NOT TO BE CITED WITHOUT PRIOR REFERENCE TO THE AUTHORS

SC/D06/J27

Trace element accumulations of Antarctic krill, Euphausia
superba, in Areas III, IV, V and VI from the Antarctic Ocean
during 1989-1999
GENTA YASUNAGA*, YOSIHIRO FUJISE* AND KATSUHISA HONDA*#* The Institute of Cetacean Research, 4-18, Toyomi-cho, Chuo-ku, Tokyo 104-0055 Japan.
*# Department of Environmental Science for Industry, Ehime University, 3-5-7, Tarumi, Matsuyama-city, Ehime, 7908566, Japan.

SUMMARY
Concentrations of Mn, Fe, Ni, Cu, Zn, Cd, Hg and Pb were determined in Antarctic krill, Euphausia
superba, collected from stomach contents of Antarctic minke whales from Antarctic Ocean Areas III, IV,
V and VI during 1989/90 and 1998/99. An interaction among Cd-Ni-Mn-Zn was observed in E. superba.
These elements have the same distribution in the sea. Levels of Mn, Fe, Cu, Zn and Cd in each of threebody length groups in Antarctic krill were significantly different. The results were not consistent with theprevious study, suggesting that trace element levels in Antarctic krill may be affected by other life history
factors rather than the body length alone. Seasonal change of trace elements in E. superba was observed
only in Cd, suggesting that it is affected by the migration pattern. Temporal trends of the toxic elements
Cd and Hg concentrations in E. superba were not observed during 1989 and 1999. Trace element, except
for Cd, concentrations found in E. superba were almost the same to those levels previously reported inkrill from the Japan Sea, the western North Pacific and the western North Atlantic, while Cd
concentrations in E. superba reported here were higher than those in the other regions.
KEY WORDS: ANTARCTIC MINKE WHALE; TRACE ELEMENT; BIOACCUMULATION,ANTARCTIC KRILL

Introduction
In 1992, the International Whaling Commission (IWC) decided to establish a regular agenda item for research on
effects of environmental change on cetaceans in the IWC Scientific Committee (SC) (IWC, 1993). Given this,"The elucidation of the effect of environmental changes on cetaceans" was added to the research objectives fromthe 1995/96 JARPA research. Furthermore, we had collected samples and monitored pollutant levels in the tissue
and stomach contents of Antarctic minke whales from 1987/88 research.
For monitoring of trace elements such as Cd and Hg in the aquatic environment, some organisms havebeen used as bioindicators (Philips, 1980; Schubert, 1985). Invertebrates such as bivalves and krill are especially
useful for monitoring trace elements in the marine environment, because trace elements are directly taken up andaccumulated in their body from solution and/or plankton. Trace elements include essential elements such as Fe,
Cu and Zn and toxic elements (or nonessential elements) such as Hg, Cd and Pb. Essential elements are necessary
to maintain normal metabolism and physiological functions in living organisms. Toxic elements induce adverse
effects through bioaccumulation.
There are reports of trace element levels of krill in the Japan Sea (Masuzawa et al., 1988), the Atlantic
Ocean (Ridout et al., 1989), the Mediterranean (Fossi et al., 2002) and the Antarctic (Yamamoto et al., 1987).
There are few studies on monitoring of trace elements in krill, and research on temporal changes is scarce.
The object of this report is to reveal temporal and spatial trends of trace elements, especially toxic
elements, in Antarctic krill obtained as stomach contents of Antarctic minke whales.

Materials and Methods
Antarctic minke whales were collected from Areas IIE (35-70E) and IV (70-130E), and V (130E-170W) and VIW(170W-145W), in alternate years in JARPA. Euphausia superba samples were obtained from stomach contents of1

100 Antarctic minke whales sampled from the Antarctic Areas III, IV, V and VI during 1989/90 and 1998/99. E.
pacifica was obtained from stomach contents of 10 common minke whales sampled from western North Pacificand examined for trace element analysis (Table 1). All samples were stored in polyethylene bags at -20℃ until
analysis.
For the analysis of Mn, Fe, Ni, Cu, Zn, Cd, Hg and Pb, the tissues were homogenized and digested in
microwave (Milestone General: MLS 1200 mega) using nitric acid in a PTFE (Teflon) vessel (Okamoto, 1994).
Mn, Fe, Ni, Cu, Zn, Cd and Pb were measured by inductively coupled plasma atomic emission spectrometry(Seiko Instruments Inc., SPS 1700R) and Hg was measured by cold vapour / atomic absorption spectrometry(Nippon Instruments Co. RA-2A) using external standard method. Concentrations of trace elements in krill are
given on dry weight basis. Accuracy and precision of the methods were confirmed using 'bovine liver' (BCRCRM No. 185) and 'pig kidney ' (BCR-CRM No. 186). Chemical analyses were performed by the Miura Instituteof Environmental Science.
A matrix of the 7 trace elements studied, which is the logarithmic conversion of Mn, Fe, Ni, Cu, Zn, Cd
and Hg concentrations from 99 krill samples was statistically analyzed for intercorrelations by cluster analysis.
The differences between sexes and areas were assessed by Mann-Whitney U test and the relationships between
concentrations of trace elements and age were assessed by Spearman rank correlation (Zar, 1999). To analyze
factors for trace element levels in Antarctic minke whales, we used the stepwise multiple regression analysis. A
single sample was found to contain high concentrations of Fe (420 ppm) which was about 3 times higher than thesecond highest concentration in the sample population of 100. This value qualified as an outlier using theSmirnoff test, and was omitted in the statistical analysis. These statistical analyses were executed by SPSS ver.11
for Windows (SPSS Co. Ltd.).

Results and Discussion
Table 2 shows the concentrations of trace elements in Antarctic krill contained in the first stomach of Antarctic
minke whales from the Antarctic Areas III, IV, V and VI during 1989/90 and 1998/99 seasons. Mn, Fe, Cu, Zn,
Cd and Hg were detected in almost all the krill samples. Ni was also detected, except for two samples. Pb
concentrations in all the krill samples were almost less than the lower level of determination limit.

In vivo interactions
The 693 data in the 99 (krill) ×7 (elements: Mn, Fe, Ni, Cu, Zn, Cd and Hg) data set were statistically examinedfor elemental interaction by cluster analysis. Pb was excluded from this analysis because almost levels were below
the determination limit. Figure 1 represents the dendrogram of a significant amount of cluster formation. Major
correlation among Cd, Ni, Mn and Zn was observed, while Fe, Cu and Hg were not correlated with the otherelements.
The appearance of a Cd-Ni-Mn-Zn correlation is of interest. From the standpoint of distribution in theocean, trace elements are categorized into 3 types, i.e., recycle type (Cd, Ni, Zn) which is low in sea-surface andhigher in deep-sea, scavenge type (Mn, Hg) which is higher in sea-surface and decreases with the depth, andmixed type (Fe, Cu) (Broecker, 1974). Also, the chemical properties of Mn and Zn are similar within the body,
because their ligand field stabilization energy is the same (Lippard and Berg, 1994). This correlation might be
attributable to the similarities of their chemical properties.

Body length effect
The life span of E. superba is in the range of 4 to 6 years; spawning generally starts at age 2 years, and its
maximum body length is over 60 mm (Siegel, 2000). Ichii and Kato (1991) reported that two size modes ofAntarctic krill (25-28 mm in body length (1 years) and 41-48 mm (3-4 years)) are mainly contained in stomach
contents of Antarctic minke whales. To examine the relationships between the body length and trace elementlevels in Antarctic krill, all individuals were classified into three body length groups (S< 40 mm, 40mm <M< 50mm, L> 50 mm).
Levels of Mn, Fe, Cu, Zn and Cd in each body length group in Antarctic krill were significantly
difference tested with Kruskal-Wallis test (Table 3). Figure 2 represents trace element levels in each body length
group and significant differences among the groups tested with Scheffe's test were found: 1) Mn, Fe, and Zn levelsof L (>50 mm) size were higher than those of M (40-50 mm) size, 2) Cd level of L (>50 mm) size was higher than2that of S (<40 mm) size, 3) Cu levels of M (40-50 mm) and L (>50 mm) sizes were higher than those of S (<40mm) size.
Yamamoto et al. (1987) reported that significant correlation between Cu, Zn, Fe, Mn, Ni, Cd, Pb, Co andHg levels in E. superba and the body length were not observed. Locarnini and Presley (1995) reported a negative
correlation between Hg levels in E. superba and the body length. These results were not consistent with our data.
It is suggested that trace element levels in Antarctic krill may be affected by other life history factors as well as
the body length.

Seasonal changes
Figure 3 represents plots of trace element levels in Antarctic krill versus sampling day. Mn, Zn and Hg levels
decreased with elapsed days. Cd levels in Antarctic krill increased from late November to middle January anddecreased from middle January to late March in Areas III, IV, V and VI. Seasonal change of Cd is consistent withthe study of Antarctic krill during 1984/85 and 1985/86 in Area V (Yamamoto et al., 1987).
Yamamoto et al. (1987) suggested that this seasonal change would be caused by changes of watercontents, however concentrations of krill are given on dry weight basis in their study. Antarctic krill migrate from
ice-edge to offshore during January and February through Antarctic intermediate water (Ichii and Kato, 1991).
This water has higher Cd levels, because this is a scavenge element (Lass et al., 2001).

Spatial and temporal differences:
Table 4 shows significant differences in trace element levels in Antarctic krill between Areas III-IV and V-VI.
Only Mn levels of krill in Area III-IV were higher than those of Area V-VI (p<0.01). Temporal differences oftrace element levels in Antarctic krill between first and last researches in Areas III-IV (1989/90 and 1997/98) and
V-VI (1990/91 and 1998/99) were tested with Mann-Whitney U test (Table 5). Mn, Ni and Zn levels in Antarctic
krill significantly decreased in Area III-IV and Cu levels in Antarctic krill significantly increased in Area V-VI.
The results were not consistent between these areas and these elements are essential elements. The results indicatethat these trends may be affected by physical processes rather than temporal changes of trace elements.
Furthermore, temporal trends of the toxic elements Cd and Hg were not observed in Antarctic krill.

Comparison of trace element levels in krill around world
Table 6 shows trace element levels in krill from other ocean areas as previously mentioned for comparison with
our data. Mn, Fe, Zn and Cd levels of E. superba in this study were twice higher than those of E. superba during
1984 and 1986 (Yamamoto et al., 1988), while Cu and Hg levels in this study were similar to other areas. Mn, Ni
and Cd levels of E. superba in this study were higher than those of E. superba in the western Antarctic Peninsula(Locarnini and Presley, 1995), while Cu level in this study was lower than that in the western Antarctic. Ni, Cu
and Cd levels in Antarctic krill were higher than those concentrations of krill in the North Pacific, however thoseof Mn, Fe, Zn and Hg were lower. In accumulation features of E. superba in the Antarctica, their Cd levels wereapproximately 1 order of magnitude higher than krill from the Northeast Pacific, the Japan Sea and the Northeast
Atlantic, while their Hg levels were 1/2 lower than those from the Northwest Pacific.

References
Broecker, W.S. 1974. Chemical oceanography. New York, Harcourt Brace Jovanovich. 214pp.
Fossi MC, Borsani JF, Di Mento R, Marsili L, Casini S, Neri G, Mori G, Ancora S, Leonzio C, Minutoli R,
Notarbartolo di Sciara G. 2002. Multi-trial biomarker approach in Meganyctiphanes norvegica: a potential
early indicator of health status of the Mediterranean "whale sanctuary". Marine Environmental Research.
54:761-7.
Fujise, Y. 1997. A brief review of studies related to research on effects of environmental changes on cetaceans in
the JARPA survey. Paper SC/M97/5 presented to the IWC Intercessional Working Group to Review Data
and Results from Special Permit Research on minke whales in the Antarctic, May 1997 (unpublished). 19pp.
Honda, K., Yamamoto, Y., Kato, H. and Tatsukawa, R. (1987) Heavy metal accumulations and their recentchanges in southern minke whales Balaenoptera acutorostrata. Arch. Environ. Contam. Toxicol., 16:209216.
3

Ichii, T. and Kato, H. 1991. Food and daily food consumption of southern minke whales in the Antarctic. Polar
Biology, 11:479-487.
Lass, H.U., Mohrholz, , V. Nausch, G. Pohl, C. Postel, L. Rüß, D. Schmidt, M. Da Silva, A. and Wasmund, N.
2001. Data Report of R/V "METEOR" cruise 48/3; ANBEN. Marine Science Reports, No. 47. 120 pp.
Lippard, S.J. and Berg, J.M. 1994. Principles of bioinorganic chemistry. New York. Material. 411pp.
Locarnini, S.J.P. and Presley, B.J. 1995. Trace element concentrations in Antarctic krill, Euphausia superba.
Polar Biology. 15:283-288.
Masuzawa, T., Koyama, M. and Terazaki, M. 1988. A regularity in trace element contents of marine zooplankton
species. Marine Biology 97:587-591.
Phillips, D.J.H. 1980 Quantitative aquatic biological indicators: Their use to monitor trace metal andorganochlorine pollution, Applide Sci. Pulb., London.
Rainbow, P.S. 1996. Heavy metals in aquatic invertebrates. In Environmental Contaminants in Wildlife. (eds.
Beyer, W.N., Heinz, G.H. and Redmon-Norwood, A.W.) New York. Lewis Publishers. 405-445pp.
Ridout, PS, Rainbow, PS, Roe, HSJ and Jones, HR. 1989. Concentrations of V, Cr, Mn, Fe, Ni, Co, Cu, Zn, As
and Cd in mesopelagic crustaceans from the North East Atlantic Ocean. Marine Biology. 100:465-471.
Siegel, V. 2000. Krill (Euphausiacea) life history and aspects of population dynamics. Can. J. Fish. Aquat. Sci.
57(Supple. 3):130-150.
Yamamoto, Y., Honda, K. and Tatsukawa, R. 1987. Heavy metal accumulation in Antarctic krill Euphausia
superba. Proc. NIPR Symp. Polar Biol., 1:198-204.

4

Table 1 Sample list of Antarctic minke and common minke whales
SpeciesYear
Area(Academic name )Antarctic minke whale(Balaenoptera bonaerensis )1989/90

Antarctic Area IV

1990/91

Antarctic Area V

1991/92

Antarctic Area IV

1992/93

Antarctic Area V

1993/94

Antarctic Area IV

1994/95

Antarctic Area V

1995/96

Antarctic Area III

1996/97

Antarctic Areas V & VI

1997/98

Antarctic Areas III & IV

1998/99

Antarctic Area V

Common minke whale
1994-1995 NW Pacific (Off shore)
1996
NW Pacific (Coastal)(Balaenoptera acutorostrata )

5

n
Sex
9 males
1 female
3 males
7 females
7 males
3 females
6 males
4 females
4 males
6 females
7 males
3 females
10 males
8 males
2 female
6 males
4 females
7 males
3 females
4 males
5 males

Body length (m)Ave. (min.-max.)
7.69 (5.50-8.80)
9.70
8.57 (8.30-8.90)
8.80 (8.30-9.10)
8.55 (7.94-9.18)
9.00 (8.66-8.27)
8.61 (8.30-8.88)
8.70 (8.68-8.72)
8.17 (7.87-8.29)
9.01 (8.83-9.24)
8.45 (7.99-9.03)
8.73 (8.28-9.10)
8.09 (6.28-9.00)
8.11 (7.30-8.74)
7.79(7.01-8.56)
7.99 (5.69-9.12)
9.08 (8.57-9.68)
8.58 (7.59-9.01)
9.25 (9.11-9.35)
6.75(4.54-8.09)
6.20(4.66-7.73)

6Table 2 Trace element concentrations (μｇ/g dry wt) of Euphausia superba from Antarctic and E. pacifica from western North Pacific
Mn
FeSpecies
Area
year
n
Ni
Cu
Zn
Cd
3.5 ± 0.7
28 ± 27
1.5 ± 0.547 ± 2354 ± 53.2 ± 2.1
1989/90 10( 2.5 - 4.6 ) ( 11 - 100 ) ( 0.8 - 2.3 ) ( 16 - 85 ) ( 44 - 60 ) ( 1.4 - 8.3
72 ± 1301.3 ± 0.4
43 ± 1349 ± 83.0 ± 1.7
3.2 ± 0.7
1991/92 10( 1.9 - 4.3 ) ( 4.9 - 420 ) ( 0.9 - 2.2 ) ( 25 - 58 ) ( 38 - 58 ) ( 0.42 - 5.5
21 ± 24
1.4 ± 0.3
51 ± 1647 ± 71.6 ± 0.7
2.8 ± 0.8
Area-III, IV 1993/94 10( 1.9 - 4.5 ) ( 7.6 - 89 ) ( 1.0 - 2.1 ) ( 26 - 77 ) ( 36 - 56 ) ( 0.51 - 2.7
11 ± 30.7 ± 0.1
50 ± 2346 ± 30.62 ± 0.4
2.8 ± 0.3
1995/96 10( 2.5 - 3.3 ) ( 8.5 - 18 ) ( 0.6 - 0.9 ) ( 20 - 76 ) ( 39 - 50 ) ( 0.32 - 1.6
18 ± 81 ± 0.2
60 ± 1348 ± 71.7 ± 1.2
2.8 ± 0.3
1997/98 10( 2.4 - 3.3 ) ( 9.0 - 31 ) ( 0.6 - 1.3 ) ( 46 - 82 ) ( 40 - 65 ) ( 0.71 - 4.4
25 ± 2239 ± 2248 ± 102.5 ± 2.3
2.5 ± 0.7
1.4 (n=9)
E. superba
1990/91 10( 1.3 - 3.4 ) ( 11 - 73 ) ( <0.5 - 2.4 ) ( 1.6 - 63 ) ( 40 - 74 ) ( 0.20 - 7.1
31 ± 25
1.0 ± 0.342 ± 1244 ± 42.2 ± 2.3
2.8 ± 0.4
1992/93 10( 2.1 - 3.7 ) ( 9.6 - 79 ) ( 0.7 - 1.5 ) ( 23 - 55 ) ( 38 - 52 ) ( 0.47 - 7.5
26 ± 2935 ± 2142 ± 71.1 ± 0.9
2.2 ± 0.4
0.9 (n=9)
Area-V, VI 1994/95 10( 1.5 - 2.9 ) ( 5.2 - 100 ) ( <0.5 - 1.4 ) ( 12 - 86 ) ( 28 - 49 ) ( 0.15 - 2.6
17 ± 171.3 ± 0.442 ± 2445 ± 71.6 ± 1.2
2.5 ± 0.4
1996/97 10( 1.8 - 2.9 ) ( 5.5 - 64 ) ( 0.7 - 2.0 ) ( 22 - 83 ) ( 34 - 55 ) ( 0.30 - 4.2
17 ± 111.4 ± 0.566 ± 2245 ± 62.1 ± 1.2
2.8 ± 0.5
1998/99 10( 2.4 - 3.7 ) ( 7.9 - 43 ) ( 0.8 - 2.3 ) ( 20 - 98 ) ( 37 - 54 ) ( 0.78 - 4.3
19891.2(n=98)
26 ± 46
47 ± 2147 ± 72.0 ± 1.6
2.8 ± 0.6
100
total
1999
( 1.3 - 4.6 ) ( 4.9 - 420 ) ( <0.5 - 2.4 ) ( 1.6 - 98 ) ( 28 - 74 ) ( 0.15 - 8.3
1994<0.572 ± 8822 ± 966 ± 130.41 ± 0.2
3.5 ± 1.7
4
Off shore1995( 2.2 - 6.0 ) ( 9.3 - 200 ) () ( 12 - 32 ) ( 49 - 79 ) ( 0.26 - 0.8
0.8(n=1)
24 ± 1134 ± 1392 ± 190.74 ± 0.2
4.2 ± 0.8
1996
Coastal5
E. pacifica( 3.0 - 4.9 ) ( 8.6 - 34 ) ( <0.5 - 0.8 ) ( 18 - 51 ) ( 71 - 120 ) ( 0.41 - 0.9
19940.8(n=1)
3.9 ± 1.3
46 ± 60
29 ± 1281 ± 210.60 ± 0.3
total
9
1996
( 2.2 - 6.0 ) ( 8.6 - 200 ) ( <0.5 - 0.8 ) ( 12 - 51 ) ( 49 - 120 ) ( 0.26 - 0.9

Hg0.029 ± 0.011) ( 0.018 - 0.051
0.020 ± 0.007) ( 0.01 - 0.031
0.025 ± 0.010) ( 0.014 - 0.048
0.028 ± 0.005) ( 0.021 - 0.037
0.037 ± 0.009) ( 0.026 - 0.054
0.037 ± 0.016) ( 0.018 - 0.066
0.029 ± 0.008) ( 0.02 - 0.043
0.027 ± 0.006) ( 0.018 - 0.041
0.026 ± 0.008) ( 0.017 - 0.045
0.025 ± 0.011) ( 0.014 - 0.046
0.028 ± 0.010) ( 0.010 - 0.066
0.047 ± 0.02
) ( 0.024 - 0.060
0.042 ± 0.016) ( 0.028 - 0.070

Pb
<2.1
) (
<2.1
) (
<2.1
) (
<2.1
) (
<2.1
) (
<2.1
) (
<2.1
) (
<2.1
) (
<2.1
) (
<2.1
) (
<2.1
) (
3.3(n=1)) ( <2.1 - 3
<2.1
) (
-

)
)
)
)
)
)
)
)
)
)
)
)
)

3.3(n=1)
0.044 ± 0.015) ( 0.025 - 0.070 ) ( <2.1 - 3 )Table 3 Trace element concentrations (μｇ/g dry wt) in each body size group of Euphausia superba from Antarctic
Body Length

n

Mn

Fe

Ni

Cu

Zn

Cd

Hg

S <40mm25

M 40-50mm

12

L >50mm47

2.7(1.9-4.3)
2.5(1.8-2.8)
3.0(1.5-4.6)*

34(5.2-420)
14(5.5-64)29(4.9-140)*

1.1(0.6-2.4)
1.3(0.7-2.0)
1.3(0.3-2.4)

31(16-61)60(25-98)54(12-86)***45(37-58)42(34-47)
48(28-60)**1.2(0.15-4.6)
1.8(0.78-3.1)
2.5(0.21-8.3)
**

0.029
(0.016-0.066)
0.027(0.017-0.043)
0.026(0.010-0.054)

Probability in Kruskal-Wallis test7

Table 4 Significant spatial difference of trace element concentrations of Antarctic krill in Areas III, IV
and V, VI during 1988 and 1998 using Mann-Whitney U test (p <0.05)
Mn
Fe
Ni
Cu
Zn
Cd
Hg
Significance (p)0.002
III,IV>V, VI

Table 5 Significant temporal difference of trace element concentrations of Antarctic krill in Areas III, IV between'89/90 and '97/98, and V, VI between '90/91 and '98/99 using Mann-Whitney U test (p <0.05)
Mn
Fe
Ni
Cu
Zn
Cd
Hg
Area-III,IV*****'89/90>'97/98'89/90>'97/98'89/90>'97/98
Area-V,VI*'90/91<'98/99*:p<0.05, **:p<0.001

8

Table 6 Trace element concentrations (μｇ/g dry wt) of Euphausia superba from Antarctic and Euphausia pacifica from western North PacificMn
2.8
W Antarctic Peninsula(1.3-4.6)
Euphausia superba
1984-86 76
Antarctic Ocean
1.8
AreaⅣ−Ⅵ(0.87-3.33)
Euphausia superba
Antarctic Ocean
1993 70
1.98
AreaⅢ−Ⅵ(0.03-3.94)
Euphausia pacifica
1994-96 9
NW Pacific3.9(2.2-6.0)
Thysanoessa longipes
Sea of Japan1984
1.8
Thysanopoda microphthalma NE Atlantic
1985 4
1.7
Meganyctiphanes norvegica NE Atlantic
1985 5
2.9
Nematoscelis megalops
NE Atlantic
1985 7
2.4
Nematobrachion boopis
NE Atlantic
1985 5
1.9
Meganyctiphanes norvegica NE Atlantic
8
SpeciesEuphausia superba

Area
Antarctic Ocean

yearn
1989-99 100

9

Fe
26
(4.9-420)
9.2(3.3-25)
28(8.5-108)46(8.6-200)
110
24.3
25.6
26.3
NA

Ni
1.2
(<0.5-2.4)
1.2(0.23-4.6)
0.54(0.10-1.5)
0.8(<0.5-0.8)
NA
0.57
0.80
0.91
0.76

Cu
47
(1.6-98)33(4.1-80)80.5(37.8-140)
29(12-51)
NA
48.6
71.9
42.0
44.9

Zn
Cd
Hg
Pb
Ref.
47
2.0
0.028
<2.1
1)
(28-74)(0.15-8.3) (0.01-0.066)
25
1.1
0.021
0.10
2)
(13-38)(0.10-4.4) (0.01-0.059) (0.026-0.26)
43.5
0.29
0.02450.22
3)(35.2-51.3) (0.13-0.75) (0.013-0.049) (0.15-1.8)
81
0.60
0.044
1)
(49-120) (0.26-0.88) (0.025-0.07)
175
NA
NA
NA
4)
56.8
0.3
5)
96.5
0.39
5)
44.0
0.2
5)
47.7
0.5
5)
104
0.25
0.26
6)

Cited from: 1) this study; 2) Yamamoto et al. , 1988; 3) Locarnini and Presley, 1995; 4) Masuzawa et al ., 1988; 5) Ridout et al. , 1989; 6) Leatherland et al. , 1973.

Cd
Ni
Mn
Zn
Fe
Cu
Hg
0

5

10

15

20

25

Rescaled Distance Cluster Combine
Fig. 1 Hierarchical Cluster analysis of trace element concentrations of Antarctic
krill. Dendrogram using average linkage between groups

10

4.0

2.0

Ni concentration (μg/g dry wt.)

3.0

1.5
1.0
0.5
0

**

100

*

100

60
40
20

**

40

Cu

75
50
25

0

Zn

<40m
40-50m
10m
20 m >50m
30 m
Body length (mm) of E. superba

125

40

0

10

<40m
40-50m
10m
20 m >50m
30 m
Body length (mm) of E. superba

**

40

Cd

8
6
4
2
0

<40m
40-50m
10m
20 m >50m
30 m
Body length (mm) of E. superba

0

Hg concentration (μg/g dry wt.)

**

200

0

<40m
40-50m
10m
20 m >50m
30 m
Body length (mm) of E. superba

80

300

0

2.0

0.0

Fe

400

40

Ni

2.5

500

0

<40m
40-50m
10m
20 m >50m
30 m
Body length (mm) of E. superba

Cu concentration (μg/g dry wt.)

0.0
0

Zn concentration (μg/g dry wt.)

Fe concentration (μg/g dry wt.)*

Mn

Cd concentration (μg/g dry wt.)

Mn concentration (μg/g dry wt.)

6.0

0.10

0

40

<40m
40-50m
10m
20 m >50m
30 m
Body length (mm) of E. superba

40

Hg

0.08
0.06
0.04
0.02
0.00
0

<40m
m
40-50m
1020 m >50m
30 m
Body length (mm) of E. superba

40

Figure 2 Comparison of trace element concentrations (ppm dry wt.) in three body size groups of E.
superba
11

200

Mn

4.0

Conc. (ppm dry wt)

Conc. (ppm dry wt)

5.0

3.0
2.0
1.0
0.0

Fe

150
100
50
0

10-Nov

30-Nov

20-Dec9-Jan

29-Jan18-Feb

10-Mar30-Mar

10-Nov

30-Nov

20-DecSampling day
100

Ni

2.0

Conc. (ppm dry wt)

Conc. (ppm dry wt)

2.5

1.5
1.0
0.5
0.0
30-Nov

20-Dec9-Jan

29-Jan18-Feb

10-Mar30-Mar

10-Mar30-Mar

18-Feb

10-Mar30-Mar

18-Feb

10-Mar30-Mar60
40
20

10-Nov

30-Nov

20-Dec9-Jan

29-JanSampling day
10.0

Zn
Conc. (ppm dry wt)

Conc. (ppm dry wt)

18-FebCu

80

Sampling day

60
40
20
0

Cd

7.5
5.0
2.5
0.0

10-Nov

30-Nov

20-Dec9-Jan

29-Jan18-Feb

10-Mar30-Mar

10-Nov

30-Nov

20-DecSampling day
0.08
Conc. (ppm dry wt)

29-Jan010-Nov

80

9-Jan

Sampling day

Hg

0.06
0.04
0.02
0.00
10-Nov

30-Nov

20-Dec9-Jan

29-Jan9-Jan

29-JanSampling day

18-Feb

10-Mar30-MarSampling day

Fig. 3 Seasonal change of trace element concentrations in Antarctic krill●: Area III and IV, ○: Area V and VI

12