Journal of

Plankton Research

academic.oup.com/plankt

J. Plankton Res. (2021) 43(3): 442–457. First published online May 3, 2021 doi:10.1093/plankt/fbab031

Vertical changes in abundance, biomass
and community structure of pelagic
polychaetes down to 1000 m depths at
Station K2 in the western subarctic
Paciﬁc Ocean covering the four seasonsand day–night
KANAKO AMEI1, *, RYO DOBASHI1 , NAOTO JIMI2 , MINORU KITAMURA3 AND ATSUSHI YAMAGUCHI1,4

faculty/graduate school of fisheries sciences, hokkaido university, 3-1-1 minato-cho, hakodate, hokkaido 041−8611, japan, 2 biosciencegroup, national institute of polar research, 10-3 midori-cho, tachikawa, tokyo 190−8518, japan, 3 japan agency for marine-earth scienceand technology, 2−15 natsushima-cho, yokosuka, kanagawa 237−0061, japan and 4 arctic research center, hokkaido university, kita-21
nishi-11 kita-ku, sapporo, hokkaido 001−0021, japan

1*corresponding author: kanakoamei@eis.hokudai.ac.jp
Received August 28, 2020; revised April 5, 2021; editorial decision April 7, 2021; accepted April 8, 2021
Corresponding editor: Xabier Irigoien

Pelagic polychaetes are distributed from the sea surface to greater depths of the oceans worldwide, but little information
is available regarding their ecology. This study investigated the vertical distribution of abundance, biomass andcommunity structure of pelagic polychaetes at a single station in the western subarctic Paciﬁc based on day–nightvertical stratiﬁed samples collected from a 0 to 1000 m water column during four seasons covering 1 year. The
polychaete abundance and biomass ranged from 0 to 757 ind. 1000 m−3 and 0–6.1 mg WW m−3 , respectively. Tenpelagic polychaete species belonging to nine genera and six families were identiﬁed. From cluster analysis based onabundance, the polychaete community was divided into ﬁve communities. Each community occurred at different depth
layers. Two surface groups seen at 0–200 m were dominated by two carnivorous species: Tomopteris septentrionalis andTyphloscolex muelleri. The deepest group, dominated by the particle feeder Pelagobia longicirrata, was seen at 500–1000 m.
Two transition groups occurred in the intermediate depths. These vertical distributions of the pelagic polychaete

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ORIGINAL ARTICLE

K. AMEI ET AL.

VERTICAL CHANGES IN ABUNDANCE, BIOMASS AND COMMUNITY STRUCTURE OF PELAGIC POLYCHAETES

communities were common throughout the season and day. Water mass, food availability and the oxygen minimum
layer are put forth as environmental factors that affect the pelagic polychaete community.
KEYWORDS: pelagic polychaetes; Pelagobia longicirrata; Poeobius meseres; Tomopteris septentrionalis; Typhloscolex muelleri

INTRODUCTION

Magellan (Guglielmo et al. 2014) and the South AdriaticSea (Guglielmo et al. 2019), these studies are based on
only one cruise (limited season), and no diel differences
have been identiﬁed. Thus, it remains unknown whether
the pelagic polychaete community structure varies withdepth, showing seasonal and diel changes.
Regionally, information on pelagic polychaete ecology
is scarce for the western subarctic Paciﬁc, although they
have been reported to occur throughout the year (Kitamura et al. 2016; Amei et al. 2020). Regarding the physicaloceanographic characteristics of the western subarctic
Paciﬁc, the presence of cold dichothermal water (DTW)(Dodimead et al. 1963; Miura et al. 2002) and warm
mesothermal water (MTW) (Dodimead et al. 1963; Ueno
and Yasuda 2000, 2005) is prominent. DTW (1–3◦ C) isobserved at 100–120 m in the western subarctic Paciﬁc.
This water is derived from the Bering Sea, where water iscooled by winter mixing and transported into the western
subarctic Paciﬁc through the East Kamchatka Current(Dodimead et al. 1963; Miura et al. 2002). MTW (3–4◦ C)
is observed at 200–400 m in the western subarctic Paciﬁcand is suggested to originate from the mixed water region
between the subarctic and subtropical areas (Ueno and
Yasuda 2000). The water in the mixed water region istransported to the Gulf of Alaska and the Bering Sea,
then into the western subarctic Paciﬁc through the East
Kamchatka Current (Dodimead et al. 1963; Ueno and
Yasuda 2000, 2005). These complex physical oceanographic conditions may affect the pelagic polychaete community, but no information is currently available.
In the western subarctic gyre of the North Paciﬁc, atime-series observation station, Station K2, was set from1999 to the present (cf. Wakita et al. 2016). The observations at St. K2 were mainly made by the Japan Agency for
Marine-Earth Science and Technology (JAMSTEC), andvarious international programmes, such as VERTIGO(Buesseler et al. 2007; Steinberg et al. 2008a) and K2/S1(Honda et al. 2016, 2017), were conducted. Through suchresearch programmes, various biological aspects, suchas primary productivity (Elskens et al. 2008; Matsumoto
et al. 2014, 2016), phytoplankton (Boyd et al. 2008; Fujiki
et al. 2014), archaea (Kaneko et al. 2016), zooplankton
community (Steinberg et al. 2008b; Kitamura et al. 2016;
Kobari et al. 2016), quantiﬁcation of zooplankton egested
fecal pellets (Wilson et al. 2008; Wilson and Steinberg
2010), sinking organic material ﬂux (Honda et al. 2016,

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Pelagic polychaetes are known to be distributed fromthe sea surface to the deep sea in the oceans worldwide(Ushakov 1974; Halanych et al. 2007). The feeding modesof pelagic polychaetes vary with species, including herbivores (Day 1967; Hopkins and Torres 1989) and carnivores (Lebour 1922; Rakusa-Suszczewski 1968; Feigenbaum 1979). For feeding modes of the cosmopolitan
pelagic polychaete family (Typhloscolecidae), the presence of specialized prey–predator linkages in carnivorous
zooplankton taxa (chaetognaths) is reported in oceans
globally (Feigenbaum 1979; Øresland and Pleijel 1991;Øresland and Bray 2005). The numerically dominant
species of pelagic polychaetes [Pelagobia longicirrata (P. longicirrata)] is an important prey of various pelagic organisms, including copepods, chaetognaths and ﬁshes (Hopkins 1985, 1987; Hopkins and Torres 1989; Øresland1990). The pelagic polychaete species dominating themesopelagic layer (Poeobius meseres) are known to feed onsinking particles by extending a mucus web (Uttal andBuck 1996; Robison et al. 2010) and have an importantrole in determining the amount of vertical material ﬂux(Christiansen et al. 2018). These facts indicate that pelagic
polychaetes may have important roles in marine ecosystems for both the food web and vertical material ﬂux ofoceans worldwide.
Concerning the ecology of pelagic polychaetes, horizontal distributions (Fernández-Álamo 1991, 2006; Fernández-Álamo et al. 2003) and seasonal changes (Peter
1975; Batistić et al. 2004, 2007) of the community structure have been reported. Some pelagic polychaetes are
known to have bioluminescence ability (Francis et al. 2016;
Gouveneaux et al. 2017, 2018) and feed on sinking particles via the deployment of a mucus web and tentacles(Uttal and Buck 1996; Robison et al. 2010; Christiansen
et al. 2018). Bioluminescence and feeding on sinking particles are considered to be adaptations of zooplankton fordeep-sea environments (Vinogradov 1968; Haddock et al.
2010).
From the viewpoint of the deep-sea adaptation of
pelagic polychaetes, information on their vertical distribution is important. However, little information is available on the vertical distribution of pelagic polychaetes.
Although several studies have investigated vertical distributions of pelagic polychaetes down to greater depths(∼1000 m) in the Scotia Front (Siciński 1988), the Strait ofJOURNAL OF PLANKTON RESEARCH

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2017 and references therein), biological pump estimation(Steinberg et al. 2008a; Wakita et al. 2016) and biologicalpump modelling (Bianchi et al. 2013), have been reported.
Based on long-term observation data, the presence of theocean acidiﬁcation trend has also been reported (Wakita
et al. 2017). Although this information is valuable, comparable data are not available for the pelagic polychaetes
at St. K2.
This study revealed diel, seasonal and vertical changes
in pelagic polychaete community structure based on day–night vertical stratiﬁcation samples collected from a 0 to1000 m water column at St. K2 in the western subarctic
Paciﬁc during four seasons covering 1 year. The pelagic
polychaete abundance, biomass and community structure results were compared with the complex physicaloceanographic conditions of the station. The results werealso compared with the results of previous studies on

pelagic polychaetes conducted down to greater depths
in oceans worldwide, as mentioned above (Siciński 1988;
Guglielmo et al. 2014, 2019). Through this comparison,
we aimed to evaluate the factors that determine thevertical distribution and community structure of pelagic
polychaetes down to greater depths.

MATERIALS AND METHODS
Zooplankton samples were collected by day and nightvertical stratiﬁed sampling from eight layers (0–50, 50–
100, 100–150, 150–200, 200–300, 300–500, 500–750,
750–1000 m) by oblique towing of the Intelligent Operative Net Sampling System (IONESS, SEA Corporation)(mesh size: 335 μm; mouth area: 1.5 m2 ) at Station K2(47◦ 00 N, 160◦ 00 E, bottom depth: 5200 m, Fig. 1) in

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Fig. 1. Location of sampling station (K2) at the centre of the western subarctic gyre in the Paciﬁc Ocean. Depth contours (1000, 3000 and 6000 m)
and approximate positions of the currents (Okazaki et al. 2005) are superimposed.

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Table I: Zooplankton samplings (eight vertical stratiﬁcation samplings between 0 and1000 m) at St. K2 in the western subarctic
Paciﬁc from October 2010 to July 2011. D:
day, N: night
Local time

D/N

29 Oct. 2010
29 Oct. 2010
26 Feb. 201126 Feb. 201122 Apr. 201123 Apr. 2011
3 July 2011
3–4 July 201112:09–13:52
22:09–23:38
12:35–14:41
22:01–23:44
21:59–23:56
12:45–14:37
12:05–13:55
22:51–0:55

D
N
D
N
N
D
D
N

the western subarctic Paciﬁc on 29 October 2010, 26
February, 22–23 April and 3–4 July 2011 (Table I). The
depths and volumes of the ﬁltered water (m3 ) of thenets were monitored on deck. Data on ﬁltered volume
are available from the Supplementary Material. Collected samples were preserved by adding 4% (v/v) boraxbuffered formalin. Temperature, salinity, dissolved oxygen(DO) and ﬂuorescence were measured by CTD (SBE 911
plus; Sea-Bird Scientiﬁc) at each sampling occasion. For
details about samplings, see Kitamura et al. (2016).
Based on temperature and salinity, water masses wereidentiﬁed for each depth and sampling date. We classiﬁed ﬁve water masses, seasonal pycnocline water (SPW),
DTW, transition water (TW), MTW and deep water(DW), from the T–S characteristics at each sampling layer(Dodimead et al. 1963; Ueno and Yasuda 2000, 2005;
Miura et al. 2002).
In the land laboratory, pelagic polychaetes were
sorted from the 1/2 to 1/64 subsamples according
to the quantity of the samples. For data on aliquots
and the counted individual number of each sample,
see the Supplementary Material 1. Specimens wereidentiﬁed and counted under a stereomicroscope. Species
identiﬁcation was made down to the lowest level possible,
following Dales (1957) and Tebble (1962). For each genus
or species, a batch of specimens in each sample wasplaced on preweighed mesh, and then water was removed
with the aid of wipe paper. The wet weight was measured
by an electronic balance (Mettler Toledo AT261) with a
precision of 0.01 mg. Then, the vertical distributions of
total abundance (ind. 1000 m−3 ) and total WW (mg WWm−3 ) were quantiﬁed.
For the community structure of the pelagic polychaetes, the similarity of samples based on abundance
was calculated by the Bray–Curtis method (Bray andCurtis 1957). Abundance data of pelagic polychaete

RESULTS
Hydrography
Vertical distributions of temperature, salinity, DO andﬂuorescence at each sampling date are shown in Fig. 2.
Throughout the sampling dates, the temperature, salinity,
DO and ﬂuorescence were 0.7–8.5◦ C, 32.5–34.5, 0.30–
7.49 mL L−1 and 0.02–2.32, respectively. Regarding temperature, the seasonalthermocline developed at 50 m in
October and June, whereas the temperature was uniform
at <100 m in February and April. Common to all seasons,temperature formed a sub-minimum (1–2◦ C) at ∼100 m
depth and a sub-maximum (ca. 3.5◦ C) at ∼200 m. Then,the temperature decreased with increasing depth below
200 m. Salinity increased with increasing depth for allseasons. At shallower depths, salinity was uniform at
0–100 m in February and April, whereas it was low(32.6–32.8) at 0–50 m in June and October. DO decreased
with increasing depth. DO was high above 200 m,
whereas it was extremely low (<1.4 mL L−1 ) below
200 m depth. High ﬂuorescence was observed only
above the thermocline. Since thermocline depths variedwith season, high ﬂuorescence was seen at 0–50 m in
October and June and at 0–100 m in February and April.
Fluorescence was higher in October and June than in
February and April.
T–S diagrams throughout the study period are shownin Fig. 3. Except for the seasonal pycnocline observed
above 50 m in October and July, water mass formation
showed little seasonal change. The formation of the water
masses greatly varied with depth. Thus, from shallow to
deep, SPW (0–50 m only October and July), DTW (50–
100 m), TW (100–150 m), MTW (150–500 m) and DW(500–1000 m) occurred.

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Sampling datespecies (X : ind. 1000 m−3 ) were log-transformed (log
[X + 1]) before analysis. Cluster analysis connected withcomplete linkage methods was performed for the grouping of the samples. Through nonmetric multidimensional
scaling (NMDS; Minchin 1987) and Pearson’s correlation
coefficient, relationships between environmental variables (depth, temperature, salinity, DO, ﬂuorescence) andpolychaete sample ordinations were analysed. To evaluate
the effects of season, day–night and depth on similarities
between samples, PERMANOVA was performed. These
analyses were carried out using PRIMER v7 (PRIMERE Ltd). Intercommunity and water mass differences in
the abundance of each species were tested by one-way
ANOVA and post hoc test (Tukey–Kramer test). These
analyses were performed using STAT-View.

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Polychaete community
In this study, 8200 polychaete specimens were counted in
total, and 8149 polychaetes were identiﬁed at the genus
or species level. For details of quantiﬁed numbers in eachsample, see the Supplementary Material 1. Throughout
the year, 10 pelagic polychaete species belonging tonine genera and six families were identiﬁed (Table II).
For population density through the 0–1000 m watercolumn, pelagic polychaetes occurred 235.3 ± 27.8 ind.
1000 m−3 (annual mean ± SE). The most numericallyabundant species was P. longicirrata (annual mean: 176.2
ind. 1000 m−3 , 73.7% of total), followed by Typhloscolex
muelleri (T. muelleri) (33.6 ind. 1000 m−3 , 14.0%), Tomopteris
septentrionalis (T. septentrionalis) (17.3 ind. 1000 m−3 , 7.2%)
and Poeobius meseres (4.9 ind. 1000 m−3 , 2.1%). These four
numerically dominant species accounted for 97.0% of
the annual mean pelagic polychaete abundance.
In terms of population density in each sampling layer,
the abundance of pelagic polychaetes ranged from 0 to
757 ind. 1000 m−3 (Fig. 4). For daytime, the maximum
abundances of the four seasons were seen at 150–500 m,
especially at 300–500 m. For night-time, the maximum
abundance was seen at 0–500 m, especially at the sea
surface (0–50 m) in February and April.
For biomass, the annual mean standing stock of
the pelagic polychaetes was 517.5 mg WW 1000 m−3(Table II). Within the annual mean biomass, theproportion of large Tomopteridae was in the order of
52% while their numerical abundances were low.
In terms of density, the pelagic polychaete biomass
ranged from 0 to 6.1 mg WW m−3 (Fig. 5). For the
daytime, biomass peaks were seen at 150–500 m depths,
especially at ∼200 m. For the night-time, the maximum
biomass was at 0–200 m, especially at the sea surface(0–50 m) in February and July.
Regarding the effect of water masses, three species(P. longicirrata, T. muelleri and T. septentrionalis) had significantly different abundances between the water masses(Table III). Within them, P. longicirrata was abundant in
the water masses in the deep layer (DW and MTW).
On the other hand, T. mulleri and T. septentrionalis showed
high abundances for the shallowest SPW. Thus, thesedifferences in pelagic polychaete abundances with thewater masses were related to the vertical distribution ofeach species.
From cluster analysis based on abundance, the pelagic
polychaete community was divided into ﬁve groups (A–E) at 58% dissimilarity (Fig. 6a). Each group contained
5–20 samples. Each group was also clearly separated in
the NMDS plot (Fig. 6b). The environmental variables
except for temperature (depth, salinity, DO and ﬂuorescence) had signiﬁcant directions in the NMDS ordination (Fig. 6b). According to the species composition, thepredominant species were present for groups A, B and E

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Fig. 2. Vertical changes in temperature (T), salinity (S), dissolved oxygen (DO, O2 ) and ﬂuorescence (F) at St. K2 in the western subarctic Paciﬁcfrom October 2010 to June 2011. Circled numbers in the right column indicate the depth strata of the zooplankton sampling.

K. AMEI ET AL.

VERTICAL CHANGES IN ABUNDANCE, BIOMASS AND COMMUNITY STRUCTURE OF PELAGIC POLYCHAETES(Fig. 6c). Thus, T. muelleri was abundant in group A, T.
septentrionalis was abundant in group B and P. longicirrata
predominated in group E. Groups C and D were composed of various species, and the dominant species in the
deep layer varied from each other. Thus, groups C and D
consisted of P. meseres (group C) and P. longicirrata (groupD), respectively.
The seven polychaete species showed signiﬁcantly
different abundances between the groups (one-way
ANOVA, Table IV). Within them, the four numericallydominant species mentioned above constituted a speciesspeciﬁc abundant group. Thus, the most abundant groupsof P. longicirrata, T. muelleri, T. septentrionalis and P. meseres
were groups D, A, B and C, respectively (Table IV).
Diel, seasonal and vertical distributions of the pelagic
polychaete community are shown in Fig. 7. The occurrence of each group varied vertically. Thus, group E wasobserved at the deepest layer (500–1000 m) throughout
the year. Groups C and D were observed at 100–300 m
and 150–500 m, respectively. In the sea surface layer (0–50 m), only groups A and B were observed. From theviewpoint of seasonality, group C was observed in limited
seasons (April and July), but the other groups occurred
throughout the year. Although the vertical distributionof each group was similar for October, February and
April, it was notable that the occurrence depths of eachgroup became shallower for July (Fig. 7). There were noclear day–night difference patterns in the group distribution. According to the results of PERMANOVA, depth
had the most prominent effect on polychaete grouping(P < 0.001) (Table V). The season and interaction of day–night × depth also had signiﬁcant effects (P < 0.05).

DISCUSSION
Sampling design
This study was based on day–night vertical stratiﬁed samples collected from a 0 to 1000 m water column at a single
station (K2) during four seasons covering 1 year. It should
be noted that this sampling design includes some disadvantages in revealing pelagic polychaete ecology. First,

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Fig. 3. T–S diagram for the 0–1000 m water column at St. K2 during October 2010, February, April and July 2011. Five water masses wereidentiﬁed: seasonal pycnocline water (SPW), dichothermal water (DTW), transition water (TW), mesothermal water (MTW) and deep water (DW).
Differences in colour for the symbols denote differences in the zooplankton sampling layers.

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Table II: List of pelagic polychaete species identiﬁed for the 0–1000 m water column at St. K2 in thewestern subarctic Paciﬁc from October 2010 to July 2011
FamilySpecies

Abundance(ind. 1000 m−3 )(%)

Biomass(mg WW 1000 m−3 )(%)

Maupasia coeca Viguier, 1886
Pelagobia longicirrata Greeff, 1879

0.81 ± 0.18
176.16 ± 24.81

0.34
73.65

2.67 ± 1.28
141.64 ± 20.61

0.45
23.74

Phalacrophorus spp.

2.28 ± 00.952.62 ± 00.44

Sagitella kowalewskii Wagner, 1872
Typhloscolex muelleri Busch, 1851

0.35 ± 033.56 ± 3.87

0.15
14.03

0.04 ± 056.66 ± 6.96

0.01
9.50

Plotohelmis capitata (Greeff, 1876)
Rhynchonereella angelini (Kinberg,
1866)

0.17 ± 00.12 ± 0

0.07
0.05

0.10 ± 022.46 ± 0

0.02
3.76

Tomopteris septentrionalis Steenstrup, 17.30 ± 3.15
1849
Tomopteris (Johnstonella) paciﬁca
0.70 ± 0.29
(Izuka, 1914)

7.23

234.89 ± 44.45

39.37

0.29

74.80 ± 1.67

12.54

4.90 ± 1.93
32.84 ± 1.33

2.05
1.19

58.11 ± 28.02
2.65 ± 1.31

9.74
0.44

Lopadorrhynchidae

Iospilidae

Alciopidae

Tomopteridae

Flabelligeridae
Poeobius meseres Heath, 1930
OthersAnnual mean abundance and biomass (mean ± 1 SE: ind. 1000 m−3 or mg WW 1000 m−3 at 0–1000 m water column) and the species
composition (%) are also shown.

Fig. 4. Vertical changes in polychaete abundance and species composition for the 0–1000 m water column at St. K2 in the western subarctic Paciﬁcfrom October 2010 to July 2011. The white symbols and black lines show the total abundance in each layer. The composition of each species isshown in a different colour.

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Typhloscolecidae

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Table III: Comparison of polychaete abundances at ﬁve water masses: seasonal pycnocline water (SPW),
dichothermal water (DTW), transition water (TW), mesothermal water (MTW) and deep water (DW)
identiﬁed by the T–S diagram (cf. Fig. 3)
Abundance (ind. 1000 m−3 )Species

Maupasia coeca
Pelagobia
longicirrata
Sagitellakowalewskii
Typhloscolex
muelleriPlotohelmis
capitata
Rhynchonereellaangelini
Tomopteris
septentrionalis
Tomopteris
paciﬁca
Poeobius meseres

One-way ANOVASPW (5)DTW (21)TW (10)MTW (24)

DW (16)00a

00.125b00.262b

1.35
174c

0.370
182c

NS
∗∗

0

0

0

0.087

NS

0
199

93.0

97.7

54.2

0.643

∗

0

0

0

0.138

0

NS

0

0.117

0.245

0

0

NS

80.7b

45.3a,b41.7a,b37.2a,b

0.284a

∗

0

0

0

0.915

0

NS

0

5.32

11.2

13.1

2.43

NS

c

b,c

b,c

a,b

a

Values are the mean abundance at each water mass. Differences between groups were tested by one-way ANOVA and post hoc Tukey–
Kramer test. For the results of the Tukey–Kramer test, differences in superscript letters indicate signiﬁcant differences (P < 0.05). Numbers inparentheses indicate the number of samples occupied by each water mass. ∗P < 0.05, ∗∗P < 0.01, NS: not signiﬁcant.

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Fig. 5. Vertical changes in polychaete biomass (wet weight: WW) and species composition for the 0–1000 m water column at St. K2 in the western
subarctic Paciﬁc from October 2010 to July 2011. The white symbols and black lines show the total abundance in each layer. The composition ofeach species is shown in a different colour.

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since the samplings were conducted at one ﬁxed station
only, spatial patterns were not addressed in this study.
Second, it should be noted that horizontal advection
may inevitably be present. Third, since only one
sample series was collected for each day–night sampling
date (no repetition), it may inevitably be an effect ofpatchy distribution. Fourth, the long net-towing depths,
especially the deep layer, may mask the small-sized
distribution patterns of the pelagic polychaetes.

Of the four disadvantages described above, the effectof horizontal advection was probably the weakest. This isbecause clear seasonal changes in water mass were only
present for the upper 50 m (Fig. 3), and the long-termhorizontal velocity around K2 seems to be weak, which
can be conﬁrmed by the distribution of climatologicalsea surface height around K2 (e.g. Fig. 2a of Isoguchi
et al. 2006). This fact is also conﬁrmed by the resultsof Onodera et al. (2014), who conducted monitoring of

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Fig. 6. (a) Results of cluster analysis based on pelagic polychaete abundance. Five groups (A–E) were identiﬁed at 58% Bray–Curtis dissimilarity
connected with the complete linkage method. Numbers in parentheses indicate the number of samples each group contained. (b) NMDS plotsof each group. Arrows indicate directions of signiﬁcant environmental parameters. Dep.: depth, Temp.: temperature, Sal.: salinity, DO: dissolved
oxygen, Fluo.: ﬂuorescence. (c) Mean abundance (white circle) and species composition of each group.

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Table IV: Comparison of polychaete abundances in ﬁve groups (A–E) identiﬁed by Bray–Curtis
dissimilarity (cf. Fig. 6)
Abundance (ind.1000 m−3 )Species

B (5)

C (9)

D (12)

E (18)

Maupasia coeca

0

0

0

2.61

0.389

∗

A

C

B

E

D

Pelagobia longicirrata

0.241

0.442

2.88

127

121

∗∗

A

B

C

E

D

Sagitella kowalewskii
Typhloscolex muelleri

0
147

0
13.5

0
43.3

0
64.1

0.077
0.918

NS
∗∗

E

B

C

D

A

Plotohelmis capitata

0

0

0.663

0

0

∗

A

E

D

B

C

Rhynchonereella angelini

0

0

0.49

0

0

∗

A

E

D

B

C

Tomopteris septentrionalis

49

73.5

35.2

32.8

0.368

∗

E

D

C

A

B

Tomopteris paciﬁca
Poeobius meseres

0
0.103

2.21
0

0
41.3

0.172
17.4

0
2.69

NS
∗∗

B

A

E

D

C

Values are the mean abundance in each group. Differences between groups were tested by one-way ANOVA and post hoc Tukey–Kramer
test. For the results of the Tukey–Kramer test, any groups not connected by the underlines are signiﬁcantly different (P < 0.05). Numbers inparentheses indicate the number of samples included in each group. ∗P < 0.05, ∗∗P < 0.01, NS: not signiﬁcant.

Fig. 7. Seasonal, vertical and diel changes in the occurrence of the ﬁve polychaete community groups (A–E) identiﬁed by Bray–Curtis dissimilarity
based on their abundance (cf. Fig. 6a). D: day, N: night.

Table V: PERMANOVA results based on Bray–Curtis dissimilarities using polychaete abundance data
in relation to environmental factors (season, day/night, depth). D: day, N: night
Factorsdf

Pseudo FP

SeasonD/N
Depth
Season × D/N
Season × Depth
D/N × Depth

3
1
7
3
21
7

2.567
1.778129.3491.80861.4893
2.568

<0.05
ns
<0.001
ns
ns
<0.05

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A (20)

OneTukey–Kramer test
way
ANOVA

452

This study
0–500
517.5 ± 74.3

Values are the mean ± SE.

IONESS(335 μm)
1.2–8.5
Westernsubarctic Paciﬁc

0–1000769

235.3 ± 27.8

0–200
359.3 ± 55.8
12.5–20.3

0–110014 50055 378 ± 34 022

BIONESS(230 μm)
BIONESS(230 μm)
7.4–10.7

Strait ofMagellan
South Adriatic
Sea

0–750

34 0001101.9 ± 176.9

200–400

Lopadorrhynchidae (95.8)
Tomopteridae (4.2)
Tomopteridae (67.2)
Alciopidae (23.8)
Typhloscolecidae (3.7)
Lopadorrhynchidae (1.9)
Lopadorrhynchidae (74.9)
Typhloscolecidae (14.3)
Tomopteridae (7.6)
Flabelligeridae (2.1)

Siciński (1988),∗RakusaSuszczewski(1988)
Guglielmo et al.
(2014)
Guglielmo et al.
(2019)
Lopadorrhynchidae (86.0)
Tomopteridae (6.3)
Typhloscolecidae (4.8)
8.36 ± 1.9
Nansen net(200 μm)−1.5 to 1.7∗
Scotia Front(Southern
Ocean)

0–1400249

40.7 ± 6.4

100–300

References
Composition of family inabundance (%)
Depths of peakabundance (m)Mean biomass(mg WW
1000 m−3 )Meanabundance(ind. 1000 m−3 )Maximum
density (ind.
1000 m−3 )Depth (m)Sampling gear
(mesh size:μm)Comparable to this study, several studies have investigatedpelagic polychaetes down to greater depths (Siciński 1988;
Guglielmo et al. 2014, 2019). The abundance, biomass,
depths of peak abundance and dominant family of
pelagic polychaetes based on the vertically stratiﬁed samples collected down to greater depths (750–1400 m) aresummarized in Table VI. All samplings were conductedby applying a 200–335 μm mesh net, which may allow
us to make a somewhat quantitative comparison withother studies. The maximum abundance of this study(769 ind. 1000 m−3 ) is similar to that at Scotia Front in
the Southern Ocean (249 ind. 1000 m−3 ) (Siciński 1988).
On the other hand, the maximum abundances in theStrait of Magellan (34 000 ind. 1000 m−3 , Guglielmo
et al. 2014) and South Adriatic Sea (14 500 ind. 1000 m−3 ,Guglielmo et al. 2019) are much higher than those in
the present study (Table VI). The high abundance of
pelagic polychaetes in the Strait of Magellan and South
Adriatic Sea might be related to the semi-enclosed
locations of the study areas (Guglielmo et al. 2014,2019).
At shallower depths, the mean abundances of pelagic
polychaetes have been reported as 143–549 ind. 1000 m−3
at 0–200 m depths in the Gulf of Tehuantepec, eastern subtropical Paciﬁc (Fernández-Álamo and Sanvicente-Añorve 2005), and 374 ind. 1000 m−3 at depths of 0–
75 m along the eastern South Adriatic coast (Batistić et al.
2007). Thus, the mean abundance of this study (50–137
ind. 1000 m−3 ) is comparable to those in the Southern
Ocean, eastern subtropical Paciﬁc and South Adriatic
coast.
In this study, the vertical distribution of wet weightbiomass was also evaluated (Fig. 4). Information on comparable biomass is available from the Strait of Magellan

2021

Temperature
range (◦ C)

Abundance and biomass

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diatom communities by a moored sediment trap at St.
K2 during 2005–2006 and 2009–2010 and found that
offshore species were commonly dominant for K2. Thus,
the effect of horizontal advection in the water mass may
be considered small in this study.
Regarding comparable information on pelagic polychaetes down to greater depths, several studies are available (Siciński 1988; Guglielmo et al. 2014, 2019). Thesestudies were based on only one-time sampling (no repetition), no day and night samplings at the same station(no diel comparison) and snap-shot sampling at a single
cruise (no seasonal examination). Considering these facts,
although some disadvantages or ﬂaws may be present, thesampling design of this study (day–night samplings fromfour seasons) may be sufficient to advance our knowledgeof pelagic polychaete ecology.

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VOLUME 43

Table VI: Comparison of the maximum density mean abundance and biomass, depths of peak abundance and composition of family in abundancefor polychaetes collected by vertical stratiﬁed sampling down to greater depths (ca. 1000 m) from worldwide oceans

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K. AMEI ET AL.

VERTICAL CHANGES IN ABUNDANCE, BIOMASS AND COMMUNITY STRUCTURE OF PELAGIC POLYCHAETES(Siciński 1988) and the Scotia Front (Guglielmo et al.
2014). The annual mean of the total wet weight biomassin this study (517 mg WW 1000 m−3 ) was set between
the two studies (Table VI). Although comparable data arescarce, from the viewpoint of material ﬂux and energy
ﬂow within the ecosystem, information on biomass isneeded for future study.

In the present study, 10 pelagic polychaete species belonging to nine genera and six families were identiﬁed fromthe 0 to 1000 m water column (Table II). Concerning
the species number of pelagic polychaetes, based on
CalCOFI samples, the presence of a clear latitudinal pattern is reported for the 0–200 m water column between
21◦ N and 40◦ N latitudes off California, eastern North
Paciﬁc (Fernández-Álamo et al. 2003). According to Fernández-Álamo et al. (2003), the pelagic polychaete community has been divided into three groups: the north,south and transition groups. The north group is characterized by high abundance and relative divergence (11species), the south group is characterized by low abundance but the most divergence (16 species) and the transition group has the lowest abundance and species diversity. The number of species in this study (10 species) is
close to that of the northern group of Fernández-Álamo
et al. (2003) (11 species). Similar latitudes of the northerngroup of Fernández-Álamo et al. (2003) and this study
may explain the comparable species diversity of the twostudies. Thus, the study region of this study is characterized by a high abundance of pelagic polychaetes, which
may be related to the high productivity of the region(Fernández-Álamo et al. 2003).
Concerning dominant species, various studies conducted down to greater depths reported that P. longicirrata
is the most numerically dominant species (Siciński
1988; Guglielmo et al. 2014). P. longicirrata was also
the most numerically dominant species in this study(Table II). From the viewpoint of family composition,
Lopadorrhynchidae, including P. longicirrata, comprised
75–96% in the Strait of Magellan, the Scotia Front andthe western subarctic Paciﬁc (Table VI). On the other
hand, in the South Adriatic Sea, Lopadorrhynchidae
occurred only at 2% and was replaced by Tomopteridae,
comprising 67% (Guglielmo et al. 2019) (Table VI). These
facts indicate that a large regional pattern is present forthe pelagic polychaete community. In addition to thecommunity structure, the vertical distribution of the same
species also varies with the region. Thus, P. longicirrata is
distributed at 100–400 m in the Strait of Magellan fromMarch to April (Guglielmo et al. 2014) and the SouthernDiel and seasonal change in community
structure
For diel changes in the pelagic polychaete community,
high density at the surface layer during the night wasobserved for abundance in February and April and forbiomass in February and July (Figs. 4 and 5). These facts
suggest that such diel changes in vertical distribution may
be caused by the nocturnal ascent diel vertical migration (DVM) of pelagic polychaetes. In fact, nocturnal
ascent DVM was detected for the shallower dwelling T.
septentrionalis in April and July in this study (Amei unpublished data). Concerning the DVM of pelagic polychaetes,
Guglielmo et al. (2011) reported that two epipelagic polychaete species (P. longicirrata, Tomopteris planktonis) showed
high abundance at night, whereas their vertical distributions were stable throughout the day based on samplings
at 0–190 m depths in the Strait of Magellan. These
facts suggest that nocturnal ascent DVM was present for
the epipelagic dwelling polychaetes. However, their dielchanges may be limited for the species distributed more
shallowly, and no diel changes were detected in termsof the community structure of the pelagic polychaetes(Fig. 7).
Concerning seasonal changes, polychaete community
group C was observed only for in limited seasons (April
and July) (Fig. 7). Group C was characterized by thedominance of P. meseres (Table IV). As a special ecologicalcharacteristic of P. meseres, this species feeds on sinking particles by extending the mucus web, which is not observedfor other pelagic polychaete species (Uttal and Buck 1996;
Robison et al. 2010). Seasonally, the amount of sinking
particles at St. K2 evaluated by the sediment trap isknown to be high during April and July (Honda et al.
2016, 2017). This season corresponds with the timing at
which group C was observed for the pelagic polychaete
community. The shallower shift in the vertical distributionof each pelagic polychaete community in July (Fig. 7) may
be related to the high sinking particulate ﬂux during that
period (Honda et al. 2016, 2017). Thus, seasonal changes
in the amount of passive sinking particle ﬂux are suggested to affect seasonality in the pelagic polychaete community, especially the sinking particle feeder (P. meseres)at St. K2.

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Regional comparison of community
structure

Ocean during October (Siciński 1988) and at 0–75 min the Adriatic Sea throughout the year (Batistić et al.
2007). In the present study, P. longicirrata occurred from
300 to 1000 m throughout the year (Fig. 4). This suggeststhat seasonal or geographical changes are present in thedepth ranges of the cosmopolitan pelagic polychaete
species (P. longicirrata). Clearly, more study is needed forgeneralization of this concept.

JOURNAL OF PLANKTON RESEARCH

VOLUME 43

Vertical changes in community structure

PAGES 442–457

20211996). These facts suggest that P. meseres is adapted for lifein the deep realm. Adding to such feeding modes, theweight-speciﬁc oxygen consumption rate of P. meseres isreported to be extremely low (1.7–6.8% of that of theother pelagic polychaete species) (Thuesen and Childress1993). In the present study region, the development of
the oxygen minimum layer, which was characterized byextremely low DO (<2 mL L−1 ), occurred below 200 m
depth (Fig. 2). For the vertical distribution of Poeobius sp.,it has been reported that they form prominent peaks justbelow the thermocline (Christiansen et al. 2018). These
ecological characteristics of P. meseres corresponded wellto the environmental characteristics of the depths (150–
500 m) of their abundance groups, C and D, e.g. below thethermocline and extremely low DO (Fig. 7).
For the deepest layer (500–1000 m) characterized by
the one water mass (DW), group E was predominatedby P. longicirrata throughout the year (Figs. 6 and 7). In
terms of feeding modes, P. longicirrata is reported to be
an herbivore feeding on phytoplankton (Hopkins andTorres 1989). However, considering their vertical distribution (500–1000 m), it is difficult to assume that fresh
phytoplankton are the main food items of P. longicirrata inthe study region. Notably, within Lopadrynchidae, only
the genus Pelagobia has a pair of diminutive mandibles
or two hooks at the pharynx (Uschakov 1974; Fauchald
and Jumars 1979; Jumars et al. 2015). From the presenceof such feeding apparatuses (fangs), Jumars et al. (2015)
suggest that Pelagobia species feed on gelatinous prey orskin and mucus from ﬁsh (as in the case of Lopadorrhynchus),
obtaining the observed diatoms secondarily from the gut
or surface of their prey. To clarify the feeding modes ofPelagobia species, the application of stable isotopes to theirbodies and molecular analysis of their gut content may
provide new insights in the future.

CONCLUSION
Through observations in four seasons covering day–night
down to 1000 m depth in the western subarctic Paciﬁc,the pelagic polychaete community was separated into
ﬁve groups. The distributions of each group separated
vertically and showed little diel and seasonal change.
Three factors are considered causes of these verticallydifferent communities of pelagic polychaetes. The ﬁrst is
the differences in feeding modes (e.g. food availability): carnivores were abundant at the surface. The second is theadaptation for the oxygen minimum layer: the vertical distribution of the low weight-speciﬁc metabolic rate species
corresponded with the oxygen minimum layer. The third
is the water mass: the water mass and pelagic polychaete

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For the grouping of the pelagic polychaete community,
the temporal factors (diel and seasonal) had a relatively
small effect (P < 0.05), and the most important factor
in determining the grouping was the depth (vertical)(P < 0.001) (Table V). The most prominent verticalchanges in the environmental parameters at St. K2 wereat the occurrence of the ﬁve water masses vertically(Fig. 3) and the development of the exclusive oxygen
minimum layer below 200 m depth (Fig. 2). Althoughother parameters (temperature, salinity and ﬂuorescence)
also showed vertical changes, these changing patterns arecommon for the worldwide ocean. Next, we argue for
their effects on the pelagic polychaete community.
Concerning water masses, the pelagic polychaete community has been reported to be strongly affected bywater masses in the South Adriatic Sea (Guglielmo et al.
2019). The effect of water masses on the polychaete
community was also present in this study (Table III). It
should be noted that although both water mass and polychaete community separated into the same numbers: ﬁve
groups, their species-speciﬁc corresponding pattern (i.e.
each water mass has a different polychaete community)
was not the case. In this study, the water masses separated and varied vertically, and the distribution showed
limited seasonal change only in the near-surface layer(Fig. 3). These stable hydrographic characteristics may
allow adaptation of each pelagic polychaete species forsuitable conditions that may vary with species. In addition
to the changes in water masses, other environmental
characteristics, such as DO (Fig. 2) and the quality andquantity of the sinking particles (Wilson et al. 2008), mayalso vary vertically. However, since these vertical changes
in environmental parameters occur sympatrically, it isdifficult to identify, distinguish or separate the effect ofeach parameter on the pelagic polychaete community.
Interestingly, the four dominant species in this study
had species-speciﬁc abundant communities (Table IV),and their feeding modes varied with species. For the shallower depths (0–150 m) characterized with the three water
masses (SPW, DTW and TW), the dominant species ofthe pelagic polychaete community groups A and B wereboth carnivorous: T. muelleri and T. septentrionalis (Figs. 6
and 7). This may be related to the biomass of their prey(other zooplankton) being high at the surface layer, which
was quantiﬁed by the same vertical stratiﬁed net samples
used in this study (Kitamura et al. 2016).
For the middle layer (150–500 m) characterized by
the two water masses (TW and MTW), the dominant
species P. meseres is known to feed on sinking particles
such as fecal pellets via the deployment of a mucus
web or grasping with ciliated tentacles (Uttal and Buck

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K. AMEI ET AL.

VERTICAL CHANGES IN ABUNDANCE, BIOMASS AND COMMUNITY STRUCTURE OF PELAGIC POLYCHAETES

matter ﬂux interception in oceanic mesoscale eddies by the polychaete
Poeobius sp. Limnol. Oceanogr., 63, 2093–2109.
Dales, K. P. (1957) Pelagic Polychaetes of the Paciﬁc Ocean, University ofCalifornia Press, Berkeley and Los Angeles.
Day, J. H. (1967) A Monograph on the Polychaeta of Southern Africa, Vol. 656,
Trustees of the British Museum, London, pp. 1–878.
Dodimead, A. J., Favorite, F. and Hirano, T. (1963) Salmon of the North
Paciﬁc Ocean, part II. Bull. Int. North Paciﬁc Fish. Comm., 13, 1–195.
Elskens, M., Brion, N., Buesseler, K., Van Mooy, B. A. S., Boyd, P.,
Dehairs, F., Savoye, N. and Baeyens, W. (2008) Primary, new andexport production in the NW paciﬁc subarctic gyre during the vertigo
K2 experiments. Deep-Sea Res. II , 55, 1594–1604.
Fauchald, K. and Jumars, P. A. (1979) The diet of worms: a study ofpolychaete feeding guilds. Oceanogr. Mar. Biol. Annu. Rev., 17, 193–284.

SUPPLEMENTARY DATA
Supplementary data is available at Journal of Plankton Research online.

Feigenbaum, D. (1979) Predation on chaetognaths by Typhloscolecid
polychaetes: one explanation for headless specimens. J. Mar. Biol.
Assoc. UK , 59, 631–633.

ACKNOWLEDGEMENTS
The zooplankton samples used in this study were collected by
R/V Mirai of JAMSTEC. We thank Hiromichi Ueno for providing valuable guidance on water mass classiﬁcation. Part of thisstudy was supported by Grants-in-Aid for Challenging Research(Pioneering) 20K20573 and Scientiﬁc Research 20H03054 (B),
19H03037 (B) and 17H01483 (A) from the Japan Society for
the Promotion of Science (JSPS). This work was partially supported by the Arctic Challenge for Sustainability II (ArCS II),
Programme Grant Number JPMXD1420318865.

Fernández-Álamo, M. A. (1991) Holoplanktonic polychaetes from theGulf of California: August–September 1977. ColCOFI Rep., 32,
97–104.
Fernández-Álamo, M. A. (2006) Composition, abundance and distribution of holoplanktonic polychaetes from the expedition “El Golfo
6311-12” of Scripps Institution of Oceanography. Sci. Mar., 70,
209–215.
Fernández-Álamo, M. A., Sanvicente-Añorve, L. and AlatorreMendieta, M. A. (2003) Changes in pelagic polychaete assemblages along the California current system. Hydrobiologia, 496,
329–336.
Fernández-Álamo, M. A. and Sanvicente-Añorve, L. (2005) Holoplanktonic polychaetes from the Gulf of Tehuantepec. Mexico. Cah. Biol.
Mar., 46, 227–239.

REFERENCES
Amei, K., Jimi, N., Kitamura, M., Yokoi, N. and Yamaguchi, A. (2020)
Community structure and seasonal changes in population structureof pelagic polychaetes collected by sediment traps moored in thesubarctic and subtropical western North Paciﬁc Ocean. Zoosymposia,
19, 41–50.
Batistić, M., Kršinić, F., Jasprica, N., Carić, M., Viličić, D. and Lučić,D. (2004) Gelatinous invertebrate zooplankton of the South Adriatic:
species composition and vertical distribution. J. Plankton Res., 26,
459–474.
Batistić, M., Jasprica, N., Carić, M. and Lučić, D. (2007) Annual cycle of
the gelatinous invertebrate zooplankton of the eastern South Adriatic
coast (NE Mediterranean). J. Plankton Res., 29, 671–686.
Bianchi, D., Stock, C., Galbraith, E. D. and Sarmiento, J. L. (2013) Dielvertical migration: ecological controls and impacts on the biologicalpump in a one-dimensional ocean model. Global Biogeochem. Cycles, 27,
478–491.
Boyd, P. W., Gall, M. P., Silver, M. W., Coale, S. L., Bidigare, R. R. andBishop, J. (2008) Quantifying the surface-subsurface biogeochemical
coupling during the VERTIGO ALOHA and K2 studies. Deep-Sea
Res. II , 55, 1578–1593.
Bray, J. R. and Curtis, J. T. (1957) An ordination of the upland forest
communities of southern Wisconsin. Ecol. Monogr., 27, 325–349.
Buesseler, K. O., Lamborg, C. H., Boyd, P. W., Lam, P. J., Trull, T. W.,
Bidigare, R. R., Bishop, J. K. B., Casciotti, K. L. et al. (2007) Revisiting
carbon ﬂux through the ocean’s twilight zone. Science, 316, 567–570.
Christiansen, S., Hoving, H., Schütte, F., Hauss, H., Karstensen, J.,
Körtzinger, A., Schröder, S., Stemmann, L. et al. (2018) Particulate

Francis, W. R., Powers, M. L. and Haddock, S. H. D. (2016) Bioluminescence spectra from three deep-sea polychaete worms. Mar. Biol., 163,
255.
Fujiki, T., Matsumoto, K., Mino, Y., Sasaoka, K., Wakita, M.,
Kawakami, H., Honda, M. C., Watanabe, S. et al. (2014) Seasonal
cycle of phytoplankton community structure and photophysiologicalstate in the western subarctic gyre of the North Paciﬁc. Limnol.
Oceanogr., 59, 887–900.
Gouveneaux, A., Flood, P. R., Erichsen, E. S., Olsson, C., Lindström,
J. and Mallefet, J. (2017) Morphology and ﬂuorescence of the parapodial light glands in Tomopteris helgolandica and allies (Phyllodocida:
Tomopteridae). Zool. Anz., 268, 112–125.
Gouveneaux, A., Gielen, M. and Mallefet, J. (2018) Behavioural
responses of the yellow emitting annelid Tomopteris helgolandica tophotic stimuli. Lumminescence, 33, 511–520.
Guglielmo, L., Minutoli, R., Bergamasco, A., Granata, A., Zagami, G.
and Antezana, T. (2011) Short-term changes in zooplankton community in Paso Ancho basin (Strait of Magellan): functional trophic
structure and diel vertical migration. Polar Biol., 34, 1301–1317.
Guglielmo, R., Gambi, M. C., Guglielmo, L. and Minutoli, R. (2014)
Composition, abundance and distribution of holoplanktonic polychaetes within the Strait of Magellan (southern America) in australsummer. Polar Biol., 37, 999–1015.
Guglielmo, R., Bergamasco, A., Minutoli, R., Patti, F. P., Belmonte,
G., Spanò, N., Zagami, G., Bonanzinga, V. et al. (2019) The Otranto
Channel (South Adriatic Sea), a hot-spot area of plankton biodiversity: pelagic polychaetes. Sci. Rep., 9, 19490.

455

Downloaded from https://academic.oup.com/plankt/article/43/3/442/6261390 by Hokkaido University user on 31 May 2021

community varied vertically. Since these vertical changes
in environmental factors occurred sympatrically, it is difﬁcult to identify, distinguish or separate their effects on
the polychaete community. To clarify the importance ofeach environmental parameter on the pelagic polychaete
community, regional comparison, which is characterizedby highly different environmental conditions and/or laboratory experiments for adaptation to low DO conditions,
may be interesting for future study.

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Haddock, S. H. D., Moline, M. A. and Case, J. F. (2010) Bioluminescencein the sea. Ann. Rev. Mar. Sci., 2, 443–493.
Halanych, K. M., Cox, L. N. and Struck, T. H. (2007) A brief review ofholopelagic annelids. Integr. Comp. Biol., 47, 872–879.
Honda, M. C., Kawakami, H., Matsumoto, K., Wakita, M., Fujiki,T., Mino, Y., Sukigara, C., Kobari, T. et al. (2016) Comparison ofsinking particles in the upper 200 m between subarctic Station K2 andsubtropical station S1 based on drifting sediment trap experiments. J.
Oceanogr., 72, 373–386.

NUMBER 3

PAGES 442–457

2021

Okazaki, Y., Takahashi, K., Onodera, J. and Honda, M. C. (2005)
Temporal and spatial ﬂux changes of radiolarians in the northwestern
Paciﬁc Ocean during 1997–2000. Deep-Sea Res. II , 52, 2240–2274.
Onodera, J., Ohashi, A., Takahashi, K. and Honda, M. C. (2014) Timeseries variation of diatom valve ﬂuxes at Station K2 in the western
Subarctic Paciﬁc. Diatom, 30, 104–121.
Øresland, V. (1990) Feeding and predation impact of the chaetognath
Eukrohnia hamata in Gerlache Strait, Antarctic Peninsula. Mar. Ecol.
Prog. Ser., 63, 201–209.
Øresland, V. and Pleijel, E. (1991) An ectoparasitic typhloscolecid
polychaete on the chaetognath Eukrohnia hamata from the Antarctic
Peninsula. Mar. Biol., 108, 429–432.

Hopkins, T. L. (1985) Food web of an Antarctic midwater ecosystem.
Mar. Biol., 89, 197–212.

Peter, G. (1975) On the seasonal distribution of some polychaetes in the
Indian Ocean area along 110◦ meridian. Mahasagar, 8, 45–52.

Hopkins, T. L. (1987) Midwater food web in McMurdo Sound, Ross
Sea. Antarctica. Mar. Biol., 96, 93–106.

Rakusa-Suszczewski, S. (1968) Predation of Chaetognatha by Tomopteris
helgolandica Greef . J. Cons. Int. Explor. Mer., 32, 226–231.

Hopkins, T. L. and Torres, J. J. (1989) Midwater food web in the vicinityof a marginal ice zone in the western Weddell Sea. Deep-Sea Res., 36A,
543–560.

Robison, B. H., Sherlock, R. E. and Reisenbichler, K. R. (2010) The
bathypelagic community of Monterey Canyon. Deep-Sea Res. II , 57,
1551–1556.

Isoguchi, O., Kawamura, H. and Oka, E. (2006) Quasi-stationary jets
transporting surface warm waters across the transition zone between
the subtropical and the subarctic gyres in the North Paciﬁc. J. Geophys.
Res., 111, C10003.

Siciński, J. (1988) Pelagic Polychaeta in the Scotia Front west of ElephantIsland (BIOMASS III, October–November 1986). Pol. Polar Res., 9,277–282.

Øresland, V. and Bray, R. A. (2005) Parasites and headless chaetognaths
in the Indian Ocean. Mar. Biol., 147, 725–734.

Jumars, P. A., Dorgan, K. M. and Lindsay, S. M. (2015) Diet of worms
emended: an update of polychaete feeding guilds. Ann. Rev. Mar. Sci.,
7, 497–520.

Steinberg, D. K., Van Mooy, B. A. S., Buesseler, K. O., Boyd, P. W.,
Kobari, T. and Karl, D. M. (2008a) Bacterial vs. zooplankton controlof sinking particle ﬂux in the ocean’s twilight zone. Limnol. Oceanogr.,
53, 1327–1338.

Kaneko, R., Nagata, T., Suzuki, S. and Hamasaki, K. (2016) Depthdependent and seasonal variability in archaeal community structurein the subarctic and subtropical western North Paciﬁc. J. Oceanogr., 72,
427–438.

Steinberg, D. K., Cope, J. S., Wilson, S. E. and Kobari, T. (2008b) A
comparison of mesopelagic mesozooplankton community structurein the subtropical and subarctic North Paciﬁc Ocean. Deep-Sea Res.
II , 55, 1615–1635.

Kitamura, M., Kobari, T., Honda, M. C., Matsumoto, K., Sasaoka,
K., Nakamura, R. and Tanabe, K. (2016) Seasonal changes in themesozooplankton biomass and community structure in subarctic
and subtropical time-series stations in the western North Paciﬁc. J.
Oceanogr., 72, 387–402.

Tebble, N. (1962) The distribution of pelagic polychaetes across theNorth Paciﬁc Ocean. Bull. British Mus. Nat. History Zool., 7, 371–492.

Kobari, T., Nakamura, R., Unno, K., Kitamura, M., Tanabe, K., Nagafuku, H., Niibo, A., Kawakami, H. et al. (2016) Seasonal variability
in carbon demand and ﬂux by mesozooplankton communities atsubarctic and subtropical sites in the western North Paciﬁc Ocean.
J. Oceanogr., 72, 403–418.
Lebour, M. V. (1922) The food of plankton organisms. J. Mar. Biol. Assoc.
UK , 12, 644–677.
Matsumoto, K., Honda, M. C., Sasaoka, K., Wakita, M., Kawakami, H.
and Watanabe, S. (2014) Seasonal variability of primary production
and phytoplankton biomass in the western Paciﬁc subarctic gyre:
control by light availability within the mixed layer. J. Geophys. Res.,
119, 6523–6534.
Matsumoto, K., Abe, O., Fujiki, T., Sukigara, C. and Mino, Y. (2016)
Primary productivity at the time-series stations in the northwestern
Paciﬁc Ocean: is the subtropical station unproductive? J. Oceanogr., 72,
359–371.
Minchin, P. R. (1987) An evaluation of the relative robustness oftechniques for ecological ordination. Vegetatio, 69, 89–107.
Miura, T., Suga, T. and Hanawa, K. (2002) Winter mixed layer andformation of dichothermal water in the Bering Sea. J. Oceanogr., 58,
815–823.

Thuesen, E. V. and Childress, J. J. (1993) Metabolic rates, enzyme
activities and chemical compositions of some deep-sea pelagic worms,
particularly Nectonemertes mirabilis (Nemertea; Hoplonemertinea)
and Poeobius meseres (Annelida; Polychaeta). Deep-Sea Res. I , 40,
937–951.
Ueno, H. and Yasuda, I. (2000) Distribution and formation of themesothermal structure (temperature inversions) in the North Paciﬁc
subarctic region. J. Geophys. Res., 105, 16885–16897.
Ueno, H. and Yasuda, I. (2005) Temperature inversions in the subarctic
North Paciﬁc. J. Phys. Oceanogr., 35, 2444–2456.
Ushakov, P. V. (1974) Fauna of the U.S.S.R.: Polychaetes, Israel Program for
Scientiﬁc Translations, Jerusalem.
Uttal, L. and Buck, K. R. (1996) Dietary study of the midwater polychaete Poeobius meseres in Monterey Bay, California. Mar. Biol., 125,
333–343.
Vinogradov, M. E. (1968) Vertical Distribution of the Oceanic Zooplankton.
Academy of Science of the USSR, Israel Program for Scientiﬁc Translations, Jerusalem.
Wakita, M., Honda, M. C., Matsumoto, K., Fujiki, T., Kawakami, H.,
Yasunaka, S., Sasai, Y., Sukigara, C. et al. (2016) Biological organiccarbon export estimated from the annual carbon budget observedin the surface waters of the western subarctic and subtropical North
Paciﬁc Ocean from 2004 to 2013. J. Oceanogr., 72, 665–685.

456

Downloaded from https://academic.oup.com/plankt/article/43/3/442/6261390 by Hokkaido University user on 31 May 2021

Honda, M. C., Wakita, M., Matsumoto, K., Fujiki, T., Siswanto, E.,
Sasaoka, K., Kawakami, H., Mino, Y. et al. (2017) Comparison ofcarbon cycle between the western Paciﬁc subarctic and subtropical
time-series stations: highlights of the K2S1 project. J. Oceanogr., 73,
647–667.

K. AMEI ET AL.

VERTICAL CHANGES IN ABUNDANCE, BIOMASS AND COMMUNITY STRUCTURE OF PELAGIC POLYCHAETES

Wakita, M., Nagano, A., Fujiki, T. and Watanabe, S. (2017) Slow
acidiﬁcation of the winter mixed layer in the subarctic western North
Paciﬁc. J. Geophys. Res., 122, 6923–6935.
Wilson, S. E., Steinberg, D. K. and Buesseler, K. O. (2008) Changes
in fecal pellet characteristics with depth as indicators of zooplankton repackaging of particles in the mesopelagic zone of the sub-tropical and subarctic North Paciﬁc Ocean. Deep-Sea Res. II , 55,
1636–1647.
Wilson, S. E. and Steinberg, D. K. (2010) Autotrophic picoplankton in mesozooplankton guts: evidence of aggregate feeding in themesopelagic zone and export of small phytoplankton. Mar. Ecol. Prog.
Ser., 412, 11–27.

Downloaded from https://academic.oup.com/plankt/article/43/3/442/6261390 by Hokkaido University user on 31 May 2021

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