Protistology
Protistology 7 (1), 51–58 (2012)
Testate amoebae of arctic tundra landscapes
A. A. Bobrov1 and S. Wetterich2
1
2
Soil Department of Moscow State University, Moscow, Russia
Alfred-Wegener-Institut for Polar- and Marine Research,
Department of Periglacial Research, Potsdam, Germany
Summary
Testate amoebae (rhizopods) from Russian tundra landscapes of the arctic mainland
and islands were studied. In a total of 274 samples analyzed, 215 species and
subspecies were found. More than half of the species diversity was represented
by hygro- and hydrophilic, and sphagnophilic species of four genera: Difflugia,
Centropyxis, Arcella and Euglypha. Almost all species belong to the cosmopolitan
group of testate amoebae. Only Centropyxis gasparella, C. gasparella v. corniculata, C.
pontigulasiformis, Difflugiella vanhoornei and Difflugia ovalisima might be attributed
to arctic endemics because they have not been reported so far from other regions
than the Arctic.
Key words: testate amoebae, tundra, arctic Yakutia, Siberian Arctic
Introduction
Testate amoebae are a group of free-living
protozoans having an external shell (testa). Some
taxa from this group are covered with exogenous
mineral material (xenosomes), plant detritus, or
endogenous material (idiosomes), such as silica or,
rarely, calcium phosphate plates. Their well-defined
ecological preferences and the relatively good
preservation of fossil shells in peats, lake sediments,
and buried soils form the basis for the development
of rhizopod analysis as a method for reconstruction
of climate and environmental changes (Meisterfeld,
1977; Tolonen, 1986; Charman et al., 2007, 2009,
2010; Booth, 2010; Tsyganov et al., 2011, 2012;
Sullivan and Booth, 2011).
Testate amoebae, being inherently aquatic,
respond to environmental changes in ground water
table, moisture, pH, content of biophilic elements
(C, N, P, K, Ca, Mg) by restructuring their
communities. Testate amoebae can be classified into
ecological groups according to their requirements
concerning moisture (hygrophiles, hydrophiles,
xerophiles), pH (acidophiles, calciophiles), habitat
preferences (sphagnophiles, soil-inhabiting, aquatic). Their density in lake sediments, peat and
soils can vary from a few hundred to tens of
thousands of shells per cm3. The number of taxa in
oligotrophic bogs can reach several tens of species
and infraspecific forms. The significance of rhizopod
analysis for paleoecological studies is based on the
fact that testate amoebae are permanently affixed to
the substrate. Their shells are normally destroyed if
the sediments are redeposited. Therefore, they are
often the only organisms that can directly indicate
the paleoenvironmental conditions during sediment
© 2012 The Author(s)
Protistology © 2012 Protozoological Society Affiliated with RAS
52
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A.A. Bobrov and S. Wetterich
formation, unlike many other biological remains.
The study of modern rhizopods in the Arctic was
initiated in the late 19th and early 20th centuries
(Scourfield, 1897; Penard, 1903; Sandon, 1924)
and was continued after a long interval. Moss and
lichen pads, soils, and small pools were studied
in eastern and western Greenland, northwestern
Spitsbergen, Brabant Island, and some other Arctic
areas (Bonnet, 1965; Schönborn, 1966; Beyens
and Chardez, 1986; Beyens et al., 1986a, 1986b;
1991, 1992, 2000; Smith, 1987; Opravilova, 1989;
Balik, 1994). In a recent study on the rhizopod
fauna of northeast Greenland (Trappeniers et al.,
2002) special attention was paid to an evaluation of
quantitative relationships between the composition
of testate amoebae soil assemblages and ecological
parameters (pH, organic matter, moisture) of their
habitats and communities.
Modern testate amoebae of the Russian Arctic
are almost not described. Only three publications
during the last 110 years were devoted to this region.
Rhizopods collected near Murmansk and Vaygach
Island in Russian Arctic were studied by Awerinzev
and Levander (Beyens et al., 2000). The rhizopods
are not numerous in the moss and aquatic biotopes
of the coastal areas of the Barents and Kara Seas,
only 45 species, varieties and forms have been found
there (Beyens et al., 2000).
Since many years, the East Siberian Arctic
attracted paleoecologists who studied late Quaternary and modern environment (Yurtsev, 1981; Sher,
1987a, 1987b). However, data about soil-inhabiting
protozoa are still lacking except of one publication
where testate amoebae findings of ground surface
samples from Bykovsky Peninsula (Central Laptev
Sea) are mentioned (Bobrov et al., 2004).
Earlier studies showed that (1) the density
and biodiversity of testate amoebae in the modern
high-latitude Arctic decrease with the decrease in
average summer temperatures, i.e. with harsher
climate conditions, and (2) some species respond
to lower temperatures by reducing the size of their
shells (Smith, 1988).
The aim of this study is to conduct a detailed
analysis of modern testate amoebae from the East
Siberian Arctic and Alaska, their geographical
distribution and ecological specifics.
Material and methods
Modern testate amoebae communities have
been studied from a total of 274 soil, lake sediment
and peat surface samples mainly from the Central
and East Siberian Arctic, but also from Alaska (Fig.
1, Table 1): Severnaya Zemlya Archipelago (1, 2),
Taymyr Peninsula (3), Western Laptev Sea (4),
Lena Delta (5, 6. 7, 8), Central Laptev Sea region
(9), New Siberian Archipelago (10, 11), Indigirka
lowland (12) and Seward Peninsula, Alaska (13).
The overall modern climate conditions are
harsh and characterized by long (>8 month), severe
winters and short cold summers with mean July
temperatures of about or below 9 °C, mean January
temperatures of about or above -34 °C, and annual
precipitation from about 80 to 300 mm (Atlas
Arktiki, 1985).
Soils in the area are mainly tundra-gley and
peaty-gley (histosols and inceptisols) with an activelayer thickness of about 30 to 40 cm. The area belongs
to the zone of northern tundra. Mosses, grasses and
low shrubs dominate the vegetation, with typical
vascular plant species such as Betula exilis, Dryas
punctata, Salix pulchra, Cassiope tetragona, Oxyria
digyna, Alopecurus alpinus, Poa arctica, Carex
ensifolia, C. rotundifolia, Eriophorum medium, mosses
Aulacomnium turgidum, Hylocomium alaskanum,
Drepanocladus iniciatus, Calliergon sarmentosum,
and lichens Alectoria ochroleuca, Cetraria cuculliata
and C. hiascus (Atlas Arktiki, 1985).
Samples of soil and sediments were suspended
in water and passed through 500 µm mesh to remove
large particles. Rhizopod shells were concentrated
with a centrifuge. A drop of suspension was placed
on the slide, and the glycerol was added. Normally,
5 subsamples from each sample were examined at
200-400× magnification with the light microscope.
The PAST software was employed to analyze the
data.
Results and discussion
In a total of 274 surface samples from different
elements of arctic tundra landscapes, 215 species
and subspecies have been identified. More than
half of the taxa belong to hygro-hydrophilic and
sphagnobiontic species of the genera Difflugia,
Centropyxis, Arcella, Euglypha (Fig. 2). Most of
the identified species belong to the cosmopolitan
group, including sphagnobionts, hygro-hydrophiles,
soil-inhabiting and eurybiontic species (Fig. 3). The
ecological structure of the communities was similar
on arctic islands and on the mainland, and dominated
by hygro-hydrophilic species. Outcrops of carbonate
rocks ensure a broad presence of calciphiles, mainly
represented by Centropyxis plagiostoma (sensu
lato) which prefers neutral to slightly acidic pH.
Protistology
· 53
Fig. 1. Map of the Arctic, the Laptev Sea region and the sampling areas: 1 – October Revolution Island; 2 –
Bol’shevik Island; 3 – Taymyr Peninsula; 4 – Cape Mamontov Klyk; 5 – Lake Nikolay; 6 – Ebe-Basyn-Sise
Island; 7 - Olenyok Channel; 8 – Samoylov Island; 9 – Bykovsky Peninsula; 10 – Bol’shoy Lyakhovsky Island;
11 – Kotel’ny, Maly Lyakhovsky, Stolbovoy, Bel’kovsky islands; 12 – Berelekh River; 13 – Kitluk River.
Eurybiontic species among dominants include
Centropyxis aerophila, C. constricta v. minuta,
C. sylvatica, Cyclopyxis eurystoma v. parvula,
Schoenbornia humicola, Euglypha laevis and Trinema
lineare.
Testate amoebae species with restricted geographical distribution are of special interest:
Centropyxis gasparella, C. gasparella v. corniculata,
C. pontigulasiformis, C. vandeli, Difflugia kabulica,
D. ovalisima, D. serpentrionalis, D. szczepanskii,
Lesquereusia sphaeroides, Lamptoquadrulla sp.,
Placocista lapponum, Difflugiella (Cryptodifflugia)
angusta, D. bassini, D. minuta, D. pusilla, D.
sacculus, D. sacculus v. sakotschawi, D. vanhoornei,
Pseudodifflugia jungi. Some of these species are
only found in arctic tundra: Centropyxis gasparella,
C. gasparella v. corniculata, C. pontigulasiformis,
Difflugiella vanhoornei, Difflugia ovalisima. The
hygrophilic species Centropyxis gasparella sensu
lato was so far reported from tundra environments
in the Canadian Arctic, in Alaska and in Northeast
Greenland (Beyens and Chardez, 1995, 1997;
Trappeniers et al., 1999). Centropyxis pontigulasiformis has a broader tolerance and distribution. It
occurs under water and on mosses on Svalbard,
on Devon and Victoria islands (Canadian Arctic),
and West Greenland (Beyens and Chardez, 1995).
Difflugia ovalisima was described from moss samples
of Devon Island (Beyens and Chardez, 1994), and
Placocista lapponum occurs on Greenland and
Northern Sweden (Penard, 1917).
Some species also occur within the taiga zone
as for instance Difflugiella (Cryptodifflugia) bassini
(Bobrov, 2001). The species Centropyxis vandeli was
described from mountain soils in southern France
(Bonnet, 1958) and found in hydrophilic soil mosses
in the Western Rhodopes, Bulgaria (Golemansky
et al., 2006). The finding of Lamptoquadrula sp. is
of special interest because the type species of the
genus (which includes so far only one species) was
described from soils in gallery forests in Côte-d’Ivore
(Bonnet, 1975). Further evidence for rare species
54
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A.A. Bobrov and S. Wetterich
Table 1. List of testate amoebae from the 13 study sites as shown in Fig. 1.
Arcella arenaria, A. arenaria v. compressa, A. arenaria v. sphagnicola, A. artocrea, A. bathystoma, A.
catinus, A. costata, A. costata, A. discoides, A. discoides v. scutelliformis, A. gibbosa, A.intermedia,
A. megastoma, A. mitrata v. spectabilis f. A (minor), A. rotundata, A. rotundata v. aplanata, A.
rotundata v. stenostoma, A. vulgaris, A. vulgaris v. crenulata, A. vulgaris v. wailesi
Bullinularia indica, B. gracilis
Trigonopyxis arcula
Centropyxis aculeata, C. aculeata v. minima, C. aerophila, C. aerophila v. minuta, C. aerophila v.
sphagnicola, C. cf. capucina, C. cassis, C. cassis v. spinifera, C. constricta, C. constricta f. minima,
C. discoides, C. ecornis, C. ecornis sensu Ogden, Hedley 1980, C. ecornis v. megastoma, C.
ecornis v. minima, C. elongata, C. gasparella, C. gasparella v. corniculata, C. gibba, C. kolkwitzi,
C. laevigata, C. orbicularis, C. plagiostoma, C. plagiostoma v. oblonga, C. plagiostoma f. A (major),
C. plagiostoma f. B (minor), C. plagiostoma f. C (lata), C. platystoma, C. platystoma f. A (minor),
C. sylvatica, C. sylvatica v. globulosa, C. sylvatica v. microstoma, C. sylvatica v. minor, C. vandeli
Cyclopyxis arcelloides, C. eurystoma, C. eurystoma v. parvula, C. intermedia, C. kahli, C. kahli v.
cyclostoma
Plagiopyxis callida, P. declivis, P. cf. declivis v. oblonga, P. labiata, P. labiata f. A (longa), P. minuta
Heleopera lata, H. petricola, H. petricola v. amethystea, H. petricola v. humicola, H. sphagni, H.
sylvatica, H. rosea
Hyalosphenia minuta, H. papilio, H. subflava
Nebela bigibbosa, N. bohemica, N. galeata, N. flabellum, N. lageniformis, N. militaris, N. minor, N.
parvula, N. penardiana, N. tincta, N. tincta v. stenostoma
Argynnia dentistoma, A. dentistoma v. lacustris, A. dentistoma v. laevis
Schoenbornia humicola, Sch. Viscicula
Difflugia ampulla, D. bacillariarum, D. bacillifera, D. brevicola, D. capreolata, D. cratera, D. humilis,
D. gassowskii, D. geosphaerica, D. difficilis, D. globularis, D. globulosa, D. globulosus, D. globulus,
D. gramen, D. kabulica, D. lata, D. linearis, D. lucida, D. mamilaris, D. mica, D. microstoma, D.
minuta, D. molesta, D. nana, D. oblonga, D. oblonga v. gigantea, D. cf. ovalisima, D. parva, D.
penardi, D. perfilievi, D. petricola, D. pristis, D. pulex, D. pyryformis, D. rotunda, D. rubescens, D.
schurmani, D. serpentrionalis, D. tenius
Lagenodifflugia vas, L. sphaeroides
Netzelia oviformis
Lesquereusia epistomium, L. longicollis, L. modesta, L. spiralis
Pontigulasia incise
Quadrulella symmetrica
Paraquadrulla irregularis, P. penardi, P. cf. rotunda
Phryganella acropodia, Ph. acropodia v. australica, Ph. hemisphaerica
Assulina muscorum, A. muscorum v. stenostoma, A. seminulum
Valkanovia delicatula, V. elegans
Sphenoderia fissirostris
Tracheleuglypha acolla, T. dentate
Placocista glabra, P. lapponum, P. lens, P. jurassica, P. spinosa
Euglypha acantophora, E. anadonta, E. anadonta v. magna, E. ciliata, E. ciliata f. glabra, E. compressa,
E. compressa f. glabra, E. cristata, E. cuspidata, E. dolioliformis, E. filifera, E. filifera v. magna, E.
laevis, E. laevis v. lanceolata, E. rotunda, E. strigosa, E. strigosa f. glabra, E. strigosa v. muscorum,
E tuberculata
Corythion dubium, C. dubium f. minima, C. dubium v. terricola, C. dubium v. orbicularis, C. pulchellum
Trinema complanatum, T. complanatum v. platystoma, T. enchelys, T. lineare, T. lineare v. minuscule,
T. lineare v. terricola, T. lineare v. truncatum, T. penardi
Wailesella eboracensis
Difflugiella angusta, D. apiculata, D. bassini, D. fulva, D. minuta, D. oviformis, D. oviformis v. fusca,
D. patinata, D. pusilla, D. sacculus, D. sacculus v. sakotschawi, D. vanhoornei
Pseudodifflugia gracilis, P. gracilis v. terricola, P. jungi
Archerella flavum
that occur in the Arctic comes from the circumaustralian species Nebela martiali which has also
been found in surface samples from Dikson Island,
Eklips, and Franz Joseph’s Land (Beyens et al.,
2000).
An important indicator of species diversity is
the relationship between the number of species
and the number of sites examined (Fig. 4). The
rarefaction curve demonstrates a high heterogeneity
of the data set and suggests that for a more complete
representation of species diversity much more than
13 sampling sites are required. Therefore, the 215
species and subspecies found in this study do not
reflect the total diversity of rhizopods in arctic tundra landscapes.
The ordination of testate amoebae assemblages
from different areas of the arctic tundra illustrates
that most rhizopod communities were rather similar.
However, pronounced differences were found e.g.
between assemblages from moss-lichen tundra of
October Island (site No. 1 in Fig. 1) and mossshrub polygonal tundra of the Berelekh River (site
No. 12 in Fig. 1). The latter had a more structured
micro-relief which led to small-scale differences
Protistology
· 55
in water content and vegetation cover as expressed
by higher occurrences of sphagnobiontic and
hygrophilic species of the genera Nebela, Difflugiella
and Difflugia.
According to literature data the list of testate
amoebae in the Arctic comprises 291 species and
subspecies (Beyens and Chardez, 1995). This
inventory is based on more than 1000 samples
representing typical soil and aquatic habitats in
arctic tundra landscapes, published in studies since
the beginning of the 20th century including regions
of the North American Arctic.
Soil habitats of the Russian forest zone (Bobrov,
1999) are dominated by the following genera:
Centropyxis (35 species and subspecies), Euglypha
(30), Nebela (20), Trinema (18). Arctic tundra
habitats show a different species composition which
is dominated by Difflugia (40 species and subspecies),
Centropyxis (35), Arcella (20), Euglypha (20) which
highlight the broader distribution of hydromorphic
habitats in the tundra environment.
The genera Geamphorella, Geopyxella, Hoogenraadia, Planhoogenraadia, Proplagiopyxis, Pseudoawerinzevia, Schwabia and other have not been
found in soil and aquatic habitats of the arctic tundra
because these taxa are restricted to pan-tropical
and circum-australian or steppe and forest zones
of the Holarctic. However, occasional findings of
rare species prove that formation of arctic testacean
communities is a complicated process.
Based on literature and own studies we can
conclude that arctic testate amoebae communities
include several biogeographic fractions: (1) endemic
arctic species; (2) sphagnobiontic species of the
tundra and taiga zones; (3) holarctic species of
the forest zone; (4) non-holarctic species of the
pan-tropical and circum-australian zones; (5)
eurybiontic cosmopolitan species.
The most interesting groups are arctic endemics
and non-holarctic species of the pan-tropical and
circum-australian zones, which can be treated as
relicts or paleoendemic species. Transportation
and distribution of testate amoebae by atmospheric
currents or birds also can not be excluded. Further
research on biogeographic aspects of arctic testate
amoebae is needed to resolve this question (Bobrov
et al., 2004)
Acknowledgements
Fig. 2. Distribution of arctic testate amoebae
species per genus.
The study has been conducted under the
auspices of the joint Russian-German RFBRDFG project ‘Polygons in tundra wetlands: state
and dynamics under climate variability in polar
regions’ (RFBR grant N 11-04-91332-NNIO-a,
56
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A.A. Bobrov and S. Wetterich
Fig. 3. Ecological groups of testate amoebae in samples from (A) the arctic islands, and
(B) the arctic mainland..
DFG grant N HE 3622-16-1). Colleagues from
the North-Eastern Federal University, Yakutsk (L.
Pestryakova), Hamburg University (F. Beermann),
Moscow State University (L. Kokhanova, V.
Tumskoy, E. Zhukova), Herzen State Pedagogical
University, St. Petersburg (V. Sitalo), and AWI
Potsdam (L. Schirrmeister, A. Schneider) who
conducted the fieldwork in the Berelekh River
area in 2011 are greatly acknowledged. Long-term
support was provided by the German-Russian
Scientific Cooperation Programs ‘Laptev Sea
2000’ and ‘System Laptev Sea’ which provided
the frame for joint Russian-German expeditions
since 1998 when most of the Siberian samples have
been obtained. Financial support came also from
the RFBR project N 11-04-01171-a ‘Geography
and ecology of soil inhabiting testate amoebae’.
The fieldwork at the Alaskan study site on Seward
Peninsula was organized by G. Grosse (University
of Alaska Fairbanks) and financially supported
by the National Science Foundation (NSF grant
N 0732735) and the DFG (DFG grants N SCHI
530/7-1, WE 4390/2-1 and KI 849/2-1). Additional
support was provided from NASA Carbon Cycle
Sciences (grant NNX08AJ37G).
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Address for correspondence: A.A. Bobrov. Soil Department of Moscow State University, Vorobievy Gory,
119991, Moscow, Russia, e-mail: [email protected]