Download Polychaete distribution in the near-shore zone of

BULLETIN OF MARINE SCIENCE, 67(1): 175–188, 2000
POLYCHAETE DISTRIBUTION IN THE NEAR-SHORE ZONE OF
MARTEL INLET, ADMIRALTY BAY (KING GEORGE ISLAND,
ANTARCTICA)
Sandra Bromberg, Edmundo Ferraz Nonato, Thaïs Navajas Corbisier
and Mônica A. Varella Petti
ABSTRACT
Although a considerable amount of literature exists on Antarctic polychaetes, comparatively few ecological studies have been carried out in shallow waters (to 30 m). In
these environments, inherent factors such as freezing of the intertidal and upper sublittoral zones, iceberg scouring and formation of anchor ice greatly influence the faunal
distribution and community structure. The aim of this study is to investigate the structure
of the polychaete assemblages in a shallow soft bottom environment in the Antarctic and
to assess the relationships with bottom type and ice effects. The samples were taken in
December 1994 along a transect comprising four sampling stations ranging from 6–25 m
depth, adjacent to the Brazilian Antarctic Station “Comandante Ferraz” at Martel Inlet,
Admiralty Bay. Two additional stations were established at a depth of 18 m in order to
study the effect of ice-scouring. Five replicates per station were sampled with corers
taken by SCUBA divers. The polychaete distribution showed a distinct zonation pattern
as a function of depth induced mainly by sedimentary differences and ice-scouring. The
polychaete density, biomass and species diversity increased with depth. In the area affected by ice-scouring, these structural parameters were more variable. A total of 31
species in 18 families was recorded across the sampling area. Four species accounted for
80% of the total abundance: Apistobranchus gudrunae, Tharyx cf. cincinnatus,
Leitoscoloplos kerguelensis and Ophryotrocha notialis. Certain tube-dwelling polychaetes, such as Leaena cf. collaris and Asychis amphiglypta, occurred only at the 18 and 25
m stations where the ice-effects are less than at the shallower stations. Conversely, some
species, notably those belonging to taxa known to be opportunistic in life-style, such as
Ophryotrocha notialis and Microspio cf. moorei, were more abundant at the shallow stations.
The study of benthic fauna in the shallow Antarctic coastal zone has been a subject of
great interest within the scientific community because, unlike deeper areas, this environment represents an unstable habitat, as a consequence of ice effects. The freezing of the
intertidal and upper sublittoral zones and the damage caused by anchor ice and icebergs
in shallow areas seems to determine the benthos distribution. The formation of anchor ice
is a major factor determining faunal zonation in shallow waters (Dayton et al., 1970,
1974) and, together with iceberg scouring, can disturb the resident benthic communities
considerably (Dayton et al., 1969, 1970; Arntz et al., 1994; Gutt et al., 1996; Sahade et al.,
1998). The Antarctic benthic fauna is also susceptible to other environmental characteristics such as the highly seasonal light regime, low but stable water temperatures, small
fluctuations in salinity and pronounced seasonal variation in food input (Arntz et al.,
1994).
Among the Antarctic soft bottom benthic community, the polychaetous annelids are
one of the dominant macrofaunal taxa both in richness and abundance (Gallardo and
Castillo, 1969; Gallardo et al.,1977; Mühlenhardt-Siegel, 1988, 1989; Gambi et al., 1997).
175
176
BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 1, 2000
These organisms are present in most benthic marine ecosystems, often comprising a large
part of the total benthic biomass and, as such, may play an important role in the food web.
Based on a knowledge of the wide range of feeding and tolerance strategies employed,
assessment of the polychaete species present in a community can give insight into the
environmental conditions in the area.
The quantitative study of the macrobenthic assemblages of Admiralty Bay (Jazdzewski
et al., 1986; Arnaud et al., 1986; Wägele and Brito, 1990) revealed that the dominant
infaunal groups in terms of abundance were Polychaeta, Bivalvia and Amphipoda. In
Martel Inlet, preliminary results regarding the abundance of shallow-water benthos showed
that the predominant group was the Polychaeta, representing about 42% of the total
macrofaunal abundance, followed by Amphipoda (32%) and Bivalvia (10%) (Bromberg,
1999).
During the past 40 yrs, a considerable amount of taxonomic literature concerning Antarctic polychaete assemblages has been made available. Information on the distribution
and ecology of the group was reported by many (Desbruyerès, 1977; Sicinski, 1986;
Gallardo et. al., 1988; Gambi et al., 1997). However, quantitative data from the shallow
Antarctic sublittoral zone are nearly non-existent, except for the work of Sicinski and
Janowska (1993), who recorded 25 species in soft bottom samples collected in Ezcurra
Inlet, a western inlet of Admiralty Bay. They distinguished two polychaete assemblages
which were influenced by the type of sediment: one in 4–20 m and the other at 25–30 m.
The aim of the present study is to describe the structure of the polychaete assemblages
in the shallow soft bottoms of Martel Inlet (Admiralty Bay, King George Island) in relation to bottom topography and physical disturbance caused by ice action. The present
survey is part of the large-scale project “Bionomia da Fauna Bentônica Antártica” carried
out by the Instituto Oceanográfico da Universidade de São Paulo since 1988; the overall
aim of which is to characterize the structure and dynamics of the near-shore benthic
community of both hard and soft bottoms of Admiralty Bay.
STUDY AREA
Admiralty Bay is the largest bay of King George Island, South Shetland Islands, covering an area of 120 km2 (Fig. 1). It is located between 62°04' and 62°14'S and 58°14' and
58°38'W, 750 km south-east of the South America. The maximum depth of the bay is
approximately 600 m (Jazdzewski et al., 1986) and the water volume is estimated to be
approximately 18 km3 distributed in its three inlets and the main part of the bay. The
Mackellar and Martel Inlets constitute the northern part of the bay and the Ezcurra Inlet
its western part. In the southern portion, the bay forms a broad opening into the Bransfield
Strait (Pruszak, 1980).
Salinity and temperature are relatively stable throughout the bay. In the austral summer they range from 32.9 to 34.2‰ and −0.2 to 3.4°C at the surface and 33.8 to 34.3‰
and −0.4 to 0.9°C at the bottom (Jazdzewski et al., 1986). Small changes in salinity,
produced mainly by the inflow of fresh water from glaciers, do not have any significant
effect on the eventual rise of the density gradient (Pruszac, 1980). The bay usually frozen from May to August. The freezing process is associated with frosty and windless
weather and an absence of waves. The ice is disrupted and disappears as a result of
intensive waves from the sea and strong northern winds by November (Brito, 1993).
BROMBERG ET AL.: ANTARCTIC POLYCHAETES
177
Figure 1. Admiralty Bay (King George Island, Antarctica) showing the location of the Brazilian and
Polish Antarctic research stations. Sampling area off the Brazilian Antarctic Station.
The presence of glaciers, their seasonal dynamics and long-term changes in the marginal zone have an essential influence on the hydrological conditions of the bay and on
the development of both the marine and land communities of the coastal area (RakusaSuszczewski, 1980).
The study area, adjacent to the Brazilian Antarctic Station “Comandante Ferraz” (62°04'S
and 58o21'W), was located in the shallow soft bottom sublittoral zone of Martel Inlet. The
Brazilian Station is ideally situated for biological field studies because it is sheltered
from the frequent storms which occur in the area. The bottom topography shows a steep
slope and, at a distance of 100 m from the coast, a depth of 25 m is attained. The presence
of ice scours at 18 m depth were recorded by echo sounder (Nonato et al., 1992). Sediment becomes fine with an increase in depth. In general, the sediment comprises gravelly
sand at 4 m and becomes muddy sand at 30 m (Sicinski and Janowska, 1993).
178
BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 1, 2000
MATERIAL AND METHODS
Sampling of infaunal organisms was carried out at four stations along a transect ranging from 6–
25 m depth, adjacent to the Brazilian Antarctic Station “Comandante Ferraz”, in December 1994.
Two additional stations, named Scour 1 and Scour 2, were sampled at 18 m depth where deep
depressions in the bottom, possibly caused by ice scouring were observed by SCUBA divers. Five
replicates were taken at each station with a corer which was 20 cm in length and sampled an area of
0.008 m2.
The samples were washed through a 0.5 mm sieve and the material retained was fixed in 10%
borax-buffered formalin and preserved in 70% ethanol. The polychaetes were sorted, identified to
species and counted. The wet weight of each species from each replicate was determined after
blotting on filter paper for 2 min with a 1 mg precision scale. The tubes of the tubicolous species
were removed prior to weighing. Additional sediment samples from the 6, 11, 18 and 25 m stations
were collected for grain size analysis and determined by using the sieving and pipeting techniques
described in Suguio (1973). Calcium carbonate content was determined after acidification with
10% HCl solution (Gross, 1971).
The replicate sample data were totaled for each station, and the polychaete density and biomass
values were recorded in 0.04 m2. Species diversity (H') was calculated using the Shannon-Wiener
index (Shannon and Weaver, 1949) on a log2 basis and expressed by bits ind−1; evenness (J') by the
Pielou index (Pielou, 1975); and the richness was expressed by the number of species per 0.04 m2.
Cluster analysis using the Bray-Curtis dissimilarity coefficient (Bray and Curtis, 1957) was employed to evaluate similarities between stations (Q mode) and to delimit assemblages (R mode).
The unweighted pair-group average method (UPGMA) (Legendre and Legendre, 1983) was used
to group the communities on the basis of their resemblances. Species with less than 15% frequency
of occurrence were excluded from the cluster analysis. The raw data were transformed by using the
transformation log (x + 1) in order to scale down the scores of abundant species (Field et al., 1982).
Non parametric analysis were used to test the variation of density and biomass among the stations (Kruskal-Wallis test). Multiple comparisons were carried out by the Nemenyi test (Zar, 1996).
Scour 1 station was not included in the cluster analysis or in the non parametric analysis since
polychaetes were not recorded in three of the replicates.
RESULTS
The sediments in the area consisted mainly of very fine sand at the 6 and 11 m stations,
fine silt at 18 m and medium silt at the 25 m station. The percentages of gravels and
calcium carbonates were higher at the 18 and 25 m stations contributing to the greater
heterogeneity of the sediment at these depths (Table 1).
A total of 31 species in 18 families were identified and totaled 2858 individuals from
the 30 replicates. The species collected at the six sampling stations together, with their
densities and relative biomass, are presented in Table 2. Some polychaetes were identified only to family or generic level although they were distinguished as species in order to
calculate diversity.
With the exception of the zone of the Scour 1 station, the polychaete density increased
with depth. The density values per station ranged from 154 ind 0.04 m−2 (6 m) to 1241
ind 0.04 m−2 (25 m). Lower values (8 ind 0.04 m−2) were observed at the Scour 1 station
(Fig. 2A).
BROMBERG ET AL.: ANTARCTIC POLYCHAETES
179
Table 1. Surface sediments grain-size and calcium carbonate characteristics for each station in
Martel Inlet.
Station /depth
Calcium carbonate (%)
Gravel (%)
Very coarse sand (%)
Coarse sand (%)
Medium sand (%)
Fine sand (%)
Very fine sand (%)
Silt (%)
Clay (%)
Mean diameter (φ)
Sorting (φ)
Folk and Ward (1957)
parameters
6m
4.50
0.44
0.34
0.62
1.78
53.73
31.13
8.54
3.42
3.05
1.07
very fine
sand
11 m
6.09
1.46
1.12
1.29
1.77
37.19
31.64
13.61
11.91
4.00
1.97
very fine
sand
18 m
10.48
1.88
1.15
1.32
1.33
11.43
16.66
27.88
38.34
6.08
2.58
fine silt
25 m
9.33
6.10
2.57
2.46
1.51
6.20
10.41
40.43
30.32
5.74
2.96
medium silt
The small-bodied, carnivorous and opportunistic Ophryotrocha notialis was the only
species present at all the sampling stations, but was dominant at the 6 and 11 m stations
where it represented approximately 70% of the total number of polychaetes found. The
deposit feeder Microspio cf. moorei, thought to be opportunistic as many spionids, was
only recorded at the shallow depths (6 and 11 m stations). The burrowing deposit feeders
and motile polychaetes Apistobranchus gudrunae, Leitoscoloplos kerguelensis and Tharyx
cf. cincinnatus were the dominant species at 18 and 25 m and Scour 2 stations. Certain
tube-dwelling polychaetes, such as Leaena cf. collaris and the maldanids Asychis
amphiglypta and Eupraxillella antarctica were also found up to 18 m depth (Table 2).
The polychaete biomass increased with depth, with the exception of the 11 m station,
where a large-sized Aglaophamus ornatus was found. Biomass values ranged from 119
mg 0.04 m−2 (6 m) to 3456 mg 0.04 m−2 (25 m) (Table 2 and Fig. 2B). The dominant
species at the shallow stations are mainly small forms, such as O. notialis and M. cf.
moorei, whereas some large-sized species, as Barrukia cristata and A. amphiglypta, were
mainly found at the deeper and scour stations. The polychaete density and biomass were
significantly different between the 6 and 25 m stations with the latter showing the highest
values (Fig 2A,B).
Diversity values ranged from 0.98 bits ind−1 (6 m station) to 3.12 bits ind−1 (18 m station) (Fig. 2C). There was also a general trend towards increasing numbers of individuals
and species from the shallow to the deeper stations. Diversity value was higher at the 18
m station than at the 25 m station, where a dominance (more than 50%) of one species: A.
gudrunae occurred. The lowest diversity and evenness values were recorded at the 6 m
station due to the small number of species and to the dominance of O. notialis.
Cluster analysis performed on the stations (Q mode), distinguished three groups, hereafter named Groups I-III, with 0.55 of dissimilarity: Group I comprised the replicates
from the 18 and 25 m and Scour 2 stations. Groups II and III comprised sample replicates
from the 11 and 6 m stations, respectively (Fig. 3). The sample replicates that comprised
Group I were characterized by higher density and diversity values than the other groups
with A. gudrunae, L. kerguelensis and T. cf. cincinnatus as dominant species. Groups II
and III were characterized with lower values of density and diversity and by the domi-
180
BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 1, 2000
Figure 2. Total density (A), total biomass (B), diversity and evenness (C) of polychaetae fauna at
the sampling stations. The horizontal bars represent the multiple comparisons obtained by the
Nemenyi test, on the basis of the existence of significant differences by the Kruskal-Wallis test (p
< 0.05), showing those stations which demonstrate similarity.
nance of O. notialis. Group II had more than twice the number of species than Group III
(Table 2).
Cluster analysis performed on the species (R mode) revealed three groups with 0.63 of
dissimilarity with the separation of M. cf. moorei which was found only at the 6 and 11 m
BROMBERG ET AL.: ANTARCTIC POLYCHAETES
181
Figure 3. Dendrogram of stations derived from abundances of 18 polychaete species.
stations (Fig 4). Group A includes nine species that showed a wider distribution along the
transect and included the seven most abundant species. Group B was characterized by six
species whose densities were not as high and were concentrated at the 25 m station with
some species also occurring at the 18 m station. Group C consisted of two species with
low densities and high occurrence at the 11 m station (Table 2).
DISCUSSION
Values of density, biomass and richness of polychaetes increased with depth. These
depth-related patterns were observed for the meiofauna in the same transect and period
(Skowronski et al., 1998). Higher concentrations of meiofauna, a potential source of food,
associated with more stable environmental conditions, were likely to make deeper areas
more favorable to the settlement of a more diverse polychaete fauna. Higher polychaete
densities and biomass were also related to medium and fine silt sediments; greater values
for richness, such as those found at the 18 and 25 m stations, may be due to the high
heterogeneity of the sediment. Polychaete biomass also showed a linear relationship to
depth in the shallow waters of the Signy Islands (Hardy, 1972).
Despite the differences in dominant species between the shallow stations (6 and 11 m)
and the deeper ones (18 and 25 m), eight species were responsible for approximately 90%
Stations
Species
Barrukia cristata (Willey, 1902)
Eteone sculpta Ehler, 1897
Phyllodoce sp.
Phyllodocidae
Brania rhopalophora (Ehlers,1897)
Exogone heterosetosa McIntosh, 1885
Sphaerosyllis sp.
Syllidae
Aglaophamus ornatus Hartman, 1967
Ophryotrocha notialis (Ehlers, 1908)
Sphaerodoropsis arctowskyensis
Hartmann-Schröder & Rosenfeldt, 1988
Pettiboneia hartmanae Orensanz, 1990
Leitoscoloplos kerguelensis
(McIntosh, 1885)
Tauberia gracilis (Tauber, 1879)
Tauberia cf. oligobranchiata
Strelzov, 1973
Cirrophorus sp.
Paraonidae
Microspio cf. moorei (Gravier, 1911)
Tharyx cf. cincinnatus (Ehlers, 1908)
Apistobranchus gudrunae
Hartmann-Schröder & Rosenfeldt, 1988
Brada villosa (Rathke, 1843)
Ilyphagus sp.
b
53
57
5
d
113
37
2
6m
22
12
63
102
15
1
1,130
84
1
266
11
59
16
5
1
7
28
11
b
d
11 m
6
1
92
139
1
1
144
44
14
205
5
100
175
5
2
340
15
10
18 m
d
b
1
30
1
2
1
2
1
1
22
5
43
33
15
915
275
575
10
265
37
151
186
712
10
10
1
1
9
6
10
5
b
340
25 m
19
1
d
4
1
4
1
2
38
4
Scour 1
d
b
1
58
118
2
185
5
105
190
5
440
20
10
2
2
23
13
8
4
Scour 2
d
b
1
685
Table 2. Density (d) and biomass (b) of polychaete species collected in Martel Inlet, expressed as numbers of individuals and milligrams (wet weight) per
0.04 m2, respectively. For each station, the total density and biomass per m2, the richness (number of species), diversity (bits/ind.) and evenness are given.
182
BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 1, 2000
Total
Total per m2
Species richness
Diversity
Evenness
Stations
Species
Ophelina gymnopyge (Ehlers, 1908)
Ophelina syringopyge (Ehlers, 1901)
Ophelina spp.
Capitella perarmata (Gravier, 1911)
Capitella capitata antarctica
Monro, 1930
Capitella spp.
Rhodine antarctica Gravier, 1907
Eupraxillella antarctica
Hartmann-Schröder & Rosenfeldt, 1989
Asychis amphiglypta (Ehlers, 1897)
Praxillella sp.
Lysilla macintoshi Gravier, 1907
Leaena cf. collaris Hessle, 1917
Pista sp.
Terebellidae
Euchone cf. pallida Ehlers, 1908
Table 2. Continued.
4
2
154
119
3,850 2,975
4
0.98
0.49
b
6m
d
23
2
639
13
1
15
60
40
10
50
5
11
10
1
8
2
18 m
d
b
69
275
43
35
9
5
5
5
1
5
1
2
30
840
13
6
25
65
5
7
13
3
25 m
d
b
16
20
8
10
384 2,206
627 1,387 1,241 3,456
9,600 55,150 15,675 34,675 31,025 86,400
14
21
19
1.88
3.12
2.19
0.49
0.71
0.52
b
22
28
11 m
d
7
6
20
16
8
80
200 2,000
4
1.67
0.83
1
1
Scour 1
d
b
2
5
444 1,579
11,100 39,475
20
2.48
0.57
1
1
5
2
5
20
35
1
4
7
1
1
5
5
2
2
Scour 2
d
b
7
10
10
15
BROMBERG ET AL.: ANTARCTIC POLYCHAETES
183
184
BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 1, 2000
Figure 4. Dendrogram of 18 polychaete species derived from their abundance distribution at stations.
of the total number of polychaetes found. This dominance was observed by Gambi et al.
(1997) as constituting a trend commonly found in polychaete assemblages in Antarctic
areas.
The lower values of density and biomass and the composition of the polychaete fauna,
with the dominance of O. notialis and M. cf. moorei found at the 6 and 11 m stations, are
typical of an impacted area. The genus Ophryotrocha, as well as some spionids, showed a
strong positive association with disturbed sediments in the Arctic (Fournier and Conlan,
1994; Conlan et al., 1998) and Antarctic areas (Leninhan and Oliver, 1995). Conversely,
tube-dwelling polychaetes such as L. cf. collaris, Euchone cf. pallida and A. amphiglypta
are among the species found at depths below the area of major ice impact. These species
were only observed at the deeper stations of the study area and were completely absent in
the shallow zones. A transition from a moderately diverse community of animals of small
body size to an assemblage which has a high biomass and is characterized by the presence
of tube-dwelling polychaetes was also verified by Kendall (1994) in an Arctic area.
The dominant species at the 18 and 25 m stations, the deposit feeders A. gudrunae, L.
kerguelensis and the genera Tharyx and Ophelina, are widely known to be very common
and abundant in Admiralty Bay (Arnaud et al., 1986; Sicinski, 1986; Jazdzewski and
Sicinski, 1993) and other areas near the Antarctic Peninsula (Lowry, 1975; Desbruyères,
1977; Richardson and Hedgpeth, 1977; Gallardo et al., 1988). The surface and subsurface
deposit feeders represented more than 90% of the polychaetes found at the deeper stations of the area studied, whereas the carnivores were responsible for approximately 70%
BROMBERG ET AL.: ANTARCTIC POLYCHAETES
185
of the polychaetes in the shallow ones. The dominance of carnivores at the shallow stations and deposit feeders at the deeper ones was also verified by Gambi et al. (1997) and
was related to favorable sediment characteristics.
The stations scoured by icebergs showed two different situations. The Scour 1 station
had almost no fauna, low density, biomass and diversity values. Conversely, the Scour 2
station showed higher values, suggesting that this scour is likely to be an older scour, in a
more advanced stage of recolonization.
The structure and composition of the polychaete assemblage verified at the Scour 2
station are very similar to those found at the 18 m station. The presence of numerous
polychaetes in the scours may imply either that there was rapid migration of adults and/or
larval recruitment or that these species survived the scouring event, possibly by being
plowed up onto the berm and subsequently tumbling back into the trough (Conlan et al.,
1998).
Inappropriate conditions for polychaete colonization, such as the anoxic condition of
the sediment, the aggregation of macroalgae debris and restricted circulation may be responsible for the low values obtained at the Scour 1 station. This situation was noted by
Skowronski et al. (1998) as explaining their results for the meiofauna communities and
similar to that described by Holte and Oug (1996) where the macroalgae Desmarestia
formed a dense lattice on the sediment surface which presumably trapped organic particles and reduced the water exchange, creating anoxic conditions.
Previous work done in the shallow waters of Ezcurra Inlet, Admiralty Bay (Sicinski
and Janowska, 1993), was in contrast with the present work. Despite the similar number
of species and their increase with depth, only eight species were found in common. Low
richness values were recorded above 6 m depth, with the dominance of M. cf. moorei, and
higher values below 20 m. Density values were much lower than in the present study and
ranged from 60 ind m−2 at the 6.5 m to 3293 ind m−2 at the 25 m depth. In relation to
biomass, the values found by Sicinski and Janowska (1993) were comparable, ranging
from 3.8 to 46.4 g m−2, with A. ornatus accounting for 75% of these values. Although
located in the same bay, the two areas studied presented different abiotic characteristics,
primarily topography. The area off the Brazilian station is more protected than the entrance to the Ezcurra Inlet, where Sicinski and Janowska’s study (1993) was done. The
authors suggested the existence of a change in the structure of the fauna at 20 m, due to
the type of sediment, but made no mention of the ice effects as one of the possible reasons
for the distribution found. Sampling was also carried out in distinct periods during the
summer which might also have contributed to the differences. Therefore, care should be
taken when making generalizations about the polychaete communities in the bay. Considerable differences were found in the composition of this group in the shallow waters of
Admiralty Bay.
The composition and distribution of polychaetes in the area studied is likely to be influenced by the action of different community structuring factors such as substrata variability (Sicinski, 1986; Mühlenhardt-Siegel, 1988, 1989; Jazdzewski and Sicinski, 1993;
Sicinski and Janowska, 1993; Skowronski et al., 1998; Gambi et al., 1997); high primary
production, even though seasonal (Lowry, 1975), abundance of macroalgae as food resource (Jazdzewski and Sicinski, 1993) and sedimentation of suspended matter in areas
near glaciers (Sicinski and Janowska, 1993). However, the major factor determining the
composition and distribution of species in the transect studied seems to be the mechanical
action of the ice. The impact caused by the ice in the benthic communities was observed
186
BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 1, 2000
by Mühlenhardt-Siegel (1988), Jazdzewski and Sicinski (1993), Skowronski et al. (1998),
Gambi et al. (1997) and Sahade et al. (1998). These latter authors also suggested that the
increase in the diversity of megafauna species and biomass in deep areas may be related
to biological interactions such as predation, competition and larval settling and development which would define the structure of the community.
In conclusion, in the area sampled, there is a depth-related increase in diversity, density
and biomass of polychaetes which appear largely to be caused by mechanical ice abrasion
in shallow areas where the mobile opportunistic species are favored. The deeper areas are
inhabited by less mobile species which require a certain degree of environmental stability. The stations at 6 and 11 m and Scour 1 have quite different species composition,
whereas there is a great deal of similarity between the assemblages at the remaining stations. The general trends show certain similarities to those seen in other areas in terms of
the dominant species as well as the population structure. Studies concerning polychaete
communities should be extended to other shallow areas in Antarctica in order to verify the
occurrence of different patterns of spatial and temporal variation.
ACKNOWLEDGMENTS
We would like to extend our thanks to the two anonymous referees for their critical reading of
the manuscript and helpful suggestions, to A. Rebelo Rocha and M. Magro for drawing the maps,
to P. Paiva and R. Skowronski for their very useful comments, as also to T. A. S. Brito, P. Paiva and
L. Candisani (SCUBA divers) for the underwater sampling. Financial support was provided by
CIRM and CNPq (Subproject 9616 ). CNPq also provided scholarship to S. Bromberg. We are also
grateful to the staff of the Brazilian Antarctic Station “Cmte Ferraz.”
LITERATURE CITED
Arnaud, P. M., K. Jazdzewski, P. Presler and J. Sicinski. 1986. Preliminary survey of benthic invertebrates collected by Polish Antarctic Expeditions in Admiralty Bay (King George Island, South
Shetland Islands, Antarctica). Pol. Polar Res. 7: 7–24.
Arntz, W. E., T. Brey and V. A. Gallardo. 1994. Antarctic zoobenthos. Oceanogr. Mar. Biol. Ann.
Rev. 32: 241–304.
Bray, J. R. and J. T. Curtis. 1957. An ordination of the upland forest communities in southern
Wisconsin. Ecol. Monogr. 27: 325–349.
Brito, T. A. S. 1993. Taxonomic and ecological studies on Antarctic Octocorals of the genus Thouarella
(Octocorallia: Primnoidae). Ph.D Thesis. Univ. Southampton, Southampton. 272 p.
Bromberg, S. 1999. Distribuição dos anelídeos poliquetas na zona rasa da Enseada Martel, Baía
do Almirantado (Ilha Rei George - Antártica). M.Sc. Thesis, Instituto Oceanográfico, Univ.
São Paulo, São Paulo. 84 p.
Conlan, K. E., H. S. Leninhan, R. G. Kvitek and J. S. Oliver. 1998. Ice scour disturbance to benthic
communities in the Canadian High Arctic. Mar. Ecol. Prog. Ser. 166: 1–16.
Dayton, P. K., G. A. Robilliard and A. L. DeVries. 1969. Anchor ice formation in McMurdo Sound,
Antarctica and its biological effects. Science 163: 273–274.
___________, ______________ and R. T. Paine. 1970. Benthic fauna zonation as a result of anchor
ice at McMurdo Sound, Antarctica. Pages 244–258 in M. W. Holdgate, ed. Vol. 1, Antarctic
ecology. Academic Press, London.
___________, ______________, _____________ and L. B. Dayton. 1974. Biological accommodation in the benthic community at McMurdo Sound, Antarctica. Ecol. Monogr. 44: 105–128.
BROMBERG ET AL.: ANTARCTIC POLYCHAETES
187
Desbruyères, D. 1977. Diversité des peuplements annélidiens benthiques dans un système fjordique
adjacent au Golfe du Morbihan (Archipel de Kerguelen) . Pages 227–238 in G. A. Llano, ed.
Adaptations within Antarctic ecosystems. Proc. 3rd SCAR Symp. Antarctic Biology, Smithson.
Inst., Washington, D.C.
Field, J. G., K. R. Clarke and R. M. Warwick. 1982. Pratical strategy for analysing multispecies
distribution patterns. Mar. Ecol. Prog. Ser. 8: 37–52.
Folk, R. L. and W. C. Ward. 1957. Brazos river bar: a study in the significance of grain size parameters. J. Sed. Petrol. 27: 3–26.
Fournier, J. A. and K. E. Conlan. 1994. A new species of Ophryotrocha (Polychaeta, Dorvilleidae)
associated with ice scours in the Canadian Arctic Archipelago. Mém Mus natl. Hist. nat. 162:
185–190.
Gambi, M. C., A. Castelli and M. Guizzardi. 1997. Polychaete populations of the shallow soft
bottoms off Terra Nova Bay (Ross Sea, Antarctica): distribution, diversity and biomass. Polar
Biol. 17: 199–210.
Gallardo, V. A. and J. G. Castillo. 1969. Quantitative benthic survey of the infauna of Chile Bay
(Greenwich I., South Shetland Is.). Gayana 16: 3–17.
____________, ___________ , M. A. Retarnal, A. Yañez, H. I. Moyano and J. G. Hermosilla. 1977.
Quantitative studies on the soft-bottom macrobenthic animal communities of shallow Antarctic
Bays. Pages 361–387 in G. A. Llano, ed. Adaptations within Antarctic ecosystems, Proc. 3rd
SCAR Symp. Antarctic Biology, Smithson. Inst., Washington, D.C.
____________, S. A. Medrano and F. D. Carrasco. 1988. Taxonomic composition of the sublittoral
soft-bottom Polychaeta of Chile Bay (Greenwich Island, South Shetland Islands, Antarctica).
Ser. Cient. INACH 37: 49–67.
Gross, M. G. 1971. Carbon determination. Pages 573–596 in R. E. Carver, ed. Procedures in sedimentary petrology. Wiley Interscience, New York.
Gutt, J., A. Starmans and G. Dieckmann. 1996. Impact of iceberg scouring on polar benthic habitats. Mar. Ecol. Prog. Ser. 137: 311–316.
Hardy, P. 1972. Biomass estimates for some shallow-water infaunal communities at Signy Island,
South Orkney Islands. Br. Antarct. Surv. Bull. 31: 93–106.
Holte, B. and E. Oug. 1996. Soft-bottom macrofauna and responses to organic enrichment in the
subarctic waters of Tromsø, Northern Norway. J. Sea Res. 36: 227–237.
Jazdzewski, K. , W. Jurasz , W. Kittel, E. Pressler, P. Pressler and J. Sicinski. 1986. Abundance and
biomass estimates of the benthic fauna in Admiralty Bay, King George Island, South Shetland
Islands. Polar Biol. 6: 5–16.
____________ and J. Sicinski. 1993. Zoobenthos. Pages 83–95 in S. Rakusa-Suszczewski, ed. The
maritime Antartic coastal ecosystem of Admiralty Bay. Dept. Antarct. Biol. Warsaw, Pol. Academy Sci.
Kendall, M. A. 1994. Polychaete assemblages along a depth gradient in a Spitsbergen Fjord. Mém
Mus natl. Hist. nat. 162: 463–470.
Legendre, L. and P. Legendre. 1983. Numerical ecology. Elsevier Scientific Publishing Company,
Amsterdam. 419 p.
Leninhan, H. S. and J. S. Oliver. 1995. Anthropogenic and natural disturbances to marine benthic
communities in Antarctica. Ecol. Appl. 5: 311–326.
Lowry, J. K., 1975. Soft bottom macrobenthic community of Arthur Harbor, Antarctica. Antarct.
Res. Ser. 23: 1–19.
Mühlenhardt-Siegel, U. 1988. Some results of quantitative investigations of macrozoobenthos in
the Scotia Arct (Antarctic). Polar Biol. 8: 241–248.
__________________. 1989. Quantitative investigations of Antarctic zoobenthos communities in
winter (May/June) 1986 with special reference to the sediment structure. Arch. Fisch Wiss. 39:
123–141.
Nonato, E. F., T. A. S. Brito, P. C. Paiva and M. A. V. Petti. 1992. Programa Antártico Brasileiro:
Projeto “Bionomia da Fauna Bentônica Antártica”. Atividades subaquáticas realizadas na Baía
188
BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 1, 2000
do Almirantado a partir da VI expedição (1988). Relat. int. Inst. Oceanogr. Univ. São Paulo 33:
1–12.
Pielou, E. C. 1975. Ecological diversity. John Wiley, New York. 165 p.
Pruszak, Z. 1980. Current circulation in the waters of Admiralty Bay (region of Arctowski Station
on King George Island). Pol. Polar Res. 1: 55–74.
Rakusa-Suszczewski, S. 1980. Environmental conditions and the functioning of Admiralty Bay (South
Shetland Islands) as a part of the near shore Antarctic ecosystem. Pol. Polar Res. 1: 11–27.
Richardson, M. D. and J. W. Hedgpeth. 1977. Antarctic soft-bottom, macrobenthic community adaptations to a cold, stable, highly productive, glacially affected environment. Pages 181–196 in
G. A. Llano, ed. Adaptations within Antarctic ecosystems, Proc. 3rd SCAR Symp. Antarctic
Biology, Smithson. Inst., Washington, D.C.
Sahade, R., M. Tatián, J. Kowalke, S. Kühne and G. B. Esnal. 1998. Benthic faunal associations on
soft substrates at Potter Cove, King George Island, Antarctica. Polar Biol. 19: 85–91.
Shannon, C. E. and W. Weaver. 1949. The mathematical theory of communication. Univ. Illinois
Press, Urbana. 125 p.
Sicinski, J. 1986. Benthic assemblages of Polychaeta in chosen regions of Admiralty Bay (King
George Island, South Shetland Island). Pol. Polar Res. 7: 63–78.
________ and E. Janowska. 1993. Polychaetes of the shallow sublittoral of Admiralty Bay, King
George Island, South Shetland Islands). Antarct. Sci. 5: 161–167.
Skowronski, R. S. P., T. N. Corbisier and F. R. Robles. 1998. Meiofauna along a coastal transect in
Admiralty Bay, King George Island (Antarctica). Pesq. antárt. bras. 3: 117–132.
Suguio, K. 1973. Introdução à sedimentologia. Edgard Blücher, São Paulo. 317 p.
Wägele, J. W. and T. A. S. Brito. 1990. Die sublitorale fauna der maritimen Antarktis, Erste
unterwasserbiobachtungen in der Admiralitäsbucht. Natur Mus. 120: 269–282.
Zar, J. H. 1996. Bioestatistical analysis. 3rd ed. Prentice Hall, Englewood Cliffs, New Jersey. 662 p.
ADDRESS: Instituto Oceanográfico da Universidade de São Paulo, Praça do Oceanográfico, 191 05508900, São Paulo, Brasil. CORRESPONDING AUTHOR: (S.B.) E-mail: <[email protected]>.