ORIGINAL PAPER

Piotr Kuklinski Æ Bjørn Gulliksen Æ Ole Jorgen Lønne

Jan Marcin Weslawski

Composition of bryozoan assemblages related to depthin Svalbard fjords and sounds

Received: 4 October 2004 / Revised: 7 March 2005 / Accepted: 7 March 2005 / Published online: 15 April 2005� Springer-Verlag 2005

Abstract Svalbard bryozoan communities were inves-tigated along a depth range from the surface to 296 mbetween the inner glacial fronts and fjord mouthsduring 2001 and 2002. The main study area wasKongsfjorden (79�N, 12�E). A total of 137 taxa ofbryozoans were identified: 108 to species, 24 to genus, 3to family, 1 to order and 1 to phylum level. Cluster andmultidimensional scaling analyses revealed four distinctassemblages of bryozoans: shallow (0–40 m; 68 taxa),deep (40–296 m; 80 taxa), inner fjordic (three taxa) andan assemblage found on small stones in shallow waters(nine taxa). The inner fjordic assemblage was recordedfrom the front of tidal glaciers extending about 10 kmout into the fjord. In terms of abundance, Celleporellahyalina Linnaeus dominated in shallow areas (18%),Hippothoa arctica Kluge (55%) in deep water, Alcy-onidium disciforme Smitt (86%) proximate to glaciersfronts and Electra arctica Borg on small stones (98%).

The species were classified according to their depthrange as a stenobathic-shallow (46 taxa), stenobathic-deep (57 taxa) and eurybathic-generalist (21 taxa).Mean diversity measures did not show any significantdifferences between the shallow and deep communities.The bryozoan assemblages seem to be structured pri-marily by processes related to depth and sedimentcharacteristics.

Introduction

Arctic bryozoan diversity is estimated to be well abovethree hundred species (Kluge 1975) and bryozoans areamongst the richest macrofauna in this area (Gulliksenet al. 1999). In spite of high species numbers, bryozoansin Arctic ecosystems have received little attention,especially with regard to studies of abundance andcomposition of assemblages. Most bryozoan assem-blages studies until now have used relative cover onstones or shells (Barnes et al. 1996; Hughes 2001) ornumber of specimens on a measured volume of algae(Lippert et al. 2001) to quantify densities. The presentstudy, to our knowledge is the first Arctic investigationof bryozoan assemblages using occurrence of species andnumber of individuals in relationship to the surface areaof the bottom.

High Arctic Svalbard archipelago fjordic systemswere chosen as the study area. The multiple gradients ofenvironmental factors in fjords of the Svalbard archi-pelago, our study area, make them good natural labo-ratories (Gorlich et al. 1987; Hop et al. 2002; Svendsenet al. 2002). In fjordic ecosystems, discharge of freshwater by tidal glaciers and rivers cause gradients insalinity, suspended particulate matter and sedimenta-tion. It has been suggested that such discharges createareas with a scarcity of biologically useful energy anddigestible organic matter (Gorlich et al. 1987) and thusinfluence species composition.

P. Kuklinski Æ J. M. WeslawskiInstitute of Oceanology,Polish Academy of Sciences,ul.Powstancow Warszawy 55,81-712 Sopot, Poland

P. Kuklinski Æ B. GulliksenThe University Center on Svalbard,P.O. Box 156, 9171Longyearbyen, Norway

Present address: P. Kuklinski (&)Natural History Museum,Cromwell Road, London,SW7 5BD, UKE-mail: p.kuklinski@nhm.ac.ukTel.: +44-207-9426062Fax: +44-207-9425546

B. GulliksenDepartment of Aquatic Biology,Norwegian College of Fishery Science,9037 Tromsø, Norway

O. J. LønneInstitute of Marine Research,9296 Tromsø, Norway

Polar Biol (2005) 28: 619–630DOI 10.1007/s00300-005-0726-5

Previous investigations have suggested changes infaunal species composition along environmental gradi-ents in Svalbard waters (Wlodarska–Kowalczuk andPearson 2004; Kuklinski 2002a). Kuklinski (2002b)suggested two distinct groups of bryozoan speciesin Svalbard, shallow and deep. However, thispreliminary study was based on presence–absence ofspecies in samples, and as such was not quantitative. Thecurrent investigation used quantitative methods to testthe hypothesis regarding differences between shallow anddeep assemblages. The main question asked is: are thereany distinct bryozoan assemblages related to depth?

Materials and methods

Study area

Svalbard is influenced mainly by two water masses. Thefirst, the West Spitsbergen Current, is a branch of thewarm (4�C) and highly saline (35 psu) Norwegian Cur-rent (Loeng 1991). Transportation of these warm watermasses causes a milder climate compared to other areasof similar latitude (Gammelsrød and Rudels 1983). Thesecond water mass influencing this area is the EastSpitsbergen Current. This cold, dense and highly salinewater (temperature �1.5–1�C, salinity 34–35 psu) orig-inates in the Arctic Ocean (Loeng 1991; Beszczynskaet al. 1997).

The main study site, Kongsfjorden, is 26-km long andon average 8-km wide (Fig. 1). The whole area of thefjord is 208.8 km2. Maximum depth is 428 m, and meandepth �140 m. Of the total length of the coastline of the

fjord (89.6 km), 15.9 km comprises glacier fronts.Important factors typically influencing the fjord ecosys-tem are bathymetry, vicinity of the ocean, glaciers andlocal climate (Wcsawski et al. 1991; Ito andKudoh 1997).In Kongsfjord, it has been reported that suspended par-ticle concentration close to glaciers can reach 200–800 mg/dm3, decreasing in the central and outer parts ofthe fjord during the summer. In the inner basin, concen-trations of suspended particles in the intermediate waterlayer may reach 20–25 mg/dm3 and 2–3 mg/dm3 in thecentral parts. In contrast, clear water in the outer parts ofthe fjord contains only 0.5 mg/dm3 (Elverhøi et al. 1983;Zajaczkowski 2000). Muds dominate the sediments ofmost of the inner and deeper parts of the Svalbard fjords(Zaborska 2001; Wlodarska-Kowalczuk and Pearson2004). Shallow subtidal parts of the fjords have a widerange of bottom types (soft sediments, sand, gravel, evenhard rock) (Hop et al. 2002). Fresh water discharge fromthe melting glaciers during the summer causes strongwater mass stratification with a maximum gradient at 5–20 m depth. This effect limits vertical exchange of energyand matter between the water mass layers, especially inthe proximity of the glaciers (Gorlich et al. 1987).

In common with most high polar shores, the Svalbardcoast is subjected to ice scour from drifting ice duringthe summer months. In winter, the sea surface freezes inthe inner fjords forming fast-ice. Fast-ice occurs lessoften and extensively in the central and outer parts ofthe fjords (Wcsawski et al. 1988; Svendsen et al 2002).

Svendsen et al. (2002) provide a more detaileddescription of the physical and environmental charac-teristics of the studied fjord. For equivalent details ofbiological characteristics, see Hop et al. (2002).

Fig. 1 The position of samplingsites in the SvalbardArchipelago (KF Kongsfjorden,W Wijdefjorden, DDuvefjorden, T Tommeløyane,H Helleysundet, B Boltodden,Be Bellsund)

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Field sampling

The main locality for sampling was Kongsfjorden, butcollections were also made from a few localities else-where in the Svalbard archipelago: Wijdefjorden, Du-vefjorden, Tommeløyane, Hellysundet, Boltodden andBellsund (Fig. 1).

Samples were taken in 2002 from the research vesselOceania, in 2001 and 2002 from the research vessel JanMayen, and with use of a rubber boat from Ny-Alesundin 2001. Two techniques were used to collect the sam-ples: 0.1 m2 van Veen grab and SCUBA diving (squareframe; 0.25 m2). From 25 sampling stations (9 SCUBA-sites, 16 grab-sites, Fig. 1), a total of 66 samples wereobtained (30 SCUBA samples, 36 grab samples). Ateach site in Kongsfjorden three replicates were taken(except for station no. 6 where three samples were takenfrom 6 m and three samples from 10 m depth). For therest of localities, scattered around Svalbard, only onesample was obtained per site. These were primarilycollected to examine if patterns observed in Kongsfjor-den were comparable with other sites.

The material collected was fixed in 4% buffered for-malin or 70% ethanol.

Data analysis

All bryozoan colonies were determined to the taxonomiclowest level possible and counted. For purposes of thisstudy, single colonies were taken to represent singleindividuals. Morphological forms of the colonies weredivided into five functional groups: membranous un-calcified, runners (= chain-like colonies), encrusting,erect flexible and erect rigid colonies. Percentage ratiosof each of the functional groups were related to themajor assemblages.

Frequency of occurrence was calculated using theequation:

F ¼ ni � n�1

F is frequency of given taxa (%), ni is number of sampleswhere given taxa were present, n is number of all sam-ples.

To compare the faunal composition of bryozoansbetween samples, the PRIMER software package wasused. Quantitative data were standardized to the 0.25 m2

unit, then the data were fourth root transformed and theBray-Curtis similarity measures were calculated (Brayand Curtis 1957). Using this similarity matrix, sampleswere then classified into groups by hierarchicalagglomerative clustering using group-average linking.This classification of samples was then visually depictedin a dendrogram. The inter-relationship between sam-ples was also mapped using the ordination techniquecalled non-metric, multidimensional scaling (MDS).Qualitative data obtained during the current investiga-tion and literature records (Gontar et al. 2001; Kuklinski2002b) were included in the cluster analyses. In an

attempt to reduce bias from methodological differencesand due to a lack of quantitative information in somestudies, these cluster analyses were based on presence–absence data. Several diversity measures were calculated:number of taxa, Margalef species richness index, Pielouevenness index, Shannon-Wiener H’ diversity index (logbase e) and Simpson index. Number of individuals persample was also calculated.

One-way analyses of similarities (ANOSIM; Clarkeand Green 1988) were used to test a priori (quantitativematerial divided according to Kuklinski 2002b) differ-ences in assemblages. ANOSIM uses the test statistic R,which is calculated using average rank similaritiesamong pairs of replicates within each of the two groups(e.g. deep–shallow samples) minus the average ranksimilarity of replicates between groups, and is scaled togive a value between �1 and 1. Thus, R=1 when allsimilarities within groups are less than any similaritybetween groups, R>0.75 when there is big differencewith the groups either well separated, R>0.5 whengroups are overlapping but clearly different, R<0.25when groups are barely separable, and R=0 when rep-licates within and between groups are equally similar(Clarke and Gorley 2001).

Results

A total 137 taxa of bryozoans were identified: 108 tospecies, 24 to genus, 3 to family, 1 to order and 1 to thephylum level. Taxon accumulation plots for shallow(<25 m) and deep (>50 m) samples (split according toKuklinski 2002b) approached an asymptote well beforeall the samples were included (Fig. 2). Thus, the samplingappears to have been representative for the study region.

The cluster diagram (Fig. 3) indicates four clusters ofsamples. Two of the clusters contain shallow samples(A1, A2), ranging in depth from 6 m to 23 m, one clustercontains samples taken in the depth-interval 50–296 m(A3), and the fourth cluster comprises eight samplestaken between 10 m and 58 m (A4). This last cluster,however, only contains samples taken in the inner basinof Kongsfjorden. One of the shallow clusters (A2) con-tains only four samples (three samples from the same

Fig. 2 Cumulative sampling curves for deep and shallow samples(samples split a priori due to Kuklinski 2002b)

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locality), and each of these four samples came fromlocalities with pebbles and gravel (<2 cm2).

The MDS analyses show roughly the same picture asthe cluster analyses (Fig. 4).

Observed patterns depicted by the cluster (Fig. 3) andthe MDS (Fig. 4) analyses are supported by ANOSIM apriori statistic (Global R) which showed significant dif-ferences between shallow and deep samples with someoverlap (R=0.461, P=0.001).

An additional cluster analyses (Fig. 5) based onpresence–absence data, including additional data fromthe literature, showed the same pattern of distribution ofbryozoan assemblages. This analysis suggests that theborder between shallow and deep samples is somewhere

between 35 m (the deepest sample in the cluster ofshallow samples) and 50-m depth (the shallowest samplein the cluster of deep samples).

Samples from sites other than Kongsfjorden followedthe pattern of assemblage structure related to depthdescribed above (see Figs. 3, 4, 5 [deep samples from theother sites fall into a cluster with deep samples fromKongsfjorden, etc.]).

Mean values of density of the most abundant speciesare shown in Table 1. All species are included in theanalyses presented in Fig. 6. Concerning species com-position, strong dominance by single species was foundin the deep (A3), shallow small stones (A2) and innerfjord assemblages (A4). For the shallow assemblage

Fig. 3 Dendrogram of Bray–Curtis similarities between thesamples based on fourth-rootedtransformed data (stationsmarked with a letter are onesoutside Kongsfjorden (WWijdefjorden, D Duvefjorden,T Tommeløyane, HHelleysundet, B Boltodden, BeBellsund); figures in brackets aredepths from which the sampleswere taken, all station signsaccording with Fig. 1)

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(A1), dominance was more evenly distributed amongdifferent species (Fig. 6, Table 1). Shallow areas (A1)were dominated by Celleporella hyalina Linnaeus (18%)and Harmeria scutulata Busk (15%). Runner-like speciesdominated the deep assemblage (A3). These were Hip-pothoa arcticaKluge (55%) and to a lesser extent Electraarctica Borg (21%). Many colonies of runner-like spe-cies were formed by fragmentation (mechanical disinte-gration). Assemblages on shallow small rocks (A2) andin the inner part of the fjord (A4) were dominated bysingle species, respectively, E. arctica Borg (96%) in A2,and Alcyonidium disciforme Smitt (86%) in A4.

The number of taxa occurring only in the shallowassemblages (A1 & A2) was 46 (all taxa present in theA2 assemblage were also present in the A1 assemblage),while 57 taxa were restricted to the deeper assemblage(A3). Twenty one taxa had broad distributions from theshallowest (A1) to the deepest sites (A3). Only threespecies were recorded in the inner basin of Kongsfjorden(A4), namely A. disciforme, Eucratea loricata Linnaeusand A. gelatinosum Linnaeus.

In total, there were more taxa (80) in the deep areabelow 50-m depth than in shallow waters above 35-mdepth (68 taxa). These species are classified according totheir depth range as either stenobathic-shallow, steno-bathic-deep or eurybathic-generalist (Table 2).

There were differences in the diversity measures be-tween the shallow (A1) and deep assemblages (A3)(Table 3). On average, there were slightly more speciesin the shallow water parts (19 species per sample) than inthe deeper parts (15 species per sample). The same pat-tern was exhibited by all the diversity indexes (e.g.Shannon-Wiener H’: shallow—1.74, deep—1.54; Pielou:shallow—0.59, deep—0.62).

There was no significant correlation between depthand any of the diversity parameters: number of taxa(r=0.10, P=0.389); Margalef species richness index(r=0.08, P=0.494); Pielou evenness index (r=0.15,P=0.226); Shannon-Wiener index (r=0.11, P=0.380);Simpson index (r=0.11, P=0.358) or number of indi-

viduals per sample (r=0.08, P=0.494). All measures ofdiversity were more variable in the shallows (A1). Inboth the shallow (A1) and deep (A3) assemblages thehighest number of taxa at a single station was 49(shallow station no. 7 and deep station no. 14). Thelowest number of taxa in the deep assemblage was 2(station no. 15), in contrast to the shallow assemblage(A1) in which there were a few stations where no bry-ozoans occurred (e.g. station 6). The abundance of col-onies was generally higher in shallow (A1) than in deepsamples (A3). The highest station value within theshallow assemblage samples (A1) was 2067 colonies(station 7), compared to a maximum of 1032 (station 14)in deep samples (A3). Variability of colony number,indicated by standard deviation (Table 3), was againhigher for the shallow assemblage (A1). The same trendwas observed for diversity measures.

The inner fjordic assemblage (A4), with only threespecies present, showed a different pattern. All of thediversity indexes were below 1. In spite of the lowdiversity, there were examples (station 4) in which thenumber of bryozoan individuals reached up to 651.Except for station 5, there were replicates at each stationin which no bryozoans were recorded. Variability inrichness, diversity and evenness data are summarised inTable 4.

Shallow (A1 and A2) and deep assemblages (A3)were dominated by cheilostome bryozoans, except theinner fjordic assemblage (A4) where ctenostome bry-ozoans were most abundant. Proportion of both num-bers of individuals and numbers of taxa for the ordersare shown in Fig. 7.

Classification of functional groups revealed an ab-sence of erect rigid bryozoans from shallow (A1 and A2)and inner fjordic (A4) areas. In these areas, runners andencrusting sheets were also absent (for more details seeTable 5).

Species considered to have an important ecologicalrole (numerical dominants) in the Svalbard Archipelagoassemblages are depicted in Fig. 8.

Fig. 4 Multidimensionalscaling (MDS) based on Bray–Curtis similarities calculatedfrom fourth - rootedtransformed data (stationsmarked with a letter are onesoutside Kongsfjorden[W -Wijdefjorden,D - Duvefjorden,T - Tommeløyane,H - Helleysundet,B - Boltodden, Be–Bellsund],figures in brackets are depthsfrom which samples were taken,all station signs according withFig. 1)

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Discussion

Our data showed strong bathymetric separation ofbryozoans at 40 m as found nearly 20� further south inthe temperate fjords of the Bergen area of Norway(Ryland 1963), and in parts of the Mediterranean(Gautier 1962). The boundary between shallow and deepassemblages in the Mediterranean Sea was about 50 m.Ryland (1963) speculated that separation into shallowand deep groups in fjordic Bergen might be caused bysubstratum limitations, bryozoan larval response to lightduring dispersal, and temperature and salinity fluctua-tions in the upper water column. Such explanations arealso relevant in our study area in Svalbard. Our obser-vations also fit with broad bathymetric distributionalpattern of bryozoan species-richness in the AtlanticOcean (Lidgard 1990, Clarke and Lidgard 2000).

In deeper parts of fjords, factors structuring com-munities in the shallow subtidal are absent or much lessintense (e.g. currents, ice scour, fresh water discharge).The deeper parts typically contain soft homogenoussediments (Zaborska 2001; Svendsen et al. 2002), andare not favourable habitats for bryozoan colonizationdue to lack of hard substrates for this mainly epifaunalphylum. In soft bottom environments, bryozoans(especially, encrusting ones) increase in diversity and

abundance as the number of exposed substrates in-creases (e.g. shells, Driscoll 1967), especially where level-bottom facies would otherwise consist of fine sediment(Gordon 1987). Sedimentation has been also recognizedas a major source of mortality for juveniles of somesessile organisms (e.g. ascidians—Young and Chia 1984;corals—Bak and Engel 1979). Low current energy in thedeep parts of the fjord, which would enable suspensionto settle, could increase mortality. Colonization of thedeep parts is, therefore, likely to depend on physicalfactors like sediment accumulation, which in turn willdepend on ambient currents, distance from source orsize of the substrate (e.g. the bigger the dropstone themore sediment is needed to bury it) and angle of sub-strate (more sediment accumulates on horizontal sur-faces than on slopes).

Light limits distribution of bryozoans which prefer-entially colonize macroalgae. Algal occurrence dependson critical light levels, the depth of which varies withwater visibility. Light can determine occurrence of cal-careous algae which cause, mostly through competition,absence or low abundance of bryozoans in shallow areas(six species were recorded, the most frequent beingCribrilina annulata Fabricius, colonizing calcareous al-gae). Light also plays a crucial role in larval dispersal.Most bryozoan larvae are photopositive on liberationbut at settlement generally exhibit a preference for sha-ded surfaces (Ryland 1974).

A potentially strong explanatory factor for differ-ences between shallow and deep assemblages is foodavailability—in the shallows, there is more phyto-plankton available. Colony size on deep substrates, in

Fig. 5 Dendrogram of Bray–Curtis similarities between the sam-ples based on presence–absence data derived both from literatureand samples collected during this study (**Gontar et al 2001;*Kuklinski 2002b)

b

Table 1 Mean values ofdensities of the most abundantspecies in the given assemblage(mean individuals number/0.25 m2)

Shallow(A1)

Shallow(small rocks)(A2)

Deep(A3)

Inner(A4)

Celleporella hyalina (Linnaeus 1767) 71 – – –Harmeria scutulata (Busk 1855) 61 – – –Tegella arctica (d’Orbigny 1852) 35 – – –Callopora spp. 31 – 5 –Cribrilina annulata Fabricius 1780 28 – – –Cylindroporella tubulosa (Norman 1868) 26 – 5 –Microporella svalbardensis Kuklinski and Hayward 2004 18 1 2 –Alcyonidium gelatinosum (Linnaeus 1767) 15 – – 1Electra arctica (Borg 1931) 13 211 2 –Lichenopora sp. 9 1 5 –Disporella hispida (Fleming 1828) 1 2 – –Pentapora boreale Kuklinski and Hayward 2004 2 1 – –Tegella sp. 1 1 – –Tubulipora flabellaris (Fabicius 1780) 1 1 – –Callopora lata (Kluge 1907) 1 1 – –Eucratea loricata (Linnaeus 1758) 2 1 2 1Hippothoa arctica Kluge 1906 1 – 310 –Electra catenularia-similis (Kluge 1962) 2 – 117 –Tubuliporidae indet. 2 – 17 –Schizoporella costata (Kluge 1962) – – 10 –Escharelloides spinulifera (Hincks 1889) – – 7 –Hippothoa expensa (Dawson 1859) – – 7 –Microporella arctica (Norman 1903) – – 7 –Smittina belli (Dawson 1859) – – 5 –Callopora whiteavesi (Norman 1903) 4 – 5 –Alcyonidium disciforme (Smitt 1871) – – – 12

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most cases, was much smaller than in the shallows.Overall rock cover by encrusters was also less on deeperrocks. This might suggest that food supply to the deeperparts is much weaker in comparison to shallowereuphotic zone. Curtis (1977) found that polychaetes inthe deeper parts of the fjord matured more slowly andreproduced with fewer, energy-rich eggs. This observa-tion was associated with the food-poor environment. Ata greater scale (across taxa), Grebmeier et al. (1989)showed that greater food supply at the bottom increasedbenthic biomass. Increased primary production in theupper water column, with increased carbon flux to thebottom, will clearly affect sediment organic content,causing changes in the structure of benthic communities(Carey 1991). This pattern fits the observations in thisstudy: the majority of bryozoan species present in deeperfjordic area had very small colonies (rarely exceeding1 cm2).

Near-bottom currents are also likely to be of impor-tance in the Svalbard region. There are many examplesof the positive influence of current velocity on suspen-sion feeding communities (Wildish and Kristmanson1997). Current velocity influences both the sediment (e.g.grain size, stability) and food supply (Wildish and

Kristmanson 1997). In the study area, the shallows aremuch more under the influence of currents, both thosegenerated by tidal forces and by wind (Svendsen et al.2002). The currents enhance the food supply which re-sults in higher biomass (e.g. of bryozoans); in compari-son to the deeper parts, encrusting colonies are biggerand large bush-like colonies (e.g. Eucratea loricataLinnaeus and Dendrobeania spp.) are present in shallowwaters.

Physical forces like wave action, strong currents andice scouring may exclude some fragile bryozoan species.These are, for example, no records of erect non-flexible(rigid) bryozoans in the shallows (see Table 5). They aremuch more susceptible than other types to mechanicaldamage. Presence of such forms is a clear indicator oflower levels of disturbance in deeper waters. Bryozoancolony morphology is strongly related to habitat (Riderand Cowen 1977; Cook 1981; Marfenin 1997). Therelationship between body shape and environment isvery complex and can be modulated through modifica-tion of growth rate, branching or in some cases reab-sorption of parts of the colony (Marfenin 1997). Thepresence of species with different colony morphologies isa function of substrate stability and longevity (Lidgard1990). The deep assemblage was dominated by runner-like Hippothoa species. These species possess the abilityto persist through colony fragmentation and to survivelocalized mortality of zooids. This is an importantadaptation in areas where they are often overgrown, orwhere the risk of physical damage is high (Bishop 1989).The wide spacing of orifices which result from uniserialgrowth (as found in species of Hippothoa) is alsoadvantageous in the deep fjord and in other environ-ments of low food supply (Harmelin 1979). There is alower probability for colonies to be buried by sedimen-tation from the water column or resuspension of parti-cles from the sea floor. Decreased competition for spaceresults in an increase in available space on the substra-tum, favouring uniserial colonies, which are weak com-petitors (Bishop 1989).

Marine bryozoan faunas are usually dominated byspecies of the order Cheilostomata (Ryland 1970). Theinner fjord environment with highly fluctuating salinityand sedimentation were, however, mostly inhabited bysoft-bodied representatives of the order Ctenostomata.This group of bryozoans seems to be the best adaptedfor changeable conditions, hence their importance inestuarine systems (Winston 1977).

The dominance of single species was much morepronounced for deep samples (A3) than for shallowsamples (A1) (see Fig. 6). The shallows were moreevenly colonized by a few good competitor species. Thisseems likely to be the result of the more heterogeneoushabitat. In the shallows, there were several habitats inwhich there were a different dominant species. Forexample, the abundance of Harmeria scutulata Buskcolonies on shallow boulders exceeded 50% of totalcolonies (Kuklinski and Barnes 2005). C. hyalinaLinnaeus, in contrast, dominated algal substrates,

Fig. 6 Dominance curve indicating numerical dominance of onespecies in most of the described assemblages

Table 2 A classification of some common Arctic bryozoans basedon their depth distribution

Bryozoanspecies type

Examplespecies

Eurybathic—Generalist Hippothoa arctica (12/69)Species which occur widelyboth in shallow down todeepest parts of the fjords

Electra catenularia-similis (16/58)Cylindroporella tubulosa (31/29)Stomachetosella cruenta (34/17)Callopora craticula (25/17)

Stenobathic—shallow Celleporella hyalina (53/0)Species found only in shallowsamples down to 40 m

Harmeria scutulata (47/0)Tegella arctica (47/0)Cribriliana annulata (37/0)Tegella armifera (37/0)

Stenobathic—deep Porella rigida (0/28)Species which occur onlyin area below 40 m depth

Schizoporella pachystega (0/24)Microporella arctica (0/17)Schizoporella biaperta (0/17)Escharelloides spinulifera (0/14)

In brackets frequency of occurrence in shallow area (%)/frequencyof occurrence in the deep area (%)

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comprising 50% of colonies (Kuklinski and Barnes2005).

Despite the large number of species present, the highabundance of bryozoans was mostly due to a few spe-cies, particularly A. disciforme Smitt in the inner asso-ciation (A4), C. hyalina, Harmeria scutulata (A1), andE. arctica in the shallows (A2), and H. arctica in deepwaters (A3). The pattern in which a few species domi-nate over a large group of rare species is a commonfeature of bryozoans (Jackson 1984; Barnes and Clarke1998).

The current study revealed the abundance of bry-ozoans to be extremely variable, for example, severalorders of magnitude difference in the numbers of indi-viduals were found between replicates at shallow station7 (Table 4). Such patchiness is generally attributed to

initial differences in the colonization of individual sub-strata magnified by subsequent biological interactions(Winston and Jackson 1984). The heterogeneous natureof shallow habitats most likely increases patchiness incomparison with the deeper parts of the fjord wheresubstrate types are less diverse.

Apart from differences in bryozoan assemblages re-lated to depth, there was distinct assemblage (A4), at theinner part of the fjord. Species numbers were lower inthe innermost fjord basin. A similar pattern has beenobserved in other macrofaunal groups (e.g. molluscs) inKongsfjorden (Wlodarska-Kowalczuk and Pearson2004) and other fjordic systems elsewhere (Farrow et al.1983; Gulliksen et al. 1985; Gorlich et al. 1987; Syvitskiet al. 1989). This correlates with substrate changes whichare due to a gradient in sedimentation rate caused by

Table 3 Biodiversity measures (mean ± standard deviation/0.25 m2) for the shallow (A1 and A2), deep (A3) and inner fjordic (A4)samples

S N d J¢ H¢ k’

Shallow (A1) 19.7±14.73 419.4±533.84 3.24±2.084 0.59±0.269 1.74±0.888 0.66±0.302Shallow (A2) 3.0±2.16 215.2±286.29 0.65±0.855 0.36±0.432 0.44±0.734 0.22±0.381Deep (A3) 15.1±12.58 323.3±299.34 2.43±1.788 0.62±0.175 1.54±0.809 0.60±0.216Inner (A4) 0.6±0.63 65.3±170.40 0.02±0.094 0.10±0.316 0.04±0.178 0.04±0.146

S species number, N number of individuals, d species richness [Margalef index], J¢ Pielou’s evenness index, H¢ diversity Shannon-Wienerindex, k ¢ Simpson index

Table 4 Biodiversity measures (mean ± standard deviation/0.25 m2) for all the sampling sites

Station no. Depth S N d J¢ H¢ k ¢

1 (A1, A2) 10 7.3±1.15 77.6±97.57 1.76±0.387 0.64±0.284 1.26±0.512 0.57±0.2512 (A2) 10 2.0±1.00 282.3±309.74 0.23±0.257 0.07±0.091 0.07±0.103 0.03±0.0413 (A1) 10 11.0±5.29 158.3±212.93 2.37±0.476 0.81±0.104 1.82±0.289 0.79±0.0214 (A4) 10 1.0±0.00 310.1±300.70 – – – –5 (A4) 10 1.0±1.00 15.5±14.21 0.11±0.197 0.50±0.707 0.23±0.400 0.16±0.2926a (A1) 10 2.6±4.61 64.3±111.42 0.44±0.767 0.17±0.298 0.35±0.620 0.17±0.3116b (A1) 6 9.0±11.53 297.3±432.90 1.33±1.623 0.45±0.397 1.03±0.964 0.46±0.4097 (A1) 10 38.0±10.14 1302.3±662.52 5.17±1.087 0.72±0.012 2.63±0.154 0.89±0.0048 (A1) 10 20.3±5.50 245.3±145.69 3.60±0.644 0.63±0.170 1.88±0.452 0.70±0.1449 (A1) 10 28.3±2.51 397.3±291.23 4.72±0.162 0.78±0.030 2.60±0.089 0.88±0.01310 (A3) 93 16.0±14.76 281.6±206.37 2.55±2.238 0.54±0.083 1.40±0.718 0.57±0.15711 (A3) 296 22.0±23.43 356.6±458.37 3.46±3.134 0.67±0.135 1.91±1.104 0.68±0.24012 (A3) 236 19.6±9.50 515.0±180.00 2.95±1.367 0.57±0.171 1.70±0.798 0.64±0.19713 (A3) 210 15.0±11.00 620.0±240.20 2.12±1.610 0.47±0.091 1.12±0.410 0.50±0.07414 (A3) 252 19.0±19.92 382.5±563.05 3.04±2.480 0.64±0.104 1.73±0.949 0.63±0.22215 (A3) 226 5.6±3.51 188.3±105.83 0.91±0.738 0.46±0.098 0.70±0.362 0.32±0.12316 (A3) 50 20.0±7.00 296.6±154.13 3.38±1.214 0.77±0.120 2.28±0.485 0.82±0.09517 (A4) 58 0.3±0.57 0.8±1.44 – – – –18 (A4) 51 0.3±0.57 0.1±0.14 – – – –19 (A4) 48 0.3±0.57 0.2±0.28 – – – –B (A1) 14 22 50.2 5.36 0.72 2.23 0.83Be (A3) 140 8 42.5 1.86 0.92 1.92 0.85D (A3) 115 3 37.5 0.55 0.73 0.8 0.48H (A1) 13 45 1555 5.98 0.58 2.22 0.82T (A1) 23 43 427 6.93 0.64 2.42 0.81W (A3) 146 6 95 1.09 0.46 0.82 0.36

S species number, N number of individuals, d species richness(Margalef index), J¢ Pielou’s evenness index, H¢ diversity Shannon-Wiener index, k ¢ Simpson index (W Wijdefjorden, D Duvefjorden,T Tommeløyane, H Helleysundet, B Boltodden, Be Bellsund, allstation signs according with Fig 1, in brackets assemblage to which

given station belongs: A1—shallow, A2—shallow, A3—deep,A4—inner; calculation for stations W, D, T, H, B, Be are based onone sample data while for the rest of stations calcualations arebased on data obtained from three replicates)

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release of glacial material. Diversity of bryozoans cer-tainly seems to follow such a pattern—the coarser thesediment, the higher the diversity of Bryozoa. Therewere, however, many other contributory factors whichmay result in the low bryozoan diversity observed in theinnermost fjord area. Melting glaciers might cause lowerflux of digestible organic matter to the bottom and dilutethe scarce food supply with high level of inorganicparticles (Gorlich et al. 1987; Syvitski et al. 1989).Higher surface turbidity and long periods of fast icecover in the innermost fjord basin suppress primaryproduction. This results in a lower flux of energy at thebottom. Intense fresh water discharge results in waterstratification (max stability is at 5–20 m depth),restricting vertical exchange of energy and matter(Gorlich et al. 1987).

On the scale examined in this study, bryozoanassemblages are considered to be structured primarily by

processes relating to depth and sediment distribution.The pattern observed by Kuklinski (2002b) with twoassemblages (shallow [A1] and deep [A3]) and highertotal diversity for the deeper parts was confirmed. Onaverage, for each sample both species diversity andnumber of individuals are shown to be slightly higher forshallow than deep samples. Additionally to Kuklinski(2002b), the current study has revealed distinct fjordinner basin (A4) and shallow small stones (A2) assem-blages.

Acknowledgements Our special thanks are to Dr. Maria Wod-arska-Kowalczuk, Dr. David Barnes and Dr. Paul Taylor forcomments leading to an improved manuscript. Thanks are also dueto Dr. Adam Sokoowski (Gdansk University, Poland), BartoszWitalis (Sea Fishery Institute, Poland) for help with samples col-lection and great company. Work in Ny-Alesund Large ScaleFacility (LSF) was supported by a grant from the EuropeanCommission’s programme (no. NP-51/2001). The study has beencompleted thanks to the funds provided by grant 3 PO4F 081 24

Table 5 Proportion (%) of bryozoan morphologies present in a given assemblage

Shallow (A1) Shallow (A2) Deep (A3) Inner (A4)

Membranous uncalcified 6.02 – 0.87 99.08Runners 4.18 98.02 76.94 –Encrusting sheets/spots 81.90 1.85 21.27 –Erect flexible 7.88 0.11 0.07 0.92Erect rigid – – 0.85 –

Fig. 7 Ratios of (numbers ofindividuals and numbers oftaxa) orders for bryozoanassemblage types

628

from Polish State Committee for Scientific Research, HIGHLATgrant to first author from the European Commission’s programmeand funds from Otto Kinne Foundation.

References

Bak RPM, Engel MS (1979) Distribution, abundance and survivalof juvenile hermatypic corals (Scleractinia) and the importanceof life history strategies in the parent coral community. MarBiol 54:341–352

Barnes DKA, Clarke A (1998) The ecology of an assemblagedominant: the encrusting bryozoan Fenestrulina rugula. InvertBiol 117:331–340

Barnes DKA, Rothery P, Clarke A (1996) Colonisation anddevelopment in encrusting community from the Antarcticintertidal and subtidal. J Exp Mar Biol Ecol 196:251–265

Beszczynska-Moller A, Wcsawski JM, Walczowski W,Zajaczkowski M (1997) Estimation of glacial meltwater dis-charge into Svalbard coastal waters. Oceanologia 39:289–298

Bishop JDD (1989) Colony form and the exploitation of spatialrefuges by encrusting bryozoa. Biol Rev 64:197–218

Bray JR, Curtis JT (1957) An ordination of the upland for-est communities of southern Wisconsin. Ecol Monogr 27:325–349

Carey AG (1991) Ecology of North American Arctic continentalshelf benthos: a review. Cont Shelf Res 11:865–883

Clarke KR, Gorley RN (2001) PRIMER v5: user manual/tutorial,Plymouth: PRIMER–E, p 91

Clarke KR, Green RH (1988) Statistical design and analysis for a‘biological effects’ study. Mar Ecol Prog Ser 46:213–226

Clarke A, Lidgard S (2000) Spatial patterns of diversity in the sea:bryozoan species richness in the North Atlantic. J Anim Ecol69:799–814

Cook P (1981) The potential of minute bryozoan colonies in theanalysis of deep–sea sediments. Cah Biol Mar 22:89–106

Curtis MA (1977) Life cycles and population characteristics ofmarine benthic polychaets from Godhaven, West Greenland.Ophelia 16:9–58

Driscoll EG (1967) Attached epifaunal–substrate relations. LimnolOceanogr 12:633–641

Elverhøi A, Lonne O, Seland R (1983) Glaciomarine sedimentationin a modern fjord environment, Spitsbergen. Polar Res 1:127–149

Farrow GE, Sivitsky JPM, Tunnicliffe V (1983) Suspended par-ticulate loading on the macrobenthos in a highly turbid fjord:Knight Inlet British Columbia. Can J Fish Aquat Sci 40:273–288

Gammelsrod T, Rudels B (1983) Hydrographic and current mea-surements in the Fram Strait, August 1981. Polar Res 1:115–126

Fig. 8 Electron micrographs ofspecies occurring with highestdensities and frequencies(compare Table 1) in particularassemblages: a Electaarctica—species dominating onsmall shallow rocks (<2 cm2),b Hippothoa arctica—speciesdominating in deeper areas;c Celleporella hyalina—speciesdominating and mostfrequently occurring in shallowareas, d Porella rigida—themost frequently occurringspecies in deeper parts,e Alcyonidium disciforme (insitu)—dominating species ininner fjordic areas

629

Gautier YV (1962) Recherches ecologiques sur les Bryozoaireschilostomes en Mediterranee occidentale. Rec Trav Sta MarEndoume 38:1–434

Gontar VI, Hop H, Voronkov AY (2001) Diversity and distribu-tion of Bryozoa in Kongsfjorden, Svalbard. Pol Polar Res22:187–204

Gordon DP (1987) The deep sea bryozoa of the New Zealandregion. In: Ross JRP (ed) Bryozoa: Present and Past. WesternWashington University, Bellingham, pp 97–104

Gorlich K, Wcsawski JM, Zajaczkowski M (1987) Suspensionsettling effect on macrobenthic biomass distribution in theHornsund fjord, Spitsbergen. Polar Res 5:175–192

Grebmeier JM, Feder HM, McRoy CP (1989) Pelagic-benthiccoupling on the shelf of the northern Bering and Chukchi Sea.II. Benthic community structure. Mar Ecol Prog Ser 51:253–268

Gulliksen B, Holte B, Jakola KJ (1985) The soft bottom fauna inVan Mijenfjord and Raudfjord, Svalbard. In: Gray J, Chris-tiansen ME (eds) Marine biology of polar regions and effectsof stress on marine organisms. Wiley and Sons, Oslo, pp 199–215

Gulliksen B, Palerud R, Brattegaard T, Sneli J (1999) Distributionof marine benthic macroorganisms at Svalbard (including BearIsland) and Jan Mayen. Research report for DN 1999 4.Directorate for Nature Management, Trondheim, p 148

Harmelin JG (1979) On some Stomatoporiform species (BryozoaCyclostomata) from the bathyal zone of the NortheasternAtlantic Ocean. In: Larwood GP, Abott MB (eds) Advances inbryozoology, systematics association special volume no 13.Academic, London, pp 403–422

Hop H, Pearson T, Hegseth EN, Kovacs KM, Wiencke C,Kwasniewski S, Eiane K, Mehlum F, Gulliksen B, Wlodarska-Kowalczuk M, Lydersen C, Wcsawski JM, Cochrane S,Gabrielsen GW, Leakey R, Lønne OJ, Zajaczkowski M, Falk-Petersen S, Kendall M, Wangberg SA, Bischof K, VoronkovAY, Kovaltchouk NA, Wiktor J, Poltermann M, Prisco A,Papucci C, Gerland S (2002) The marine ecosystem of Kon-gsfjorden, Svalbard. Polar Res 21:167–208

Hughes DJ (2001) Quantitative analyses of a deep-water bryozoancollection from the Hebridean continental slope. J Mar BiolAssoc UK 81:987–993

Ito H, Kudoh S (1997) Characteristics of water in Kongsfjorden,Svalbard. In: Proceedings of NIPR symposium, polar meteo-rology and glaciology 11:211–232

Jackson JBC (1984) Ecology of cryptic coral reef communities. III.Abundance and aggregation of encrusting organisms withparticular reference to cheilostome Bryozoa. J Exp Mar BiolEcol 75:37–57

Kluge GA (1975) Bryozoa of the northern seas of the USSR.Amerind Publishing Pvt. Co, New Delhi

Kuklinski P (2002a) Fauna of Bryozoa from Kongsfjorden, WestSpitsbergen. Pol Polar Res 23:193–206

Kuklinski P (2002b) Bryozoa of the high arctic fjord–a preliminarystudy. In: Wyse Jackson P, Buttler C, Spencer-Jones M (eds)Bryozoan studies 2001. Balkema, Abingdon, pp 175–182

Kuklinski P, Barnes DKA (2005) Microhabitat diversity of Sval-bard Bryozoa. J Nat Hist 39:539–554

Lidgard S (1990) Growth in encrusting cheilostome bryozoans: II.Circum—atlantic distribution patterns. Paleobiology 16:304–321

Lippert H, Iken K, Rachor E, Wiencke C (2001) Macrofaunaassociated with macroalgae in the Kongsfjord (Spitsbergen).Polar Biol 24:512–522

Loeng H (1991) Features of the physical oceanographic conditionsof the Barents Sea. In: Sakshaug E, Hopkins CCE, OritslandNA (eds) Proceedings of the Pro Mare symposium on polarmarine ecology, vol 10, Trondheim, Polar Res, pp 5–18, 12–16May 1990

Marfenin NN (1997) Adaptation capabilities of marine modularorganisms. Hydrobiologia 355:153–158

Rider J, Cowen R (1977) Adaptive architectural trends inencrusting ectoprocts. Lethaia 10:29–41

Ryland JS (1963) Systematic and biological studies on Polyzoa(Bryozoa) from Western Norway. Sarsia 14:1–61

Ryland JS (1970) Bryozoans. Hutchinson, LondonRyland JS (1974) Behaviour, settlement and metamorphosis of

bryozoan larvae: a review. Thalassia Jugoslavica 10:239–262Svendsen H, Beszczynska-Møller A, Hagen JO, Lefauconnier B,

Tverberg V, Gerland S, Ørbæk JB, Bischof K, Papucci C, Za-jaczkowski M, Azzolini R, Bruland O, Wiencke C, Winther JG,Dallmann W (2002) The physical environment of Kongsfjor-den-Krossfjorden, an Arctic fjord system in Svalbard. Polar Res21:133–166

Syvitski JPM, Farrow GE, Atkinson RJA, Moore PG, Andrew JT(1989) Baffin Island fjord macrobenthos: bottom communitiesand environmental significance. Arctic 42:232–247

Wcsawski JM, Zajaczkowski M, Kwasniewski S, Jezierski J,Moskal W (1988) Seasonality in an Arctic fjord ecosystem:Hornsund, Spitsbergen. Polar Res 6:185–189

Wcsawski JM, Jankowski A, Kwasniewski S, Swerpel S, Ryg M(1991) Summer hydrology and zooplankton in two Svalbardfiords. Pol Polar Res 12:445–460

Wildish D, Kristmanson D (1997) Benthic suspension feeders andflow. Univesristy Press, Cambridge, p 409

Winston JE (1977) Distribution and ecology of estuarine ecto-procts: a critical review. Chesapeake Science 18:34–57

Winston JE, Jackson JBC (1984) Ecology of cryptic coral reefcommunities. IV. Community development and life histories ofencrusting cheilostome Bryozoa. J Exp Mar Biol Ecol 76:1–21

Wlodarska - Kowalczuk M, Pearson T (2004) Soft-bottom mac-robenthic faunal associations and factors affecting species dis-tributions in an arctic glacial fjord (Kongsfjord, Spitsbergen).Polar Biol 27:155–167

Young CM, Chia F-S (1984) An experimental test of shadow re-sponse function in ascidian tadpoles. J Exp Mar Biol Ecol85:165–175

Zaborska A (2001) Lithology of the fiordic bottom sediments,Kongsfjorden (Spitsbergen). MSc Thesis. (in Polish). Universityof Gdansk

Zajaczkowski M (2000) Inflow and rate of sedimentation of chosenfiords of Western Spitsbergen (in Polish). Doctoral Thesis.Gdansk University

630