Environmental influences on bacterial diversity of soils on Signy Island, maritime Antarctic

transcript

Polar Biol (2009) 32:1571–1582

ORIGINAL PAPER

Environmental inXuences on bacterial diversity of soils on Signy Island, maritime Antarctic

Chun Wie Chong · Michael J. Dunn · Peter Convey · G. Y. Annie Tan · Richard C. S. Wong · Irene K. P. Tan

Received: 10 April 2009 / Revised: 20 May 2009 / Accepted: 29 May 2009 / Published online: 16 June 2009© Springer-Verlag 2009

Abstract Soil bacterial diversity at environmentally dis-tinct locations on Signy Island, South Orkney Islands wasexamined using the denaturing gradient gel proWlingapproach. A range of chemical variables in soils at each sitewas determined in order to describe variation between loca-tions. No apparent diVerences in Shannon Diversity Index(H�) were observed. However, as revealed in an analysis ofsimilarity (ANOSIM), the dominant bacterial communitiesof all eight studied locations were signiWcantly diVerent.Within this, higher levels of similarity were observedbetween penguin rookeries, seal wallows and vegetatedsoils, all of which share varying levels of impact from ver-tebrate activity, in contrast with more barren soil. In addi-tion, the lowest H� value was detected from the latter soilwhich also has the most extreme environmental conditions,and its bacterial community has the greatest genetic dis-tance from the other locations. DGGE analyses indicatedthat the majority of the excised and sequenced bands were

attributable to the Bacteroidetes. Across a range of tenenvironmental variables, multivariate correlation analysissuggested that a combination of pH, conductivity, copperand lead content potentially contributed explanatory valueto the measured soil bacterial diversity.

Keywords Bacteria · DGGE · Soil chemical properties · South Orkney Islands · Terrestrial

Introduction

Baseline understanding of bacterial diversity in Antarcticais currently limited despite long-standing recognition thatmicrobial processes underlie the functioning of all ecosys-tems, and that microbiota are often the dominant and some-times the only components of Antarctic ecosystems inparticular (Convey 2001; Vincent 1988; Wynn-Williams1996). Relatively few studies of Antarctic bacterial diver-sity have been reported in comparison with multicellularorganisms (see Adams et al. 2006; Frenot et al. 2005; Wall2005). Although there has been some increased researchattention in recent years, the spatial coverage of terrestrialdiversity studies remains very limited (Chown and Convey2007; Tin et al. 2009).

To date, studies of bacterial diversity on Signy Islandhave focused almost entirely on the freshwater environment(Pearce 2003; Pearce et al. 2003). Only Yergeau et al.(2007a, b) have addressed the bacterial communities of cer-tain terrestrial habitats, as part of a larger microbial diver-sity study spanning the wide environmental gradientbetween the Falkland Islands and southern Antarctic Penin-sula. Nevertheless, a variety of bacteria has been reportedin these studies from diVerent ecosystems on Signy Island(see also Moosvi et al. 2005).

Electronic supplementary material The online version of this article (doi:10.1007/s00300-009-0656-8) contains supplementary material, which is available to authorized users.

C. W. Chong (&) · G. Y. A. Tan · I. K. P. TanFaculty of Science, Institute of Biological Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysiae-mail: cchhoonngg81@yahoo.com

M. J. Dunn · P. ConveyBritish Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge CB3 OET, UK

R. C. S. WongDepartment of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia

1572 Polar Biol (2009) 32:1571–1582

Signy Island harbours a wide range of terrestrial habitats(see Smith (1972) and Holdgate (1977) for detailed descrip-tions of terrestrial habitats and vegetation). The island’sgeology is predominantly quartz-mica-schist with someoutcrops of marble and amphibolites (Caulkett and Ellis-Evans 1997). Being a small island experiencing typicallystrong winds, the entire island is considered to receivenutrient inputs through sea-spray (Bokhorst et al. 2007).Additionally, most terrestrial lowland habitats on the islandare impacted by marine vertebrate activities, notably ornith-ogenic input (guano, etc.) from birds and in particularpenguin rookeries, along with elephant seal (Miroungaleonina) wallows in certain coastal locations, and from rest-ing and moulting fur seals (Arctocephalus gazella) in mostaccessible coastal areas. Thus, levels of vertebrate impactcan be considered along a “gradient” from the mostimpacted sites at the centre of dense penguin rookeries andseal wallows, to the relatively few “non-impacted” loca-tions mostly restricted to higher altitude areas, and areasnot directly accessible from the coast.

The primary objective of the current study was to pro-vide baseline understanding of the dominant contributionsto soil bacterial diversity across soils with widely varyinglevels of vertebrate inXuence on Signy Island. In addition,ten soil chemical parameters were assessed in order to

elucidate the abiotic factors having the greatest inXuence onthe structure of bacterial communities across an environ-mental gradient.

Materials and methods

Study sites

Signy Island (60°43�S 45°36�W) is a maritime Antarcticisland within the South Orkney Island archipelago. Theannual soil temperature is around ¡2°C and annualprecipitation approximates 400 mm year¡1 (Bokhorstet al. 2008). We investigated the dominant soil bacteriacommunity structure and soil chemical proWles fromeight locations (Table 1; Fig. 1), including three associ-ated with penguin rookeries (Gourlay Peninsula, NorthPoint and Cummings Cove), three with seal wallows(Cemetery Flats 1, Cemetery Flats 2 and Elephant Flats),one typical low-altitude vegetated fellWeld soil (Bernt-sen Point) and one more barren high altitude fellWeldsoil (Jane Col). Between them, these diVerent sites pro-vide a subjective gradient or ranking of the level of ver-tebrate impact on their neighbouring terrestrialecosystems.

Table 1 Locations and description of the study sites on Signy Island

Site GPS and elevation Batch Date of collection Description

Gourlay Peninsula 60°43.854�S GL1 17/12/2006 Penguin rookery

45°35.297�W GL2 03/02/2007

Elevation = 22 m

North Point 60°40.495�S NP1 09/01/2007 Penguin rookery

45°37.484�W NP2 18/02/2007

Elevation = 14 m

Cummings Cove 60°44.020�S CCO1 21/01/2007 Penguin rookery

45°39.593W CCO2 18/02/2007

Elevation = 30 m

Elephant Flats 60°42.207�S EF1 21/12/2006 Seal wallows

45°36.584�W EF2 02/02/2007

Elevation = 7 m

Cemetery Flats 1 60°42.343�S CF1.1 10/12/2006 Seal wallows

45°36.196�W CF1.2 04/02/2007

Elevation = 2 m

Cemetery Flats 2 60°42. 408�S CF2.1 10/12/2006 Seal wallows

45°36.246�W CF2.2 04/02/2007

Elevation = 12 m

Berntsen Point 60°42.442�S BP1 14/12/2006 Vegetated fellWeld

45°35.547�W BP2 15/02/2007

Elevation = 28 m

Jane Col 60°41.861�S JC1 09/01/2007 Barren fellWeld

45°37.760�W JC2 07/02/2007

Elevation = 159 m

Polar Biol (2009) 32:1571–1582 1573

North Point is located on the northern coast of theisland, whilst Cummings Cove and the Gourlay Peninsulaare situated in the south-west and south-east parts of theisland, respectively. Three penguin species breed onSigny Island, Adélie (Pygoscelis adelie), chinstrap (P.antarctica) and gentoo (P. papua). Approximately 30,000pairs of Adélie penguin and 50,000 pairs of chinstrap pen-guins constitute the majority of this breeding populationand, of these, 18,000 and 13,000 pairs respectively arelocated on the Gourlay Peninsula (Lynnes et al. 2002)while the rest are distributed around North Point, Cum-mings Cove and the island’s south-west coast (BritishAntarctic Survey, unpublished data). Small colonies (total»700 pairs) of gentoo penguins breed exclusively only atNorth Point. In total, 25% of the Signy breeding penguinpopulation is located at North Point, 26% at CummingsCove and the south west coast, and 49% at the GourlayPeninsula. The Gourlay Peninsula was the most heavilyimpacted site, with soils being obtained within the

penguin rookery. The sampling location at North Pointprovided an intermediate level of penguin impact. Cum-mings Cove and the south west coast of the island includea large area, with individual sub-colonies being more dis-persed, and provided the least impacted of the three rook-ery sites; the chinstrap penguin rookery adjacent to thesample collection site in Cummings Cove included only150–180 pairs of birds.

Cemetery Flats and Elephant Flats are coastal supralit-toral areas including wallows of elephant seals as well asmoulting and resting areas of fur seals during the australsummer. The number of fur seals present on Signy Islandincreases greatly from mid January each year and peaks at15–20,000 individuals in February (Smith 1998). Samplingsites Cemetery Flats 1 and Cemetery Flats 2 were located»250 m apart. The former was closer to the shore and wal-low location, as was the sampling site at Elephant Flats,while the latter was located more inland and was relativelyless impacted, showing visible moss cover.

Fig. 1 Sampling locations on Signy Island

1574 Polar Biol (2009) 32:1571–1582

Berntsen Point is a low altitude vegetated fellWeld sitelocated approximately 500 m from the Signy Research Sta-tion. Although not hosting permanent colonies of penguins orseals, in common with most such terrestrial habitats on SignyIsland, Berntsen Point experiences vertebrate impact in theform of occasional visits of penguins and seals, along withoverXight of smaller petrels from nearby nesting cliVs andscrees, and nesting skuas. Finally, and contrasting with theother locations, Jane Col is largely free of animal inXuence,and shows very limited development of fellWeld vegetation.

Soil sampling

Surface soil samples were collected from eight study siteson Signy Island during the austral summer season 2006/2007 (Fig. 1). General descriptions of each site are given inTable 1. At each sampling location, six replicate soil sam-ples of approximately 50 g each were collected from thetop 5 cm of the soil using sterile falcon tubes. Samples werekept at 4°C prior to soil DNA extraction (within 24 h ofcollection) and frozen at the earliest opportunity (¡20°C)after soil DNA extraction. Traces of plant material (mossand algae) were observed in soil samples from CummingsCove, North Point, Cemetery Flat 2 and Berntsen Point,while samples from the Gourlay Peninsula, Cemetery Flats1 and Jane Col were free of visible vegetation.

Penguin diet data

Penguin diet samples are routinely collected on SignyIsland as part of the Convention for the Conservation ofAntarctic Marine Living Resources (CCAMLR) EcosystemMonitoring Programme (CEMP), using the water-oZoad-ing technique (CCAMLR 1997). These data were accessedfor the purposes of the current study in order to identify anyinXuence on soil chemical variables.

Soil chemical analysis

Soil samples for chemical analysis were processed at SignyResearch Station by drying at 70°C until constant mass todetermine water content and as preparation for subsequentmeasurements. Soil pH was measured in 1:2 (w/v) suspen-sions of dry soil in distilled water. Salinity, measured aselectrical conductivity (�S/cm), was measured in 1:5 (w/v)suspensions of dry soil in water. Analyses of total carbon,hydrogen and nitrogen content of the soils were performedby the Chemistry Department of the National University ofSingapore, using a Perkin-Elmer PE 2400 CHN/CHNS Ele-mental Analyser (Perkin-Elmer, USA) and EuroVectorEA3000 Elemental Analyser (EuroVector, Italy).

Contents of Wve heavy metals were measured as poten-tial indicators of vertebrate inXuence on soils: iron, zinc,

lead, nickel and copper. The metals were extracted from thesoil by digesting 2 g dry soil in 40 mL of 1 M HCl for 4 h inan orbital shaker (Snape et al. 2004). This extractionmethod targets only labile, or bioavailable metals from soil,the component which is most likely to exert inXuence onbiota (Santos et al. 2005; Scouller et al. 2006). The extractswere then Wltered and analysed using an Avanta atomicabsorption spectrometer (GBC ScientiWc Equipment,Australia).

Extraction of total DNA from soil

The UltraClean™ Soil DNA Isolation Kit (MoBio Inc.,USA) was used to extract DNA from soil samples within24 h of collection at Signy Research Station. Approxi-mately 1.0 g soil (wet mass) was loaded into the bead col-umn and the manufacturer’s instructions followed. After aseries of washings, the DNA was eluted in 50 �L TE buVer(10 mM Tris–HCl, 1 mM EDTA, pH 8.0). The extractedDNA samples were stored at ¡20°C before shipment tolaboratories at the University of Malaya, Malaysia.

AmpliWcation of 16S rDNA fragments using nested PCR

For the primary ampliWcation, PCR was Wrst conductedwith primers 27F and 1492R (Newberry et al. 2004). The50 �L reaction mixture contained 1 �L template (50£ dilu-tion of extracted DNA), 0.5 �M of each primer, 0.25 mMof each dNTP, 1£ PCR buVer and 1.25 U Taq DNA Poly-merase. For the secondary ampliWcation, the primer pair341F-GC (with 40 bp GC-clamp) and 907R (Powell et al.2003, 2005) was used and the reaction mixture consisted of0.5 �M of each primer, 0.40 mM of each dNTP, PCR buVer1£ and 2.5 U Taq DNA Polymerase.

Denaturing gradient gel electrophoresis (DGGE)

For bacterial diversity Wngerprinting, DGGE was per-formed with a D-Code Universal Mutation Detection Sys-tem (Bio-Rad, USA). 45 �L of the secondary PCR productswere loaded on a 6% acrylamide gel with a denaturing gra-dient of 35–60% (where 100% denaturant is 7 M urea and40% formamide). Gels were pre-run at 80 V, 60°C in 1£TAE for 30 min before the samples were loaded, and laterat 80 V for 15 h (Powell et al. 2003, 2005).

Gels were stained in 1:10,000 Sybergold in the dark for60 min and then rinsed with distilled water prior to viewingon a UV transilluminator (Syngene Bio Imaging, UK).

Sequencing of DGGE bands

Dominant bands in the DGGE were excised using a scalpelblade and incubated at 4°C overnight in sterile distilled

Polar Biol (2009) 32:1571–1582 1575

water before they were re-ampliWed using the secondaryprimers. The positions of the excised bands in the DGGEgel were conWrmed with repeated DGGE. Bands showingthe expected melting position were ampliWed with the sec-ondary primer without GC-clamp (341F, 907R). The PCRproducts were puriWed using PCRquick-spinTM PCR Prod-uct PuriWcation Kit (iNtRON Biotechnology, Korea) andsequenced with ABI Big Dye Terminator V3.1 kit inABI377-96 upgrade and ABI3100 Genetic Analyzer. Taxo-nomic identities of the partial 16S rRNA gene sequenceswere obtained using the Sequence Match search tool in theRibosomal Database Project II (RDP)-Release 9 andBLAST search in the GenBank database. Genetic distanceof the sequences within each location was analysed byMEGA 3.1 (Kumar et al. 2004) under Jukes Cantor calcula-tion model which averages the pairwise genetic distance of“unique” sequences (bands from diVerent melting posi-tions) detected within six replicates from each location.

Statistical analyses

DiVerences in soil chemical properties between locationswere analysed using one-way ANOVA and the Tukey HSDtest for post hoc analysis.

The DGGE bands were detected and transformed into anabsent/present binary matrix using Quantity One 4.6.5(Bio-Rad, USA). The banding patterns of diVerent gelswere normalized with respect to marker and sequencingresults of bands. The dominant bacterial diversity of eachsite was then described using Shannon’s Diversity Index(H�). Binary data were also aggregated by including a“factor column” for further analysis of the similarities/diVerences between locations subjected to diVerent envi-ronmental inXuences (vertebrate inXuences, vegetatedfellWeld or barren fellWeld).

Comparisons between the sampling sites were madeusing analysis of similarity (ANOSIM) in which an R valueof 1 indicates maximum variation between sites while an Rvalue of 0 shows no diVerence between sites. The resem-blance matrix for DGGE banding pattern was generatedusing Bray-Curtis similarity (Clarke and Gorley 2006)while the resemblance matrix for soil variables was calcu-lated based on Euclidean distance after Log (1 + V) trans-formation. These data were used only in the initialcalculations and hence are not shown in the Results.

The BEST procedure was used to identify the strongestrelationships (correlation) between measured environmen-tal variables and the bacterial community composition asdescribed by DGGE proWles. Spearman correlations wereused and the signiWcance level of the sample statistic wascalculated by permutation test (99 permutations). In orderto measure the variation within sampling locations, multi-variate dispersion indices (MVDISP) were calculated.

All ANOSIM, BEST and MVDISP routines (Clarke andGorley 2006) were carried out using the Primer 6 multivar-iate data analysis package (Plymouth Marine Laboratory,UK).

Results

Soil chemical properties

The pH values of the eight studied soils were generallyacidic (Table 2), with the most alkaline condition beingfound in barren inland soil from Jane Col. SigniWcantlyhigher carbon, nitrogen, water and copper content weremeasured from the densely populated penguin rookeries(North Point, Gourlay Peninsula) in contrast to other loca-tions. Although not statistically signiWcant, samples frompenguin rookeries and seal wallows contained higher levelsof copper and lead than Jane Col and Berntsen Point. Dueto the close proximity of most study locations to sea, mostof the soils registered high electrical conductivity, particu-larly those with strong ornithogenic inXuence (North Pointand Gourlay Peninsula) and Cemetery Flats 1. Conversely,Jane Col which is situated at an elevated inland locationwith much lower vertebrate inXuence, generated the lowestcarbon, nitrogen and conductivity levels.

DGGE proWling and bacterial diversity

The DGGE proWles (Fig. S1) and occurrence frequency ofbands within each location (Table S1) are provided as sup-plementary materials. High within site variability wasobserved from the DGGE proWles (Table 3, Dispersion),with Cummings Cove showing the highest variation andGourlay Peninsula the least. Although no clear pattern inthis intra-site variability was apparent, a trend of lower var-iation in sites with greater nutrient content (carbon andnitrogen; Table 2) was observed when comparison wasmade within the three penguin rookeries (lowest variationin Gourlay Peninsula, followed by North Point and Cum-mings Cove) and within the three seal wallows (lowest var-iation in Elephant Flats, followed by Cemetery Flats 2 andCemetery Flats 1).

A total of 31 DGGE band positions were detected acrossall sampling sites, and the identities of 29 bands were deter-mined (Table 4). The majority of the identiWed bands (21sequences) were assigned to the Bacteroidetes group. Thisclass of bacteria was dominant in all sites (Table 3), withhigher abundance in vertebrate-inXuenced sites (77.27–83.33%) compared to Bernsten Point (72.72%) and JaneCol (70.83%). Most of the sequences aYliated to the Bac-teroidetes showed high homology to uncultured clonesextracted from ornithogenic sites in Antarctica (Table 3). In

1576 Polar Biol (2009) 32:1571–1582

addition, representatives from Firmicutes (three bands),Cyanobacteria (two bands), Acidobacteria (one band), Pro-teobacteria (one band) and an unclassiWed group (one band)were also retrieved. Acidobacteria were identiWed onlyfrom Jane Col.

No statistically signiWcant diVerence in diversity (H�)was apparent between sampling sites (Table 3). However,higher values of H� were observed from penguin rookeriesand seal wallows (with the exception of Cummings Cove).Nevertheless, as shown in Table 3, this might simply bedue to more bands being detected in DGGE from thosesites. The diversity index was not correlated with the esti-mate of genetic distance, with the site with lowest H� (JaneCol) showing the greatest genetic distance while that withthe highest H� (Gourlay Peninsula) showed only moderategenetic distance (Table 3).

Analysis of Similarity (ANOSIM) between samplinglocations (Table 5), indicate signiWcant diVerences in bacte-rial community assemblages between locations (ANOSIM,Global R = 0.393, P = 0.001). The highest discrepancy wasobserved between North Point and Cemetery Flats 2, whileconsiderable diVerence was seen between Gourlay Penin-sula and North Point, and between Gourlay Peninsula andthe three wallow sites. In addition, ANOSIM was per-formed on groups of aggregated data: Cemetery Flats 1,Cemetery Flats 2 and Elephant Flats were grouped as sealwallows; North Point, Gourlay Peninsula and CummingsCove as penguin rookeries (R = 0.324; P = 0.001). Com-parison was then made between these two groupings andJane Col (barren soil) and Berntsen Point (vegetated fell-Weld soil). Notwithstanding the overall diVerences indicatedby ANOSIM, this analysis also indicated that the dominantbacterial groups clearly overlapped within both the animalinXuenced sites and between animal inXuenced sites andvegetated soil, while barren soil community from Jane Colwas again signiWcantly distinct from the other locations(Table 6).

In order to clarify the relationship between soil variablesand bacterial community structure as indicated by DGGEbanding patterns, the bacterial assemblage pattern and soilvariable data were subjected to the BEST routine from thePrimer 6 package (Table 7). The highest correlated singlevariables to the DGGE banding patterns were pH,followed by conductivity and Cu, while the combination ofenvironmental variables with strongest explanatory valueincluded pH, conductivity, Cu and Pb (global R = 0.361,P = 0.0001).

Discussion

High within site variation was observed in both the envi-ronmental variables and DGGE banding patterns of soilT

5a,b§

2a,b§

0a,b§

1a,b§

7a,b§

8a,b§

4a,b§

Polar Biol (2009) 32:1571–1582 1577

samples collected from Signy Island. Analogous observa-tions including variations in soil inorganic nutrient (Arnoldet al. 2003), soil physical and chemical properties (Daveyand Rothery 1993; Holdgate 1977), and patchiness in ter-restrial Xora and fauna (Holdgate 1977; Usher and Booth1986) have been reported previously from Signy Island andalso from Alexander Island (southern maritime Antarctic)(Engelen et al. 2008).

Ornithogenic soils (Gourlay Peninsula, North Point,Cummings Cove) were generally enriched in nutrients,water, salinity and heavy metals compared to non-ornitho-genic soils (Jane Col, Berntsen Point) (Table 2) (Aislabieet al. 2008; Barrett et al. 2006; Melick et al. 1994; Michelet al. 2006; Simas et al. 2007). The higher level of carbonand nitrogen content may be due to constant deposition ofguano and moulted feathers (Mizutani and Wada 1988).Soil pH was consistently slightly acidic in penguin rooker-ies, which can be attributed to mineralization processes act-ing on guano to produce nitric and sulphuric acid (Bölteret al. 1997; Simas et al. 2007).

Despite not being statistically evident in the currentstudy, seal wallows have been reported to possess greaternutrient levels in comparison to mineral soil in Antarctica(Smith 2005). In this study, the total carbon and nitrogenlevels measured in the Signy Island seal wallows weregreater than those found at Jane Col (Table 2) and in min-eral soil elsewhere in Antarctica (Aislabie et al. 2006;Chong et al. 2009). The elevated nutrient contents mea-sured at Berntsen Point may also be attributed to vertebrateinXuence as although this site does not support breedingcolonies, it is clearly close to sites of bird activity (petrelspp. and skua) and is regularly transited by these birds as

well as by penguins and seals. The potential importance ofnutrient input from overXying birds was noted by Bokhorstet al. (2007).

A trend of increasing zinc and copper were observed inseal wallows and penguin rookeries. Krill, which containsenriched levels of trace metals (Table 8), is likely to bethe main source of copper and zinc in penguin and sealdiet, before ultimately being deposited in the soil. Dietdata (between 2004 and 2006), obtained from the routineCCAMLR monitoring programme, indicated that gentoopenguins from North Point, together with chinstrap andAdélie penguins from both North Point and GourlayPeninsula, mainly consume crustaceans consisting ofaround 98% Antarctic krill, Euphausia superba (data notshown). Krill had also been reported to be one of themain diet components in Antarctic seal populations(Green and Williams 1985; Reid 1995). Other dietsincluding Wsh (Table 8) might also contribute to the ele-vated metal content. The copper content in the denselypopulated penguin rookeries (North Point and GourlayPeninsula) was about 10 fold greater than in seal wallows(Table 1). This might be related to the diVerence in metalcontent in animal excrement (10 times more copper inpenguin excrement compared to seal excrement) (Yinet al. 2008). The elevated iron content in vegetated sites(North Point, Cummings Cove, Cemetery Flats 2 andBerntsen Point) as opposed to non-vegetated sites (Gour-lay Peninsula and Jane Col) might have originated fromlocal plant material (algae and moss) (Table 8). Yergeauet al. (2007a) reported that soil iron content in vegetatedsites was approximately twice that in fellWeld locations onSigny Island.

Table 3 Diversity indices, multivariate dispersion indices, genetic distance and taxonomic composition derived from DGGE banding patterns

Number in parentheses refers to number of “unique” bands in each phylum detected from six replicates within each locationa Genetic distance by Jukes Cantor Modelb Total speciesc Shannon Diversity Indexd Multivariate dispersion indices

Gourlay Peninsula

North Point Cummings Cove

Elephant Flats

Cemetery Flats 1

Cemetery Flats 2

Berntsen Point

Jane Col

Distancea 0.236 0.203 0.236 0.236 0.217 0.245 0.276 0.283

Sb 14.83 § 3.54 7.83 § 2.32 7.00 § 3.90 10.67 § 2.34 9.50 § 2.26 9.00 § 2.37 8.67 § 5.39 9.67 § 6.19

H�c 2.68 § 0.22 2.02 § 0.33 1.76 § 0.72 2.35 § 0.23 2.23 § 0.23 2.17 § 0.27 1.97 § 0.69 2.00 § 0.90

Dispersiond 0.346 0.853 1.401 0.836 1.342 0.722 1.142 1.387

Bacteroidetes 81.82% (18) 82.35% (14) 78.95% (15) 77.27% (17) 83.33% (20) 81.25% (13) 72.72% (16) 70.83% (17)

Firmicutes 4.55% (1) 5.88% (1) 10.52% (2) 9.09% (2) 8.33% (2) 6.25% (1) 13.64% (3) 12.5% (3)

Cyanobacteria 9.09% (2) 5.88% (1) 10.52% (2) 4.55% (1) 4.17% (1) 0% (0) 9.09% (2) 8.33% (2)

Proteobacteria 4.55% (1) 5.88% (1) 0% (0) 4.55% (1) 4.17% (1) 6.25% (1) 0% (0) 0% (0)

Acidobacteria 0% (0) 0% (0) 0% (0) 0% (0) 0% (0) 0% (0) 0% (0) 4.17% (1)

UnclassiWed 0% (0) 0% (0) 0% (0) 4.55% (1) 0% (0) 6.25% (1) 4.55% (1) 4.17% (1)

1578 Polar Biol (2009) 32:1571–1582

As suggested by Kowalchuk et al. (2006), the dataobtained from DGGE proWling is more accurately consid-ered as the “structure of dominant populations” rather thana general measure of bacterial diversity, due to the fact thatonly numerically abundant phylotypes will be detected(Nakatsu 2007). Thus, the Shannon Diversity Index (H�)reported here more accurately describes the diversity ofdominant bacteria. No signiWcant diVerences were observedfrom H� values obtained from all eight studied sites(Table 3). Nevertheless, vertebrate inXuenced sites (with

the exception of Cummings Cove) showed a tendency forgreater H� values.

One of the limitations in interpretation of presence-absence binary data generated from DGGE using diversityindices relates to the inability to diVerentiate between siteswith same or similar number of bands (Gafan et al. 2005).For example, a site which produces three bands associatedwith Pseudomonas in DGGE will have no diVerence (interms of index) with another site which produces threebands associated with cyanobacteria. Hence, analysis of

Table 4 Identity of excised and sequenced DGGE bands from BLAST search in GenBank

Band Closest relative from GenBank BLAST search

Hit (%) Phylum/sub-phylum

Accession no.

Origin

B1 Uncultured cyanobacterium clone A822 99 Cyanobacteria EU283559 Anderson Lake, USA

B2 Uncultured bacterium; KD8-75 99 Bacteroidetes AY218692 Penguin Droppings Sediments, Ardley Island

B5 Uncultured bacterium clone KD7-36 99 Bacteroidetes AY218708 Penguin Droppings Sediments, Ardley Island

B6 Uncultured bacterium; UOXD-e10 98 Bacteroidetes EU869765 Onyx River, Antarctica

B8 Uncultured Bacteroidetes; AI-1F_E12 99 Bacteroidetes EF219546 Unvegetated soil environments, Anchorage Island

B9 Uncultured bacterium; KD8-102 99 Bacteroidetes AY218677 Penguin Droppings Sediments

B10 Uncultured soil bacterium; E08_bac_con 100 Bacteroidetes EU861850 Dry meadow surface soil

B11 Uncultured bacterium clone KD5-100 100 Proteobacteria AY218723 Penguin Droppings Sediments, Ardley Island

B13 Uncultured bacterium; zEL27 97 Bacteroidetes DQ415821 Frasassi sulWdic cave stream bioWlm

B14 Pedobacter kribbensis strain PB93 96 Bacteroidetes EF660752 Soil

B15 Lewinella nigricans, strain ATCC 23147T 90 Bacteroidetes AM295255 Beach Sediment

B16 Uncultured bacterium; BFA_075 95 Bacteroidetes EF444134 Freshwater wetland soils

B19 Uncultured soil bacterium; TIIA5 98 Bacteroidetes DQ297951 Hydrocarbon contaminated soil

B20 Uncultured bacterium; SRRB35 98 Bacteroidetes AB240509 Environmental sample

B21 Ginsengisolibacter sp. NP11 99 Bacteroidetes EU196345 Cold Saline SulWdic Spring, Canadian High Arctic

B22 Uncultured bacterium clone FCPT767 97 UnclassiWed EF516481 Grassland soil

B23 Uncultured Firmicutes; GASP-MA1W3_H06 97 Firmicutes EF662740 Cropland

B25 Phormidium autumnale CCALA 697 99 Cyanobacteria AM778710 Cultures

B26 Uncultured Clostridiaceae; pCOF_65.7_F11 94 Firmicutes EU156149 Hot Spring

B27 Uncultured Firmicutes; GASP-MB1S2_E01 91 Firmicutes EF664607 Forest Soil

B29 Uncultured bacterium; 1/2/3B 99 Bacteroidetes FJ380137 Antarctica: Cape Hallett

B31 Uncultured bacterium; Elev_16S_1335 85 Acidobacteria EF019956 Trembling aspen rhizosphere

Polar Biol (2009) 32:1571–1582 1579

similarity (ANOSIM; Tables 5, 6) was carried out to sup-plement H�. ANOSIM indicated a signiWcant diVerenceacross all sites, and that the dominant bacteria communitystructure in all the studied locations was signiWcantly diVer-ent. Notwithstanding this diVerence between sites, whencomparison was made between aggregated site data(Table 6), the highest similarity was observed between sealwallows, penguin rookeries and vegetated fellWeld soil,suggesting a general eVect of vertebrate guano and vegeta-tion in inXuencing soil bacterial community structure. Con-versely, Jane Col exhibited the most distinct dominantbacteria community structure. This observation was

partially in agreement with the genetic distance (Table 3),as Jane Col also showed the greatest genetic distance. Siteswith animal inXuence (rookeries 0.203–0.236; wallows0.217–0.245) recorded lower genetic distances than vege-tated fellWeld soil (0.276) and barren soil (0.283).

The majority of the retrieved bacterial sequences wasfrom the Bacteroidetes. This class is commonly found inAntarctica and has been reported to possess the ability todegrade a wide range of polymeric substances such as chi-tin and cellobiose (Aislabie et al. 2006, 2008; Li et al.2006). The highest Bacteroidetes proportion was obtainedin DGGE proWles from seal wallows and penguin rookeries(77.27–83.33%). Members of the Bacteroidetes have beenfound to be prevalent in the intestine and faeces of mam-mals (Dick and Field 2004; Flint et al. 2007), and membersof Flavobacteriaceae are prominent during the early stagesof guano decomposition (Zdanowski et al. 2004).

The cyanobacterium Phormidium autumnale had beenisolated previously from Jane Col, Signy Island (Wynn-Williams 1996). In the current study, sequences showinghigh homology to this cyanobacterium were detected fromall sites except Cemetery Flats 1 and 2. In addition,sequences aYliated with Firmicutes were also presentacross all sampling sites. A sequence associated with Aci-dobacteria was only detected at Jane Col. This group ofbacteria is commonly extracted from Antarctic soils (Aisla-bie et al. 2006) and tends to occur in moist soils with alka-line pH and low EC (Aislabie et al. 2008), as found here inJane Col. The low occurrence of cyanobacteria and acido-bacteria in this study is generally in agreement with studiesconducted elsewhere in Antarctica (Aislabie et al. 2006;2008; Powell et al. 2003), suggesting lower overall abun-dance of these groups in Antarctic soil.

Although our Wnding of pH as the most important factorinXuencing bacterial diversity is in agreement with Fierer andJackson (2006), care has to be taken when interpreting thesedata as no consistent correlations between soil variables and

Table 5 Pairwise ANOSIM of DGGE derived bacteria community structure (Global R = 0.393; P = 0.001)

ns Not signiWcant, BT Berntsen Point, JC Jane Col, CCO Cummings Cove, GL Gourlay Peninsula, EF Elephant Flats, CF2 Cemetery Flats 2,CF1 Cemetery Flats 1

* P < 0.05, ** P < 0.01

BT JC CCO GL NP EF CF2 CF1

JC 0.334*

CCO 0.206ns 0.235*

GL 0.560** 0.530** 0.404**

NP 0.496** 0.514** 0.260* 0.791**

EF 0.357* 0.524** 0.460** 0.706** 0.387**

CF2 0.468** 0.629** 0.447** 0.743** 0.859** 0.443**

CF1 0.091ns 0.420** 0.23ns 0.376** 0.254* 0.020ns 0.126ns

Table 6 Grouped pairwise ANOSIM of sites with and without animalinXuence (Global R = 0.324; P = 0.001)

a Berntsen Pointb Jane Colc Gourlay Peninsula, North Point and Cummings Coved Cemetery Flats 1, Cemetery Flats 2 and Elephant Flats

* P < 0.05, ** P < 0.01

Vegetated Barren Rookeries Wallows

Vegetateda

Barrenb 0.334*

Rookeriesc 0.262* 0.362*

Wallowsd 0.285** 0.609** 0.261**

Table 7 Spearman rank correlations of environmental variables withthe bacterial DGGE banding proWles (Global R = 0.316; P = 0.0001)

Correlation coeYcients

Variables

Single variables 0.230 pH

0.145 E.C.

0.136 Cu

Multiple variables 0.316 pH, E.C. Cu and Pb

0.313 pH, E.C. and Pb

0.309 pH and Pb

1580 Polar Biol (2009) 32:1571–1582

bacterial diversity or bacterial abundance had been reportedfrom previous studies. Based on Yergeau et al. (2007a), theabundance of 16S rRNA genes obtained from the soil of veg-etated and fellWeld sites from three locations across diVerentlatitudes progressing into Antarctica (Falkland Islands, SignyIsland, Anchorage Island) was signiWcantly positively corre-lated with water content (r = 0.56), conductivity (r = 0.54)and chloride (r = 0.51). Stark et al. (2003) found that certainheavy metal (Cd, Cu, Pb, Sn, and Zn) concentrations mightprovide the strongest explanatory power for the microbialassemblage pattern in near shore sediments.

Conclusions

The bacterial communities of all eight studied locations onSigny Island diVered signiWcantly, despite those from vege-tated soil, seal wallows and penguin rookeries also showingconsiderable overlap. Although vertebrate inXuenced sitesgenerally showed greater dominant bacterial diversity, thegenetic distances calculated from retrieved sequences sug-gested otherwise. Thus, the greatest genetic distance wasobserved at Jane Col, a site with alkaline pH and the lowestnutrient (carbon and nitrogen) levels. A combination of pH,conductivity, Cu and Pb showed the highest explanatoryvalue for the bacterial community structure across thesestudy locations.

Acknowledgments This project was funded by the Malaysian Ant-arctic Research Programme (MARP), and the British Antarctic Survey(BAS) provided logistic support and Weld training. It also forms acontribution to the BAS BIOFLAME and SCAR EBA research

programmes. We thank Roger Worland and David Routledge for assis-tance in sample collection.

References

Adams BJ, Bardgett RB, Ayres E, Wall DH, Aislabie J, Bamforth S,Bargagli R, Cary C, Cavacini P, Connell L, Convey P, Fell JW,Frati F, Hogg ID, Newsham KK, O’Donnell A, Russell N, SeppeltRD, Stevens MI (2006) Diversity and distribution of VictoriaLand biota. Soil Biol Biochem 38:3003–3018. doi:10.1016/j.soilbio.2006.04.030

Aislabie JM, Chhour K, Saul DJ, Miyauchi S, Ayton J, Paetzold RF,Balks MR (2006) Dominant bacteria in soils of Marble Point andWright Valley, Victoria Land, Antarctica. Soil Biol Biochem38:3041–3056. doi:10.1016/j.soilbio.2006.02.018

Aislabie JM, Jordan S, Barker GM (2008) Relation between soil clas-siWcation and bacterial diversity in soils of the Ross Sea region,Antarctica. Geoderma 144:9–20. doi:10.1016/j.geoderma.2007.10.006

Arnold RJ, Convey P, Hughes KA, Wynn-Williams DD (2003)Seasonal periodicity of physical factors, inorganic nutrients andmicroalgae in Antarctic fellWelds. Polar Biol 26:396–403.doi:10.1007/s00300-003-0503-2

Barrett JE, Virginia RA, Wall DH, Cary SC, Adams BJ, Hacker AL,Aislabie JM (2006) Co-variation in soil biodiversity and biogeo-chemistry in northern and southern Victoria Land, Antarctica.Antarct Sci 18:535–548. doi:10.1017/S0954102006000587

Bokhorst S, Huiskes A, Convey P, Aerts R (2007) External nutrientinputs into terrestrial ecosystems of the Falkland Islands andthe Maritime Antarctic region. Polar Biol 30:1315–1321.doi:10.1007/s00300-007-0256-4

Bokhorst S, Huiskes A, Convey P, van Bodegom PM, Aerts R (2008)Climate change eVects on soil arthropod communities from theFalkland Islands and the Maritime Antarctic. Soil Biol Biochem40:1547–1556. doi:10.1016/j.soilbio.2008.01.017

Bölter M, Blume HP, Schneider D, Beyer L (1997) Soil properties anddistributions of invertebrates and bacteria from King George

Table 8 Heavy metal content (�g/g dry weight) of representa-tive Antarctic organisms

Species Cu Zn Fe Pb Ni References

Palmaria decipiens (n = 10) – 37.8 4,450 – – Santos et al. (2006)

Macrocystis spp. (n = 10) – 27.7 91 – – Santos et al. (2006)

Desmarestia spp. (n = 10) – 39.6 460 – – Santos et al. (2006)

Bryophytes

Bryum spp. (n = 5) – 18.1 3,040 – – Santos et al. (2006)

Polytrichum spp. (n = 5) – 28.0 4,348 – – Santos et al. (2006)

Lichen

Usnea spp. (n = 10) – 5.6 139 – – Santos et al. (2006)

Crustacea

Euphausia superba (n = 76) 12.7 9.6 3.6 0.04 0.45 Yamamoto et al. (1987)

E. superba (n = 76) 54.1 44.5 14.4 0.45 1.87 Honda et al. (1987)a

E. superba (n = 20) 36.0 122.0 140 0.019 3.0 Deheyn et al. (2005)

Trematomus scotti (n = 12) 2.0 27.0 90 1.0 13.0 Deheyn et al. (2005)

Champsocephalus gunnari (n = 5) 12.0 86.0 800 8.0 1,020.0 Deheyn et al. (2005)

Trematomus bernacchii (n = 30) 0.29 7.78 2.12 – 0.07 Honda et al. (1987)a

Pagothenia borchgrevinki (n = 22) 0.65 11.1 6.51 0.15 0.08 Honda et al. (1987)aa As �g/g wet weight

Polar Biol (2009) 32:1571–1582 1581

Island (Arctowski Station), Maritime Antarctic. Polar Biol18:295–304. doi:10.1007/s003000050191

Caulkett AP, Ellis-Evans JC (1997) Chemistry of streams of SignyIsland, maritime Antarctic: sources of major ions. Antarct Sci9:3–11. doi:10.1017/S0954102097000023

CCAMLR (1997) CCAMLR ecosystem monitoring program: standardmethods for monitoring studies. Commission for the Conserva-tion of Antarctica Living Resources (CCAMLR), Hobart

Chong CW, Tan GYA, Wong RCS, Riddle MJ, Tan IKP (2009) DGGEWngerprinting of bacteria in soils from eight ecologically diVerentsites around Casey Station, Antarctica. Polar Biol 32:853–860.doi:10.1007/s00300-009-0585-6

Chown SL, Convey P (2007) Spatial and temporal variability acrosslife’s hierarchies in the terrestrial Antarctic. Philos Trans R Soc B362:2307–2331. doi:10.1098/rstb.2006.1949

Clarke KR, Gorley RN (2006) PRIMER v6: User Manual/Tutorial.PRIMER-E, Plymouth

Convey P (2001) Antarctic ecosystems. In: Levin SA (ed) Encyclope-dia of biodiversity, vol 1. Academic Press, San Diego, pp 171–184

Davey MC, Rothery P (1993) Primary colonization by microalgae inrelation to spatial variation in edaphic factors on Antarctic fell-Weld soils. J Ecol 81:335–343. doi:10.2307/2261503

Deheyn DD, Gendreau P, Baldwin RJ, Latz MI (2005) Evidence forenhanced bioavailability of trace elements in the marine ecosys-tem of Deception Island, a volcano in Antarctica. Mar EnvironRes 60:1–33. doi:10.1016/j.marenvres.2004.08.001

Dick LK, Field KG (2004) Rapid estimation of numbers of fecal bac-teroidetes by use of a quantitative PCR assay for 16S rRNAgenes. Appl Environ Microbiol 70:5695–5697. doi:10.1128/AEM.70.9.5695-5697.2004

Engelen A, Convey P, Hodgson DA, Worland MR, Ott S (2008) Soilproperties of an Antarctic inland site: implications for ecosystemdevelopment. Polar Biol 31:1453–1460. doi:10.1007/s00300-008-0486-0

Fierer N, Jackson RB (2006) The diversity and biogeography of soilbacterial communities. Proc Natl Acad Sci 103:626–631.doi:10.1073_pnas.0507535103

Flint HJ, Duncan SH, Scott KP, Louis P (2007) Interactions and com-petition within the microbial community of the human colon:links between diet and health. Environ Microbiol 9:1101–1111.doi:10.1111/j.1462-2920.2007.01281.x

Frenot Y, Chown SL, Whinam J, Selkirk PM, Convey P, Skotnicki M,Bergstrom DM (2005) Biological invasions in the Antarctic: ex-tent, impacts and implications. Biol Rev Camb Philos Soc 80:45–72. doi:10.1017/S1464793104006542

Gafan GP, Lucas VS, Roberts GJ, Petrie A, Wilson M, Spratt DA(2005) Statistical analyses of complex denaturing gradient gelelectrophoresis proWles. J Clin Microbiol 43:3971–3978.doi:10.1128/JCM.43.8.3971-3978.2005

Green K, Williams R (1985) Observations on food remains in faeces ofelephant, leopard and crabeater seals. Polar Biol 6:1432–2056.doi:10.1007/BF00446239

Holdgate MW (1977) Life sciences: terrestrial ecosystem in Antarctic.Philos Trans R Soc B 279:5–25. doi:10.1098/rstb.1977.0068

Honda K, Yamamoto Y, Tatsukawa R (1987) Distribution of heavymetals in Antarctic marine ecosystem. Proc NIPR Symp PolarBiol 1:184–197

Kowalchuk GA, Drigo B, Yergeau E, van Veen JA (2006) Assessingbacterial and fungal community structure in soil using ribosomalRNA and other structural gene markers. In: Nannipieri P, SmallaK (eds) Nucleic Acids and Proteins in Soil, Soil Biology, vol 8, pp159–188

Kumar S, Tamura K, Nei M (2004) MEGA3: integrated software formolecular evolutionary genetics analysis and sequence align-ment. Brief Bioinform 5:150–163. doi:10.1093/bib/5.2.150

Li S, Xiao X, Yin X, Wang F (2006) Bacterial community along ahistoric lake sediment core of Ardley Island, west Antarctica.Extremophiles 10:461–467. doi:10.1007/s00792-006-0523-2

Lynnes AS, Reid K, Crozall JP, Trathan PN (2002) ConXict or co-exis-tence? Foraging distribution and competition for prey betweenAdélie and chinstrap penguins. Mar Biol (Berl) 141:1165–1174.doi:10.1007/s00300-004-0617-1

Melick DR, Hovenden MJ, Seppelt RD (1994) Phytogeography ofbryophyte and lichen vegetation in the Windmill Islands, WilkesLand, Continental Antarctica. Plant Ecol 111:71–87. doi:10.1007/BF00045578

Michel RFM, Schaefer CEGR, Dias LE, Simas FNB, Benites VDM,Mendonça EDS (2006) Ornithogenic Gelisols (Cryosols) frommaritime Antarctica: pedogenesis, vegetation, and carbon studies.Soil Sci Soc Am J 70:1370–1376. doi:10.2136/sssaj2005.0178

Mizutani H, Wada E (1988) Nitrogen and carbon isotope ratios in sea-bird rookeries and their ecological implications. Ecology 69:340–349. doi:10.2307/1940432

Moosvi SA, McDonald IR, Pearce DA, Kelly DP, Wood AP (2005)Molecular detection and isolation from Antarctica of methylo-trophic bacteria able to grow with methylated sulfur compounds.Syst Appl Microbiol 28:541–554. doi:10.1016/j.syapm.2005.03.002

Nakatsu CH (2007) Soil microbial community analysis using denatur-ing gradient gel electrophoresis. Soil Sci Soc Am J 71:562–571.doi:10.2136/sssaj2006.0080

Newberry CJ, Webster G, Cragg BA, Parkes RJ, Weightman AJ, FryJC (2004) Diversity of prokaryotes and methanogenesis in deepsubsurface sediments from the Nankai Trough, Ocean DrillingProgram Leg 190. Environ Microbiol 6:274–287. doi:10.1111/j.1462-2920.2004.00568.x

Pearce DA (2003) Bacterioplankton community structure in a mari-time Antarctic Oligotrophic Lake during a period of Holomixis,as determined by Denaturing Gradient Gel Electrophoresis(DGGE) and Xuorescence in situ hybridization (FISH). MicrobEcol 46:92–105. doi:1007/S00248-002-2039-3

Pearce DA, van der Gast CJ, Lawley B, Ellis-Evans JC (2003) Bacte-rioplankton community diversity in a maritime Antarctic lake,determined by culture-dependent and culture-independent tech-niques. FEMS Microbiol Ecol 45:59–70. doi:10.1016/S0168-6496(03)00110-7

Powell SM, Bowman JP, Snape I, Stark JS (2003) Microbial commu-nity in pristine and polluted nearshore Antarctic sediments.FEMS Microbiol Ecol 45:135–145. doi:10.1016/S0168-6496(03)00135-1

Powell SM, Snape I, Bowman JP, Thompson BAW, Stark JS, McCam-mon SA, Riddle MJ (2005) A comparison of the short term eVectsof diesel fuel and lubricant oils on Antarctic benthic microbialcommunities. J Exp Mar Biol Ecol 322:53–65. doi:10.1016/j.jembe.2005.02.005

Reid K (1995) The diet of Antarctic fur seals (Arctocephalus gazellaPeters 1875) during winter at South Georgia. Antarct Sci 7:241–249. doi:10.1017/S0954102095000344

Santos IR, Silva-Filho EV, Schaefer CEGR, Albuqueque-Filho MR,Campos LS (2005) Heavy metal contamination in coastal sedi-ments and soils near the Brazilian Antarctic Station, King GeorgeIsland. Mar Pollut Bull 50:185–194. doi:10.1016/j.marpolbul.2004.10.009

Santos IR, Silva-Filho EV, Schaefer C, Sella SM, Silva CA, Gomes V,Passos MJACR, Ngan PV (2006) Baseline mercury and zinc con-centrations in terrestrial and coastal organisms of Admiralty Bay,Antarctica. Environ Pollut 140:304–311. doi:10.1016/j.envpol.2005.07.007

Scouller RC, Snape I, Stark JS, Gore DB (2006) Evaluation of geo-chemical methods for discrimination of metal contamination inAntarctic marine sediments: a case study from Casey Station.

1582 Polar Biol (2009) 32:1571–1582

Chemosphere 65:294–309. doi:10.1016/j.chemosphere.2006.02.062

Simas FNB, Schaefer CEGR, Melo VF, Albuquerque-Filho MR,Michel FM, Pareira VV, Gomes MRM, Da Costa LM (2007)Ornithogenic cryosols from maritime Antarctica: phosphatizationas a soil forming process. Geoderma 138:191–203. doi:10.1016/j.geoderma.2006.11.011

Smith RIL (1972) Vegetation of the South Orkney Islands with partic-ular reference to Signy Island. Br Antarct Surv Sci Rep 68:124

Smith RIL (1998) Destruction of Antarctic terrestrial ecosystems byrapidly increasing fur seal population. Biol Conserv 45:55–72

Smith VR (2005) Moisture, carbon and inorganic nutrient controls ofsoil respiration at a sub-Antarctic island. Soil Biol Biochem37:81–91. doi:10.1016/j.soilbio.2004.07.026

Snape I, Scouller RC, Stark SC, Stark J, Riddle MJ, Gore DB (2004)Characterisation of the dilute HCl extraction method for the iden-tiWcation of metal contamination in Antarctic marine sediments.Chemosphere 57:491–504. doi:10.1016/j.chemosphere.2005.07.040

Stark JS, Riddle MJ, Snape I, Scouller RC (2003) Human impacts inAntartic marine soft-sediment assemblages: correlations betweenmultivariate biological patterns and environmental variables atCasey Station. Estuar Coast Shelf Sci 56:717–734. doi:10.1016/S0272-7714(02)00291-3

Tin T, Fleming ZL, Hughes KA, Ainley DG, Convey P, Moreno CA,PfeiVer S, Scott J, Snape I (2009) Review: impacts of local humanactivities on the Antarctic environment. Antarct Sci 21:3–33.doi:10.1017/S0954102009001722

Usher MB, Booth RG (1986) Arthropod communities in a maritimeAntarctic moss-turf habitat: multiple scales of pattern in the mitesand Collembola. J Anim Ecol 55:155–170. doi:10.2307/4699

Vincent WF (1988) Microbial ecosystems of Antarctica. CambridgeUniversity Press, Cambridge, p 303

Wall DH (2005) Biodiversity and ecosystem functioning in terrestrialhabitats of Antarctica. Antarct Sci 17:523–531. doi:10.1017/S0954102005002944

Wynn-Williams DD (1996) Antarctic microbial diversity: the basis ofpolar ecosystem processes. Biodivers Conserv 5:1271–1293.doi:10.1007/BF00051979

Yamamoto Y, Honda K, Tatsukawa R (1987) Heavy metal accumula-tion in Antarctic krill Euphausia Superba. Proc NIPR Symp PolarBiol 1:198–204

Yergeau E, Bokhorst S, Huiskes AHL, Boschker HTS, Aerts R,Kowalchuk GA (2007a) Size and structure of bacterial, fungaland nematode communities along an Antarctic environmentalgradient. FEMS Microbiol Ecol 59:436–451. doi:10.1111/j.1574-6941.2006.00200.x

Yergeau E, Newsham KE, Pearce DA, Kowalchuk GA (2007b) Pat-terns of bacterial diversity across a range of Antarctic terrestrialhabitats. Environ Microbiol 9:2670–2682. doi:10.1111/j.1462-2920.2007.01379.x

Yin X, Xia L, Sun L, Luo H, Wang Y (2008) Animal excrement: apotential biomonitor of heavy metal contamination in the marineenvironment. Sci Total Environ 399:179–185. doi:10.1016/j.scitotenv.2008.03.005

Zdanowski MK, Weglenski P, Golik P, Sasin JM, Borsuk P, ZmudaMJ, Stankovic A (2004) Bacterial diversity in Adélie penguin,Pygoscelis adeliae, guano: molecular and morpho-physiologicalapproaches. FEMS Microbiol Ecol 50:163–173. doi:10.1016/j.femsec.2004.06.012

Environmental influences on bacterial diversity of soils on Signy Island, maritime Antarctic

Documents