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Open Access ρ Emiliania and Discussions 0.32 for nutrients), = ρ Ocean Science Ocean ], pH, and salinity ( 4 − 2 3 613 614 , and T. Tanhua 3 oceanica, G. muellerae systems parameters. However, very few studies have 2 , M. Álvarez , in unraveling the distribution of heterococcolithophores, the − 1,2 2 3 , P. Ziveri 1 morphotype B/C are spatially distributed together and trace the influx of At- erently to environmental factors. For instance, changes in heterococcolithophore as- ff This discussion paper is/has beenPlease under refer review to for the the corresponding journal final Ocean paper Science in (OS). OS if available. Institute of Environmental Science and Technology (ICTA), Universitat Autonoma de Earth & Climate Cluster, Department of Earth Sciences, FALW, VrijeIEO Universiteit – Amsterdam, Instituto Espanol deGEOMAR Oceanografia, Helmholtz-Zentrum Apd. für 130, Ozeanforschung A Kiel, Coruna, Marine 15001, Biogeochemistry, Spain alyzing changes in assemblages and diversity. Our findings clearly show that tribution. Holococcolithophores, on theshowed other higher hand, species were diversity preferentiallythriving distributed in and oligotrophic in areas (Best nutrientthree fit, depleted groups of waters. speciesassigned Clustering sharing to more of the than eastern heterococcolithophores 65 andtively. % In western revealed similarities. basins, These addition, and clusters the deeperhuxleyi could layers species be (below 50 m),lantic respec- waters into thethe Mediterranean importance Sea. of The considering results holo- of and the hetero- separately present when work an- emphasize chemistry, especially CO most abundant life phase. Holo-di and hetero-coccolithophores respond semblages were best linkedalthough to salinity the might combination be of not [CO functionally related to coccolithophore assemblage dis- ing changes in seawatercovered CO the entire Mediterraneantar physiochemical to gradients the from Eastern theof Mediterranean knowledge Strait Levantine of Basin. of the We Gibral- this provide coccolithophore to here distribution a an in broad updated theduring state set Mediterranean the of Meteor Sea (M84/3) in and oceanographic situ relate cruisedepth in measured from April environmental 28 2011, stations. variables. between 0–100tions Samples Total m diatom, are were water dinoflagellate also taken and presented. silicoflagellate Our cell results concentra- highlight the importance of seawater carbonate The Mediterranean Seaacterized is by considered oligotrophic a tochemistry. “hot-spot” Coccolithophores ultra-oligotrophic are waters for considered and climate awaters. rapidly dominant change, As phytoplankton changing being a group carbonate in marine char- these calcifying organism they are expected to respond to the ongo- Abstract Ocean Sci. Discuss., 11, 613–653, 2014 www.ocean-sci-discuss.net/11/613/2014/ doi:10.5194/osd-11-613-2014 © Author(s) 2014. CC Attribution 3.0 License. Is coccolithophore distribution in the Mediterranean Sea related to seawater carbonate chemistry? A. M. Oviedo 1 Barcelona (UAB), 08193 Bellaterra,2 Spain FALW, HV1081 Amsterdam, the3 Netherlands 4 Duesternbrooker Weg 20, 24105 Kiel, Germany Received: 31 December 2013 – Accepted: 15Correspondence January to: 2014 A. – M. Published: Oviedo 20 ([email protected]) FebruaryPublished 2014 by Copernicus Publications on behalf of the European Geosciences Union. 5 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 10 % of Emiliania ∼ erent basins are ff 46 % of the primary pro- ∼ increase towards the eastern − production and flux) throughout erently to the variability in sea- 2 3 ff 3 . Carbonate chemistry parameters have 2 616 615 CO p blooms (Merico et al., 2006) and of changes in coccolithophore assemblage The present work investigates the regional and vertical distribution of living coccol- The Mediterranean Sea provides an ideal ground to explore the factors controlling Most studies looking at coccolithophore assemblages and distribution take into ac- scarce and the influence ofassemblages carbonate remains chemistry therefore parameters uncertain. on actual coccolithophore ithophores in the Mediterraneanparameters Sea and with with respect attentionto-date to to state in those of of situ the the measuredMediterranean coccolithophore carbonate environmental Sea, assemblage’s chemistry. composition It with and provides aalong an distribution basin physical up- in and resolution chemical the that gradients. has not been assessed before, and well as the overallbution plankton in community the structure. Mediterraneanet Studies Sea al., are on 2003), mostly coccolithophores loosing regional distri- parteast (Dimiza of transect et the was sampled above al., mention (Knappertsbusch, 2008;chemistry gradients. 1993; Malinverno Additionally, parameters Ignatiades when et were a al., not. west 2009) to Thus carbonate comparisons between the di basin. The Mediterranean Seaocean is (Dugdale one and Wilkerson, of 1988),in the with the most a northwest nutrient-poor trophic to status extremely regions1984; oligotrophic ranging of Berland in from et the the mesotrophic al., east global 1988; (Kromfication Yacobi et et of al., al., the 1991; 1995; phytoplankton Berman Psarrathat community et et dinoflagellates al., al., structure and 2000). along coccolithophores The an dominate spatial inthe east–west diversi- the western transect eastern basin shows basin (Ignatiades and etin diatoms al., in nutrient 2009). Ocean availability acidification, are warming expected and changes to significantly alter primary production rates, as should facilitate coccolithophore’s growth in the ocean. coccolithophore distribution because of thecal well parameters. known large It gradient has in aitation physicochemi- negative and fresh-water surface balance water with temperature, evaporation salinity, exciting TA, precip- CO Therefore, the availability of the necessary resources for carrying out calcification 1994; Balch, 2004) that changes the carbonate chemistry of their surrounding media. eters related toimportance the seawater for carbonate calcificationto system and the have the rapidly been ongoing increasingbeen considered and suggested atmospheric due projected as to changes drivers(Beaufort their of: directly et coccosphere related al., morphology 2008; modificationhuxleyi Triantaphyllou in et field al., samples 2010;composition Beaufort (Charalampopoulou et et al.,ithophores 2011), al., calcify, of calcification 2011). is a Although key physiological it energy spending is process not (Brand, clear why coccol- the year (Knappertsbusch, 1993; Ziveri et al., 2000; Malinverno etcount al., parameters 2003). such1994; as Ziveri nutrients, et PAR, al., 1995; temperature,Thierstein, Hagino salinity, 2001; et oxygen al., Cortés (i.e. 2000; et Takahashi Young, and al., Okada, 2001; 2000; Haidar Ignatiades and et al., 2009). Only recently, param- Marine phytoplankton constitutes aboutproducers 1–2 % (Falkowski, of 1994); theduction however, global in it biomass a contributes amongglobal global primary to phytoplankton scale biomass (Field (Tyrrellin and et biogeochemical Young, al., cycles, 2009). contributing 1998). They to play boththrough Coccolithophores the photosynthesis an represent organic and important and calcification, inorganic role beingling carbon PIC pumps calcification : the POC main (rain ratio). processmain For contributor control- instance, to in the the inorganic eastern carbon Mediterranean pump Sea, (CaCO they are the they have life stageswater that carbonate are chemistry expected and to nutrient respond concentrations. di 1 Introduction coccolithophores are a dominant phytoplankton group in the entire Mediterranean Sea; 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 | 1 m wa- and sili- < 1 − 102 and for = seawater) were U 1 C − 82, C on the total scale. ◦ C for temperature and = ◦ . pH was measured by L 1 − C ) was calculated for hetero- 0 (Method No. Q-068-05 Rev. H 3 analysis and quality control are pre- , phosphate 0.007 µmolkg 1 2 sensor. Samples collected at − http://cdiac.ornl.gov/ftp/oceans/CLIVAR/ 2 618 617 (Tanhua, 2013; Tanhua et al., 2013a). Here we related variables from pH and total alkalinity (TA) for 422. Cell densities (number of cell L erent stages of a coccolithophore’s life cycle, and tax- 2 ff = Meteor was sub-classified into morphotypes according to Young U and the accuracy is 2.5 µmolkg C 1 − 382, . 12 h and stored in sealed Petri dishes. A portion of each filter = ) confidence intervals at 95 % significance were estimated follow- . ∼ 1 U L . More details about the CO − 1 C C − 0.6 µmolkg C for ◦ ± (Method No. Q-031-04 Rev. 2) and Si (Method No. Q-066-05 Rev. 3). The 3 − 4 C and as output conditions in situ temperature and pressure, we calculated the ) and upper ( ◦ L The carbonate system was characterized by measuring dissolved inorganic carbon For each sample the Shannon–Wiener diversity index ( Between 1.5 and 4.5 L of water were gently filtered onto acetate cellulose mem- C 25 in situ conditions for other CO (DIC), pH and totala alkalinity SOMMA (TA). (Single-Operator DICanalysis Multi-Metabolic content is Analyzer) was measured system.double-wavelength coulometrically The spectrophotometry, using precision and of itThe the is reproducibility reported of at thea 25 pH double measurements end was pointwas 0.0012. potentiometric 0.1 TA µmolkg technique. was The analyzedsented precision following of in the Álvarez TA et measurements al. (2013). Using as input conditions atmospheric pressure and lowing protocols from SEAL analytics4), were PO followed: NO nutrient analytical error wasstations. determined The on error 5–7 is:cate sample 0.10 for µmolkg replicates nitrate taken 0.08 µmolkg at selected 2.2 Environmental parameters A detailed protocol ofet all al. measured (2013a). In environmental(described situ variables in salinity, can temperature Sect. be and 2.1). found0.003 oxygen Overall in data for data were Tanhua salinity. accuracies determined Macronutrientswere were: by (phosphate measured CTD 0.002 and on-board with nitrate a and QuAAtro silicate auto-analyzer concentrations) from SEAL analytics. The fol- et al. (2003). coccolithophores and holococcolithophores. These two groupsbecause were they treated separately represent twoonomy di between the two does not always account for it. calculated. investigate a subset ofwater 81 depth. samples Figure 1 from showsjectory. 28 the Samples stations location were collected of all taken betweenconnected sampled to 0 using stations a and a SeaBird during 100 SBE911 the SeaBirdter m plus cruise depth carousel CTD-O tra- were (24 obtained Niskindepths by and bottles) filling a the Rossette 5 bottle L data plastic container can with be surface found water. in: Sampling 2.1 Hydrography and phytoplankton A detailed waterApril sampling 2011 on was board conducted the R/V during the M84-3 cruise from 6 to 28 2 Material and methods ing Bollmann et al. (2002).a For 420 a cell 100 count: cell count these were: quantified as coccolithophores, diatoms,ithophore dinoflagellates species were and identified, silicoflagellates. and theirIn Coccol- absolute samples and with relative very abundances counted. fewquantify coccospheres a minimum a of larger 100 filter cells( portion (a maximum was number observed of in 420 cells order were to counted). Lower branes (Millipore, 0.45 µmdried pore at size, 40 47 mmwas diameter). placed Membrane on filters aluminumcoater. The were stubs quantification oven and and identification goldcolithophore of species coated the were main performed using phytoplankton by groups an JEOL-JSMning and 6300 EMITECH electron and coc- microscopes ZEISS-EVO K550X MA10 (SEM). scan- 5–15 sputter mmaverage transects of on the 2.3 filter, mL corresponding to of an seawater were observed at 3000X and phytoplankton groups Met_84_3_Med_Sea/ 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 | nitrite ), and 2 + E. hux- CO p ), nitrate 2 Emiliania huxleyi − 3 2 % to the total as- > ) of environmental variables ρ cient, cient was used to examine similarity STD) to bring data into a compara- ffi · ffi ), carbonate ion (CO − 3 . mean 620 619 − ) to avoid overemphasizing the dominant species. x + .) accounted in average for 1 % of phytoplankton (max- concentration at a date approximating the sampling period a C and 0 dbar respectively. ◦ Dictyocha spp Meringosphaera mediterranea that largely dominated the assemblages in our samples. When clusters among For the analyses performed by E-PRIMER software, the biological data was trans- A characterization of the upper 100 m environmental parameters is shown in Fig. 2; the Mediterranean transect.xanthophyta A species present mostly at low cell densities was the (Fig. 1). Coccolithophoressampling, were relative the to most diatoms,in abundant dinoflagellates great and phytoplankton numbers in silicoflagellates. group all Theyphytoplankton. during the were Dinoflagellates main the present reached Mediterranean basins only and anatoms, accounted although average for present of 68 in 2 to % all 99ern studied (maximum % Mediterranean. basins, of of They displayed 5 low were %). concentrations on Di- in averageSilicoflagellates 6 the ( % east- (maximum 25 %)imum of total 9 %). phytoplankton. Figure 3 shows the distribution of the first three phytoplankton groups in The overall totalcoflagellates phytoplankton and coccolithophores, cell was increasing density,with westwards the including maximum Mediterranean Sea, diatoms, densitiesderived dinoflagellates, at chlorophyll sili- Gibraltar Strait. This is in agreement with the satellite- the biological data the Bray–Curtisbetween similarity each coe sample’s pair.mental data Euclidean matrix. distances Pair werenon-transformed wise non-standardized used Spearman data. correlations to were create performed the on environ- the basis of 3 Results 3.1 Main phytoplankton community each species abundance. formed in logarithmic scale logEnvironmental (1 data were standardizedble ( scale. Similarity matrices were created for biological and environmental data. For software SPSSv18 to assess the environmental parameters influencing changes in species were detected, pair wise Spearman correlations were performed using the among environmental variables andwere: selected salinity, a temperature, oxygen, subset pH, of partial themthe pressure of for concentrations carbon this dioxide of routine. ( These and bicarbonate phosphate. ion (2) (HCO Hierarchicalformed Cluster Analyses for by heterococcolithophore group andmorphotype average. holococcolithophore These A species. were was removed per- ofdone the to data emphasize set used ourleyi to results run on the overall cluster community analyses. This composition was and not on changes in environmental parametersroutine examines and all species possible distribution“best combinations fit” among of (highest stations. environmental Spearman The rankexplaining variables correlation changes and coe in gives biological the coccolithophore communities. This and test holococcolithophore wassemblage species performed of contributing each for group. all Before hetero- running the routine, we checked for mutual correlation a full description of theÁlvarez physicochemical setting et are al. presented (2013) in in Tanhua et this al. OS (2013b); special issue. 2.3 Statistical analyses The E-PRIMERv.5 package was usedtine, for which the following computes analyses: afor (1) rank the environmental BIOENV correlation parameters rou- between and the biological elements data, of similarity was matrices run to detect the combined (Lewis and Wallace, 1998). EquilibriumDickson constants and of Millero Mehrbach (1987) et werepressure al. chosen, were (1973) Álvarez 25 refitted et by al. (2013). Input temperature and the profiles for the complete water column at a higher spatial horizontal resolution and the first 100 m water column. Calculations were performed using the program CO2Sys 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 | : , , − 2 3 erent ff species H. carteri Florisphaera and Rabdosphaera Emiliania huxleyi were correlated to index at 100 m was and 0 H Gephyrocapsa A. robusta showed a high positive cor- G. flabellatus E) were rather weak, the trend was ◦ D. tubifer 0.001) (Fig. 8). and 0.328, Table 2) and were almost absent = = Corisphaera gracilis p Type B/C and the 0.004) while holococcolithophore species was very close to this cluster but similarity ρ . A third group was formed by = 622 621 U. tenuis, D. tubifera, P. vandelii, S. pulchra p 0.41; , being closely related to = F. profunda ρ 0.35, however was patchily distributed all along the tran- E. huxleyi R. xyphos − ( G. oceanica = ρ and ) changed slightly in the W–E transect. Although correlations 0 0.566 (Table 1). Holococcolithophores were preferentially dis- H = P. vandelii ρ ] and pH and in the surface. Some of these species were negatively S. protrudens − 2 3 Gladiolithus flabellatus and and the longitude of the sample sites ( ] and negatively with temperature. Table 3 shows these results. 0 2 were the dominant species. and H NO + 3 From the five morphotypes proposed by Young et al., 2003 (A, B, B/C, C, and R) only In the first 50 m water column, heterococcolithophore and holococcolithophore When clustering all the species within the heterococcolithophore life stage, 3 groups The results from the Spearman’s rank correlation based routine (BIOENV) suggest Single Spearman correlations for the species that were clustered together reveal that have often suggested that coccolithophoreston are one groups of in the this most abundant sea, phytoplank- in both, eastern (e.g. Gotsis-Skretas et al., 1999; Malinverno to the western region. 4 Discussion 4.1 Main phytoplankton community Although picoplankton canMediterranean seasonally Sea dominate (Decembrini phytoplankton et assemblages al., in 2009; the Yacobi et al., 1995), previous studies diversity tended to increase W–Eoften ( zero formostly both present groups at surface, being and on 1.3 for average heterococcolithophores. 0.3morphotypes for A holococcolithophores, and that B/C were are observed in Mediterranean waters. The latter restricted present from the Algerian tocolith the phase Levantine did basins. not Clustering revealsamples. analysis any for pattern the in holococ- the species composition among thespecies di diversity index ( between opposite for the two life stages.decrease For towards instance, heterococcolithophore the diversity east tended ( to sect. The second group includes G. ericsonii, G. muellerae profunda (the last two with similaritiesrestricted below to 60 %). depths The below species 50 m, in with the latter higher group abundances were at almost 100 m, and were patchily was less than 60 %). R. clavigera, [NO were identified sharing more thanther 65 % clustering similarities. the Figure species 4 with presents highthe the similarities. east–west The results distribution transect of of fur- (stations thesein with species the along black Levantine, Ionian labels (excluding inborean 307–309), and Fig. Tyrrhenian Gibraltar (excluding 1) regions 319), that shows Algerian, thatthe includes Al- the Mediterranean the three Sea groups stations (Figs. are 5, distinctivelymore distributed 6 in abundant and 7). in The the first eastern group comprises stations: species that were their distribution can be better explainedfor by instance, seawater species carbonate chemistry that parameters; with were higher mostly [CO abundant atcorrelated eastern to phosphate stations concentrations thrived andrelation in only waters with temperature. Finally, the center ofclavigera the Tyrrhenian basin), where that the heterococcolithophore distributionpH, was and best salinity linked with totributed a in low combination nutrient–high of pH seawaters. CO ( at 100 m. A total ofthe 70 holococcolithophore coccolithophore stage species werequantified in cells recorded were heterococcolithophore in (see the life Appendix heterococcolithophorelargely phase. stage A). dominated The species the and The coccolithophore majority 45 counts in of in all the stations except for station # 319 (at 3.2 Heterococcolithophores and holococcolithophores 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 | ects ff 5.0 µM, and their ± 2 CO p ect their popula- ff ) to support large 1 − (Fig. 3). Even though 1 ] waters of the western − − 2 3 cellsL ). Similar concentrations have 3 1 − 10 × outcompeted the otherwise dominant cellsL 4 . Egge and Aksnes (1992) observed that 10 1 . Diatoms were preferentially distributed in − 1 × 624 623 − 1 < erent phytoplankton groups at a basin scale. This ff cellsL 3 Emiliania huxleyi 10 × . For the dataset here presented, nutrients variability alone does ) and at Gibraltar ( 1 − cellsL 3 10 × P ratios in both the eastern and western basins as well as in the Gibraltar Strait) 3 / < organisms could respond tointeraction the with rapidly ocean’s carbonate accumulation chemistry of (Kroeker atmospheric et al., 2013). It has been shown of the ongoing climate change andon ocean their acidification on distribution. this Carbonate lifeconsidered stage chemistry and when the parameters looking impacts are in onlyAlthough general recently at it coccolithophore sampled is assemblages and notconsuming and conclusive distribution. process why for coccolithophores coccolithophoresnatural selection calcify, (Brand, through calcification millions 1994; of is Balch, years.the It an necessary 2004), is resources energy therefore for maintained plausibly carrying that by outgrowth the calcification in availability should of the facilitate ocean. coccolithophore’s In this context, it is important to understand how marine calcifying explanations are also discussed. 4.2 Heterococcolithophores and holococcolithophores Coccolithophores have a heteromorphiccoccoliths life and cycle haploid cells with producing diploid holococcoliths. Nothing cells is producing know about hetero- the e lence does not account for itwater neither, since density coccolithophores was dominated homogeneous inisoclines regions thought were can the be first distinguished 100We (e.g. m suggest see as that salinity the well and relative asand temperature success in of profiles silicoflagellates coccolithophores from regions during over Fig. where diatoms,to April 2). dinoflagellates a 2011 in combinationalone. all of For Mediterranean environmental instance, Sea parameters heterococcolithophoretem basins, rather distribution parameters can was than (Table 1) related be nutrients as to due we and carbonate will turbulence sys- discuss in the following section, where alternative However, a threshold in nutrientperform concentrations, better below than which othertions. coccolithophores groups A in would possible a phosphate competitiveN limitation scenario; for would other a phytoplanktoncannot groups be (notice ruled out the of high explaining coccolithophore dominance over other groups. Turbu- not explain the dominance of coccolithophores during April 2011, at least not directly. at Si values lower thanSkeletonema 0.6 costatum µM plankton groups was clear inand all phosphate the basins, were including availableration the and constant Gibraltar silicate strait, for where concentrations diatoms nitrate Sarthou were (Ks_Si: et above 3.46–4.97 al., µM, the 2005; Leblancthe half or et 0.8–2.3 community satu- µM, al., to Nelson 2003; et beMediterranean 3.9 al., dominated [Si] 1976) by was and probably fast wediatom too growing could populations, low have phytoplankton. except expected (often In for belowbasin the the 1.0 which µmolkg interior deeper layers ranged of (100 from the m) 0.8–1.4 of µmolkg the Ionian and Levantine 1–2 orders of magnitudeto the higher so than called Margalef’s fordepend Mandala on the (Margalef, nutrient 1978) other concentrations and phytoplankton phytoplankton turbulence. successionabundances Temporal groups. would changes are in According also phytoplankton often1953). referred In as this light–nutrients study, controlled however, the features dominance (Sverdrup, of coccolithophores over other phyto- low concentrations, were more( abundant in the Aegeanbeen stations, reported at in Sardinia previous channel almost studies absent (e.g. at Ignatiades 100 et mwith al., and cell 2009). more densities Silicoflagellates abundant were upthe at to higher surface 6.7 waters nutrients, of colder, the lessMediterranean Tyrrhenian Sea saline Sea, at and maximum cell withonly density lower of reached [CO 1.6 at the Gibraltar Strait, the highest cell density of coccolithophores was western basins (e.g Barlow ettive al., analysis 1997; of Barcena the et abundancestudy of al., documents di 2004). the We dominance present(Fig. of a 3), coccolithophores quantita- including in the thefell ultra-oligotrophic phytoplankton community eastern below region detection where limits. nutrients concentrations Dinoflagellates, although present in all studied basins at et al., 2003; Ignatiades et al., 1995, 2009; Rabitti et al., 1994; Ziveri et al., 2000), and 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 | − 2 3 Retic- is the ma- and CO and − 3 − 2 3 0.566; Table 1). = ρ to survive at a wide , the most abundant ]. Nevertheless, the ro- − 2 3 and no other parameter of erentially calcified species ects (Probert and Houdan, 2 ff ff CO and produce particulate organic for their intracellular calcification increases gradually towards the p 2 blooms in the Baltic Sea coincide − 3 − ects of carbonate chemistry modi- 2 3 ff ] for coccolithophore distribution, as Emiliania, Gephyrocapsa − Emiliania huxleyi , resulting in particulate inorganic car- 2 3 Emiliania huxleyi ], pH, and salinity ( ects on phytoplankton species assem- − ff − 2 3 2 3 erent e (Balch et al., 2013) and the coccolith mor- ff 2 626 625 , one of the parameters considered to run the 2 CO is hampered by p ]. They argue that di CO 2 3 p Emiliania huxleyi and pH as functionally related important variables in cult to disentangle which parameter of the carbonate − 2 3 ffi and we can assume the uptake of both HCO 3 erences that allow ff ]. has been found in oceanographic regions characterized by − 2 3 ] and [HCO erent among species and strains (Langer et al., 2006, 2009). ff − limitation of photosynthesis in the observed species. Mimicking 2 3 2 than those that prosper in the western Mediterranean. Using a com- is di calcification is sensitive to low pH and bicarbonate, while photosyn- CO − 2 ect coccolithophore populations. Under laboratory culture conditions, 2 3 p ff E. huxleyi Calcidiscus leptoporus ) with [CO erences, as pointed out by Rost et al. (2008) could imply that changes in ff Salinity, even if one of the environmental variables that optimized the best fitting Changes in pH are concomitant with changes in the ratio between bicarbonate and Our findings documented that during the time of the M84/3 cruise heterococcol- Although coccolithophores preferentially use HCO combination of variables explainingtrolling the heterococcolithophore distribution biological since data,indicates experimental might strain evidence not specific (Brand, be 1984) di salinity crucial range. in con- very diferent salinities (reviewedithophores by isolated Tyrrell from ettained the al., at Mediterranean 2008). salinities Sea of Furthermore,2004). 32–33 (CODENET heterococcol- Overall, with collection) we non-observed suggest were adverse CO explaining e main- heterococcolithophore distribution in the Mediterranean Sea. was no evident the experimental design of thescale above mentioned could culture help experiments elucidating into howfication a will on mesocosm the coccolithophore’s di physiology and morphology shape the community. thesis and growth is sensitivephogenesis in to low the carbonate chemistry (Langer andto Bode, a 2011). community How scale will in the thesecolithophore ocean? species responses Charalampopoulou distribution translate et between al. the (2011) Northto found Sea pH that and the and the coc- Atlantic irradiance. Ocean InBIOENV related this routine, study, was notdistribution part patterns. This of might the be an best indication fitting that, during variables the to time of explain the coccolithophore study there with periods of high [CO carbonate ions. This makessystem di could a Emiliania huxleyi observed by Merico et al. (2006); studies also highlighted the importance of [CO (Ziveri et al., 2012).east. In Thus, the it is Mediterranean possible Sea, thatatively those CO more species thriving CO in the easternpilation basins from utilize world-wide compar- plankton samplesBeaufort and sediments et spanning al. the lastlonging (2011) 40k to years, recorded the significant familyulofenestra correlations (genera between coccolithare mass distributed be- in the ocean according to the ocean’s carbonate chemistry. Modeling behind them should be pursuedsis) by (Austin, other 2002 ways and (e.g. references by therein). experiments, theoretical analy- within a calcifying vesicle (Mackinder et al.,jor 2010) at carbon alkaline source pH for values CO CaCO the carbonate system mightblages have and profound succession. Finally, e the carbonateunder-looked, system to parameters solve might the be coccolithophore critical, distribution but patterns. ithophore distribution was bestThe linked to single [CO abiotic parameterin a that manner best consistent groupedbustness with heterococcolithophore the of sampling assemblages the locations relationships was described [CO by correlations and the causal mechanisms living coccolithophores, utilized seawaterbon; CO while during photosynthesis, theycarbon consume (for CO details see Zeebesensitivity and to Wolf-Gladrow, 2001). CO Even further,These coccolithophore di in culture experiments that during calcification, 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 | F. er- er- ff ff Type erent ff . A third obtained ] support Gephyro- 2 ρ F. profunda or . Most of the NO + E. huxleyi 3 appears not to be spp.; Triantaphyllou G. oceanica − 2 3 . The lower and , found in nutrient-depleted Emiliania huxleyi Syracosphaera U. tenuis, D. tubifera, P. vandelii, S. Gladiolithus flabellatus have been considered typical in olig- , associated with deep photic-zone as- and species widely associated to oligotrophic 0.328, Table 2) typical of the surface (upper 628 627 . The second group includes = Rabdosphaera clavigera ρ as factors that could be controlling their distribu- Umbellosphaera tenuis − : G. ericsonii, G. muellerae 3 4 erent between the coccolithophore life stages is the de- ff syrocosphaera are widely recognized depth euphotic zone species, often species S. protrudens and PO Florisphaera profunda − 3 Florisphaera profunda and ect on the species. For instance, higher abundances of ff G. flabellatus Gephyrocapsa and spp. found in coastal or mid-ocean upwelling regions and a last group, composed The clustering of coccolithophore species resembles those proposed by Young Another feature that was di In contrast to what was shown for heterococcolithophores, CO ing species as well as some not a negative e have been observed in sedimentswaters with underneath a relatively deep warmer nutricline and (Boeckel stratified et surface al., 2006). (1994): umbelliform group suchwaters; as a second group of placolith-bearingcapsa cells such as of floriform cells, such as semblages in low to mid-latitudes. We would add in his first group the Rabdolith bear- 1990; Triantaphyllou et al.,the 2004). 50 Both m; with species highest abundances were aroundlocate an 100 the m, deep important where chlorophyll fluorescence maximum. component data The below the (not positive previous correlation shown) observations. with However, [NO the negative correlationreflects with temperature the obtained fact that nutrients are generally linked to deep mixing and colder waters, and McIntyre, 1977, 1979;2001; Malinverno Nishida, et 1979; al., 2003; Ziveri Ziveriet et et al., al., al., 2004). 2004 for 2000; Theareas gephyrocapside Haidar (Kleijne species and et have Thierstein, al., beenhigher 1989; considered temperature Broerse typical et (Takahashi of and al., eutrophic profunda Okada, 2000) with 2000; lower Knappertsbusch, density,living 1993). lower below Finally, salinity the and 100 mcontrolled depth by (Okada the and Honjo, dynamics 1973; of Boeckel the et al., nutricline 2006); and and thermocline are (Molfino and McIntyre, B/C and the group was formed by species in these clusters have beenU. found tenuis, to D. share tubifera, an S. ecological pulchraotrophic niche in and warm other R. waters studies: clavigera and/or surface water species (Okada and Honjo, 1973; Okada pulchra, R. clavigera, species shared more than 65that % were similarities (Fig. more 4). abundant The in first the group eastern comprises species stations: the statistical analysis, of an importantnot parameter measured (e.g. during irradiance, zooplankton this grazing) study. velopment of species assemblages. Holococcolithophore speciesassemblages did along not the form Mediterranean di Sea (noin species abundance clustering with and high distribution).ent similarities Interestingly, species during seem this tocal haploid niche. behave On life as the stage a contrary, three the homogeneous heterococcolithophore di group, clusters were exploiting identified a whose similar ecologi- photic zone, nutrient depleted waters. Theyentiation linked of the ecological observed niches. segregation Dimiza toaround et a the al. di (2008) Andros observed Island thatheterococcolithophore were holococcolithophores species more such as abundant inin surface the BIOENV waters analysis together for with holococcolithophores some (Table 3) might be due to the lack, in (2009) hypothesized NO tion form the Gulf ofphytoplankton Lions cell to counts the were Levantine performed basin. usingis It an alleged should inverted microscope, to be a noticed underestimate method that coccolithophorecalcified that in counts, species this especially study (O’Brien of the etwere, smaller in al., and general 2013; low- present Bollmannalmost in et absent all at al., samples 100 m. collected 2002).ranean Higher in Holococcolithophores Sea abundances Mediterranean have in been surface very reported waters oligotrophic beforereported but waters (Kleijne, 1991, of on 1992). the Cros the Mediter- and environmental Estrada (2013), preferences of the holococcolithophores being upper relevant to holococcolithophore distribution. Instead, they werein preferentially low distributed nutrient –50 high m) Mediterranean pH waters seawaters but almost ( absentsidering at the deeper two depths life (100 stages m). as Although single con- species of a homogeneous group, Ignatiades et al. 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 | G. , spp). Emil- Emil- erent ff . Future erences 0 ff to surface H was highly and morphotype B/C ecting ff erent water mass. ff Gephyrocapsa G. oceanica ) waters with low calcite sat- blooms to an end (Nejstgaard 1 − Emiliania huxleyi Emiliania huxleyi and E. huxleyi E, after the Sardinian channel and in the ◦ 10 630 629 and the morphotype B/C of the species ∼ 10 µmol nitrate kg has been associated to cold (Hagino et al., 2005; > erent species assemblage in a di ff G. muellerae E. huxleyi , ect on smaller populations could be more important. Possibly erences in the morphology and ecology of the two life phases en- ff ff ected the results here presented is zooplankton grazing: although ff erent physiology and reveals that the two phases are exploiting di in heterococcolith phase can end by viral attacks (Martínez et al., 2007; were mostly present until, ff and the morphotype B/C of the species and the longitude of the sample site should be notice. Giving the taxonomical Gephyrocapsa oceanica, G. muellerae 0 ], in unraveling the distribution of heterococcolithophores, the most abundant H − 2 3 During April 2011, the distribution of the species Atlantic waters (AW), with a winter salinity around 36.515 (Rohling, 2009), enter the Overall, distribution patterns and their relation with environmental parameters are dif- Heterococcolithophores and holococcolithophores also displayed opposite trends in Our results highlight[CO the importance of seawater carbonate chemistry, especially uration states. These characteristicssoon can in be the found Mediterranean Sea. inAtlantic Knappertsbusch Atlantic (1993) waters’ waters related influence but are givenpropose lost the very highly negativeas correlation tracers for with AW salinity. influx Here into the we Mediterranean. 5 Conclusions Tyrrhenian Sea. They areand all Bé, present 1967) and in haveCros Atlantic been and waters reported Fortuño, 2002; (Ziveri before Knappertsbusch, for etThe 1993 western al., morphotype the Mediterranean latter 2004; B/C waters only (e.g. of McIntyre for Mohan et al., 2008), nutrient-rich ( Sea could still host them. muellerae negatively correlated with salinity.ithophore We distribution have is argued notreflect that critical. the salinity A carry-over constrain highGephyrocapsa of to correlation oceanica coccol- with a this di iania parameter huxleyi might just The modified Atlantic waters (MAW)clonic in the circulation western starting Mediterranean mainlycurrent. along follows The a the cy- main North partreferences African of therein). coast it Therefore, flows if eastwards,optimal into there as environment the are the is Tyrrhenian species Algerian Sea not that (Tanhua typical arrive et of within al., eastern AW 2013b (but Mediterranean and whose waters), the Tyrrhenian water increases in salinity, TA, temperature and decreases in nutrient concentrations. Mediterranean Sea through the Gibraltar Strait. In its eastwards pathway, the surface (Frada et al., 2008, 2012):as therefore, new the starting occurrence point of in haploidthat case individuals of would could viral serve have attack to a thegenerally, zooplankton heterococcolith grazing phase. does Another not factor drive et al., 1997),important their factors e that wereirradiance. not Therefore, addressed their in contributionholo- our to and study heterococcolith the life are control phase zooplankton cannot of grazing be the ruled and out. observed distribution of ecological niches. Di able the species to surviveimply under a a wider wider range distribution ofiania range environmental huxleyi or conditions and its could seasonalVardi lasting. et For al., instance, 2012) blooms to of which the haploid phase (i.e. holococcolithophores) can resist index problems between the twogroup life would stages lead (see to Sect.work the 2.1) overestimation on considering of the the the two topicorder number as to of discriminating clarify a species, between the single a the trends here two suggested. life stagesferent would between be the necessary holo-result and in of hetero-coccolithophore a life di phases. This is probably the in our study. Asposed Balch by (2004) Young, “it suggested is when likelyin referring that their the to growth three strategies this groups which species of ultimately grouping coccolithophores would show pro- relate di to theirspecies natural diversity (Fig. abundance”. 8). However the weak correlation obtained between the diversity (Ziveri et al., 2004) surface waters (Malinverno et al., 2003) and cluster them together 5 5 25 20 10 15 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | and , 2013. 10.5194/bg- , 2006. , 1997. 10.5194/osd-10-1447-2013 and pH on the mechanisms of photosynthe- system in the Mediterranean Sea: a basin wide 2 Gephyrocapsa oceanica, G. muellerae 2 632 631 10.1016/j.dsr.2005.11.006 er. Our results emphasize the importance of consider- ff 10.1016/S0967-0645(96)00089-6 , 2013. 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A.: Sensitivity of phytoplankton to future changes 5 5 20 15 10 30 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (0.226); 2 (0.204); 2 CO p (0.328); Salinity (0.310); O − 2 NO + − 3 (0.358); NO , Salinity, Salinity, Temperature (0.299) (0.283) 2 2 − (0.236); pH (0.214); ,O ,O 640 639 3 4 2 2 , Salinity (0.311) 2 CO CO 0.2 are shown. − p p 3 4 (0.397); PO ρ > pH (0.328) 2 , Salinity (0.311) , Temperature (0.507) 2 2 , ,, pH, O , pH, pH, CO − − − − p 3 4 3 4 3 4 3 4 values for the rank correlations at a given number of variables. In PO pH, O PO PO PO (0.275); PO pH (0.327) ρ , Salinity (0.539) , Salinity, Temperature (0.517) , Salinity, O ) − − − 4 3 3 4 3 4 ρ − 2 − 2 − 2 − 2 − 2 − 2 − 2 ) for the best Spearman’s rank correlations for all possible combinations ) for the best Spearman’s rank correlations for all possible combinations ρ ρ , PO , PO , PO , Salinity (0.565) NO NO NO NO NO NO 2 2 2 NO − 4 3 + + + + + + value for each variable is shown in decreasing order of contribution to explain + CO CO CO 0.2 are shown. Description as in Table 1. p p p − 3 − 3 − 3 − 3 − 3 − 3 − 3 ) ρ ρ (0.551); pH (0.498); Salinity (0.563) pH, SalinitypH, PO pH, pH, (0.566) pH, NO ρ > − − − − − − − 2 3 3 2 3 2 3 2 3 2 3 2 2 3 CO Rho values ( Rho values ( 678 NO NO All (0.275) variables 45 NO NO Number of Variables ( 1 NO 23 NO Number ofvariables Variables ( 1 CO 5 CO 3 4 CO 6 CO 2 CO 7 CO 8 All (0.491) Table 2. between the environmentalblages. parameters Only explaining patterns in holococcolithophores assem- the first row, the changes in the biological data. Only Table 1. between the environmental parametersblages. explaining On patterns the in left, heterococcolithophores thevariables assem- number and of the variables highest taken into account; on the right, description of the Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | huxleyi stylifera 0.450; 74) Above 50 m E 0.399; 74) 0–100 m E 0.546; 74) Above 50 m E 0.551; 74) Above 50 m E − − − − (0.541; 73) Above 50 m E ( ( ( ( 0.468; 73) Below 50 m W–E 0.707; 73) 0–100 m W 0.731; 73) 0–100 m W 0.576; 73) Above 50 m W 0.616; 73) 0–100 m W 0.481; 73) Below 50 m W–E − − − − − − − − − − − clavigera 2 3 ( 3 4 3 4 3 4 3 4 2 ) results for each of the species belonging ρ 0.553; 81), pH ( 0.522; 81), O − − 642 641 0.830; 81), pH ( 0.803; 81), pH ( − − 0690; 73), pH ( 0.685; 73), pH ( − − (0.489; 73), PO (0.528; 73), PO ( ( − − − − 2 3 2 3 2 3 2 3 (Lohmann, 1919); Deflandre, 1952 Gran, 1912 (Murray and Blackman, 1898); Loeblich(Bramlette and and Tappan, 1978 Riedel, 1954); Bukry,(Braarud 1973 and Fagerland, 1946); Christensen,(Weber-Van 1978 Bosse, 1901); Gaarder, 1970 (Kamptner, 1963; ex Kleijne, 1993)Gaarder, Geisen 1970 in Sáez et al., 2003 (Wallich, 1877) Kamptner, 1954 Okada and McIntire, 1977 (Lohmann, 1902) Hay and Mohler,McIntire in and Hay Be’, et 1967 al., 1967Heimdal, var. 1973 Kamptner, 1943 Bréhéret, 1978 (Okada and McIntyre, 1977) Biekart, 1989 Tangen, 1972 (Takayama, 1967) Nishida, 1971 Lohmann, 1902 Kleijne, 1992 Lohmann, 1903 (Lecal-Schlauder, 1951) Young, Probert and(Lohmann, Kleijne, 1902) 2003 Norris, 1984 (Schiller, 1925) Deflandre, 1952 Kleijne, 1992 (Murray and Blackman, 1898) Ostenfeld,Lecal, 1900 1965 Murray and Blackman, 1898 var. (Lohmann, 1902) Kleijne and Jordan,(Deflandre 1990 and var. Fert, 1954); Norris, 1984 ). Significance levels were 0.000 in all cases. (0.583; 81), Temperature ( (0.637; 81), Temperature ( ) Preferential depth Distribution − 2 − 2 N 0.805; 81), CO 0.691; 81), CO N , − − 0.835; 73), Salinity ( 0.833; 73), Salinity ( r NO NO − − (0.727; 73), pH (0.701; 73), PO (0.626; 73), pH (0.605; 73), PO ( ( + + − − − − − 3 − 3 2 3 2 3 2 3 2 3 H. pavimentum Emiliania huxleyi G. ornata G. oceanica G. muellerae Reticulofenestra parvula Papposphaera lepida Pontosphaera japonica Scyphosphaera apsteinii Acanthoica biscayensis A. quattrospina Algirosphaera cucullata Algiropsphaera robusta Anacanthoica acanthos C. lecaliae Discosphaera tubifer Palusphaera vandeli Rhabdosphaera clavigera Gephyrocapsa ericsonii R. clavigera R. xiphos NO NO pH (0.557; 73), CO pH (0.600; 73), Temperature (0.597; 81), CO pH (0.551; 73), CO CO CO CO CO Salinity ( Calciosolenia murrayi Calcidiscus leptoporus Hayaster perplexus Pleurochrysis carterae Umbilicosphaera sibogae U. sibogae U. hulburtiana Helicosphaera carteri Anoplosolenia brasiliensis [2] Family Coccolithaceae[3] [4] [5] Poche,[6] 1913 [7] [8] Family Helicosphaeraceae[9] [10] Black, 1971 Family Noelaerhabdaceae[11] Jerkovic, 1970 [13] [14] [15] [16] Family Papposphaeraceae[17] Family Pontosphaeraceae Jordan and Young, 1990 [18] [19] Lemmermann, 1908 Family Rhabdoaphaeraceae[20] Ostenfeld,[21] 1899 [22] [23] [24] [25] [26] [27] [28] [12] [29] [30] Family Calciosoleniaceae[1] Kamptner, 1937 Coccolithophore species list. Heterococcolithophores. Three highest Spearman’s correlation ( Type B/C Salinity ( G. flabellatus F. profunda S. protrudens D. tubifer S. pulchra R. clavigera U. tenuis G. muellerae G. oceanica G. ericsonii SpeciesE. huxleyi Varible ( Table A1. Table 3. to the observed clusters withalong the the environmental parameters. west Preferential depth toanalysis and is east distribution also transect shown ( is described. Number of samples taken into account for the Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (Kamptner, 1941) Heimdal in Heimdal and Gaarder, 1980 Cros et al., 2000 Kamptner, 1937, emend. Kleijne, 1991 (Lecal, 1967); Kleijne, 1991 Kleijne, 1991 Kleijne, 1991 (Halldal and Markali, 1955) Heimdal,(Heimdal, 1982 in Heimdal and Gaarder,(Gaarder, 1980) in Heimdal, Heimdal 1982 and Gaarder,(Halldal, 1980) 1953) Norris, Heimdal, 1985 in HeimdalBorsetti and and Gaarder, Cati, 1980 1976 Kleijne, 1991 Norris, 1985 Schiller, 1913 Gaarder, 1962 Kamptner, 1937 Gaarder, 1962 Kleijne, 1991 644 643 Heimdal, in Heimdal and Gaarder,(Kamptner, 1981 1941) Kleijne, R. W.(Kamptner, Jordan, 1941) Heimdal, Kleijne, Samtleben, Jordan, A. Heimdal, H.Okada Samtleben, L. and Chamberlain Chamberlain McIntire, and and 1977 Cros, Cros,Gaarder 2002 2002 and Ramsfjell, 1954 Heimdal, 1981 (Kamptner, 1927) Gaarder, in Gaarder(Lohmann, and 1902) Heimdal, Gaarder, 1977 in Gaarder(Schiller, and 1914) Heimdal, Manton 1977 et al.,Gran, 1984 1912, emend. Manton etGran, al., 1912 1984 Gran, 1912 Okada and McIntire, 1977 (Lohmann, 1912) Jordan and Young,(Borsetti 1990 and Cati, 1976) CrosOkada et and al., McIntire, 2000 1977 (Lecal, 1966) Cros et al., 2000 (Heimdal, in Heimdal and Gaarder,Kamptner, 1981) 1941 Jordan, Kleijne andLecal-Schlauder, Heimdal, 1951 1993 Knappertsbusch, 1993 Schiller, 1925 (Kamptner, 1941); Okada and McIntyre,Kamptner, 1977 1941 Knappertsbusch, 1993 (Lecal, 1966); Loeblich and Tappan,Halldal 1968 and Markali, 1955 Gran, 1912, ex Lohmann, 1913 Okada and McIntyre, 1977 Lohmann, 1902 Okada and McIntire, 1977 sensu Kleijne, 1993 Sánchez-Suárez, 1990 (Kamptner, 1937); Paasche, in MarkaliOkada and and Paasche, Honjo, 1955 1973 (Halldal and Markali, 1955) JordanManton and and Green, Oates, 1994 1980 Norris, 1965 HOL (Murray and Blackman, 1898) Loeblich and Tappan, 1978 sp. Calyptrolithophora gracillima Crystallolithus braarudii = = sp. Type Asp. Type C Cros and Fortuno, 2002 Cros and Fortuno, 2002 sp. Kleijne, 1991 ssp. quadriperforatus HOL Kamptner (1937) Geisen et al., 2002 -type HOL Sphaerocalyptra ff Coccolithophore species list. Holococcolithophores. Continued. Alisphaera capulata A. extentata A. gaudi A. unicornis Calciopappus caudatus C. rigidus Coronosphaera binodata C. mediterranea Michaelsarsia adriaticus M. elegans Ophiaster formosus Ophiaster hydroideus Syracosphaera ampliora S. anthos S. bannockii S. borealis S. corolla S. delicata S.dilatata S. histrica S. lamina S. marginoporata S. molischii S. nana S. nodosa S. noroitica S. ossa S. pirus S. prolongata S. protrudens S. pulchra S. rotula Syracosphaera sp. type D S. tumularis Syracospahaera Umbellosphaera tenuis F. profunda Gladiolithus flabellatus Polycrater galapagensis Ceratolithus cristatus sp. a gracillima = braarudii Calyptrolithina divergens C. divergens f. tuberosa C. multipora Calyptrolithophora papillifera Calyptrosphaera cialdii C. dentata C. heimdalae C. sphaeroidea pelagicus Corisphaera gracilis C. strigilis C. tyrrheniensis Corisphaera Coronosphaera mediterranea Family [31] [32] Lemmermann, 1908 [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52] [53] [54] [55] [56] [57] [58] [59] [60] [61] [62] [63] [64] [65] Family Umbellosphaeroideae[66] Kleijne, 1993 [67] [68] [69] [70] Anthosphaera fragaria A. lafourcadii A. periperforata Anthosphaera Anthosphaera Calcidiscus leptoporus C. leptoporus Calicasphaera concava Acanthoica quattrospina [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] ssp. [19] [20] [21] [22] [23] HOL [1] HOL Table A2. Table A1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) at an approximate date of the sampling 3 − Kamptner, 1937 Lohmann, 1902 Kamptner, 1937 Kamptner, 1937 Norris, 1985 orthog. Emend. Jordan(Kamptner, 1937) and Deflandre, Green, 1952 1994 (Schiller, 1913) Kamptner, 1937 (Kamptner, 1941) Kleijne, 1991 (Kamptner, 1941) Deflandre, 1952 Halldal and Markalii, 1955 Borsetti and Cati, 1979 (Borsetti and Cati, 1967) Kleijne,sp. 1991 2 of Cros andKleijne, Fortuño, 1991 2002 (Schiller, 1913) Deflandre, 1952 sp. 1 of Cros andsp. Fortuño, 3 2002 of Cros andsp. Fortuño, 6 2002 of Cros and(Kamptner, Fortuño, 1927) 2002 Loeblich and Tappan, 1963 (Schiller, 1925) Kamptner, 1937 (Borsetti and Cati, 1976) Heimdal, 1982 646 645 Zygosphaera hellenica Calyptrosphaera oblonga = = erent basins. The transect shown in the following figures includes the stations Calyptrosphaera pirus sp. type A Kleijne (1991) ff = Continued. Syracolithus catilliferus Periphyllophora mirabilis Zygosphaera bannockii Sampling stations presented in this study collected during the M84-3 research cruise. = = = Syracosphaera pulchra Zygosphaera amoena Coronosphaera mediterranea Gliskolithus amitakarenae Helicosphaera carteri Helladosphaera cornifera Homozygosphaera arethusae H. spinosa H. triarcha Homozygosphaera vercellii Poricalyptra gaarderae Poritectolithus Sphaerocalyptra adenensis S. quadridentata Sphaerocalyptra Sphaerocalyptra Sphaerocalyptra Syracolithus schilleri Syracolithus Syracosphaera anthos Syracosphaera bannockii Syracosphaera pulchra [44] HOL pirus type [45] [24] HOL hellenica type [25] [26] HOL [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] HOL [42] HOL [43] HOL oblonga type Fig. 1. Superimposed are the images ofperiod chlorophyll (mgCm in the di labeled in black. Table A2. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 648 647 Environmental parameters at sampling stations for surface waters during the M84-3 Distribution of diatoms (upper panel), dinoflagellates (middle panel) and total coccol- Fig. 3. ithophores (lower panel) in astations west in to Fig. east transect 1). along the Mediterranean Sea (black labelled Fig. 2. cruise. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 650 649 Hierarchical cluster for the heterococcolithophores species that shared more than 65 % Distribution, along a west to east transect, of the heterococcolithophore species forming Fig. 5. the cluster compriseda mainly group is by added “eastern in the Mediterranean bottom species”. right panel. Holococcolithophores as Fig. 4. similarity in their abundance and distribution patterns. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

34

652 651 exclusively by deep photic zone species. zone photic deepby exclusively Distribution, along a west to east transect, of the heterococcolithophore species forming the the forming species of heterococcolithophore the a transect, to along east west Distribution,

. 7

smallest of the observedthecomprised smallestof clusters Figure Figure Distribution, along a west to east transect, of the heterococcolithophore species forming Distribution, along a west to east transect, of the heterococcolithophore species forming Fig. 7. the smallest of the observed clusters comprised exclusively by deep photic zone species. Fig. 6. the cluster comprised mainly by “western Mediterranean species”. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

35 Page 1 confidence interval. α Heterococcolithophores Holococcolithophores 40,00 30,00 (green). Bands represent 1α confidence

considering considering all samples until 50 m for 653 20,00

ndex Longitud (ºE) 10,00 holococcolithophores ncertainty ncertainty in correctly guessing the “next species” that would be iversity i d

) and ,00 ner Wei - -10,00 Shannon ,00

. 1,00 3,00 2,00

8 Shannon-Weiner H´ (log_e) H´ Shannon-Weiner

Shannon–Weiner diversity index considering all samples until 50 m for heterococcol- sampled, is representative of a morea sampled,representativeof diversecommunity. is Figure heterococcolithophores (blue interval. A higher index, or higher u ithophores (blue) and holococcolithophores (green). Bands represent 1 Fig. 8. A higher index, orsampled, is higher representative uncertainty of a in more correctly diverse community. guessing the “next species” that would be