Vol.2, No.10, 1155-1163 (2010) Natural Science
http://dx.doi.org/10.4236/ns.2010.210143
Distribution of polychaetes in the shallow, sublittoral
zone of Admiralty Bay, King George Island, Antarctica in
the early and late austral summer
Letícia de Souza Barbosa1, Abílio Soares-Gomes1, Paulo Cesar Paiva2*
1Department of Marine Biology, Fluminense Federal University, Niterói, Brazil;
2Department of Zoology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; *Corresponding Author:
Received 20 July 2010; revised 25 August 2010; accepted 28 August 2010.
ABSTRACT
This study assessed the spatial distribution pa-
ttern of soft-sediment polychaetes on the near-
shore of Admiralty Bay, King George Island,
Antarctica. In the early and late summer of 2003
/04, seven sites at three different depths (20, 30
and 60 meters) were sampled using a van Veen
grab. 8,668 individuals all told, belonging to 67
species and 23 families, were identified. The
families Terebellidae, Syllidae and Maldanidae
were the most speciose. Mean densities ranged
from 45.2 to 388.1 ind. 0.1 m-2 in the early sum-
mer, and from 29 to 183 ind.0.1m-2 in the late.
The species Aphelochaeta cincinnata, Levin-
senia gracilis and Rhodine antarctica were the
most frequent and abundant. Initially, mean
biomass ranged from 0.11 to 5.27 g.0.1 m-2, in
the early season and from 0.35 to 5.86 g.0.1 m-2
towards the end. Aglaophamus trissophyllus,
Eupolymnia sp. and Barrukia cristata were the
species with the highest biomass. Polychaete
taxocoenosis structure remained similar in both
periods. In the early summer, mean densities,
biomass and number of species were lower at
30 meters and higher at 60, whereas in the late,
these differences were higher among transects.
Ice impacts, mainly anchor-ice, in the early sum-
mer, as well as icebergs later on, most likely
caused the differences encountered.
Keywords: Polychaeta; Soft-Sediment; Benthic
Structure; South Shetland Islands; Antarctic
Peninsula
1. INTRODUCTION
The Antarctic benthos is characterized by pronounced
endemism and a marked dependence on physical condi-
tions, such as sediment patterns, waves and ice effects
[1]. Distribution of the benthic community in shallow
waters (up to 100 m) could be influenced by depth [2].
According to Sahade et al. [3], benthic density is the
highest at 25 meters. From here down to 50 meter depth,
there is a decrease [4]. Below this, the community is free
from the impacts of icebergs and storms, thereby reach-
ing an advanced stage in development. Besides depth,
distribution is also influenced by habitat heterogeneity,
bottom topography and hydrodynamics, among other
factors [2]. Low and stable water temperatures, low
fluctuations in salinity during the summer, reduced terri-
genous sediment input and the seasonality of food re-
sources, could also exert an influence on both the struc-
ture and distribution of the Antarctic fauna [1]. Never-
theless, according to Barnes & Conlan [5], ice remains
as one of the foremost agents of disturbance in shallow
water benthos.
The benthic fauna of the Southern Ocean is well
known, the polychaetes being one of the most represen-
tative groups in soft-sediment habitats [6-8]. The group
can account for over 50% of the macrofauna in several
Antarctic areas, such as Chile Bay, Greenwich Island [9],
Port Foster, Deception Island [10], Arthur Harbour, An-
vers Island [11], McMurdo Sound [12] and Admiralty
Bay, King George Island [6]. Polychaete composition
and distribution in Admiralty Bay was already studied by
several authors [6,13-19] and can be summarized in the
following zonation patterns: the dominance of Leito-
scoloplos kerguelensis, Ophryotrocha notialis and Mi-
crospio cf. moorei on shallow bottoms (down to 12 m)
and higher densities of Aphelochaeta cincinnata, Apis-
tobranchus glacierae, Rhodine antarctica and Levin-
senia gracilis further down. According to Conlan et al.
[20], certain polychaetes, such as Ophryotrocha notialis,
Capitella perarmata, Aphelochaeta sp. and Leitoscolop-
los kerguelensis, are dominant in areas under the impact
of sea-waste disposal, besides being capable of coloniz-

L. de S. Barbosa et al. / Natural Science 2 (2010) 1155-1163
1156
ing ice-disturbed areas [21,22].
The aim of this survey was to investigate polychaete
spatial distribution in the nearshore soft-sediments at
three depths in Admiralty Bay, during the early and late
austral summer.
2. STUDY AREA
Admiralty Bay, the largest bay in King George Island,
is approximately 122 km², with depths exceeding 500
meters [23]. The fjord-like shaped bay has three inlets,
Mackellar and Martel located in the northern portion,
and Ezcurra located in the western [17]. The bay re-
ceives water from the Bransfield Strait through a 500-
meters-deep channel. Coarse sediments mixed with fine
mud occur down to a depth of 50 meters, the rest con-
sisting mainly of fine mud [24]. The sediment in front of
the Brazilian Antarctic station contained high concentra-
tions of trace metals (B, Mo, Pb, V, Zn, Ni, Cu, Mg and
Mn), organic matter and oil contaminants. However,
despite the evidence of contamination, the low bioavail-
ability of these pollutants is an indication of low envi-
ronmental risk [25]. Variation in temperature and salinity
is slight, ranging from −0.4°C to 0.9°C and 33.8 to 33.4,
respectively, at the bottom [24]. The phytoplankton from
Admiralty Bay is dominated by diatoms, under the in-
fluence of benthic species from sediment resuspension
or ice defrosting [26].
3. MATERIAL AND METHODS
Seven transects located in the Mackellar and Martel
inlets were sampled (Figure 1): Research Station “Co-
mandante Ferraz” (CFA, CFB and CFC), Botany Point
(BP), Hennequin Point (HE), Machu Picchu (MP) and
Thomas Point (AR), during the austral summer of 2003-
2004. At each site, samples were collected at three dep-
ths (20, 30 and 60 meters) with a van Veen grab (0.056
Figure 1. Sampling sites at Admiralty Bay.
m²). In the early summer (November and December,
2003) three replicates were collected, whereas four were
in the late season (February and March, 2004). Samples
were sieved through a 0.5 mm mesh. Specimens were
fixed in 4% formaldehyde and preserved in 70% alcohol.
The polychaetes were identified at the species level.
Unidentifiable individuals were included in the analysis
as morphotypes. Biomass was estimated by the meas-
urement of wet-weight (± 0.01 mg). Dry-sieve and pi-
pette methodologies were used for grain-size analysis, as
described by Suguio [27]. Calcium carbonate content
was determined by dry-weight difference after HCl 10%
attack, and that of total carbon and nitrogen by using an
Elemental Analyser CHNS/O Perkin Elmer (2400 Series
II), with a detection limit of 0.02% for C and 0.03% for
N [28]. Species densities (ind. 0.1 m² ± standard-error)
were used to calculate species dominance, according to
the formula:
Do = (Na/N) * 100
where Do = dominance of species A, Na = density of
species A and N = sum of all species densities.
Species occurrence frequencies were calculated by
using the following formula:
Fa = (Pa/P) * 100
where Fa = frequency of species A, Pa = number of
samples in which species A occurred, and P = total of
samples.
Species with higher than 50% occurrence were con-
sidered constant, those between 50% and 10%, common,
and those with less than 10%, rare. Density data were
transformed (square root), and Two-way ANOVA em-
ployed to check differences between early and late sum-
mer surveys. Cluster analysis was with the UPGMA al-
gorithm using a Bray Curtis similarity index calculated
by densities. Diagrams of ordination were produced
through non-metric Multi-Dimensional Scaling (nMDS)
analysis. The significance of differences among depths
during early and late summer was tested by One-Way
Analysis of Variance by Similarities-ANOSIM [29].
Canonical Correspondence Analysis (CCA) was ap-
plied with a matrix of 10 abiotic variables (gravel, coarse
sand, medium sand, fine sand, silt, clay, carbonate, total
carbon, organic carbon and total nitrogen), together with
the most frequent species in each of the summer periods.
The transect AR 60 m was not considered, due to the
lack of grain-size data. Statistical analysis was under-
taken with the Statistica 6.0 program, multivariate ana-
lysis with the Primer 6, program, and CCA by using the
Biplot 1.1 add-in routine for Excel [30].
4. RESULTS
4.1. Abiotic Variables
The sediment consisted mainly of silt and clay (more

L. de S. Barbosa et al. / Natural Science 2 (2010) 1155-1163
1157
than 60%) at most transects and depths, although the
percentages of fine sand were higher (ca. 30%) in some
stations like HE and AR. At 60 meters, slightly lower
percentages of both gravel and coarse sand were ob-
served, when compared to shallower transects. Calcium
carbonate content was slightly higher in the late summer
(more than 12%), whereas in the early season, this was
lower at 20 and 30 meters, with the lowest (6.5%) at MP.
Carbon and nitrogen content were very low (< 1%). CFA,
CFB and CFC presented the highest percentages of car-
bon content (0.54% to 0.75%), and MP the lowest (0.28%
to 0.46%). There was no apparent variation of either
variable with the increase in depth.
4.2. Polychaete Composition
A total of 8,668 individuals were collected throughout
the period. The set of samples yielded 67 species and
four morphotypes (Cirratulidae gen. sp.1, Cirratulidae
gen. sp.2, Maldanidae gen. sp. and Terebellidae gen. sp.),
belonging to 23 families (Table 1). 21 species were col-
lected in each sampling survey. The most speciose fami-
lies were Terebellidae and Syllidae with seven species
each, and Maldanidae with six. The families Glyceridae
and Sabellidae were exclusive to the early summer,
whereas Nereididae and Serpulidae were to the late sum-
mer. The families Nereididae, Serpulidae and Glyceridae
were each represented by only one species, viz., Nicon
ehlersi, Helicosiphon biscoensis and Glycera capitata,
respectively. The sabellids were represented by three
species: Euchone pallida, Perkinsiana litorallis and
Perkinsiana milae, all somewhat scarce during the sum-
mer.
4.3. Dominance and Frequency
In terms of density, the species Aphelochaeta cincin-
nata, Levinsenia gracilis, Cirratulidae gen. sp. 1, Apis-
tobranchus glacierae and Rhodine antarctica dominated,
throughout the whole period studied. The exceptions
were Cirratulidae gen. sp. 1 and A. glacierae, dominant
only at the beginning. Throughout, Aphelochaeta cin-
cinnata was the most frequent species, with 93.55% in
the early summer and 85.71% in the late. The species
Levinsenia gracilis and Rhodine antarctica were also
constant during the whole study period, with 69.35% and
56.45%, respectively, in the first part, and both 65.48%
towards the end. These three species were responsible
for 33.7% of total polychaetes in the early summer and
34.7% in the late. Aricidea (Acmira) strelzovi, Leito-
scloplos geminus, Brada villosa, Apistobranchus glaci-
erae, Barrukia cristata and Cirrophorus brevicirratus
were considered common throughout. Scalibregma in-
flatum, besides being a low-frequency species during the
whole period (8.06% in the early part and 5.95% in the
late), occurred only at 60 meters (Table 1).
4.4. Density and Biomass
Polychaete density ranged from 45.24 to 388.10
ind.0.1 m-2 in the early summer. Apistobranchus glaci-
erae, with the highest score all told, was also responsible
for the high result observed at CFC (20 m) (173.21 ±
76.79 ind. 0.1 m-2). The species Aphelochaeta cincinnata
at CFB (60 m), Rhodine antarctica at CFC (20 m) and
Levinsenia gracilis at CFC (60 m) also presented high
values (Figure 2). In the late summer, polychaete den-
sity varied from 29.02 to 183.93 ind.0.1 m-2. The highest
densities, attributed to R. antarctica, were observed at
the MP transect at 20 and 30 meters (Figure 3).
During sampling, a significant variation in density
among depths was observed (ANOVA, p < 0.002) (Ta-
ble 2), with lower densities at 30 meters when compared
to both 20 and 60 (Tukey test, p < 0.005), although no
differences among transects were detected (p = 0.599).
Nevertheless, this pattern seems to be rather complex,
since the interaction between transect and depth was
significant (p < 0.02). This interaction occurred at tran-
sects CFA and CFC, with no clear bathymetric pattern.
On the contrary, in late summer, significant differences
were found only among transects (p < 0.002), but not
depths (Table 2), with MP and AR presenting higher
densities than CFA and CFC (Tukey test, p < 0.05).
These differences occurred due to the high densities of
cirratulids (Aphelochaeta cincinnata and Cirratulidae
gen. sp.1), paraonids (Levinsenia gracilis, Aricidea (Ac-
mira) strelzovi and Cirrophorus brevicirratus) and the
maldanid Rhodine antarctica, at MP and AR. On the
other hand, biomass encountered at both CFA and CFC
was low. Surprisingly, polychaete density at CFB was
similar to that observed at MP and AR.
In the early summer, biomass means (± standard-error)
ranged from 5.27 ± 4.19 g.0.1 m-2 at CFC-20 m, to 0.11
± 0.06 g.0.1 m-2 at BP-30 m (Figure 4). In the late sea-
son, the highest biomass mean was observed at CFB-30
m (5.86 ± 4.72 g.0.1 m-2) and the lowest at BP-30 m
(0.35 ± 0.27 g.0.1 m-2) (Figure 5). The species Aglao-
phamus ornatus, Eupolymnia sp. and Barrukia cristata
presented the highest values. Although Rhodine antarc-
tica biomass was not high, it remained constant at MP,
all through the later part of summer, this constancy
probably contributing to the proximity of values found at
all depths.
4.5. Multivariate Analysis
In the early summer, the samples were grouped
through cluster analysis, according to depth. The results
indicated that in the first group, composed of transects
MP, BP, AR at 20 meters, and MP and AR at 30 meters,

L. de S. Barbosa et al. / Natural Science 2 (2010) 1155-1163
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Table 1. Frequency (Fo) and dominance (Do) of polychaete species in early and late summer, and species codes used in canonical
correspondence analysis.
Species Code Family Early summer Late summer
Fo (%) Do Fo (%) Do
Levinsenia gracilis Lev 69.35 17.51 65.48 28.64
Aricidea (Acmira) strelzovi Ari 35.48 4.45 33.33 4.45
Cirrophorus brevicirratus Aph
Paraonidae
12.90 0.85 23.81 3.94
Leitoscoloplos kerguelensis Lek 22.58 1.02 16.67 0.95
Leitoscoloplos geminus Leg 29.03 1.76 21.43 1.13
Scoloplos (Leodamas) marginatus 3.23 0.04 2.38 0.08
Orbinia minima
Orbiniidae
- - 2.38 0.08
Scalibregma inflatum Scalibregmatidae 8.06 0.38 5.95 0.43
Ophelina syringopyge 4.84 0.22 4.76 0.33
Ophelina breviata 3.23 0.07 1.19 0.03
Ophelina sp.
Ophellidae
1.61 0.09 2.38 0.08
Capitella sp.1 1.61 0.02 4.76 0.13
Capitella sp. 2 Capitellidae - - 1.19 0.08
Asychis ampliglypta Asy 11.29 0.44 21.43 1.21
Maldane sarsi antarctica Mal 11.29 0.58 11.90 0.60
Lumbriclymenella robusta Lur 1.61 0.02 10.71 0.38
Rhodine antarctica Rho 56.45 9.50 65.48 20.30
Praxillella sp. 1.61 0.02 - -
Maldanidae gen. sp. Mas
Maldanidae
24.19 0.76 19.05 0.98
Austrolaenilla antarctica 4.84 0.07 5.95 0.13
Barrukia cristata Bar 22.58 0.47 21.43 0.73
Harmothoe sp.
Polynoidae
- - 1.19 0.03
Glycera capitata Glyceridae 1.61 0.02 - -
Eulalia varia - - 2.38 0.05
Eulalia sp. - - 4.76 0.13
Eteone sculpta 1.61 0.02 2.38 0.05
Genetyllis polyphylla 3.23 0.07 3.57 0.15
Anaitides sp.
Phyllodocidae
1.61 0.04 1.19 0.03
Sphaerodoropsis arctowskyensis 6.45 0.20 2.38 0.05
Sphaerodoropsis sp. 1.61 0.02 - -
Ephesiella muelenhardte
Sphaerodoridae
1.61 0.04 1.19 0.05
Aglaophamus ornatus Agl Nephtyidae 11.29 0.18 8.33 0.23
Nicon ehlersi Nereididae - - 1.19 0.03
Exogone heterosetosa 4.84 0.20 - -
Exogone minuscula 1.61 0.04 - -
Exogone heterosetoides 4.84 0.11 8.33 0.30
Exogone sp. 4.84 0.16 1.19 0.03
Syllis sp. 1.61 0.02 - -
Branchiosyllis sp. 8.06 0.18 1.19 0.05
Syllides liouvillei
Syllidae
- - 2.38 0.05
Pettiboneia kerguelensis Pet 17.74 1.69 1.19 0.03
Ophryotrocha notialis Dorvilleidae - - 1.19 0.03
Lumbrineris kerguelensis Lum 8.06 0.11 15.48 0.35
Augeneria sp. Lumbrineridae 1.61 0.02 2.38 0.05
Apistobranchus glacirae Api Apistobranchidae 24.19 10.03 15.48 0.73
Spiophanes tcherniai 1.61 0.04 4.76 0.15
Laonice antarcticae 1.61 0.02 - -
Microspio sp. 1.61 0.33 1.19 0.03
Scolelepis eltaninae 1.61 0.04 - -
Pygospiopis dubia
Spionidae
- - 1.19 0.05
Aphelochaeta cf. cincinnata Aph 93.55 30.57 85.71 21.71
Cirratulidae gen. sp. 1 Cir 1 32.26 13.59 19.05 6.11
Cirratulidae gen. sp. 2 Cir 2
Cirratulidae
16.13 2.38 5.95 1.76
Brada villosa Bra 25.81 0.62 25.00 1.18
Pherusa kerguelarum Flabelligeridae - - 1.19 0.08
Ampharete kerguelensis 3.23 0.04 4.76 0.10
Amphicteis gunneri antarctica Amp 6.45 0.09 15.48 0.70
Anobothrus cf. patagonicus 1.61 0.04 2.38 0.05
Phyllocomus crocea
Ampharetidae
- - 1.19 0.03
Hauchiella tribullata 1.61 0.02 - -
Proclea cf. graffii 3.23 0.09 1.19 0.03
Amphitrite kerguelensis - - 1.19 0.03
Eupolymnia sp. Eup 8.06 0.20 21.43 0.53
Terebellides stroemii kerguelensis 8.06 0.24 5.95 0.25
Pista cristata 6.45 0.13 4.76 0.13
Trichobranchus sp. - - 1.19 0.03
Terebelidae gen sp.
Terebellidae
1.61 0.02 - -
Euchone palida 1.61 0.02 - -
Perkinsiana milae 1.61 0.02 - -
Perkinsiana littoralis
Sabellidae
1.61 0.02 - -
Helicosiphon biscoensis Serpulidae - - 1.19 0.05

L. de S. Barbosa et al. / Natural Science 2 (2010) 1155-1163
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Figure 2. Mean densities (± stardard-error) of Polychaeta at the
transects in early summer. Depths: 20 m = black bars; 30 m =
white bars; 60 m = gray bars.
Figure 3. Mean densities (± stardard-error) of Polychaeta at the
transects in late summer. Depths: 20 m = black bars; 30 m =
white bars; 60 m = gray bars.
Figure 4. Mean biomass (± stardard-error) of Polychaeta at the
transects in early summer. Depths: 20 m = black bars; 30 m =
white bars; 60 m = gray bars.
Figure 5. Mean biomass (± stardard-error) of Polychaeta at the
transects in late summer. Depths: 20 m = black bars; 30 m =
white bars; 60 m = gray bars.
Table 2. Results of Two-way ANOVA in early and late sum-
mer.
Factors Early summer Late summer
p F p F
Transect 0.5990.737 0.0014.286
Depth 0.00111.716 0.5810.547
Transect * Depth 0.0151.554 0.5830.867
the density of Cirratulidae gen. sp. 1 was high, whereas
both Bran chiosyllis sp. and S. arctowskyensis were ab-
sent. In the second group (CFB and CFC at 20 m, HE at
30 m, and MP and HE at 60 m), both R. antarctica and A.
glacirae were the most abundant. In the third group,
formed by CFA at 20 meters, and CFA, CFB, CFC and
BP, all at 30 meters, richness and densities were low in R.
antarctica, A. amphiglypta and A. cincinnata. In the last
group, A. cincinnata, L. gracilis and Cirratulidae gen. sp.
2 were abundant, and both S. inflatum and A. strelzovi
present (Figure 6). The results from cluster analysis were
confirmed through nMDS. In the late summer, no clear
pattern of clustering, in relation to either transects or
depths, was apparent.
When using ANOSIM, no differences were detected
in the polychaete community between the periods sam-
pled (R global = 0.031; p = 20.5%), although the con-
trary was the case as regards depths. In the early summer,
communities at 60 meters differed from those found at
20 and 30 meters, whereas in the late season, the only
difference was between 20 and 60 meters (Table 3).
Results through Canonical Correlation Analysis (CCA)
were rather similar, in both early and late summer. The
first axis was responsible for 45.9% of the variance in
early summer and 42.8% in late and was positively re-
lated to gravel, coarse and fine sand and negatively so to
silt, clay, carbonate, carbon and nitrogen contents. The
sediment in all transects at 20 meters was coarser,
whereas that at 60 meters was characterized by the
dominance of silt and clay fractions, and that at 30 me-
ters an intermediate pattern between the former two. The
second axis accounted for 25.5% and 20.8% of the vari-
ance in early and late summer, respectively (Figures 7
and 8). In both summer periods, most species appeared
to be associated with gravel, and coarse and fine sand.
The maldanids Maldane sarsi antarctica and Asychis
amphiglypta were related to stations at 60 meters. The
species L. geminus, L. kerguelensis, A. glacirae and C.
brevicirratus and Cirratulidae gen sp.1 were positively
related with gravel, and coarse and fine sand.
5. DISCUSSION
The number of polychaete species found in the present
study was higher than that presented by Sicinski & Ja-

L. de S. Barbosa et al. / Natural Science 2 (2010) 1155-1163
1160
(a)
HE 30m HE 60m
CFB 20m
CFC 20m
MP 60m MP 30m
MP 20m
BP 20m AR 20m
AR 30m
CFC 60m
CFA 60m CFB 60m
BP 60m AR 60m
CFC 30m CFB 30m
BP 30m
CFA 20m CFA 30m
100
80
60
40
Similaridade (%)
CFA 20m
CFA 30m
CFA 60m
CFB 20m
CFB 30m
CFB 60m
CFC 20m
CFC 30m
CFC 60m
MP 20m
MP 30m
MP 60m
BP 20m
BP 30m
BP 60m
AR 20m
AR 30m
AR 60m
HE 30m
HE 60m
2D Stress: 0,16
(b)
CFB 20m CFC 20m
MP 20m MP 30m
AR 20m
HE 30m MP 60m HE 20m
BP 20m
CFB 30m
CFA 30m CFA 20m
CFC 30m
BP 60m
CFA 60m
CFC 60m
AR 30m BP 30m
CFB 60m
AR 60m
HE 60m
100
80
60
40
Similaridade (%)
CFA 20m
CFA 30m
CFA 60m
CFB 20m
CFB 30m
CFB 60m
CFC 20m
CFC 30m
CFC 60mMP 20m
MP 30m
MP 60m
BP 20m
BP 30m
BP 60m
AR 20m
AR 30m
AR 60m
HE 20m
HE 30m
HE 60m
2D Stress: 0,15
Figure 6. Cluster analysis and nMDS from the transects. (a) polychaete density in early summer; (b) polychaete density in late sum-
mer.
Table 3. Results of One-way ANOSIM for effect of depth (20,
30 and 30 m) on polychaete abundance data.
Early summer Late summer
Groups R-value
Significance
level (%) R-value Significance level (%)
All depths 0.43 0.1 0.25 1.8
20,30 0.21 8.2 0.15 11.1
20,60 0.60 0.1 0.48 0.3
30,60 0.49 0.1 0.13 13.7
nowska [16] and Bromberg [17], in Admiralty Bay, at
similar depths. However, this richness was low when
compared with that in other Antarctic areas, such as Ar-
thur Harbor on Anvers Island [31], Chile Bay on Green-
wich Island [32], Terra Nova Bay [33], Livingston Island
and Port Foster on Deception Island [34], the Weddell
Sea continental shelf and slope, and the Antarctic Pen-
insula [35]. The relatively low richness found in the
present study might be related to differences in sampling
effort, seeing that in the aforementioned studies, differ-
ent sampling techniques were used. The dominance of
Aphelochaeta cincinnata is in accordance with the re-
sults obtained by Sicinski [6], Gambi et al. [33] and
Bromberg [17]. The high density of Rhodine antarctica
Figure 7. Graphic representation of the two axis of canonical
correspondence analysis for early summer. For species codes
see Table 1.

L. de S. Barbosa et al. / Natural Science 2 (2010) 1155-1163
1161
Figure 8. Graphic representation of the two axis of canonical
correspondence analysis for late summer. For species codes see
Table 1.
at the MP transect could be related to its life cycle. Ac-
cording to Dayton & Oliver [12], in McMurdo Sound,
the individuals of the family Maldanidae may have
evolved asexual reproduction in response to high preda-
tion and juvenile mortality. The dominance of maldanids
was also reported by Gallardo et al. [9], who found a
benthic community dominated by Maldane sarsi antarc-
tica (Maldane assembly) in Chile Bay. Jazdzewski et al.
[24] and Sicinski [6,13] also observed typical maldanid
communities at depths over 100 meters.
The highest mean density observed in the early sum-
mer was similar to that reported by Sicinski [14]. On the
other hand, mean density itself, although in accordance
to that observed by Sicinski & Janowska [16], was lower
than that reported by other authors [17,33-35]. These
differences may reflect variations in sampling design,
depth and seasonality. The mean values of biomass were
similar to those observed in Admiralty Bay by Sicinski
& Janowska [16], and were within the range reported by
Gambi et al. [33]. According to Sicinski [13], polychaete
biomass at 50 m may vary from 30 to 40 g.m-2 and might
be responsible for 15% of the local zoobenthic biomass
itself. The species responsible for the increase in bio-
mass values, Aglaophamus ornatus and Eupolymnia sp.
occurred mainly at 20 and 30 meters, respectively. This
may be related to the deposition of organic matter from
phytoplankton bloom, which occurs in the early summer
[36].
Polychaete taxocoenosis structure remained the same
throughout the period under study, possibly as a result of
the prevailing sedimentary conditions (grain-size per-
centages) remaining invariable between transects. Nev-
ertheless, certain differences were observed during the
early and late summer, separately. During the early
summer, polychaete mean density, biomass and richness
declined at the 30 meters level and increased at the 60.
An increase in density related to depth had been previ-
ously reported in the Martel inlet [16]. The results in
early summer may be an outcome of ice impact. Accor-
ding to Sahade et al. [3], ice impacts (icebergs and an-
chor-ice) seem to be the major regulating factor of ben-
thic assemblages in shallow waters. Although actually
not observed in this study, but based mainly on under-
water observations, anchor-ice impacts have been im-
puted as promoting winter structuring in benthic com-
munities. The displacement of established fauna in their
area of influence may be attributed to these phenomena,
thereby accounting for the low diversity in early summer
[37]. According to Dayton et al. [38], the influence of
anchor-ice impacts extends down to 33 meters, thus con-
stituting the main cause of low diversity in shallow wa-
ters. Anchor-ice usually occurs during the winter, but its
influence might have extended throughout the early
summer of 2003/04, with consequential superficial
sediment defaunation, thus making it difficult for the
community to recover within a few months.
The increase in temperature in the late summer pro-
motes the formation of icebergs. Echeverría & Paiva [39]
reported the presence of one in the summer of 2001 at
the CFB 25 meter station, where it remained for over 20
days. Iceberg impacts are likely to affect benthic com-
munities down to 20 meters. Below this, conditions are
more stable, with higher densities, biomass and richness,
the area below 30 meters thus presenting a substantial
change in benthic megafauna structure, composition and
diversity [37]. In both summer periods, most of the spe-
cies which appear to be related to coarser sediment frac-
tions are motile or discretely motile polychaetes. On the
other hand, the maldanids (sessile polychaetes) related to
higher percentages of silt and clay, appear mostly at 60
meters. Further analysis of polychaete feeding guilds is
necessary to better evaluate their distribution in Admi-
ralty Bay.
The possible environmental impacts related to active-
ties of the Brazilian research station (Cmte. Ferraz) were
not revealed in this survey, since variability among those
transects under the influence of the station itself (CFA,
CFB and CFC) was higher than among all the others.
Furthermore, the slight variation between early and late
summer seems to be more related to natural impacts than
to the more intense activities at the research station it-
self.

L. de S. Barbosa et al. / Natural Science 2 (2010) 1155-1163
1162
6. ACKNOWLEDGEMENTS
The authors would like to thank the staff of the Brazilian Antarctic
Station “Comandante Ferraz” and the Brazilian Antarctic Programm
(PROANTAR) for logistical support, Laboratorio de Ciências Ambi-
entais/UENF for the abiotic data, Lucia Campos (GEAMB/UFRJ) for
providing biological material, and Rafael Moura for the map. This
work was supported by grant from CNPq/MCT/MMA (PROANTAR),
and a MSC fellowship from Coordenadoria de Aperfeiçoamento de
Pessoal de Nível Superior (CAPES) for first author and research fel-
lowships from Conselho Nacional de Desenvolvimento Científico e
Tecnológico (CNPq) for second and third author.
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