ICES Journal of Marine Science, 61: 535e541 (2004)
doi:10.1016/j.icesjms.2004.03.009
Metabolism and chemical composition of mesopelagic
ostracods in the western North Pacific Ocean
Hideki Kaeriyama and Tsutomu Ikeda
Kaeriyama, H., and Ikeda, T. 2004. Metabolism and chemical composition of mesopelagic
ostracods in the western North Pacific Ocean. e ICES Journal of Marine Science, 61:
535e541.
Oxygen consumption rates and bodily elemental composition (carbon (C) and nitrogen (N))
were determined on three dominant ostracods (Discoconchoecia pseudodiscophora,
Orthoconchoecia haddoni, and Metaconchoecia skogsbergi) from the mesopelagic zone
of the Oyashio region. Specific oxygen consumption rates of the three species at near in situ
temperature (3(C) were similar (0.39 ml O2 mg DW 1 h1), but bodily C composition and
C:N ratios of D. pseudodiscophora were significantly higher than those of the other two
species. Metabolic comparison in terms of ‘‘daily body C loss’’ or ‘‘adjusted metabolic
rate’’ revealed that metabolic rates of the ostracods are 0.3e0.4 times those of other
zooplankton at comparable temperature conditions. The present results were combined with
standing stock data of each ostracod in the Oyashio region to estimate their POC ingestion.
Our calculation indicates annual ingestion by the ostracods to be 875 mgC m2 yr1, which
equates to 3.7% of annual POC flux reaching 200e600-m depth (mid-point: 400-m depth)
in this region.
Ó 2004 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
Keywords: C:N ratio, mesopelagic, ostracods, oxygen consumption, Oyashio region.
H. Kaeriyama and T. Ikeda: Marine Biodiversity Laboratory, Graduate School of Fisheries
Sciences, Hokkaido University, 3-1-1, Minato-cho, Hakodate, Hokkaido 041-0821, Japan;
e-mail: tom@fish.hokudai.ac.jp (T. Ikeda). Correspondence to H. Kaeriyama: present
address: Nakaminato Laboratory for Marine Radioecology, National Institute of Radiological Sciences, 3609 Isozaki-cho, Hitachiraka-shi, 311-1202 Japan; tel./fax: C81 29 265
9659; e-mail: [email protected].
Introduction
The majority of oceanic holoplanktonic ostracod species
belong to the Family Halocyprididae, and a few to the
Family Cypridinidae (Cohen, 1982). Despite their broad distribution throughout the world oceans (Vinogradov, 1968;
Poulsen, 1973; Angel, 1999), biological and ecological information about pelagic ostracods is in short supply. This is
largely because they are small in size (mostly between
1 and 2 mm), their contribution to total zooplankton
biomass is usually only a few percent at most, and the
lack of comprehensive reference for their identification
(Deevey, 1968; Angel, 1983, 1999; Vannier et al., 1998).
Planktonic ostracods are considered to be microphagous or
opportunistic feeders on any large pieces of food they
encounter (Angel, 1983, 1993; Vannier et al., 1998). Recent
studies have shown that the number of species and
abundance of planktonic ostracods are elevated in the
mesopelagic zone in the Japan Sea (Ikeda, 1990), North
Atlantic (Deevey, 1968; Angel, 1993), and Southern Ocean
(Benassi et al., 1992; Chavtur and Krulk, 2003), but there is
1054-3139/$30.00
no information about their roles in energy flow and material
re-cycling in the mesopelagic zone.
The Oyashio region, western North Pacific, is characterized by the incidence of a large phytoplankton bloom
(O4 mg m3) in spring, and higher zooplankton biomass
than within the North Pacific Ocean (Kasai et al., 1998). As
part of a research programme to evaluate life cycle patterns
of major zooplankton species in the Oyashio region, the
vertical distribution, biomass, and population structure
(‘‘instar’’ composition) of pelagic ostracods were made by
Kaeriyama and Ikeda (2002a, b). They found that pelagic
ostracods were concentrated at 200e600-m depth throughout the year, and were almost exclusively composed of the
three species; Discoconchoecia pseudodiscophora, Orthoconchoecia haddoni, and Metaconchoecia skogsbergi. The
population structure data suggest that the three ostracods
were reproducing year-round. The total population
biomass integrated over 0e2000-m water column is
171 mg DW m2 (annual mean), or 1.4% of the total zooplankton biomass (copepods and chaetognaths) in the same
region.
Ó 2004 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
536
H. Kaeriyama and T. Ikeda
In this study, we determined oxygen consumption rates
and chemical composition (carbon and nitrogen) of the
body of these three dominant ostracods in the Oyashio
region, and the results are compared with literature data for
other ostracods and other groups of marine zooplankton.
Then, the metabolic and body compositional data were
combined with the population biomass data of each species
to calculate the amount of organic carbon needed to
maintain their populations, and this was finally compared
with the POC flux in the mesopelagic zone of the Oyashio
region.
Materials and methods
Samplings
Live ostracods were collected at Site H (off southeastern
Hokkaido, delimited by latitude 41(30# and 42(30#N and
longitudes 145(00# and 146(00#E) and other stations in the
western Subarctic Pacific during the period from May 2002
through March 2003 (Figure 1) aboard TS ‘‘Oshoro-Maru’’
and RV ‘‘Ushio-Maru’’ of the Faculty of Fisheries,
Hokkaido University. Ostracods were collected from two
depth strata: 100e500 m or 500e1000 m with closing nets
(60-cm mouth diameter, 0.10-mm mesh, or 80-cm mouth diameter; 0.33-mm mesh), or from vertical tows (0e200 m or
0e500 m) with a ring net (80-cm mouth diameter, 0.33-mm
mesh). When the net was retrieved on board, the contents of
the codend were gently transferred to 5-liter plastic bottles
filled with chilled seawater collected from 300-m depth.
Live ostracods were quickly sorted and placed in 250e500ml glass containers filled with seawater, and kept in
incubators at 3(C. In order to obtain metabolic rates under
near natural oxygen concentrations, seawater was collected
from 300-m depth with Niskin bottles prior to each
experiment and passed gently through 20-mm mesh netting
to remove other zooplankton, thus minimizing as much as
possible the change in oxygen levels in the seawater.
Metabolic measurements and chemical composition
A water-bottle method (Omori and Ikeda, 1984) was used
to determine oxygen consumption rates. The size of the
bottles used to incubate specimens was 30- or 40-ml capacity. Experimental bottles containing specimens (3e15
ind bottle1) and control bottles without specimens were
prepared concurrently, and incubated at 3(C for 36 h in the
dark. The temperature (3(C) was chosen as the typical
habitat temperature for the ostracods at 200e600-m depth
in the Oyashio region. At the end of each experiment,
dissolved oxygen was determined on duplicated water
subsamples (7e10 ml) siphoned out from experimental and
control bottles by the Winkler titration method. General
procedures and precision of this titration method are
described elsewhere (Ikeda and Hirakawa, 1998). Specimens recovered from the bottles at the end of the experiments were rinsed briefly with a small amount of distilled
water, blotted on a filter paper, and deep-frozen (30 or
80(C). In the laboratory, frozen specimens were freezedried to obtain dry weight (DW). Freeze-dried samples
were pooled for each species and carbon and nitrogen
composition was analyzed with an elemental analyzer
(Yanako CHN Coder MT-5 and MT-6).
Metabolic comparison
‘‘Daily body C loss’’ and ‘‘adjusted metabolic rate (AMR)’’
were used for metabolic comparisons.
Daily body C loss: Oxygen consumption rate (R) was
converted first to CO2-C production rate, R!RQ!12/
22:4!24!103 , where RQ is the respiratory quotient, 10/
22.4 is C mass in 1 mol of CO2 (22.4 liters), 24 is the number of hours d 1 and 103 is to convert mg to mg. An
RQ ¼ 0:84 (a mixture of protein (RQ ¼ 0:97, cf. Gnaiger,
1983) and lipid metabolism (RQ ¼ 0:71) of equal amounts)
was assumed. The daily body C loss due to metabolism was
expressed as a fraction of body C (% of body C loss d 1)
for each species.
Figure 1. Location of sampling stations in the western North Pacific Ocean, including Site H, Station KNOT, and others (shown as
crosses).
Metabolism and chemical composition of mesopelagic ostracods
AMR: The relationship between oxygen consumption
rate (R: ml O2 individual 1 h1) and body mass (W: mgN)
can be expressed as R ¼ aW b , where a and b are constants.
AMR is defined as RW b, or the rate adjusted to 1-mg
body N (cf. Ikeda, 1988). Body N was chosen as the body
mass unit since this reduces interspecific variations in the
relationship between metabolic rate and body mass (Ikeda,
1988). A weight exponent (b) of 0.85 was used. This value
was derived from statistical analyses of the oxygen
consumption rates and body N of epipelagic zooplankton
(Ikeda, 1985).
Results
Oxygen consumption
Adult female Discoconchoecia pseudodiscophora weighed
from 0.049 to 0.074-mg DW (mean 0.060), adult male and
female Orthoconchoecia haddoni from 0.284 to 0.396-mg
DW (0.34) and from 0.358 to 0.542-mg DW (0.50),
respectively, and pre-adult (Instar VII)/adult Metaconchoecia skogsbergi from 0.069 to 0.088-mg DW (0.08 mg)
(Table 1). No separation of males from females was made
for M. skogsbergi.
Oxygen consumption rates varied from 0.021 to
0.033 ml O2 ind.1 h1 (mean: 0.026) for adult female Discoconchoecia pseudodiscophora, from 0.114 to 0.208 ml O2
ind.1 h1 (0.159) for adult female Orthoconchoecia
haddoni, from 0.114 to 0.136 ml O2 ind.1 h1 (0.127) for
adult male O. haddoni, and from 0.030 to 0.036 ml O2
ind.1 h1 (0.033) for pre-adult/adult male and female
Metaconchoecia skogsbergi (Table 1). Differences in
oxygen consumption rates between adult male and female
Orthoconchoecia haddoni were not significant (t-test, pO
0:05), but differences between the three species were highly
significant (ANOVA, F ¼ 142:8, d:f : ¼ 3:68, p!0:0001).
It is noted that the observed interspecific differences in
oxygen consumption rates per individual were largely attributed to species-specific body mass, since such differences
537
were not seen in terms of specific oxygen consumption
rates (ml O2 mg DW 1 h1, Figure 2) (ANOVA, F ¼ 2:6,
d:f : ¼ 3:68, p > 0:05).
C and N composition
Among four groups including adult female Discoconchoecia pseudodiscophora, adult male and female Orthoconchoecia haddoni, and pre-adult/adult Metaconchoecia
skogsbergi analyzed, C and N composition ranged from
39.8% to 50.8% of DW and 7.8% to 9.4% of DW, respectively; the C:N ratios varied from 4.2 to 6.6 (Table 2).
Among them, adult female D. pseudodiscophora was
characterized by high C and C:N ratio but low N, and
pre-adult/adult M. skogsbergi and male O. haddonii by low
C and C:N ratio but high N with adult female O. haddonii
as intermediate between the two (Fisher’s PLSD, p!0:001;
Table 2).
Daily body C loss and AMR
The ranges of the daily body C loss were 0.62e1.22%
(mean: 0.90) for adult female Discoconchoecia pseudodiscophora, 0.69e1.16% (0.86) for adult female Orthoconchoecia haddoni, 0.87e0.89% (0.88) for adult male
O. haddoni, and 1.09e1.26% (1.16) for pre-adult/adult
Metaconchoecia skogsbergi (Table 1). Daily body C losses
differed significantly among the three species (ANOVA,
F ¼ 3:764, d:f : ¼ 3:64, p!0:02). Subsequent betweenmean analysis revealed that the daily C loss of M. skogsbergi was significantly higher than that of the other two
species (Fisher’s PLSD, p!0:02, Table 1).
AMR ranged from 1.93 to 2.97 ml O2 mgN 0.85 h1
(mean: 2.36) for adult female Discoconchoecia pseudodiscophora, from 1.42 to 3.66 ml O2 mgN 0.85 h1 (mean 2.44)
for adult female Orthoconchoecia haddoni, from 2.33 to
2.81 ml O2 mgN 0.85 h1 (mean: 2.60) for adult male
O. haddoni, and from 1.92 to 2.23 ml O2 mgN 0.85 h1
(mean: 2.10) for pre-adult/adult male and female Metaconchoecia skogsbergi (Table 1). Between-species differences
Table 1. Oxygen consumption rates, metabolic body C loss, and adjusted metabolic rate (AMR) of the three dominant ostracods in the
western North Pacific Ocean. Differences between species were tested by Fisher’s PLSD.
N
DW (mg)
Oxygen consumption
rate (ml O2 ind.1 h1)
Metabolic loss
(% body C d 1)
AMRO2
[ml O2 (mgN)0.85 h1]
Discoconchoecia pseudodiscophora
Adult female
40
0.06G0.01
0.026G0.005
0.90G0.23
2.36G0.49
Orthoconchoecia haddoni
Adult female
Adult male
12
7
0.50G0.11
0.34G0.06
0.159G0.050
0.127G0.026
0.86G0.27
0.88G0.16
2.44G1.06
2.60G0.55
13
0.08G0.01
0.033G0.007
1.16G0.24
2.10G0.43
Ostracods, Instar
Metaconchoecia skogsbergi
Mixtures (Instar VII/Adults)
Fisher’s PLSD
538
H. Kaeriyama and T. Ikeda
Figure 2. Relationships between oxygen consumption rate (R: ml O2 ind.1 h1) and dry weight (DW: mg), and between specific oxygen
consumption rate (R/DW: ml O2 DW 1 h1) and DW of the three dominant ostracods in the Oyashio region, western North Pacific.
Vertical and horizontal bars crossing means denote standard deviations.
in AMRs were not significant (ANOVA, F ¼ 0:674,
d:f : ¼ 3:68, p > 0:5).
Discussion
Metabolism
Presently available information about oxygen consumption rates of marine ostracods is limited to eight species
(Table 3). Among them, Philomedes interpuncta and Vargula hilgendorfii were studied in coastal regions and may
be benthic or benthopelagic species (cf. Cohen, 1982), but
the other seven species are truly pelagic. According to
Ivleva (1980), Conchoecia spp. were collected from surface tows at night, and are thus epipelagic species. Two
Gigantocypris species are giant carnivorous ostracods living
in meso- and bathypelagic zones in the ocean (Childress,
1975; Moguilevsky and Gooday, 1977). Boroecia borealis
occurs from mesopelagic and bathypelagic depths in the
northern North Atlantic (Deevey, 1968). Discoconchoecia
pseudodiscophora studied by Ikeda (1990) is from the
mesopelagic zone of the southern Japan Sea.
Oxygen consumption rates of ostracods with different
sizes and measured at dissimilar temperatures cannot be
compared directly. As a solution to this problem, the rates
were converted to AMR assuming a weight exponent of
0.85 and a Q10 value of 1.89 (cf. Materials and methods). In
calculating AMR, 3(C was chosen as a representative temperature at which the main populations of the three ostracods live in the western North Pacific (Kaeriyama and
Ikeda, 2002a). Thus, calculated AMRs at 3(C (2.1e
2.6 ml O2 mgN 0.85 h1) of the three ostracods in this study
appear to be slightly less than those from other mesopelagic
species, including the same D. pseudodiscophora but from
the southern Japan Sea or Boroecia borealis in the northern
North Atlantic, but much higher than the AMRs of
Table 2. Carbon (C), nitrogen (N), and body carbon:nitrogen (C:N) ratios of the three dominant ostracods in the western North Pacific
Ocean. Values are meanG1 SD and range (in parentheses). Differences between species were tested by Fisher’s PLSD.
Ostracod, Instar
N
C (% DW)
N (% DW)
C:N ratio by weight
Discoconchoecia pseudodiscophora
Adult female
31
50.8G4.7 (42.8e58.5)
7.8G0.8 (6.5e10.0)
6.6G1.0 (5.6e7.6)
Orthoconchoecia haddoni
Adult female
Adult male
39
17
45.7G3.8 (38.6e57.8)
42.3G4.5 (31.8e47.1)
8.7G1.0 (7.1e10.2)
9.2G1.3 (7.4e10.5)
5.3G0.6 (5.0e5.8)
4.6G0.3 (4.4e4.8)
12
39.8G1.6 (37.7e42.4)
9.4G0.5 (8.4e10.1)
4.2G0.3 (4.0e4.5)
Metaconchoecia skogsbergi
Mixtures (Instar VII/adults)
Fisher’s PLSD
Metabolism and chemical composition of mesopelagic ostracods
539
Table 3. Comparison of oxygen consumption rates and adjusted metabolic rate (ARMO2) of marine ostracods.
Ostracods
Halocyprida
Discoconchoecia pseudodiscophora
Orthoconchoecia haddoni
Instar
Conchoecia spp.
Boroecia borealis
Adult female
Adult female
Adult male
Mixed
Adult female
VII
VI
?
?
Mydcopida
Gygantocypris agassizii
G. muelleri
Philomedes interpuncta
Vargula hilgendorfii
Mixed
Mixed
Adult male
Adult
Metaconchoecia skogsbergi
D. pseudodiscophora
DW
(mg)
T
((C)
R
(ml O2 ind.1 h1)
AMRO2 at 3(C
[ml O2 (mgN)0.85 h1]
0.059
0.495
0.337
0.078
0.042
0.028
0.01
0.048
0.32
3
3
3
3
1
1
1
29
5.5
0.026
0.159
0.127
0.033
0.021
0.015
0.011
0.58
0.18
2.4
2.4
2.6
2.1
3.3
4.1
6.9
13.6
3.7
158
108
0.596
1.18
4
0.2
9.6
25.5
5.4
1.01
0.3
0.25
1.4
0.9
4.1
0.7
Gigantocypris species from bathypelagic zones. It is known
that pelagic crustaceans living in deeper environments have
reduced metabolic rates (cf. Childress, 1975). Ivleva’s
AMRs for epipelagic ostracods are much greater than those
of the other ostracods, including the present results. AMRs
at 3(C predicted from ‘‘general’’ epipelagic zooplankton
(Ikeda, 1985) and from epipelagic copepods (Ikeda et al.,
2001) are 6.90 and 6.32 ml O2 mgN 0.85 h1, respectively.
Thus, it is now evident that excepting the anomalously high
data of Ivleva (1980), AMRs of marine ostracods are close
(D. pseudodiscophora from the Japan Sea) or less (the rest
of the ostracods including the three species studied here)
than those of ‘‘general’’ epipelagic zooplankton and copepods. Higher metabolic rates of D. pseudodiscophora in the
Japan Sea than those in the Oyashio region may reflect
a higher oxygen concentration in the mesopelagic habitat of
this ostracod in the former (ca. 5 ml l 1, cf. Ikeda and
Hirakawa, 1998) than in the latter (ca. 2 ml l 1, our unpublished data). Reduced oxygen consumption rates of zooplankton living in lower oxygen environments have been
reported for a euphausiid Euphausia pacifica (Paranjape,
1967).
Body C and N composition
The chemical composition of marine zooplankton is known
to be highly variable between and within taxonomic groups
of animals, depending not only on intrinsic factors (development stages, sex, trophic condition) but also on extrinsic
factors (season, geographical location, depth of occurrence)
(Omori, 1969; Ikeda, 1974; Båmstedt, 1986).
In the present study, we observed some between-species
differences in C and N composition; Discoconchoecia pseudodiscophora was characterized by higher C and lower N,
Source
This study
Ikeda (1990)
Ivleva (1980)
Båmstedt (1979)
Childress (1975)
Ikeda (1988)
Ikeda (1974)
Nakamura (1954)
and Orthoconchoecia haddoni by lower C but higher N
(Table 2). As noted by Ikeda (1974), C composition greater
than 45% of DW accompanied by C:N ratios greater than 5
indicates lipid accumulation in the body. From this view,
D. pseudodiscophora of this study (C ¼ 50:8% of DW,
C : N ratio ¼ 6:6, cf. Table 2) shows indications of accumulation of lipids in the body. These between-species
differences in C and N composition in the three ostracods
may be due to depth-related trophic conditions in the
Oyashio region. In the Oyashio region, the three ostracods
are known to partition their vertical distribution in the top
2000 m of the water column, e.g. D. pseudodiscophora
inhabits shallow (ca. 400 m) and Metaconchoecia skogsbergi deep (700 m), with O. haddoni occurring at intermediate depths (600 m) (Kaeriyama and Ikeda, 2002a).
While the nutrition of pelagic ostracods is poorly known,
the decrease in C content and C:N ratios of the ostracods
with increasing depth of distribution may reflect the abundance of their food particles. A rapid decrease in POC with
increasing depth in the western Subarctic Pacific including
the Oyashio region is well documented (Yamaguchi et al.,
2000).
The available data on C and N composition of marine
ostracods are those for Philomedes interpuncta (Ikeda,
1974), Discoconchoecia pseudodiscophora (Ikeda, 1990),
and Gigantocypris muelleri (Ikeda, 1988, Childress, 1975).
Compared with the present results (Table 2), both C (22.5%
of DW) and N contents (4.7%) of P. interpuncta and C
contents (29.6e35.4%) in G. muelleri are much less than
those of the three mesopelagic ostracods in this study. The
N content (8.2e9.3% of DW) of G. muelleri is similar to
that of the three ostracods in this study. These differences
may reflect the dissimilar ecology of P. interpuncta (likely
benthic or benthopelagic) and G. muelleri (bathypelagic) to
540
H. Kaeriyama and T. Ikeda
the three ostracods compared to this study (mesopelagic),
but the overall paucity of relevant data makes it difficult to
decide.
According to Ikeda (1990), C and N contents of adult
Discoconchoecia pseudodiscophora from the southern
Japan Sea were 39.9% and 7.3%, respectively, of DW.
The present results on adult female D. pseudodiscophora
from the Oyashio region show that while N composition
(6.5e10.0% of DW) is similar, C composition (42.8e
58.5% of DW) is much higher than in the southern Japan
Sea. As discussed above, C-rich D. pseudodiscophora in
the Oyashio region may reflect better the trophic condition
of this region ( primary production; 146 gC m2 yr1, cf.
Kasai, 2000) as compared with those in the Japan Sea (ca.
57 gC m2 yr1; K. Hirakawa, pers. comm.). The effect of
food availability on body composition has been reported on
some midwater fishes in the eastern North Pacific (Bailey
and Robison, 1986).
central, is estimated to be 24 gC m2 yr1 from the equation
of Pace et al. (1987). From this, it becomes evident that the
total annual POC ingestion by three mesopelagic ostracods
(875 mgC m2 yr1) accounts for 3.7% of the annual POC
flux at 400-m depth. This value is only one-tenth that (37%)
of the ingestion by copepod suspension feeders below 500-m
depth estimated at nearby Station KNOT (cf. Figure 1) in the
same region of the western Subarctic Pacific in summer
(Yamaguchi et al., 2002). If one assumes that the ostracod
biomass at Station KNOT is the same as that at Site H of
this study (171 mg DW m2; Kaeriyama and Ikeda, 2002a)
the greater POC ingestion by copepod suspension feeders
may be explained largely by their larger biomass (ca.
1000 mgC m2 or 2000 mg DW m2, assuming C:DW ratio
of 0.5:1, cf. Yamaguchi et al., 2002) compared to that of the
ostracods.
Acknowledgements
Estimated POC ingestion by ostracods
From oxygen consumption data, we have estimated POC
ingestion by the population of the three ostracods. In order
to sum up total oxygen consumption (R) for a population
including variously sized specimens, we adopted the relationship between R and DW expressed as R ¼ aDW 0:80
(Ikeda, 1988) and constant a was estimated for each species
(Table 4). The population structure in terms of instar composition was converted to DW composition using instarDW equivalents of each ostracod (Kaeriyama and Ikeda,
2002b). The oxygen consumption by the three ostracod populations (Rpop) thus computed was finally converted to
annual POC ingestion by assuming assimilation efficiency
and gross growth efficiency of ostracods to be 70% and 30%,
respectively. Resultant ingestion was 393 mgC m2 yr1 for
Discoconchoecia pseudodiscophora, 451 mgC m2 yr1 for
Orthoconchoecia haddoni, and 31 mgC m2 yr1 for Metaconchoecia skogsbergi (Table 4). Annual primary production has been reported as 146 gC m2 yr1 in the Oyashio
region (Kasai et al., 1998; Kasai, 2000). From this primary
production value, annual POC flux reaching 400-m depth,
where the mid-point of the three ostracods distribution is
Table 4. Constant (a) of the regression model, R ¼ aDW0:8 ,
population oxygen consumption and calculated annual POC
ingestion by the three dominant ostracods in the Oyashio region,
Subarctic Pacific.
Ostracods
a
D. pseudodiscophora 0.25G0.06
O. haddoni
0.33G0.08
M. skogsbergi
0.26G0.05
Annual POC
Rpop
(ml O2 m2 h1:
ingestion
0e2000 m) (mgC m2 yr1)
39.9G7.5
45.7G9.1
3.2G0.2
393G74
451G90
31G2
We are grateful to Dr S. Hernandez-Leon and one anonymous reviewer for comments which improved the text.
CHN elemental analysis was done by Ms H. Matsumoto
and A. Maeda of the Center for Instrumental Analysis,
Hokkaido University. The work was partly supported by
JSPS KAKENHI 14209001.
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