methane substrata the appeared concentrations higher to in dominance explainulids. of the ampharetids abundance of hesionids and bathyspin- macrofaunal community composition was significantly influenced by the first axis of foundation species reached 56 familiesecosystem at and the 15 seep at ecosystem, thesite 22 reference were families also site at found (G_ref). the at All vent at seep the and the families eight reference found of site at themseep was the were and shared estimated reference vent with on ones vents. only As wasvent one the not macrofaunal diversity assemblage, estimated. composition diversity was The estimated comparison Sorensenness at dissimilarity to (species 42 between % loss), seep and whereas and corresponds the only dissimilarity to linked nested- to turnover (species replacement) 3.2.4 Similarity in community composition betweenAt vent the and family seep level, gamma ecosystems diversity of macrofaunal communities that are associated to A. gigas of high fluid input thanthe biomass the of other foundation assemblages. species, The discriminatingwith S_VesP second high from axis frequencies the was other of assemblages mainly nuculanidlower bivalves, driven frequencies ophiurids, by dominance and of gastropods severalrelated polychaete compared to families. with di This pattern may be also ratulidae and Bathyspinulidae families. Inassemblages this (S_VesA, V_VesA) latter were group, found the to seep have and more vent a at seep and vent microbialcontributed mats and to gastropod the assemblages (S_Mat, highall V_Mat, other dominance S_Gast) assemblages of were ampharetids characterised and by a dorvilleids. higher At proportion the of taxa other from end, the Cir- the CIA and the biomassables ( of foundation species, which were the best explanatory vari- position (adjusted CIA, which we interpreted asnificant, a whereas proxy the for relationship fluid with inputas the across second being ecosystems, axis was vent-specific, of highly the was sig- respectively CIA, not. 31 which % we The ( interpreted first two components of the RDA accounted for than those dominated by bial mats (S_Mat, V_Mat)were and closely vesicomyid related, (S_VesP, S_VesA, whereasamong V_VesA) di siboglinid assemblages assemblages (S_Sib, V_Sib).those Of dominated the by three vesicomyid assemblages, 5 5 25 20 15 10 10 15 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | and ered in the two Branchiplicatus ff er from the original ff e et al., 2003, 1998; ff Eulimella lomana erences between seep and ff ering an ideal case study for ff – in sediment-covered vent fields, fluid ). 8522 8521 Pyropelta musiaca erences in site biogeochemistry ff e et al., 2003; LaBonte et al., 2007; Von Damm et al., 1985). ff sp.) and two were restricted to vent one (the polynoid – seven sampled assemblages were associated with soft sediment (at and the gastropod Vent and seep physico-chemical conditions 26 species belonging to 18 seep and vent common families were identified (Table 6). Within our study, the high methane and hydrogen sulphide concentration ranges end-member fluids and potentiallycrepancies lead as to shown reduced elsewhere seepet in al., and 2005; terms vent Tunnicli environmental of dis- temperature and geochemistrywere (Sahling similar inwithin each seep assemblage, concentrations andsubstratum of interface vent these and reduced ecosystems.mas among compounds sites chemosynthetic As at were habitats the fluidecosystems: water– used can those fluxes as be with low fluid thus were fluidsiboglinid inputs input divided (seep not assemblages proxies. in and and vent The measured two vesicomyid seep Guay- assemblages, groups, seep siboglinid regardless periphery of assemblages) the and those with ecosystems. At seeps, the originbeen of authigenic attributed carbonates to colonised AOM by microbialthe siboglinids consortiums has increase that, of through pore the waterminerals production alkalinity, (Paull of facilitate DIC the et and precipitation al.,sediments of 2007). authigenic retains At carbonate enough vents, metals thesulphide and edifices, hydrothermal sulphides such fluid to as percolating produceblages the through were hot Rebecca’s the found, Roost, fluids or on that smaller tophave form sulphide settled of mounds large (Jørgensen which such et the as al., alvinellid Mat 1990). assem- Mound where siboglinids Substratum seeps: vesicomyid, microbial matblage and at gastropod the assemblages as peripherybial mat well of assemblages). as a Only an(seep three siboglinid assem- siboglinid assemblages assemblage; assemblage, were vent at associated siboglinidter with vents: and hard-substratum alvinellid hard vesicomyid assemblages). assemblages, substrata and Of the these nature micro- lat- of the hard substrata di 4.1 Similarities and di properties are modified whenfluid the emissions fluid at passes the through water–substratum the interface sediment may layer. strongly Therefore, di Paralepetopsis cupreus 4 Discussion Previous comparative studies have highlighted strong di a better understanding oftion chemosynthetic patterns community in density, diversity regarddrogen and to sulphide composi- local appear to environmentalvent be conditions. ecosystems, potential Although ecosystem common methane specificpatterns. structuring and In fluid factors hy- addition, across properties other seepthe may environmental and role further factors of such shape foundation as speciesnities community the as (Govenar, type 2010; engineers of Cordes add substratum et avent al., and potential common 2010). complexity assemblages within In may commu- addresses ourand the study, composition the on issue comparison macrofaunal of communities. of the seep specific and role of fluid input Of these, the vast majoritytwo (22 species species) were of found gastropods in both were ecosystems, specific whereas only to seep ecosystem ( was nil. Indeed, allwhile the seep 22 had 28 families additional found families. at vent were also found at seep ecosystem vent macrofaunal communities (Bernardino etSibuet al., and 2012; Olu, Tunnicli 1998;jima Turnipseed et et al., 2014). al.,barriers However, 2003, to have 2004; limited date, large-scale Watanabe anyenvironmental direct ecological et conditions. comparisons factors al., and Guaymas of 2010; biogeographic the seepssettings Naka- impact and and of vents depths seep- have and and comparable vent-specific no sedimentary biogeographic barriers, o 5 5 20 25 10 15 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C in the vesi- ◦ siboglinids pump hydrogen sulphide through 8524 8523 erent ecological niches along a gradient of fluid – in addition to the type of substratum and bio- – AOM has been shown to represent a major ff E. spicata C in the microbial mat assemblage. Vent habitats were ◦ and captures the chemical elements through its gills, in stronger fluid L. barhami R. pachypila N vents in the East Pacific Rise (EPR) showed that concentrations in metals were 0 Heterogeneity of foundation species AOM-related microbial populations Vent-specific factors in regards of temperature, metals, pH and petroleum-like hydro- Although the Guaymas seep and vent habitats shared comparable ranges of 50 ◦ geochemical conditions, foundation species may contributeand to between add ecosystems heterogeneity through within both2010; allogenic and Cordes autogenic et engineering al., (Govenar, can 2010). provide The substratum and tubes increasevivorship of of habitat siboglinid associated complexity, species worms promoting (Govenar, settlement and 2010).laterally or and, Vesicomyids the that to sur- shells move a vertically lesser of and extent,may bivalves gastropods rework sediments that thus can increasing reach oxygen exceptionallying penetration high sulphide depth densities, and production indirectly (Wallmann promot- etsiboglinid al., tubeworms 1997; can Fischer also et stimulate al., sulphide 2012). production In through seep bio-irrigation habitats, and microbial process not only2014), at but also the in Sonorathe sedimented margin Guaymas vents Basin cold (Teske and et seepsBiddle in al., (Vigneron methane-rich et 2002; et Dhillon hydrothermal al., al., et sedimentstially 2012). al., 2013, of involved 2003, In in 2005; our Holler AOMsoft-sediment study, et processes assemblages. al., the Variations co-varied 2011; were composition with mainlyabundance of at physico-chemical related both microbial to conditions seep higher and communities among of vent ANME poten- high archaeal ANME fluid-input clades habitats. Nevertheless, aremicrobial compositions mat distinct assemblage among whereas these seepshowed co-dominance assemblages: microbial of mats ANME1 ANME1 and and dominated gastropodANME1 2. at are Indeed, assemblages associated previous vent with studies more have stable suggestedthan anoxic that ANME2 environments (Rossel and et higher al., temperatures 2011;2011; Biddle Nauhaus et al., et 2012; al., Vigneron 2005). et al., 2013; Holler et al., 9 lower in vent fluid butDamm higher et in al., organism 1985). tissuesof This at the suggests Guaymas total (Von that metal Damm, heavyet concentrations, 2000; al., but metal Von 2003; depend bioaccumulation Demina on is et metal independent al., bioavailability 2009). (Ruelas-Inzunza high fluid inputsvent (seep alvinellid and assemblages). vent In microbial addition,semblages (vesicomyid two mat, and microbial of seep mat the assemblages) gastropod,fluid three showed relatively inputs. seep vent comparable Indeed, and siboglinid vent habitats and by common at as- strong microbial mat fluid assemblages(Levin, inputs are 2005). whereas usually The characterized vesicomyid thirdvent habitats siboglinid common are habitat assemblage related related to didboglinids to strongly at not higher seeps lower and exhibit fluid vents fluid inputs the occupy than di inputs same seep one. pattern Indeed, with si- comyid assemblage to 55.5 tions in Guaymas vent fluids arepresumably known due to to be the lower high thanbility typical alkalinity (Von basalt-hosted Damm and systems, et high al., pHties 1985), of (Decho heavy the and metals fluids may Luoma, that be 1996). reduce potentially In metal toxic solu- addition, in a minute comparative quanti- study of the Guaymas and carbons may limit fauna, but not much is known about them. Although metal concentra- also characterised byganese higher ammonium concentrations concentrations, thanvent lower seeps, pH fluids reflecting and the (Vonthe higher end-member Damm thermocatalytic man- concentration et percolation of of al.,a sedimentary the process 1985). organic that matter produces Vent by methanebons enrichment and hydrothermal (Bazylinski petroleum-like fluids, in et aliphatic al., and ammoniumet 1988; aromatic al., is hydrocar- Von 1992). Damm related et to al., 1985; Pearson et al., 2005; Simoneit flow (Arp and Childress, 1983). methane and hydrogen sulphideature concentrations, anomalies, vent which are assemblages correlated showed to temper- fluid inputs, ranging from 6.5 flow. The seep their roots deep in thetaxon sediment in low-flow settings (Julian et al., 1999) while the vent 5 5 25 20 10 15 15 25 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | cult ffi E. spi- alvinel- A. gigas P. soyoae erentiate the two assemblage sug- ff Paralvinella clusters in seep and at vents than vesicomyid. ) was found in relatively erentiated in terms of type C and the presence of oily ff ◦ P. soyoae A. gigas A. gigas A. gigas may thus have stronger allogenic R. pachyptila A. gigas erences are found among seep and vent vesicomyid assemblages, vesicomyid den- ff , due to its larger size and lower motility, may 8526 8525 A. gigas dominates at the Ayala site where individuals seemed P. soyoae C. In contrast, among seep and vent vesicomyid assem- ◦ ects (i.e. habitat provision). ff (a closely related species to and vent P. soyoae at seeps, suggesting potentially stronger engineering influence of er. ff lived in dense clusters, on more solidified sediment and at sites with P. soyoae gastropods) was only present at seeps and another ( C. Thus, in order to reinforce patterns observed among all assemblages, ◦ L. barhami at the Vasconcelos and Morelos sites, where it lives buried in soft and fine sed- , seep bushes, particularly regarding habitat provision and complexity. Between seep P. soyoae and Archivesica ochotica ects (i.e. bioturbation) while Overall, our results showed that the Guaymas seep and vent environmental condi- Seep and vent assemblages characterized by common major taxa, siboglinids, vesi- ff Hyalogyrina siboglinid assemblages with the venttially one stronger characterised engineering by higherby role fluid temperature of input, reaching a foundation 30 poten- speciesblages, relatively and comparable low vent-specificities fluid depicted variations inputs according were to found. the In species, addition,relatively seep despite similar and potential engineering vent roles. vesicomyids Specific arecomyid environmental suspected assemblage conditions to were have at depicted the by vent temperature vesi- of 6.5 sediment (pers. obs.) together withsites. slightly Finally, seep higher and fluid vent flow microbial thaninput mat found habitats settings, at had but the also herein relatively twoditions related comparable seep fluid- at to the high microbial fluid matup inputs. assemblage Vent-specific to were environmental 55.5 depicted con- by high temperatures reaching comyids and microbial matsmental are conditions. characterized Strong environmental by di more or less comparable environ- only comparison ofcan vesicomyid be and used microbial to attempt maton to macrofaunal assemblages specifically communities. assess across the ecosystems role of vent environmental conditions e tions are characterised by(methane, hydrogen comparable sulphide), concentration but ranges that they of can reduced also compounds be di have stronger authigenic e of hard substratum andseep and vent vent physico-chemical fluid homologies and proprietiesulations specificities linked (temperature, influenced to microbial magnesium, AOM pop- processes pH). ingeneity the associated These soft-sediment with assemblages. the Moreover, hetero- foundation speciesecosystems identity with may only further one di foundation species shared, small aggregations in soft-sediment sitestrast, with higher sulphide levels,apparently whereas, lower in fluid con- fluxes (Krylova, 2014). restricted to the water–sediment interface inA. relatively gigas compact sediments compared to iments (pers. obs.). Moreover, numerousassemblages, indicating trace high paths motility werebetween for observed two this around vesicomyid species. species A inbile similar the Sea pattern of was Okhotsk observed (Krylova, 2014): the more mo- the release of sulphate2008). deep Foundation in species the can sediments alsoviding (Cordes foster colonisation et access to al., surfaces highly 2005; for productiveorganic Dattagupta microbial habitats matter et mats by (Levesque al., pro- and et al., contributingity 2005; to provided Sarrazin the et by segregation al., foundation of 2002). species The level and of the heterogene- processes involved are however di Riftia A. gigas vent assemblages. Furthermore, thespecies, highest which biomass also have was larger observedthe sizes. in two In species addition, the di the behaviour and biological traits of to assess. Incommon our major study, taxa three (siboglinids, assemblages( vesicomyids were and characterised microbial by mats), the one presence assemblage of cata gest the presence of denser clusters in comparison with lids) was only presenttimes higher at and vents. biomass Among was siboglinid 14 times assemblages, higher densities for were two sities and biomasses were comparablesame due assemblage. to However, high visual variability between observations samples of of the the 5 5 15 20 10 25 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ect ff e, 1991; ff ects. ff ect of chemosynthesis ff ects on density. 30 µM, leading to the production of anoxic ff 8528 8527 ∼ erences may result from distinct fluid flow and/or engineering ff erences between the seep and vent ecosystems and comparisons of vesi- ff Alpha diversity showed a more straightforward relationship to fluid input through Overall, density and diversity patterns observed within each ecosystem were rela- In the Guaymas Basin, the majority of seep and vent assemblages had higher den- bottom waters are poorly oxygenated, background sediment and decreased withselection increasing of fluid tolerant input highlighting taxadiversity enhanced along di a gradient ofcomyid fluid and microbial intensity. There mat assemblages were across no ecosystems significant did not confirm any e a highly significant logarithmic correlation. Diversity appeared to be maximal in the tively consistent with theresults conceptual suggest model that proposed diversity in andof Bernardino density reduced et patterns compound al. are concentrations, (2012). without shaped any along Our vent-specific a e similar gradient of vent-specific conditions on diversity. sediments (Campbell and Gieskes, 1984),be whereas found chemosynthetic on assemblages can hardWithin substrata both and ecosystems, foundation species fluidaccount may inputs, for provide depicted a habitat by oxygenation. large methanefluid-input part concentrations, sites appear of were to enhanced thehighest in variability densities comparison in were with related faunal the to density.semblage, two background Densities seep of sediment the at gastropod and high relatively assemblage). the fluid-inputwhich Seep low habitats showed and (vent the siboglinid highest vent as- fluid microbial inputs,ingly, within mat were both characterised assemblages, ecosystems, by high reduced variation in density.parable Interest- density high was found fluid-input among relatively habitats. com- assemblages At were vents, denser macrofaunal than communitiesassociated in within community the siboglinid in alvinellid themicrobial assemblage. gastropod mats. Similarly, assemblage These di at had seeps, higherroles the densities of than foundation in speciesassemblages the among characterised assemblages. by Comparison relatively comparable acrossof fluid foundation ecosystems inputs species of and (microbial engineeringlead mat role to assemblages, any vesicomyid conclusions assemblages) on vent-specific did e not 4.2 Community patterns and structuring factors Bernardino et al. (2012) proposed aversity, density conceptual and framework of biomass factors of shapingadapted macrofaunal the communities biodi- from within reducing the ecosystems, within Pearson each and ecosystem, Rosenberg, density increases (1978)to along organic model. a enrichment gradient The up oforganic model to increasing enrichment, a fluid predicts thus flow threshold leading that, due where toa fluid reduced pattern densities. toxicity In of overwhelms parallel, diversity the the asflow benefit model a of intensities. describes unimodal Low function ofchemosynthetic fluid fluid endemic intensity flow, macrofauna, peaking allows whereas at increasingthe colonisation intermediate fluid selection fluid by flow of intensity a tolerantcommunities leads macrofauna. mix are to Likewise, of primarily many shaped background studiesRoy, by 2003; and report fluid Bergquist that flow et macrofaunal al., gradients 2003, atet 2005; seeps al., Sahling (Sibuet et 2012; and al., Olu-Le Robinson 2002; Thurber Levin et et et al., al., al., 2004; 2003;2008; Decker Olu 2010; Bates et Levin et al., al., and 1996) 2005; Dayton, and Mills vents 2009; et (Levin al., Ritt et 2007; et al., Cuvelier 2009; al., et Matabos al., 2010, 2009a, et 2012; b; al., Tunnicli Our first working hypothesis wasdensity that and seep diversity and patterns ventsulphide macrofaunal fluid that communities inputs, are exhibit regardless similarly of the governed ecosystem. by methanesities and than hydrogen the reference site, attesting to positive, productive e Sarrazin et al., 1997,nar 1999; et Desbruyères al., et 2005). al., Nevertheless,concentrations 2001; to consistent date, MacDonald across no et the conceptual seep al., framework and 2003; including vent Gove- compound ecosystems has4.2.1 been proposed. Density and diversity patterns and/or to lower anoxic conditions.mas Indeed, despite Basin, high at sedimentation 1500 within m the depth, Guay- organic matter may be refractory. In addition, Guaymas 5 5 20 25 10 15 10 15 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C) ◦ assemblage R. pachyptila erentiate seep ff ect. ff bushes at the Jaco Scar R. pachyptila L. barhami tubes and their absence in C, suggesting their immersion in sulphide- within the Guaymas Basin has been previ- was first sampled and described from tube ◦ 8529 8530 tube worms and of mucus secretions in alvinellid E. spicata use, low fluid-flow sites, whereas the more focused ff R. pachyptila and L. guaymensis R. pachyptila L. barhami ect of tube worms at seeps than vents, despite their lower densities ff ects in the structuring of macrofaunal communities at seeps and vents, with the ff Surprisingly, the overall macrofaunal composition patterns did not di Comparison across ecosystems of assemblages characterised by relatively compa- In addition to fluid input, the type of substratum and the engineering influence of foun- The estimation of the respective role of fluid flow and taxa engineering on the struc- position of macrofaunaalvinellid in microhabitat, the was siboglinid notthe attributed microhabitat, exception to and of the polynoids, to presencefound the a of in composition a of high lesser hard these fluid-flow extentbial substratum. last soft-substratum in mat With communities assemblages. at resembles the The the that presence baseassemblages of may of have a fostered thick colonisation by micro- fluid soft-substratum fluxes taxa. and temperature In in addition, the high restricted siboglinid faunal and alvinellid colonisation, vent while assemblageshave may relatively favoured have the low establishment of fluid less fluxes tolerantengineering taxa. at e Furthermore, siboglinid stronger authigenic seepsand may biomass as well asClearly, there compared is to the a alvinellids stronging engineering interplay e role between may fluid beinfluence flow involved. of input, the substratum latter and two factorslepetodrilid engineer- here limpets decreasing found as in fluid the inputat seep increases. vents siboglinid Interestingly, and assemblage are the known lepetodrilid worms to mainly and occur rocks of thedition, lepetodrilid Guaymas Southern limpets have Through also vent been site found (McLean, in 1988). In ad- hydrothermal seep as were serpulidsthese (Levin two et taxa al., on 2012). In our study, the presence of 4.2.2 Community composition patterns Our second working hypothesis was thatvents variation and in macrofaunal seeps composition is between ecosystem-dependent:faunal more overlap specifically, is we larger predicted among that di macro- and between ecosystems. The abundancesidae), of Polynoidae, gastropods Serpulidae (Lepetodrilidae, and Neolepetop- Nereididaesignificantly in linked the to siboglinid the seep presence assemblage was of a hard substratum. At vents, however, the com- bushes may result from the particular setting of the sampled rich and hot fluid flow. Indeed, (Robidart et al., 2011). ture of macrobenthicecosystems assemblages because is the distribution often of a foundation challenge species is within strongly both correlated with seep and vent rable fluid inputs andblages, vesicomyid engineering assemblages) did role not of indicate any foundation vent-specific species e (microbialdation mat species significantly assem- contributed to variations in community composition within emission of hot fluids at vents creates niches that arefrom vent-specific. vent ecosystems. Substantialblages overlap characterised by was low found fluid inputs. amongfamilies, These seep including assemblages were and some colonised vent by thatecosystems similar assem- are (e.g. endemic Neolepetopsidae,along or extremely Provannidae, with common Lepetodrilidae otherParaonidae in and and chemosynthetic families Spionidae) Polynoidae), thatfluid-input (Menot assemblages are et were similar al., typicalassemblages at 2010). were deep-sea seeps characterised Contrary and sediments bypolychaetes, to vents. the known In (e.g. our presence as both of Cirratulidae, hypothesis, highly ecosystems,thermal Ampharetidae specialised high these stress, and taxa. ampharetid Dorvilleidae Indeed, polychaetestheir to live gills cope in over with and vertical sulphide aboveditions tubes and/or the (Treude from substrata et which as al., an theycolonise 2009). heavily adaptation deploy polluted Dorvilleids to areas are harsh (Fauchald andseeps environmental known Jumars, in con- to 1979); the they be most are sulphide-rich sulphide-tolerant usually found environments and at (Levin, often 2005). as suggested by thetogether with particularly temperatures thick reaching ca. microbial 30 mat at theously base found at of lower fluid the flow as tube suggested worms, by the lower temperature measured (14 5 5 10 15 25 20 25 10 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) in P. soyoae ect of rare ff P. soyoae and ect within seeps ects (i.e. habitat ff ered an opportu- ff ff A. gigas to have stronger allogenic ef- ort and thus, to a better charac- ff erences nevertheless still emerged assemblages cannot be specifically ff A. gigas 5 %). Furthermore, the number of sam- ect was found related to the < ff 8532 8531 A. gigas to have stronger authigenic e ect the structure of macrofaunal communities in ff assemblages. The engineering e species. We hypothesize that oxygenation of sediments P. soyoae ect of vent-specific factors. In addition, diversity and den- A. gigas ff sp. Thus, these results suggest a non-negligible engineering A. gigas assemblage may have limited the establishment of dense and diverse Nuculana species may explain the colonisation by the denser, species-rich endo- erences among seep and vent ff P. soyoae A. gigas Overall, Guaymas vent and seep macrofaunal communities were mainly structured 4.3 The vent and seep connectivity In the Guaymas Basin, comparison ofto macrofaunal foundation community species composition did associated notinance discriminate of seep common and vent families.between ecosystems Gamma seep due diversity to and the di 22 vent dom- at ecosystems. vents, In leadingtems. total, to However, this 56 a value remains relatively families lower than(93 high were %; that dissimilarity reported Bernardino found from (42 et at %) Pacific seepness al., between seeps and rather 2012). vents the than and Moreover, two by dissimilarity species ecosys- of was turnover those because characterised found vent at by families seeps nested- representedfound (i.e. all a at vent sub-sample seeps families may were be foundterisation at due of seeps). to seep The the higher diversity, especially higher richness communities because sampling in rare e chemosynthetic species environments can (Baker reach et up al., 50 % 2010). of This the e fects (i.e. bioturbation) and characterised by similar fluidnity inputs to assess among their the respectivebehavioural roles seep and in ecosystem biological their o associated traits, communities. we Considering expected their provision). Indeed, significant structuring e may thus overwhelm the e species is supported byseeps the were fact found that in 30pled low species sites relative from was densities the higher ( 34 atsites families seeps is exclusive (6) frequent to than at the semblages at seeps were vents (Cordes sampled (4) et at and seeps al., highcharacterised (four 2009). species compared by A with turnover higher higher just among taxonomic one numbercontrast, richness at of a with vents), higher low these the number fluid-flow being presence of as- compared high of fluid-flow with background assemblages two taxa. were at In sampledcertain at seeps), vents taxa. harbouring (three In conditions addition, that thespecies may substratum may prevent and have colonisation helped biogenic by to heterogeneityOverall, due enhance we to the suggest foundation beta-diversity that in thepresence low greater of fluid-flow gamma assemblages. a diversity greater atvironmental variety seep heterogeneity of ecosystem found is foundation in due species lowwe fluid-input to in habitats the cannot association at exclude with seep the the thaninfluence vent. higher possibility the However, en- of distribution seep of and the vent rare “ecosystem macrofaunal filtering”, families, with which harsher may conditions at sity di microbial mat assemblages. comparison to the the associated with vent-specific factorsdistinctions (temperature, are petroleum) also as related to their relatively environmental higher fluid inputs andby flows the at fluid the input ventof one. regardless substratum of and the the foundation ecosystem.tions species In with appeared an addition, to increased vary heterogeneity influence accordingassemblages due with characterised to to by decreasing abiotic relatively fluid type similar condi- input. fluidthat inputs Comparisons vent-specific across of conditions ecosystems common are suggest not theassemblages dominant and structuring factors that among they vesicomyid did not a by fauna dominated by polychaetes we observed whereas lower bioturbation activity in fluid flow (Cordes et al.,presence 2009; of Sahling two et distinct al., vesicomyid-dominated assemblages 2002; ( Roy et al., 2007). In our study, the communities and reduced endofaunalidae taxa bivalve at therole expense of of foundation species epifaunal onthe Bathyspinul- the Guaymas structure seeps, of instructure associated low macrofaunal variation fluid-flow communities between settings. at between Furthermore, the the macrofaunal two seep and community seep vent vesicomyid assemblages exceeded those 5 5 10 20 25 15 20 25 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , er- ff Par- ect on ff were oc- ) have al- P. soyoae have been ). These di are vent-endemic, E. spicata C. pacifica gastropods have been -axis magma intrusion ff and B. cupreus , C. pacifica/C. lepta P.bactericola, Hyalogyrina P. soyoae and P. musaica , despite its absence in our vent samples, sp.), two ( 8534 8533 has been reported in East Pacific sedimented E. lomana specimens were detected in the hydrothermal vent erences between seep and vent species compositions ff Hyalogyrina L. barhami ) and two to vents ( R. pachyptila, P.grasslei and C. pacifica has been reported from eastern Pacific seep sites (Jalisco Block E. lomana sp., L. barhami Mexico: (Sasaki et al., 2010). Thus, our study suggests relatively weak P. musaica , ff erences among macrofaunal communities found at the ecosystem level within our ect the assessment of community structure patterns (Gauthier et al., 2010). Shallow In addition, the analysis of the distribution of foundation species revealed that the Despite these limitations, species distribution across seep and vent families of Finally, we suggest that the di Overall, Guaymas seep and vent species compositions suggest that, with the excep- ff ff found at the peripheryet of al., microbial 2010). mats The at absencethe numerous of lack vents these around of assemblages the sampling within world at our (Sasaki vent the study vent may periphery. be In due addition, to although ences may even be lower because has already been1993) collected and at theseeps, Guaymas o Basin vent sites (Warén and Bouchet, di study may in fact be minimal. Of the four seep-specific foundation species ( macrofaunal communities suggests abased sustained ecosystems exchange of between the Guaymas chemosynthesis- 18 Basin families (Table 6). common Of to the seepsalepetopsis 26 and species vents, only identified two within species were specific to seeps ( “ecosystem filtering” between Guaymas seeps and vents. casionally sampled at seepspersonal in communication, our 2015) study, and identifiedmunication, COI by 2015), sequencing both no (Arnaud-Haond, morphology personal (E. com- Krylova, vents. Furthermore, comparison of seepa and vent communities atwater the studies family have level shown may thatand in species terms levels of are macrofauna2003). strongly taxonomic Similar correlated richness, conclusions (e.g. the have (Jameson family in also et been deep-sea al., drawn chemosynthetic 1995; for communities OlsgardPearson the et (Doerries study and al., and of Rosenberg Van taxonomic Dover, (1978)manifest richness 2003). at suggest However, decreasing that taxonomic increasing resolutionsmay and still environmental thus be changes suggest lost are in that a some lower information range of environmental changes. area, though some specimens of the species complex E. spicata reported at Guaymas vents (Grassle etvent al., foundation species, 1985; Simoneit et al.,they 1990). did Although not three appear in our study to exert an important ecosystem engineering e ecosystems in the absence of20 biogeographic additional barrier. species In addition, to ouroceans the results (Table list 6). contribute of species common to seeps and vents in the world’s tion of a fewpart species, of including macrofaunal the communities can foundation coloniseronmental species variable variation. ecosystems that Therefore, and our are cope study with vent-endemic, envi- supports a strong large connectivity among reducing community composition, mainly due to the influence of high fluid inputs. generally observed at largeand spatial heterogeneity due scales to mayingly, foundation mainly the species ability reflect identity of and biogeographic macrofaunalspecificities type barriers communities of seems to substratum. higher adapt Accord- than tocontext seep previously of and suggested. the vent Nevertheless, Guaymas environmental thevent Basin fluid sedimentary in discrepancies, comparison allowing greater tocomparative connectivity other studies among along settings ecosystems. the Thus, may seep more confirm reduce and the seep vent faunal and environmental commonality of continuum reducing are ecosystems needed communities. to ready been recorded atids Guaymas have vents been (Table found 6). on In addition, authigenic seep-related carbonate siboglin- crusts at an o vent areas at Middle Valley (Black et al., 1997) and site within the Guaymasspecies Northern found Trough at segment Guaymas (Lizarralde seeps,in et but not other al., found 2011) vent at and ecosystems: the other vents, have already been found 5 5 15 20 10 15 20 25 10 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | : Bivalvia submersible Nautile : Protobranchia) from erence is related to the ff erences due to the pres- ff ” LabexMER (ANR-10-LABX- Bivalvia ( crew for their steadfast collaboration Nuculana L’Atalante ect on associated macrofauna. A high pro- ff 8536 8535 Laboratoire d’Excellence erentiate the two ecosystems studied here despite the pres- ff e, V., and Lee, R. W.: Role of thermal conditions in habitat selection by We are grateful to the R/V ff , Science, 219, 295–297, 1983. erences in gamma diversity with a higher overall diversity at seeps mainly reflected A more functional approach is currently underway to analyse the ecological pro- Vesicomyidae: Pliocardiinae) in415, chemosynthetic 2012. environments, Syst. Biodivers., 10, 403– of whale-fall vesicomyid clamsProg. Ser., based 182, 137–147, on 1999. mitochondrial COI DNAbilier, sequences, N., Mar. Fisher, C., Ecol.- Levin,of L. chemosynthetic A., ecosystems andDistribution, in Metaxas, and A.: the Abundance, Biogeography, edited deep ecology by: and sea, McIntyre, vulnerability A., in: 161–183, Life 2010. Ecol. in Biogeogr., the 19, 134–143, World’s 2010. Oceans: Diversity, in Ecology and Evolution, 3, 808–812, 2012. hydrothermal vent gastropods, Mar. 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This study was supported by the “ 5 Conclusion Macrofaunal patterns in terms ofthe density, alpha family diversity level and did taxonomic not composition di at ence of vent-specific environmentalshared conditions. between the Structuring two factorscentrations, ecosystems, were the including found type methane to of andwhereas substratum hydrogen be vent-specific sulphide conditions and (temperature, con- the pH, manganese heterogeneityobserved concentrations due or petroleum) even to had foundation no species, significant e portion of identified speciesof were macrofauna common to to colonise seepsdi various and vents, environmental highlighting conditions. the At ability the ecosystem scale, the presence of additional rare families. We suggest that this di higher intrusion of background macrofaunaand and diverse to communities the establishment inseeps. of low-flow However, more our assemblages, complex study which may have were overestimated variable these at di Guaymas mas vent and seepchemosynthetic ecosystems communities. will pave the way toAcknowledgements. a better understandingin of the these success of thepilots BIG for cruise, their to patience thehelp and chief constant both scientist support at of and sea theidentification to cruise, and and the to Elena in LEP the Krylova the technicalon for lab. team bivalve vesicomyid for We species taxonomy, their also identification morphology valuable (France) as greatly and and held well thank a as behaviour. Anders work helpful This permit Warén for comments cruise for study in gastropod was Mexican waters species funded (DAPA/2/281009/3803, 28 by October IFREMER cesses that occur withinecological niches, these biotic interactions communities. and trophic An adaptations assessment within and of between Guay- the food resources, ence of additional low-flowbut assemblages were missing at from Guaymas our vent study. that have been reported, 5 5 15 20 25 10 10 25 20 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , R., Hourdez, S., Car- ff 8538 8537 erent temperature regimes in Guaymas Basin hy- ff in British Columbia with a description of a new spices, el Tower edifice (Lucky Strike, Mid-Atlantic Ridge), Mar. Ecol.-Evol. ff Calyptogena ) populations from hydrothermal vents of the eastern Pacific, Mar. 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G., Pignet, P., Caprais, J.-C., Callac, N., Ciobanu, M.- 5 5 10 30 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | min ] − 2 4 [SO mM 27.0 26.5 Vesicomyi- + + int ] − 2 2 4 2 2 [SO mM 27.3 21.3 15.0 A. gigas max ] 4 Faunal sampling Macrofauna: 4 SBC Microbiota: 1 TC Macrofauna: 3 LBC Microbiota: 1 TC Macrofauna: 3 LBC Microbiota: 1 TC Macrofauna: 3 LBC Microbiota: 1 TC Macrofauna: 3 LBC Microbiota: 1 TC Microbiota: 1 TC GS: 720 cm submersible grab GS: 1134 cm submersible grab GS: 694 cm Microbiota: 1 TC [NH µM int ] 4 Vesicomyidae (V_VesA), Microbial [NH µM 33.8 55.91260 11.7 1800 7.1 for the large cores (LBC) whereas tube characterisation 5 PEPITO 2 CALMAR 7 PEPITO 2 CALMAR 3 PEPITO 2 CALMAR 12 PEPITO 8 PEPITO 2 CALMAR max 2 S] 2 A. gigas Vesicomyidae (S_VesP), [H µM ground surface sampled. Substrata Physico-chemical Vesicomyidae (S_VesA), Microbial mat (S_Mat), int 8552 8551 = S] 2 µM [H 22 700 31 300 2890 9000 P.soyoae . GS (m) 2 A. gigas max ] 4 [CH µM 803 890 erent assemblages sampled in the Guaymas Basin and sampling int ] ff 4 µM [CH 787 220 max Vesicomyidae (V_VesA), Microbial mat (V_Mat), Alvinellidae (V_Alv) and Si- C T ◦ 55.5 29.7 182 275 – – – – – – Latitude Longitude Depth int C T ◦ 22.7 Vesicomyidae (S_VesP), Temperature and methane concentrations measured on all assemblages (pore-water Location of the di for the small blade cores (SBC) and 360 cm A. gigas V_Sib N 27 00.386 W 111 24.576 2004 Hard 5 PEPITO Suction sampler Seep assemblages S_VesP N 27 35.365 WS_VesA 111 28.395 N 1561 27 35.587 W SoftS_Mat 111 28.963 1576 NS_Gast 27 35.580 Soft 1 TC N W 27 111 35.583 28.986S_Sib 1576 W 111 28.982 1 N TC 27 35.274 Soft 1576 W 111 Soft 28.406 1562 2 TC Hard 2 TC 6 PEPITOV_Mat NV_Alv 27 00.445 W 111 Macrofauna: 24.530 N 1 Suction 27 SBC sampler 00.664 2012 W 111 24.412 Soft 1995 Hard 1 TC 2 PEPITO Suction Macrofauna: sampler 2 LBC Reference assemblage G_ref N 27 25.483 W 111 30.076 1850 Soft 2 TC S_Sib_P N 27 35.273 W 111 28.407 1562 Soft 1 TC Macrofauna: 4 SBC Vent assemblages V_VesA N 27 00.547 W 111 24.424 2007 Soft 2 TC 2 Soft substrata G_refS_VesPS_VesA 2.9 2.9S_Mat 2.9S_Gast 2.9 2.9 2.9S_Sib_P 2.9 2.9V_VesA 2.9 0.4 0.6V_Mat 2.9 3.1 0.4 2.9 2.9 3.2 6.5 192 0.7 13.0 0.6 0.7 2.1 0.0 680 0.0 4.6 0.0 45.7 2470 0.0 0.0 0.0 0.0 0.0 15600 13.4 11.5 0.0 5.4 33.0 1700 47.5 12.8 12.4 32.6 33.0 25.6 26.8 27.1 29.8 384 27.0 14.8 26.8 26.5 27.2 7.2 24.7 Hard substrata S_SibV_AlvV_Sib 2.9 8.1 2.9 20.0 18.2 371 30.1 382 – – – – – – – – – – – – Table 2a. measurements within softhydrogen sediment sulphide, and ammonium water andassemblages. measurements sulphate Physico-chemical above pore-water factors hard concentrations areues substratum) within summarised and soft and as maximum sediment P. substratum–water values soyoae interface measured val- amongGastropoda assemblages. (S_Gast), Siboglinidae REFERENCE: (S_Sib), sediment (G_ref), atVENTS: Siboglinidae SEEPS: Periphery (S_Sib_P) and boglinidae (V_Sib). Highest values are highlighted in bold. Table 1. details. REFERENCE: (G_ref), SEEPS: dae (S_VesA), Microbial matat (S_Mat), Siboglinidae Gastropoda Periphery (S_Gast), (S_Sib_P) Siboglinidae and VENTS: (S_Sib), sediment corer (TC) samples a surface of 26 cm mat (V_Mat), Alvinellidae (V_Alv) and180 cm Siboglinidae (V_Sib). Blade corers sample a surface of Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 05 06 06 07 07 06 05 07 A. gigas + + + + + + + + (28.1) 1.15E 8.12E TdCu (nM) 21.6 06 5.42E 06 7.78E 06 1.35E 07 1.97E 07 06 2.16E 06 8.60E 06 + + + + + + + + Vesicomyidae (S_VesP), Vesicomyidae (V_VesA), 4.00E 5.28E phyla potentially involved in the (0.50) 2.5 (0.9) 08 4.08E 08 4.88E 08 4.44E 08 08 08 3.62E 08 5.80E 07 6.36E Vesicomyidae (S_VesP), A. gigas + + + + + + + + P. soyoae TdMn (µM) 1.41 Vesicomyidae (V_VesA) and Microbial Bacteria P. soyoae and 06 1.10E 05 1.60E 06 2.40E 08 4.72E 0707 3.78E 2.18E 06 1.44E 06 7.08E + + + + + + + + A. gigas (0.002) 0.46 (0.10) 11.5 (6.4) 8554 8553 TdFe (µM) 0.16 1.45E 3.38E Archaea 06 2.74E 07 2.32E 08 3.42E 08 09 08 1.65E 05 2.42E 08 1.33E ) 1 + + + + + + + + − d 2 ) − 4 (0.7) 0.06 (0.03) 0.06 (0.04) (CH 0.1 (0.3) NA NA NA (molm F − 8.5 04 1.40E 07 6.94E 08 1.47E 08 7.56E 0907 1.47E 2.62E 05 5.28E 09 1.17E + + + + + + + + )), Total dissolved Iron (TdFe), Total dissolved Manganese (TdMn) and 4 (0.10) NA 0.12 (0.19) 0.06 (0.07) 8.0 (5.6) (CH ANME1 ANME2 ANME3 DSS DBB SRB2 1.12E F pH 7.7 Supplementary physico-chemical factors measured on some assemblages: pH, Vesicomyidae (S_VesA), Microbial mat (S_Mat), Gastropoda (S_Gast), sediment at Quantitative PCR results on six Reference assemblage G_ref 8.16E Seep assemblages S_VesP 3.84E S_VesA 1.28E S_Mat 7.84E S_Gast S_Sib_P 5.10E Vent assemblages V_VesA 2.34E V_Mat 1.09E Reference assemblage G_refSeep 7.5 assemblages (0.06) S_VesP 7.6S_VesA (0.12) 7.5S_Mat (0.04) 2.3(0.6)S_Sib 1.8(0.2)Mean 7.6 (0.04)Vent 7.6 assemblages NA (0.10) 0.09 (0.03)V_VesA – 0.08 (0.08) 7.4 (0.05) 0.02 0.04 (0.006) 0.14 (0.11) 9.2 (5.1) 0.10 (0.10) 12.5 0.16 (5.2) (0.005) 0.07 (0.07) 9.4 (7.8) 9.6 (5.8) V_SibMean 7.0 (0.13) 7.2 NA (0.26) – 0.15 (0.06) 0.10 (0.06) 0.40 (0.60) 15.7 (23.1) V_MatV_Alv NA 6.9 (0.13) NA NA NA NA NA Table 3. anaerobic oxidation of methane (AOM):sults ANME1, are cumulated ANME2, across ANME3, the DSS,ber 0–10 DBB cm per and sediment gram layer SRB2. of and Re- sediment. expressed REFERENCE: in 16S (G_ref), rRNA SEEPS: copy num- Vesicomyidae (S_VesA), Microbial matsediment (S_Mat), at Gastropoda Siboglinidae (S_Gast), Periphery SiboglinidaeMicrobial (S_Sib_P) (S_Sib), mat and (V_Mat), VENTS: Alvinellidaegiven (V_Alv) in and parentheses Siboglinidae and (V_Sib). the Standard highest deviations values are per factor are shown in bold. A. gigas Siboglinidae Periphery (S_Sib_P) and VENTS: mat (V_Mat). The highest values for each group of AOM micro-organisms are shown in bold. Table 2b. methane flux ( Total dissolved Copper (TdCu). Due toall sampling assemblages. limitations, REFERENCE: these (G_ref), factors were SEEPS: not available for Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | di- 41 Vesi- ) 2 − ) in the 2 − 81.3 (107) 6630 2.4 Biomass (gm 405 (358) ) and ES Vesicomyidae A. gigas 2 ) 0 28 472 194 2 − − 806 361 (48.1) 10 170 Density (indm (69.9) P. soyoae Vesicomyidae (S_VesA), Gas- Vesicomyidae (V_VesA), Alvinel- 444 194 1056 28 0 0 (133)/D: 19.9 (9) 1280 A. gigas A. gigas 431 83 1417 1583 972 333 28 111 167 167 6472 3889 2750 L: 57.0 (20.6)L: 24.2 (14.4)/D: 2.2 (1.0) 1070 55.6 31.2 L: (mm) L: 368 (116)/D: 6 (3)L: 75.0 (8.9)L: 87.1 (27.8) 721 457 102 (42) 74.1 262 (119) 8556 8555 1778 361 28 28 167 56 Vesicomyidae (S_VesP), sp. D: 2.0 (0.3) Vesicomyidae (S_VesA), Microbial mat (S_Mat), Gastropoda (S_Gast), Si- G_ref1234 S_VesP 123 S_VesA 123 S_Mat 123167 278 P. soyoae A. gigas Paralvinella grasslei/Paralvinella bactericola Archivesica gigas Riftia pachyptila Hyalogiorina SpeciesEscarpia spicata/Lamellibrachia barhami Archivesica gigas Phreagena soyoae Length (L), Diameter (D), Characteristics of foundation species (size, density and biomass) in the Guaymas Macrofaunal community composition (expressed in terms of density: indm Bivalvia BathyspinulidaeCuspidariidae 0MytilidaeSolemyidae 0 0Thyasiridae 0 0Gastropoda 0 0 0 Aplustridae 0 0Cataegidae 0 0 0Hyalogyrinidae 56Lepetodrilidae 0 0 0 0 0 0Neolepetopsidae 0 0 0Neomphaloidae 0 0 0 0 0 0Provannidae 0 0 0 0Pyramidellidae 0 28 0 0 0 0Pyropeltidae 0 0 0 0 0 0 0 0 56 0Polychata 0 0 0 0 0 0 0 0Acoetidae 0 0 0Ampharetidae 0 28 28 0 0 0 0 0 56 0 0 0 0 0 0 0 0 0 0 0 0 0 83 0 0 0 167 0 0 28 0 0 0 111 0Cossuridae 167 0 0 0 0 0Dorvilleidae 0 0 56 167 0 28 0 0 0 0 0 83 0 0 0 0 56 0 56 0 0 28 0 0 0 0 0 0 0 0 56 0 0 0 0 0 0 0 0 0 0 28 28 28 0 0 0 56 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 556 0 0 0 28 28 0 0 0 1806 0 0 0 0 0 56 0 0 0 28 0 0 0 0 28 0 0 0 0 0 0 0 0 250 28 0 0 444 0 0 0 0 0 AmphinomidaeArchinomidae 0CapitellidaeCirratulidae 0 0 0 0 0 0 0 0 0 56 0 0 0 0 56 0 0 0 0 0 28 0 0 0 0 0 83 0 0 0 0 0 0 0 0 0 0 0 V_Alv V_VesA Vent assemblages V_Sib S_Gast Seep assemblages S_Sib S_VesA S_VesP Table 5. Guaymas Basin assemblages at the familyversity. level, Standard including deviations total densities are (indmassemblage given in are parentheses. highlighted The(S_VesP), in highest values bold. observedboglinidae Reference: for (S_Sib), (G_ref), each sediment at SEEPS: Siboglinidae Periphery (S_Sib_P) and VENTS: Basin. SEEPS: comyidae (V_VesA), Microbial mat (V_Mat), Alvinellidae (V_Alv) and Siboglinidae (V_Sib). Table 4. tropoda (S_Gast), Siboglinidae (S_Sib) and VENTS: lidae (V_Alv) and Siboglinidae (V_Sib).est Standard deviations values are are given shown in in parentheses bold. and high- Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 0 0 0 0 444 611 1543 85 946 417 111 111 56500 28 1389 0 0 0 0 11.1 12.2 6.4 8558 8557 944 1444 556 167 1944 167 0 0 0 0 56 0 83 0 0 0 0 0 0 0 0 0944 0 0 0 14 0 111 14 2104 0 0 0 0 0 167 28 194 139 83 86 8269 56 56 0 0 0 0 167 0 222 0 0 0 167 G_ref12341231 S_VesP S_VesA 2 S_Mat 3123 S_Gast S_Sib1112341231211 S_Sib_P V_VesA V_Mat V_Alv V_Sib 17 222 Continued. Continued. 41 Total densityMean density 446ES 1058 335 447 569 (328) 2447 1112 724 14 005 11 281 1426 (903) 7835 1751 527 361 11 037 (3090) 880 (762) FlabelligeridaeGlyceridae 0GoniadidaeHesionidae 0Lacydonidae 0Lumbrineridae 0Maldanidae 0 0 0 0Nautiniellidae 0 0Nephtyidae 0 0 0 0 0Nereididae 0 0 0Opheliidae 0 56 0 0Paraonidae 0 0 0 0 0Pholoidae 56 56 0Phyllodocidae 28 0 0 0 0 0 0 222Pilargidae 0 0 0Polynoidae 0 0 0 0 0 0 0 0 0Serpulidae 0 0Sigalionidae 0 0 0 0 0 56 0 0Sphaerodoridae 0 28 0 0 0 28Spionidae 0 0 0 0 0 0 0 0 0Sternaspidae 0 0 0 28 0 0 56 28Syllidae 0 28 0 0 0 56 28Terrebellidae 0 0 56 0 0 1278 56 0 0 0Trichobranchidae 361 278 0 0 0 0 0 111 583 0 0 0 0 0 0Others 0 0 56 0 0 139 0 0 56 0 0 0Actinaria 0 0 167 0 0 0 0 0Amphipoda 0 0 0 0 56 0 250Aplacophora 83 0 0 111 0 0 56 0 0 0 28Cnidaria 0 0 0 0 0 0 0Cumacea 0 0 0 28 0 0 194 0 0 0 0 0Nemertina 0 0 0 0 0 0 0 0 28 0Ophiuridae 56 0 0 0 28 0 0 28 0 0Scaphopoda 0 0 0 0 0 0 0 0 0 0 139 0Sipuncula 0 111 0 0 0 0 0 0 0 56Tanaidacea 0 0 0 0 0 28 0 0 0 0 0 0 0 0 0 0 0 0 56 0 139 0 0 0 0 0 0 0 0 0 0 28 0 0 0 0 0 28 83 0 0 0 0 0 0 0 0 0 0 0 28 0 0 0 0 0 0 0 0 56 0 83 56 0 83 0 56 0 0 0 0 0 28 0 0 0 0 0 0 0 0 0 28 28 83 0 0 0 0 56 0 0 0 0 0 83 0 0 0 28 0 0 0 0 0 0 0 0 83 0 1250 194 0 0 0 28 0 0 0 0 0 0 917 0 28 0 0 0 0 0 0 0 0 0 0 0 0 222 0 56 28 0 306 0 0 194 0 0 0 28 0 0 0 861 28 0 28 0 389 0 0 0 27 833 0 167 0 0 0 0 56 0 0 0 28 0 0 0 28 0 0 0 0 0 0 0 56 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 CossuridaeDorvilleidae 0 7611 231 0 556 611 222 722 389 0 0 0 0 0 0 0 Bivalvia Bathyspinulidae 0 144 556 167 333 111 167 222 CuspidariidaeMytilidaeSolemyidae 0ThyasiridaeGastropoda 0 0 0Aplustridae 55.6Cataegidae 58Hyalogyrinidae 0 86 0Lepetodrilidae 0 0 0Neolepetopsidae 0 56 0 0Neomphaloidae 0 0 389 58Provannidae 0 0 56 0 0 130Pyramidellidae 222 735Pyropeltidae 56 389 0 0 0 0 0 0 0 0Polychata 0 28 0 0 0Acoetidae 0 0 0 43 0 0Ampharetidae 111 0 0 0Amphinomidae 0 0 0 0 0Archinomidae 0 0 0 0 0 0 0 0 0Capitellidae 0 0 0Cirratulidae 0 0 0 28 0 28 0 0 0 0 0 28 0 0 0 0 0 0 0 0 0 0 0 87 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 29 0 0 0 0 0 0 0 0 417 0 250 0 0 111 0 28 0 0 0 0 28 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 71 0 0 0 0 0 0 0 0 0 0 28 0 0 0 0 0 0 0 0 0 0 18 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Table 5. Table 5. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 94 348 94 348 : not found within ∗ e (1991) ff et al. (2014), Levin et al. (2012a) Tunnicli et al. (2014),et Sahling al. et (2012a) al. (2002), Sasaki et al. (2010), Levin et al. (2003), Levin (2005), Smith et al. (2014) 8560 8559 x x x Baco et al. (1999), Audzijonyte et al. (2012) CRHS CS HV OF References x x x Black et al. (1997), Levin et al. (2012a), Feldman et al. (1998), ∗ ∗ Guaymas Vent xxx x x Desbruyères and Laubier Desbruyères (1991) and Laubier (1982), Zal et al. (1995) Black et al. (1994) xx x x x x x x Krylova and Sahling (2010), Audzijonyte et al. (2012), Smith Guaymas Seep xx x x x x Huber (2010), Audzijonyte et al. (2012), Smith et al. (2014) x xx x x xxx Black et al. (1997), x Levin et al. (2012a) x x Allen (1993) x x Weiss and Hilbig (1992), Levin et al. Blake (2003), and Smith Hilbig et (1990) al. (2014) x x x Kamenev (2009) xx xx x x x x Petrecca and Grassle (1990) Blake and Hilbig (1990) Blake and Hilbig (1990) 2.1 10.9 12.9 10.3 5.4 3 2 S_Gast S_Sib1112341231211 S_Sib_P V_VesA V_Mat V_Alv V_Sib sp. x genus genus genus genus Smith and Baco (2003), Bernardino et al. (2010), Smith . johnsoni ff sp. x x genus genus genus Smith and Baco (2003), Bernardino et al. (2010), Levin Continued. Presence/absence of seep and vent species in the Guaymas Basin ( a 41 Total densityMean density 24 889ES 8029 24 889 8028 5779 4112 4169 4558 1946 4653 (776) 2224 834 695 722 1667 2614 (735) 708 (20) 2614 FlabelligeridaeGlyceridae 0GoniadidaeHesionidaeLacydonidae 0 0Lumbrineridae 0Maldanidae 0 0Nautiniellidae 0 0 0 0NephtyidaeNereididae 0 0 0 0 43Opheliidae 0 56 0Paraonidae 0 43 444Pholoidae 0 0 0 833 0 0Phyllodocidae 0 0 444 167Pilargidae 0 0 56 111 0 0 111Polynoidae 0 0 259 56 0 0 0Serpulidae 0 0 111 0 0Sigalionidae 0 56 1000 0 0 0Sphaerodoridae 332 0 0 83 0 0 28 28Spionidae 0 0 0 0 0 0 0 444 0Sternaspidae 0 0 0 0 0 0 0Syllidae 0 1629 389 0 0 0 0Terrebellidae 0 1485 14 0 0 0 0 0 0 0 0 444Trichobranchidae 0 0 0 0 0 0 0 0 0 0 333 0 0 0Others 0 0 0 0 0 0 0 43 28 56Actinaria 0 0 0 0 0 56 0 56 0Amphipoda 0 0 0 0 0 0 28 404 111 0 0 0Aplacophora 0 222 0 0 0 0 0 0 0 0Cnidaria 0 0 56 0 0 0 0 0 0 0Cumacea 0 0 56 0 0 0 0 0 0 167 0Nemertina 0 0 0 0 0 0 0 0 0 0 0Ophiuridae 0 0 56 56 0 0 0 0Scaphopoda 0 29 0 0 0 0 0 14 0 0 0 0 0 0 0 0Sipuncula 111 0 0 0 111 0 0 0 56 0 0Tanaidacea 28 0 0 28 0 56 0 0 0 0 0 56 0 0 0 0 0 0 0 0 0 0 0 0 0 0 56 0 0 0 0 0 0 0 0 0 29 56 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 56 0 0 0 0 0 0 0 0 0 111 0 0 0 0 0 0 0 0 0 0 0 0 0 0 167 0 0 0 28 0 0 0 0 611 0 0 971 0 0 0 0 0 0 0 0 333 0 0 0 56 0 0 0 0 0 18 0 0 0 28 0 0 0 0 0 0 0 0 56 56 0 0 0 0 0 0 0 0 0 0 0 28 0 56 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 26 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Archivesica gigas Foundation species Vesicomyidae Phreagena soyoae Calyptogena pacifica Alvinellidae Paralvinella bactericola Paralvinella grasslei Siboglinidae Riftia pachyptila Escarpia spicata Lamellibrachia barhami Associated macrofauna Nuculanidae Nuculana grasslei Hyalogyrinidae Hyalogyrina Solemyidae Acharax Hesionidae Sirsoe grassleiDorvilleidae Ophryotrocha platykephale Ophryotrocha akessoni Parougia x x Blake and Hilbig (1990) Exallopus jumarsi Polynoidae Branchinotogluma sandersi Branchinotogluma hessleri Table 6. our study but previouslyCosta recorded Rica in “hydrothermal Guaymas) seep” and (CRHS)organic and species falls more records (OF) generally, at from around cold the other seeps world. studies (CS), in vents (HV) the or Table 5. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | e (1991), Sasaki et al. (2010) ff -axis reference site. ff (2003), Levin andand Sibuet Bouchet (2012b), (1993) Levin et al. (2012a), Warén (2003), Levin andand Sibuet Bouchet (2012b), (1993) Levin et al. (2012a), Warén 8562 8561 CRHS CS HV OF References x x x Sahling et al. (2002), Sasaki et al. (2010), Smith and Baco ∗ Guaymas Vent x x Blake and Hilbig (1990) x x x x Smith and Baco (2003), Tunnicli Guaymas Seep x xxx x xx x x x Pettibonex (1993), x Smith (2003), Blake andx Hilbig (1990) x Blake x and Hilbig (1990) x x Blake and Hilbig (1990) x x x Stiller et al. (2013) Levin et al. Sahling (2012a) et al. (2002), Sasaki et al. (2010), Smith and Baco xx x x x Sahling et al. (2002), Sasaki et al. (2010) xx x x x x x x Levin et al. (2012a), Sasaki et al. (2010) Sasaki et al. (2010), Levin et al. (2012a), Smith and Baco (2003) . fauchaldi ff sp. x genus genus genus Sasaki et al. (2010) sp. x x sp. x x genus Levin et al. (2003) .(spinny) Localisation of the study sites on the Sonora margin cold seeps (Ayala, Vasconcelos sp. x x genus x Levin and Mendoza (2007), Dahlgren et al. (2004) sp Continued. sp. x x genus genus Levin et al.(2012a), Sasaki et al. (2010) Bathykurila guaymasensis Branchiplicatus cupreus Nereididae Nereis sandersi Maldanidae Nicomache venticola Cirratulidae Aphelochaeta Pilargidae Sigambra Ampharetidae Amphisamytha a Aplustridae Parvaplustrum Provannidae Provanna Provanna laevis Neomphaloidea Retiskenea diploura Pyramidellidae Eulimella lomana Neolepetopsidae Paralepetopsis Cataegidae Cataegis Lepetodrilidae Lepetodrilus guaymasensis Pyropeltidae Pyropelta corymba Pyropelta musaica and Juarez sites),Morelos the and Southern Mega Mat Trough sites) hydrothermal and vents the Guaymas (Rebecca’s Basin Roots, o Mat Mound, Figure 1. Table 6. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | spp. ) and rel- 4 Vesicomyi- Beggiatoa (e) A. gigas Paralvinella grasslei d = 0.5 (g) Vesicomyidae (S_VesA), spp. microbial mat (S_Mat) ), ammonium (NH 4 Siboglinidae (V_Sib). Beggiatoa Escarpia spicata and Lamellibrachia

max ] ANME_1 4 max (a) ] S_Mat S_Gast (d) S int CH 2 ] [

Archivesica gigas 4 H

Vesicomyidae (S_VesP), ANME_2 [ int S), sulphate (SO

] 2 CH S max [ ] Riftia pachyptila

2

4 (b) int H Axis 1 (85%) Vesicomyidae (V_VesA), ] V_Mat [ 8564 8563

4 NH (h) [ Tmax

NH [ DSS

P. soyoae DBB SRB2 ANME_3 Vesicomyidae (V_VesA) and Microbial mat (V_Mat). Tint S_VesA S_Sib_P A. gigas G_ref V_VesA S_VesP

Archivesica gigas int ] min 4 Vesicomyidae (S_VesP), ] ), hydrogen sulphide (H 4 (f) 0.01, Axis 1 accounts for 85 % of the variation and Axis 2 represents 4 SO [ = SO

[

p

Alvinellidae (V_Alv) and sp. Gastropoda (S_Gast), Axis 2 (15%) 2 Axis Co-inertia analysis of physico-chemical factors in soft-sediment assemblages: tem- Images of studied assemblages at seeps: Siboglinidae (S_Sib) and their periphery (S_Sib_P) and vents: Hyalogyrina P. bactericola Phreagena kilmeri dae (S_VesA), Microbial mat (S_Mat),ery Gastropoda (S_Sib_P) (S_Gast), and sediment VENTS: at Siboglinidae Periph- ative abundances of microbialDSS, groups DBB, potentially SRB2. involved in AOM: ANME1, ANME2, ANME3, 15 %. REFERENCE: (G_ref), SEEPS: Figure 3. perature, methane (CH Figure 2. and (c) barhami microbial mat (V_Mat), and Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ... Vesicomyidae 1200 V_Mat esP esA esA 800 G_ref S_V S_Sib_P S_Sib S_Mat S_Gast S_V V_Mat V_Sib V_V V_Alv S_Mat A. gigas 1000 Vesicomyidae (S_VesP), S_Gast 600 800 P. soyoae Vesicomyidae (V_VesA) and Microbial Vesicomyidae (V_VesA), Microbial mat 600 A. gigas 400 [CH4]max (µM) A. gigas Vesicomyidae (S_VesP), 8566 8565 V_Alv Number of individuals 400 V_Sib P. soyoae 200 200 esA esP esA V_V S_Sib S_Sib_P S_V 0

0 S_V

G_ref

40 30 20 10 0 5.0 4.5 4.0 3.5 3.0

Rarefaction curves on pooled macrofaunal abundances from each assemblage. log10(Density) Log-transformed macrofaunal densities according to maximum methane concen- ichness r Expected Vesicomyidae (S_VesA), Microbial mat (S_Mat), Gastropoda (S_Gast), sediment at (V_Mat), Alvinellidae (V_Alv) and Siboglinidae (V_Sib). Figure 5. REFERENCE: (G_ref), SEEPS: (S_VesA), Microbial mat (S_Mat), Gastropodaboglinidae (S_Gast), Periphery Siboglinidae (S_Sib_P) (S_Sib), and sediment VENTS: at Si- Figure 4. trations in assemblages. REFERENCE:A. (G_ref), gigas SEEPS: Siboglinidae Periphery (S_Sib_P) and VENTS: mat (V_Mat). Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | P. soyoae dae dae dae i a dae dae i dae dae oi dae i dae l i dae i i dae l i opsi dae i i dae l nul dae l dae dae dae et na dae dae dae dae dae dae i dae a i i dae i dae i dae i l dae i el dae del ner t i r i Vesicomyidae i i poda y i ei dae dae dae phal l spi dacea odr oni ul di el l ni nom dae i odoci er acea ur i i doni t epet i anni oni gi oi br noi l dae ebel l l nar asi v at ei i dani i aoni pul aegi phi phar hy r cer am acophor y i oni em l t r l r ar y chi ov r gal l y al l phi or api esi i ossur em eol er um at eom aut at m ct m pl ar ol er hy r pi y ol i y r i hol er hy anai D C B A A A A H O C Lum C N P Lacy Lepet P S N T P N C C M A T S S S T S P P P P N N M G V_Mat v l A A. gigas _ 800 V S_Mat A s e V _ V S_Gast Vesicomyidae (S_VesA), Micro- b i S _ V 600 t a M _ A. gigas V A s e V _ S 400 [CH4]max (µM) V_Alv t 8568 8567 s a G _ S V_Sib t a M Vesicomyidae (V_VesA), Microbial mat (V_Mat), Alvinelli- _ S 200 Vesicomyidae (S_VesA), Microbial mat (S_Mat), Gastropoda b i S _ esA S esP A. gigas Vesicomyidae (S_VesP), esA V_V P _ S_Sib b i S_V A. gigas S_Sib_P S G_ref S_V _ S 0 P

s

e 14 12 10 8 6 4 2 V _

S

P. soyoae ar r S f e r _ G Logarithmic regression between species richness (ES(41), Srar) and maximum Histograms of relative macrofaunal compositions at the family level in assemblages 0 0 0 0 0 0 0 0 0 0 0 0 9 8 7 6 5 4 3 2 1 1 Figure 7. shown for each study(G_ref), site, SEEPS: only taxa contributing to more than 1 % are shown. REFERENCE: bial mat (S_Mat), Gastropoda (S_Gast), Siboglinidaeery (S_Sib), (S_Sib_P) sediment and at VENTS: Siboglinidae Periph- dae (V_Alv) and Siboglinidae (V_Sib). (V_VesA) and Microbial mat (V_Mat). Vesicomyidae (S_VesP), Figure 6. methane concentration indata all points macrofaunal and red assemblages. squares Black represent fitted squares values. REFERENCE: represent(S_Gast), (G_ref), observed SEEPS: sediment at Siboglinidae Periphery (S_Sib_P) and VENTS: Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Vesi- V_Sib Dorvilleidae V_Mat Vesicomyi- S_Gast V_Alv Ampharetidae S_Mat The first axis A. gigas ulidae (a) V_VesA yspin ilidae olynoidae P

Bath 1 0 S_VesA P. soyoae Lepetodr pulidae Hesionidae Axis 1 (27%) idae Vesicomyidae (S_VesA), idae Ser yidae max idae ] asir 4 y S_Sib anaidacea Cossur Neolepetopsidae S_VesP iner Nereididae Th T CH [ esicom

V Spionidae 1.0 Lumbr aonidae ar S_Sib_P P A. gigas villeidae V_Alv V_Sib Dor V_Mat atulidae 0.5 S_Gast G_Ref Cirr Hard_sub Ampharetidae olynoidae ilidae S_Mat P

pulidae

0.0 Axis 3 (10%) 3 Axis a A1 (27%) r S_Sib villeidae Ser Lepetodr idae V_VesA RD Dor Soft_sub Vesicomyidae (V_VesA), Microbial mat (V_Mat), S_VesA Hesionidae 8569 8570 Neolepetopsidae aonidae Ophiur ar Aplacopho ulidae Lumbrineridae P −0.5 V_Sib Dorvilleidae yspin S_Sib_P V_Mat G_ref S_VesP atulidae Bath S_Gast V_Alv Cirr A. gigas S_Mat Vesicomyidae (S_VesP), −1.0 Ampharetidae ulidae V_VesA annidae yspin v −1.5 value associated with the RDA1 axis is 0.01 and with the RDA2 axis,

S_VesA idae

Pro Bath

1.5 1.0 0.5 0.0 −0.5 −1.0 p P. soyoae Axis 1 (27%) Vesicomyidae (S_VesA), Microbial mat (S_Mat), Gastropoda (S_Gast),

Ophiur

A2 (13%) A2 D R Spionidae Neolepetopsidae S_Sib S_VesP aonidae ar P S_Sib_P A. gigas of 0.25). The Canonical redundancy analysis (RDA, scaling type 1) of Hellinger-transformed atulidae 2 Between-group principal component analysis (PCA) on Hellinger-transformed macro- G_Ref Cirr R 0.20) are shown on the plot. REFERENCE: (G_ref), SEEPS: >

The first axis accounts for 27 % of the variance in the macrofaunal data and Axis 3 ac- Axis 2 (14%) 2 Axis Alvinellidae (V_Alv) and Siboglinidae (V_Sib). Microbial mat (S_Mat), GastropodaPeriphery (S_Gast), (S_Sib_P) Siboglinidae and (S_Sib), VENTS: sediment at Siboglinidae Figure 9. macrofaunal densities on alltitative assemblages environmental as conditions. a Onlyconcentration function significant and of substratum explanatory type). qualitative variablesance The and are in first normalised shown macrofaunal canonical quan- abundance (methane axis whilemulated represents the 27 % second of axis the represents total 13 % vari- (with an adjusted cu- 0.08. Only the namesvalue of the taxa that showed good fit with the first two canonical axes (fitted counts for 10 %.ENCE: Only (G_ref), taxa SEEPS: contributing to more than 2 % to either axis are shown. REFER- accounts for 27 %(b) of the variance in the macrofaunal data and Axis 2 accounts for 14 %. dae (S_VesP), Siboglinidae (S_Sib), sediment at Siboglinidae Peripherycomyidae (S_Sib_P) (V_VesA), and Microbial VENTS: mat (V_Mat), Alvinellidae (V_Alv) and Siboglinidae (V_Sib). faunal densities on the 26 sampling units studied in the Guaymas Basin. Figure 8. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

A. gigas

1 0 −1 ] 4 S] 1.5 2 [CH [H ANME 1.0 S_Gast Ampharetidae 0.5 V_Mat S_Mat Dorvilleidae value associated with the RDA1 axis is 0.03 A1 (31%) 0.0 p V_VesA RD Vesicomyidae (S_VesA), Microbial mat (S_Mat), S_VesA 8571 Pyramidellidae Sigalionidae Spionidae/Pilargidae Ophiuridae Thyasiridae/Nereididae Paraonidae Aplacophora Provannidae Neolepetopsidae G_ref −0.5 S_Sib_P Bathyspinulidae Cirratulidae S_VesP A. gigas −1.0 0.20) are shown on the plot. REFERENCE: (G_ref), SEEPS: of 0.31). The Biomass > 2 R

−1.5

1.0 0.5 0.0 −0.5 −1.0 −1.5

A2 (20%) A2 D R Canonical redundancy analysis (RDA, scaling type 1) of Hellinger-transformed Vesicomyidae (S_VesP), Gastropoda (S_Gast), sediment at Siboglinidae Periphery (S_Sib_P) and VENTS: P. soyoae and with the RDA2two axis, canonical axes 0.06. (fitted Only value the names of the taxa that showedVesicomyidae good (V_VesA), Microbial fit mat with (V_Mat). the first macrofaunal densities in soft-sedimentenvironmental assemblages conditions. as Only a significantprior function explanatory of co-inertia variables normalized analysis are quantitative 31 and % shown engineer of (First species the axis biomass).(with total of an The the variance adjusted first in cumulated canonical macrofaunal axis abundance represents and the second axis represents 20 % Figure 10.