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Climate Sciences Sciences Dynamics Chemistry of the Past Solid Earth Techniques Geoscientific Methods and and Physics and Atmospheric Atmospheric Atmospheric Data Systems Geoscientific Earth System Earth System Measurement ect of the substrate type Instrumentation Hydrology and ff Ocean Science Annales ective populations would Biogeosciences The Cryosphere Natural Hazards Natural Hazards ff and Earth System and Earth Model Development 1 Geophysicae between a more limited dispersal capability 3708 Open Access Open Access Open Access Open Access Open Access Open Access Open Access Open Access Open Access Open Access Open Access Open 3707 Access Open Access ff

, and M. R. Cunha 1 Climate Sciences Sciences Dynamics Chemistry of the Past Solid Earth Techniques Geoscientific Methods and and Physics and Advances in Atmospheric Atmospheric Atmospheric Data Systems Geoscientific Geosciences Earth System Earth System Measurement Instrumentation Hydrology and Ocean Science , F. L. Matos Biogeosciences ´ The Cryosphere Natural Hazards Natural Hazards enio ([email protected]) 2 EGU Journal Logos (RGB) EGU Journal Logos and Earth System and Earth ´ en Model Development , A. War 1,* ´ enio This discussion paper is/has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG if available. Departmento de Biologia & CESAM,Department Universidade of de Invertebrate Aveiro, Aveiro, Zoology, Portugal Swedish Museum of Natural History, Stockholm, now at: IMAR/DOP-Universidade dos Horta, Ac¸ores, Portugal Ac¸ores, Our results suggest that distributionmined of by gastropod the assemblages occurrence may of be suitable primarilyon habitats deter- probably feeding due strategies to e andtion that of larval the development deep is sea.lecithotrophy, not However, suggests the a that predominance limiting of the non-planktotrophy, factorand and trade-o the for especially higher coloniza- potential forinhabiting self-recruitment may reducing be environments favoured by andnetwork the other gastropod of patchily species suitable distributed habitatsexplain deep-sea the that habitats. predominance ensures A and connectivity relatively wide of distribution e of short-distance dispersing similarities were found with Mediterreanean cold-seepsother (species- chemosynthetic and genus-level) environments and inColonization the experiments Atlantic with organic and substrataabundances Pacific (wood of Oceans and gastropod (genus-level). species. alfalfa grass) Thesecal yielded organic species inputs high but allowed also the of recruitment wood of lo- specialist taxa that were not known to occur in the GoC. tropod assemblages from deep-seatributional habitats in patterns the in GoC relationDistinct and to analyse gastropod their the assemblages dispersal species weresites, dis- capabilities and found and organic-falls. at Overall, substrate the mud availability. include GoC volcanoes, 65 comprises taxa carbonate a representing 32 high and families, diversitynumber 48 coral of genera of and gastropods taxa 30 that was named species. founddle The at highest slope the (500–1500 highly m heterogeneous depth),Captain carbonate Arutyunov and province mud in higher volcano, the abundance one mid- of of the individuals most was active sites observed found in in the GoC. Faunal Bridging the Atlantic and Mediterraneanhas continental recently margins, been the South theCadiz Iberian focus (GoC) region for encompasses geological adiverse and biological great communities. biological In variety investigations. this of The study, we deep-sea Gulf describe habitats the of taxa that composition harbour of gas- highly Abstract Biogeosciences Discuss., 10, 3707–3733, 2013 www.biogeosciences-discuss.net/10/3707/2013/ doi:10.5194/bgd-10-3707-2013 © Author(s) 2013. CC Attribution 3.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. 1 2 Sweden * Received: 11 December 2012 – Accepted: 11Correspondence February to: 2013 L. – G Published: 27 February 2013 The snails’ tale at deep-seaGulf habitats of in Cadiz the (NE Atlantic) L. G 5 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ´ en, 1994; 3710 3709 erent substrate types. We compiled information on lar- ff nity with di ffi ´ en, 1982). Life-history traits (e.g. egg size, type of larval development, Samples collected in the Gulf of Cadiz during the past decade, encompassing var- Despite the recognized importance of gastropods in deep-sea communities, both in cent habitats such asate fossil concretions cold-water at coral depths stands, between carbonate 250 chimneys and and 4000 carbon- m along the Moroccan, Spanish and their potential a val development of each specieshypothesis and is inferred that their species dispersal distributionscapability capabilities. and are Our habitat the working selection outcome and/or of substrate the availability. interaction of dispersal 2 Material and methods The present work reports on samples collected from mud volcanoes (MVs) and adja- species is vital to understand speciesand distributions fragmented and deep-sea the habitats. connectivity of highly patchy ious habitats over aments, large provided depth an range, opportunity complemented to by investigate in-situ distribution colonization patterns experi- of gastropods and Rex and War larval feeding behaviour) can bepreserved inferred in from the the adult larval (Sasaki shell(planktotrophic et that al., larvae) remains 2010). are usually Species well with assumedcal a to ranges. feeding pelagic extend By larval their contrast, stage energy distributions non-planktotrophic source to (e.g. species, lecithotrophic wider which species, brooders, geographi- developlittle intracapsular using potential development), a of have long-distance maternal tions dispersal, (Sasaki and et therefore, al., have 2010). more Information restricted on distribu- life history traits and dispersal of deep-sea al., 2010). Gastropod species areas also sunken known wood from and organicallygastropod bones enriched fauna (Sasaki habitats associated et such with al., cold-waterhabitats 2010), corals (Young, 2009). but and Gastropods there other have hard isreproduction been substrate little often and deep-sea information the dispersal on focus in of the the studies deep-sea investigating environment (Bouchet and War seep gastropods are often part of a vast and more diverse surrounding fauna (Sasaki et are often highly abundantgastropod in vent reducing fauna is ecosystems fairly (Sasaki well known, et the al., cold 2010) seep taxa but are while less the studied, because array of deep-sea habitats;tions these and habitats cold-water include corals that mudrelevant sustain volcanoes, role rich in carbonate biological this concre- communities. vast seepage Gastropodsabundance region; play in they a the account for best-sampled up mud toin volcanoes 5 and the % rank most of among total active macrofaunal the ones dominant (Cunha species et al., 2012). terms of diversity and biomassDecker (Bernardino et et al., al., 2011), 2012; Levin, very 2005; little Ritt is et al., known 2012; on their distributional patterns. Gastropods heterogeneity hypothesis, structurally complex habitatsdiversity lead by providing to a an higher increase numberexploiting of in resources distinct (see species niche Cordes dimensions et and al.,gion diverse 2010a). (NE ways This Atlantic) of is where the the casesetting interaction of of the and the Gulf hydrographical of structurally Cadiz circulation complex re- convergent favour tectonic the occurrence of a particularly diverse Understanding biodiversity, and howchemical and the geological faunal aspects ofof assemblages the highly interact deep-sea, is productive with farseeps communities physico- from and at complete. large The organic chemosynthetic food discovery reefs, falls), sites and where (hydrothermal the unsuspected species vents, frequency richnesscompletely cold of changed cold-water and coral our diversity perception rivalsgeomorphologic, of hydrographic, that the geochemical deep-sea of and environment. biotic their Thegenerate features habitat tropical of combination heterogeneity continental of counterparts, at margins spatial scalesand ranging from tens centimetres to to hundreds kilometres, of kilometres (Levin and Sibuet, 2012). According to the habitat gions. 1 Introduction non-planktotrophic species at the GoC deep-sea habitats and other geographical re- 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | )– O Coccopygia erent purposes ff 3712 3711 ) – mostly mud breccia from the craters and the S ` es (1 set) and Darwin (1 set) MVs using a ROV. After recov- ) – carbonate slabs, crusts, and chimneys, rocks (limestones H , which may include more than one species. Species identifications ) – a mixture of mud breccia, small carbonate concretions and/or biogenic erent substrates were sub-sampled and processed for di M ff Copulabyssia Additional samples were obtained from in situ colonization experiments (CHEMECOLI tion and will be published elsewhere. in the future followingcase more of thorough the taxonomic specimens revisionsand ascribed of to the material. thewere This family based Marginellidae, is on and the morphological genera cal observations and of scanning shells, radula electronwere and microscopy treated opercula and according using criticalcases, opti- to species point the identification dried also methods soft requiresin described DNA parts. progress. sequence Taxonomical in Specimens analyses, considerations which Geiger and is descriptions et currently of al. new taxa (2007). are In in prepara- many 2.2 Taxonomic identifications and data analyses Gastropod specimens were identified towere species not level yet whenever matched possible. with Several a taxa and species ascribed name but a they codename were consistent allspecies throughout sorted the richness into samples. putative can species Therefore be the estimated considered accurate, although minor changes may be made in Mercator (2 sets), Mekn ery, the di according a standardised protocolwere (Gaudron kept et for al., biodiversity 2010).(one Two studies third). thirds The and of whole fixed sub-sample eachArtificial in (not sample substrates sieved) included 95 was eight % samples sorted ethanol ofgrass) under Organic and (one a substrata four (wood stereomicroscope. third) samples and dried of and alfalfa Hard formalin substrate (carbonates). – CHEMosynthetic Ecosystem COlonization2010) by using Larval three Invertebrates, types (Gaudronartificial et of substrates al., substrate were – includedsation inside wood, of Nylon dried the net alfalfa substrates of grass byspecies. 2 and Four mm metazoan sets larvae mesh carbonate. of or allowing The experiments juveniles the were but coloni- deployed not and recovered by after the approx. adults 1 of or most 2 yr at the flank of Carlos Ribeiro MV). flanks of MVs; (ii) Hardand ( other lithologies) and(iii) coral Mixed ( framework usually collecteddebris from (coral the rubble, shell vicinitywood. ash) of From collected MVs; the in total theand of craters were 58 of ascribed samples, MVs; to 40 and17 one were (iv) samples of collected Organic of the from ( Hard three MVs substratesample bathymetric (Soft: corresponds were sub-regions 34; to obtained (EA, a Mixed: from CP, naturally DF). 6) cold-water occurring Another coral wood sites fall (encountered and during only a one ROV dive and non-quantitative sampling gears andet processed al., on 2011). board The accordinglyethanol material (Rodrigues for retained further by examination.21 a locations Overall, 500 µm (Fig. gastropods 1). mesh were The sieveare metadata found was provided of in fixed the in sampling in 58 Table sites 1categories 70 samples (including in or of the from the sampling 96 substrate: % Supplement. gear) (i) Each sample Soft was ( ascribed to one of four coral stands; the deep-water fieldseveral of (DF), mostly the within most theronmental active Portuguese settings mud are margin volcanoes provided includes in in the Cunha region. et al. Further (2012). 2.1 details on GoC Sampling envi- Macrofaunal samples wereduring collected 14 from cruises numerous carried locations out in between 2000 the and Gulf 2009 of using Cadiz a variety of quantitative characterised by distinct geological, geochemical anddetail biogenic by features as Rodrigues described et in al.volcanoes (2011): in the the El shallow Arraiche Moroccanto field margin; an (EA) the extensive encompasses carbonate bathymetric several province mud gins, strip (CP) characterized (700–1200 m) corresponds by along the the widespread Moroccan of an authigenic Spanish carbonates mar- and fossil cold-water Portuguese margins of the Gulf of Cadiz (GoC). Herein, we consider three sub-regions 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | erent major ff sp.), a group that was Fedikovella ) of gastropods in quantitative samples 2 − 3714 3713 ) and their relative contribution to the total macrofau- 2 The most striking feature of the observed bathymetric distribution of gastropods is the Finally, distributional patterns were compared for each of three dispersal strategies: The bathymetric range of each species in the region was assessed and the total sediments was much higher (22) than the one observed exclusively in Organic (3) or by a much higherrespectively in number “Mixed” and of “Hard”), taxastrate and clearly type. in dominated Mixed Soft the sediments assemblage sedimentstaxonomic showed of the groups this (19 (Fig. sub- most in 4a) even and distributionNeomphalina opposition occurred. were of to The the the only 8 only di sample substratefall and representing where collected organic 10, Patellogastropoda at substrate and (a the small flankstwo wood of were Carlos Cocculiniformia Ribeiro (Cocculinidae MV) n.never yielded gen. found only in and three the species other from substrata. which The number of species occurring exclusively in Soft 3.1 Species distributions The taxonomic composition ofcording gastropod to assemblages shows the abranchia substrate taxa distinct type showed variation little (Fig. ac- variationSoft 4a). (7–9 and and The Mixed 2–5 substrata. number species, On respectively) of the among other Vetigastropoda Hard, hand, and the Caenogastropoda Hetero- were represented contrasting with the scarce numberlation, of species loss at and greater depthswhere turnover (Fig. few curves 2). locations The (Fig. were accumu- sampled,replacement: 3) and the reflect highlight Mercator the the MVwhere three scarcity major more (EA) of locations species (18 data of are speciestyunov species lost at MV added than great where gained and depths (13 ten 8first and species occurrence lost), 10, from was respectively), the recorded the and for Darwin shallower six Captain areas MV taxa. Aru- have their deepest limit, and the Patellogastropoda and Neomphalina represented byproportion only one (35 %) species each. of Awas taxa high recorded were in just singletons, one and or more two samples. than halfhigh number (63 %) of species of with overlapping the distributions at species the middle slope (500–1500 m) to the family Cocculinidae, including one new genus that waits formal description and by the Vetigastropoda (24in species 3 in families). 11 Less families) diverse and were the the Heterobranchia Cocculiniformia (9 with species three species all belonging lecithotrophic), brooders and intra-capsularcompiled development. In in some the cases,category literature information of allowed “lecithotrophs” to (Table 2 ascribe in the species Supplement). to the non-planktotrophic3 sub- Results A total of 2362 gastropodCaenogastropoda specimens is were the examined and most ascribed diverse to subclass 65 taxa (27 (Fig. species 2). in 15 families), followed from protoconch morphology using1983) the and “Thorson’s comparisons apexconsider to theory” that closely (Jablonski planktotrophic and related larvae Lutz, planktothrophs have taxa an develop with obligate using feeding known pelagicgies a development stage, include mode. maternal while life cycles non- We energy with a source. non-feeding Non-planktotrophic pelagic phase strate- (herein designated loosely as into one of fivecurrences, categories (ii) of distribution: Rare (i)(iii) species Singletons Moderate - – – more corresponding two thanstrate to three or types, and single three (iv) less oc- than Abundant individuals 10 –types, individuals taxa found and found with (v) in at more Ubiquitous one than one or – 10 more taxa substrate individuals sub- found found type, at in all two threeplanktotrophic, substrate substrata. non-planktotrophic and lecithotrophic.obtained Type of from larval available development data was in the literature (Table 2 in the Supplement), or inferred dataset of taxa wasing used the to species draw replacement accumulation, with2003; Hurlbert, increasing loss 1971). depth and Data (Colwell turnover on et(USNEL density curves al., (ind. boxcores; m represent- 2004; area: Ugland 0.25 m etnal al., abundance was obtained from Cunha et al. (2012). Each taxa was then classified 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | spA Copu- (5), and , found in Coccopy- Pseudose- spA (Merca- Leptogyra (10 samples) and spp. with a couple and the xylodisculid spD (Mercator MV), spp. and 3 ` es and Darwin with over Alvania zylensis Xylodiscula Alvania cimicoides ` es and Darwin. Overall, the P. echinata Coccopygia spB (6) were the most common Pseudosetia Copulabyssia erent bathymetric sub-regions. Veti- ff spA, one individual) and Darwin (seven Obtusella intersecta Anatoma (5 samples), (6 individuals) and 3716 3715 (6) and Xylodiscula ` es ( P. porcupinae Alvania cimicoides Putzeysia wiseri (11 samples). The major contributors to the species richness in each spA (Darwin MV). Interestingly the rissoid spA were the fourth, fifth and sixth most dominant species in the macrofau- ` es and Darwin MVs), Margenellidae and spp. was the most abundant taxa especially in Mekn Leptogyra spp.) were also collected in Mercator. Preliminary DNA results suggest that two spD, 26 specimens), Mekn Three Caenogastropod species showed a wide bathymetric range and were found Mixed and Soft sediments represented respectively by 6 and 34 samples were col- A total of 21 taxa were found in Hard substrate samples from carbonate and coral and carbonate and coral sites at Pen Duick Escarpment (in the vicinity of EA MVs), was 1200 individuals collected, followedof by hundred the individuals. cocculinid Muchgia lower numbers (21 cryptic species may be presenttypical in mud these volcano sites. These settingseral species in had species the never (12) GoC. been found Colonization occurringorganic in experiments substrata. in showed These the that include mudtor, abundant sev- Mekn volcanoes species can such as also explore opportunistically Colonization of the carbonatepod substrata species was (9) generally were scarce, collectedtia from and the only experiments a deployed in fewtaxa, Mercator gastro- 15 ( individuals). Thetotal eight of samples 17 of taxa experimental (Fig.labyssia organic 4c). substrates Pseudococculinids yielded were a by large the dominant taxa – nal assemblage associated with2.9 gas % hydrates of in the total Captain macrofaunal Arutyunov abundance, MV respectively; (5.7, Cunha3.2 et 4.9 al., and 2012). Colonization of artificial substrata CHEMECOLI experiments werewood densely substrate colonised and bycolonization the gastropods, experiments alfalfa showed in grass high particular diversity deployed at in the the major Mekn taxonomic level (Fig. 4c). are not available for estimateswas of the abundance. However most the abundant neomphalin from gastropod this collected MV using –gastropod a this (Vetigastropoda suction gastropod spA), sampler occured theXylodiscula rissoid exclusively in in mytilid this beds MV. An undetermined veti- MV is covered with large authigenic carbonate slabs and therefore quantitative samples counting up to 4.9 % of the total abundance (Cunha et al., 2012). The crater of Darwin richness, Fig. 4b). The carbonatetherefore province shows includes the most only even Mixed taxonomic sediment(Fig.4a–b). composition samples of and all three mud volcano regions across the three sub-regions, A. acutecostata region were the assemblagesCaptain Arutyunov from MVs (DF, Mercator 1300 m) (EA, withlidae 8, were 350 17 m), always and abundant Darwin 11 in species, (CP, the respectively. 1100 Marginel- faunal m) assemblages and from the crater of Mercator ac- gastropod assemblages were thelected best (Fig. characterized, 4b). From withand these, a only 14 total eight species of species weregastropoda 42 were present were species shared in poorly EA, col- between representedthat 20 di in were in the clearly dominated shallower CP by mud Caenogastropoda and (10 volcanoes 19 species; (EA: 70 in % 1 DF of species) the total species Moroccan and Spanish margins (Table 1viduals in were the collected Supplement). from Very these low habitats,The numbers and Caenogastropoda of the indi- majority of speciesthe were singletons. Vetigastropoda species, but the two Caenogastropoda were restricted to shallower depths. lected from mud volcanoment). sites In (except fact, for the one mud volcanoes Mixed were sample the from main sampling Pen target Duick of escarp- this study and their more than one type of substrate (7 and 15habitats respectively). usually locatedseeps in (Fig. the 4a). vicinity Most samplesthe of were El MVs, collected Arraiche in with and the little several Pen other Duick or samples Escarpment no are located influence in scattered along of the the upper cold slope of the Hard (12) substrata. The remaining 22 taxa were found either in Mixed substrate or in 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | is ) were 2 − A. acutecostata , on the other hand, occurs in have non-planktotrophic larvae. ˚ akon Mosby MV and Nyegga “pingoes” (Nor- 3718 3717 P. porcupinae Obtusella intersecta and P. echinata ` es MV. ` es and Darwin MVs. Our results do not show a relationship between a large distributional range and a regions). Gastropods are often found2005 and among references the therein), but dominantreported the taxa from highest in frenulate abundances (over habitats several 30wegian in 000 cold Margin, ind. the m Decker seeps H et (Levin, al.,of 2012). the Decker high et densities al. of (2011)by gastropods suggested the is that presence explained the by presence ofphysical geochemical tubeworms. structure conditions However, provided rather Governor by than and thetendant tubeworms Fisher epifauna may (2006) be in found particularly areas that important of the for high the at- and intermediate fluid flow (more than in low-flow in the vicinity offrom mud Mercator, volcanoes), Darwin they were andmost among Capt. active the respectively Arutyunov dominant in MVs; speciesActive the gas these in bubbling EA, was samples MVs observed CP both areand and in thought Mercator gas DF and to hydrates sub-regions Darwin occur (Vanreusel be considered et in al., the in 2009) the this near study. surface at Capt. Arutyunov (Cunha et al., 2012). 4.1 Abundance and distribution This study provides thenoes and first adjacent report deep-sea on500 habitats µm the in sieve we gastropod the may Gulf assemblagesmost have of deep-sea from gastropods underestimated Cadiz. have mud the minute By sizes species volca- (Geiger usingabundances richness et have in al., been and 2007). many recovered Considerably abundances from cases higher as cold2012; a seep Decker sites et using al., 250 µm 2011).the sieves Nevertheless, GoC (Ritt and, gastropods et although showed al., practically diverse absent assemblages in in reference samples (hemipelagic sediments planktotrophic. 4 Discussion planktotrophic. Also most of the species occurring in various substrate types are non- and DF is planktotrophic; only one has lecithotrophic development and three are non- feeding pelagic larvae, their dispersalto the ability other is development assumed modes; to theseSingleton species be and showed Moderate intermediate in distributions in fact (40 a relation % more and even 36 balance %, of respectively). planktotrophic development. The(all three mud species volcano exhibiting sub-regions)planktotrophic, wider have while bathymetric distinct ranges larvalNone development of – the four species with distribution ranging the two deeper sub-regions, CP usually in more than one substrateclassified and as in relatively Singleton high numbers) andhave with Rare only pelagic-feeding about (Fig. 30 larval 5). % tances. phases Planktotrophic However, 82 species, that % on of are the therestricted likely gastropod other distributions species to hand, and with occurred this result typeand mostly in Rare of in taxa development one greater (55 showed % type and transport of 27 %, dis- substrate respectively). only Because lecithotrophic as species Singleton have non- From the 65 gastropod speciessettings, 25 found are in lecithotrophs, the another 17 GoC speciesand deep-sea were only considered habitats as 11 and non-planktotrophic experimental speciesremaining have larval 12 shells species typicalferred type of from of planktotrophic the development. larval Forplanktotrophic available development species the specimens presumably is have the (Fig. unknown lowestto dispersal 2 have and capability, distributional but and patterns yet could categorised showed Table mostly not 2 as Ubiquitous be in or Abundant in- (occurring the Supplement). Non- deeper Mekn the crater of Capt.shallower Arutyunov Mekn MV and was able to3.3 colonise dried alfalfa Larval grass development in the also able to colonize wood and dried alfalfa grass not only in Mercator but also at the 5 5 20 25 15 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , M , spp., H ects of ects of ff ff ˚ akon Mosby appears to be Eulimella spp., P. wiseri Odostomia 3720 3719 ` es MV and an undetermined species at Capt. Aru- at Mekn is a presumed grazer that explores opportunistically the increased cient in the collection of all range of individual sizes, from recruitment ffi erential adaptation to hydrostatic pressure; (iii) topography; (iv) e ff P. wiseri Neptunea contraria ) but this analysis is cofounded by the very high percentage of singletons. If we O There is a high similarity at genus and even at species level between the gastropod Gastropod densities are much more modest in the GoC than in the H , The artificial substrata deployedto for be colonization very experiments e (CHEMECOLI) proved species distributions is observed ating the with depth the range between increased 500of habitat and carbonate heterogeneity 1500 concretions, m promoted carbonate coincid- by chimneysrubble. the and The scleractinean widespread perception coral occurrence of frameworkis and structurally dependent complex on habitats with thediverse distinct size, ways niche mobility of exploiting dimensions and resources dispersal (Cordes capability et of al., 2010a). the4.3 organisms enabling Dispersal and connectivity are commensals orSasaki parasitic et al., on 2010) polychaetes orbuccinid on (e.g. carnivores echinoderms are (e.g. often Eulimidae,(e.g. Sasaki seen et actively al., foraging 2010)tyunov at and MV; the M. large R. craters Cunha, personal of observation, mud 2006). Moreover, volcanoes the highest overlap of conspicuous faunal change haveation; been (ii) explained di by:sedimentary (i) temperature pattern mean and and substratedeep vari- boundary type currents on on feedingof larval strategies; substrate dispersal types and (Rex, (point (v) iv) 1981).in the seems the For gastropod to e our assemblages be dataset, occur ofincreased the at particular the availability pattern relevance. most of High active rates food MVstrophic of and sources diversity change may can for be also grazers related be to sustained (microrganisms, the by detritus). these A productive ecosystems: higher some species The patterns of speciesmented for replacement several with taxa; depth intransition general in in the the species shelf-slope North composition. breakobserved shows Atlantic A at the more are most bathyal continuous well pronounced depths, but docu- and high lessens rate at of abyssal replacement depths is (Rex, 1981). Regions of 4.2 Species replacement with depth the MV sediments and hard substrata were also able to recruit on organic substrata. the possible, and in someseep cases species confirmed, with overlap other in deep-seaor the environments disturbed distribution characterized sediments by of sulfidic, (Bernardino heterotrophic low-oxygen, gastropod et al., species 2010; in Levin theS et GoC al., 2009). occurred Apparently exclusivelyremove many single in occurrences one the typetype number is of of similar substrate species to found ( thethe exclusively number colonization in of experiments one species showed occurring substrate that in many two gastropods or (12 more species) substrata. occurring Moreover, in carbonates or mixed substrata. Likeand the vents, majority of gastropodbacterial biomass. species About found half in of seeps known the from genera other recorded reducing in habitats the (vent,al., GoC seep 2010; (26 and out Decker organic-falls) et of (reviews 48) by al., Sasaki are 2011; et also Ritt et al., 2012). In fact, there is some consensus about Other studies with species levelness: resolution five mention even species lower in gastropod the(1000–2000 species m, Marmara rich- Olu Sea et (Ritt al., etthe 1997) al., Gulf and 2012), of eight five Mexico species species (1000–2750 in m, in tubeworm Cordes the and et mussel Barbados al., habitats 2010b). in fauna in the seeps(Ritt of et the al., E 2012)particularly Mediterranean and common (Olu-Le GoC across Roy (this these et study). three al., The geographical 2004), trochid regions, Marmara species often Sea associated with MV but, on the otherseeps. hand, In species the richness GoCmixed is sediments among a in the total highest the poolwhich reported MVs’ of is from craters; cold 17 more 43 species than speciesregions were in the were the recorded total E collected in Mediterranean of (ca. Darwin from 1700–2000 11 m MV mud water species alone, depth; breccia Olu-Le reported Roy and et for al., the 2004). Anaximander and Olimpi 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , O. and erences ected by ff ect popu- ff ff ective popu- Xyloskenea ff , erentiation of popu- ff A. cimicoides Copulabyssia erence in distribution between ff is known to have planktotrophic spA), but also favoured the re- B. macra Xylodiscula 3722 3721 erent larval development modes that a ff ) that were not found in the natural GoC deep-sea ˚ akon Mosby mud volcano (1257 m) and the cold seeps spD and Lissospira Pseudosetia and cf. ), and also wood specialist taxa (Cocculinidae, erent temporal and spatial scales (Bell, 2008). ff Colonization of patchy habitats, such as wood and bones, by non-planktotrophic Among the gastropod taxa found in the GoC, three species are also found in the Planktotrophic larvae, transported over large distances by ocean currents, are as- ing habitats, often separated by hundreds or thousands of kilometres. Other authors understand the consequences of di lation connectivity, divergence time amonglation populations sizes and must changes also in be e consideredand (Hart connectivity and Marko, between 2010). populations Larvallocal dispersal hydrodynamics of potential that marine can create invertebratesat significant are di variability highly in gene a flow and recruitment larvae, with limitedcrawling dispersal adults ability, does is not seem yet to rather explain colonization intriguing. of Relying organic-falls and on other dispersal reduc- by ters may hinder the successfulor establishment of at species the (at time the oftemperature time of reproduction) and metamorphosis due high to salinity. itsMediterranean This deep-sea hydrographical fauna characteristics, led represents including Bouchet reproductive high are sterile and constantly pseudopopulations Taviani dependent that (1992) on to pelagic larval postulate inflow that from Atlantic source populations. To in the deep-sea, and alsoproduction challenged and the development modes assumption (Reynolds of et phylogenetic al., conservative 2010). re- Eastern Mediterranean cold seeps, butdevelopment. The only present knowledge of oceanographic circulationtonic indicates larvae that plank- can besurface transported currents, into while Mediterranean the Outflowopposite Mediterranean direction water from at would the 50–300 only m Atlantic allow depth (Quentel by transport et inflowing in al., the 2011). Mediterranean bottom wa- velopment is not a limitingshow factor a for preponderance the of dispersal non-planktotrophictotrophic of and development deep-sea especially in gastropods, lecithotrophic the our over gastropodtats. results plank- species A inhabiting remarkable the discovery studied(the of Waren’s deep-sea a larvae) called habi- new attention development to how strategy much of is yet Provannid unknown gastropods regarding life histories directly out of the egg-capsule (Sasaki et al., 2010). Although the type of larval de- species with a planktotrophic larvae, a non-feeding dispersal phase or those that crawl the parental habitat (MacArthur and Wilson, 1967). sumed to allow wider geographical distributionslations. and But low a genetic long di pelagicule duration concentrations (planktotrophic) may and lead therefore toplanktotrophic extremely development low low is levels propag- often of associatedels with recruitment. of narrow On distributions endemism the and (Castelinrealistic high other for et lev- hand, species al., non- colonizing 2011).are deep-sea found These in chemosynthetic assumptions the habitats. literature have that Several proven showed examples to no noticeable be di un- ments. In contrast, short distance dispersal,a resulting favoured into strategy high at self-recruitment, ephemeral, may sparselyby be distributed the reducing habitats, predominance as and suggested many propagules ubiquitous show distributions a negative ofan exponential elevated non-planktotrophic colonisation survival rate species. with would distance As be from anticipated the with parent, proximity to the larval pool, i.e. These organic inputstheir not vicinity only (e.g. allowedcruitment proliferation of species of only species knownintersecta from already relatively distant occurring MVsBathyxylophila in (e.g. habitats. Larval development issubstrates, and known only for two 17 speciesveloping are of through planktotrophic. an the Remarkably, obligate most 20 feeding of pelagic species the phase taxa collected were rare de- in in the organic mud volcano sedi- CHEMECOLI deployments in the GoCthan retrieved similar a experiments higher in number the of H at gastropod species Nile Deep Seain Fan (1693 sample m) (Gaudron processing, etspecies artificial al., compared 2010). organic-falls to Regardless yielded the of numbers the high di obtained abundances in of background gastropod mud volcano sediments. to reproductive maturity, including a high number of recently settled juvenile stages. 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ), which is fi- ect on gastropod ff http://www.synthesys.info/ ´ ario (CESAM) for the supportive discus- 3724 3723 We are grateful to Clara F. Rodrigues (CESAM) for her invaluable help 2005-511234, funded by the European Comission’s Sixth Framework Pro- . cult to envisage; this would provide suitable habitats allowing survival and ffi ective populations may be common; these can serve as larval sources for coloniza- tary environments and ecosystems ofPreliminary the results Black and of TyrrhenianJune–August, investigations Seas 2005, and during IOC the Technical the Gulf Series, of 72, TTR-15 Cadiz. 2007. cruise ofsitional RV systems Professor and cold Logachev, seeps of the Western Mediterranean, Gulf of Cadiz and Norwegian ff supplement.pdf with sample sorting andsions preservation, during the and course to of Anatains this work. and Hil The crew authors of wish(SE-TAF-1543) the to received acknowledge oceanographic the support cruises chief-scientists, cap- that from collected SYNTHESYS samples ( for this work. This project to better understand current speciesacross distributions ocean and basins. potential population connectivity Supplementary material related to thishttp://www.biogeosciences-discuss.net/10/3707/2013/bgd-10-5 article 3707-2013- is available online at: Acknowledgements. Akhmetzhanov, A., Kenyon, N., Ivanov, M., Westbrook, G., and Mazzini, A.: Deep-water depo- knowledge of local and regional hydrography are also of utmost importance in order ities” Specific Programme. This researchcontract was GOCE-CT partially supported by the HERMES project, EC Akhmetzhanov, A., Ivanov, M., Kenyon, N., and Mazzini, A.: Deep-water cold seeps, sedimen- nanced by the European Community – Research Infrastructure Action under the FP7 “Capac- gramme under the priorityis “Sustainable a Development, contribution to Global HERMIONECommunity’s Change project, Seventh and Grant Framework Ecosystems”, Agreement Programme no. and EURODEEP (FP7/2007-2013) 226354 project funded and by (FCT; by the EURODEEP/0001/2007). thedoctoral European The fellowship CHEMECO lead (SFRH/BPD/51858/2012) ESF author fromtion was the (FCT), funded and Portuguese FLM by National was a Science supported post- Founda- by the FCT grant (BI/UI88/4610/2011). References gastropod populations. Future research shouldulation focus dynamics on species-level and taxonomy, pop- genetic structure. Mapping of deep-sea habitats and a better fauna includes species from Atlantichypothesis and Mediterranean and areas. gives Our new study evidenceties confirms for this inhabiting connectivity reducing of environments. deep-seaits This associated gastropod work biotic communi- also and shows abioticdistribution that characteristics, in substrate has the a type, deep-sea, determinant with of e and dispersal a strategies diversity contributes oftats. feeding to Moreover, types our their combined work successfulsuitable with suggests environments, colonization a which that of enhances variety diversity various deep-sea and deep-sea habi- ensures connectivity habitats of form deep-sea a network of and sites with various seepage regimes. 5 Concluding remarks It is expected from its geographical position that Gulf of Cadiz deep-sea gastropod and their primary nutrition strategiesmay (grazing in and fact detritus be feeding),is very additional habitats not frequent. di The possibilityreproduction of of connectedness individuals of andsingletons reduced the in sediments our persistence samples ofmore suggests populations. frequent that and The the diverse large thane GoC number reported deep-sea of here. gastropod Consequently, the faunation occurrence may of of be highly small productive but patchily distributed habitats, such as wood and bone falls viduals could stay afloat andwood drift a chips). long distance Another attachedspecies to possible in gliding explanation deep-sea objects habitats (e.g. for small wouldrelies widely be on the the distributed so-called colonization stepping-stone non-planktotrophic ofand/or hypothesis, additional which sunken intermediate wood sites and found bones. between distant Considering seeps the size-scale of deep-sea gastropods, suggested an alternative dispersal strategy by rafting (Sasaki et al., 2010), where indi- 5 5 10 25 15 20 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , doi:10.1890/03- , 2011. doi:10.1016/j.dsr.2010.03.004 ´ en, A.: Techniques for collecting, , 2012. ´ ario, A., Ravara, A., and Pfannkuche, O.: Macro- 3726 3725 , 2010a. doi:10.1111/j.1439-0485.2011.00503.x , 2010b. 10 ´ enio, L., Hil , 2012. ´ en, A.: Ontogenetic migration and dispersal of deep-sea gastropoda larvae, doi:10.1371/journal.pone.0033515 , 2004. ies of the Gulfgations of during Cadiz the andTechnical TTR-14 Series, Western 70, cruise Mediterranean 2006. of basins: RV preliminary Professor results Logachev of July–September, investi- 2004, IOC Implications, Biol. 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AI: Al Idrisi MV; Bon: Bonjardim ff ` es MV; PDE: Pen Duick Escarpment; Pip: Pipoca MV; Por: Porto : unknown. U Bathymetric distribution of the gastropod taxa collected in the Gulf of Cadiz. Type of Map of the study area (Gulf of Cadiz) showing samples locations. Multi-coloured cir- : non-planktotrophic; N Fig. 2. larval development is indicated after each taxon’s name. MV; Sag: Sagres MV;Gibraltar Strait. Stu: Student MV; TTR: TTR MV; VR: Vernadsky ridge; WG: West of MV; CA: CaptainGem: Arutyunov Gemini MV; MV; GR: CR: GaudalquivirMer: ridge; Carlos Mercator Ib: MV; Iberico Ribeiro Mek: MV; Mekn MV; JB: Jesus Dar: Baraza MV; Darwin Kid: Kidd MV; MV; Fiu: Fi Fig. 1. cles represent several samples with di Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | : Soft; S : Mixed; M : Hard; H Comparison of mud volcano (B) Comparison between Hard and Organic artificial 3732 3731 ) in each assemblage. (C) S erent substrate types. ff erent GoC sub-regions. ff Comparison between di ) and the number of species ( n (A) Regional accumulation, loss and turnover of gastropod taxa along the depth gradient in Taxonomic composition of gastropod assemblages at the Gulf of Cadiz (GoC) deep-sea : Organic; EA: El-Araiche; CP: Carbonate Province; DF: deep field. O assemblages at di substrata from in-situsamples colonization ( experiments. Figures below bars indicate the number of habitats. Fig. 4. Fig. 3. the Gulf of Cadiz. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 3733 Distributional patterns of Gulf of Cadiz deep-sea gastropod taxa with distinct larval de- Fig. 5. velopment types. See text andand Supplementary larval Table 2 development for data. explanation of distribution categories