15n and 13c abundances in the atlantic ocean

8/3/2019 15N and 13C Abundances in the Atlantic Ocean

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)eep-Sea Research, Vol. 34, No s 5/6, pp. 829-84 1. 1987. (1198-t1149/87 $3.0t~ + !1.(10' r ime d in Grea t B r i t a in . 1987 Pergam on Journa l s Ltd .

~SN and 13C a b u n d a n c e s i n t h e A n t a r c t i c O c e a n w i t h e m p h a s i s o n t h eb i oge oc h e m i c a l s t r u c t u r e o f t h e food w e b~ I T A R O W A D A , * M A K O T O T E R AZ A K I,'~ Y U K O K A B A Y A * a n d T A K A t tl S A N E M O T O t

(Received 15 August 1985: in revised for m 1 February 1986; accepted 15 M ay 1986)

A b s t r a c t - - D i s tr i b u t io n s o f ~ISNand ~5~3C for bio genic substances in the A ntar ctic Oce an wereinvest igated to const ruct a biogeochemical f ramew ork for assessing the An tarc t ic ecosystem.Ph yto plan kton exh ibited par ticula rly low ~515N ((I.5%) and ~;C (-26.9%o) value s in pelagicplankton samples. High ni t ra te concentra t ions, and high PCO, in the surface waters on thesouthern side of the pola r f ront and the resul t ing slow growth ra te of phytoplan kton unde r lowlight intens ity are suggested a s possib le factors in causing the low isoto pic com positio ns. Meanfract ionat ion fac tors of 1 .029 and 1.006 were est imated for photosy nthet ic carbon f ixation and forthe assimi la t ion of inorganic ni t rogeno us compou nds (am mon ium p lus ni t ra te) during algalgrowth, respectively.En richm ent o f LSN with increasing tro ph ic level was confirmed for An tarctic ecosystems:615N,nim,l%o = 3.3 (trop hic le v e l- 1) + 6LSN,Ig~,

whereas 13C content d id not increase in the same m anner . Differences in l ipid content am onganimals may be the main fac tor in causing this 6~C anom aly.I~N and 13C abundance of sedimentary organic ni t rogen di ffered from phytoplankton andset t l ing par t ic les. An exact mechanism for expla ining the high g~SN (around 5% ) is not know n.The v ery high ~3C value of-20.5%o at Sta . 3B may originate in ice a lgae that had grown und erCO , - l imi t ed cond i t ions .Part ic les col lec ted by sedim ent t rap s gave c haracter ist ica l ly low 6L~N values (-3.0 to 0.9%,,) ,strong ly suggesting a ph ytop lank ton origin. The 15~5N and 6L~Cvalues of se t t l ing mater ia l showedsimilar vertical profiles with de pth w hich might arise from te mp oral variatio n of algal growth.

I N T R O D U C T I O NC ON SID ER AB LE a t t e n t i o n h a s b e e n f o c u s e d o n c y c l e s o f b i o p h i l i c e l e m e n t s i n n a t u r a ls y s t e m s . A t a g i v e n t i m e , l iv i n g o r g a n i s m s a c c o u n t f o r a n e g li g i b l y s m a l l p o o l s i ze w h e nc o m p a r e d t o g lo b a l i n v e n t o r ie s . H o w e v e r , n a t u r a l e c o s y s t e m s a r e a c t i v e s i t e s w h e r ei m p o r t a n t t r a n sf e r s o f o r g a n i c m a t t e r o c c u r r a p i d ly a n d i n a c o m p l e x m a n n e r . I n th i sc o n t e x t , n e w w a y s t o c la s s i fy c o m p o n e n t s o f t h e a n i m a l k i n g d o m a r e h i gh l y d e s i r a b l e toc o n s t r u c t a b i o g e o c h e m i c a l f r a m e w o r k f o r a s s e s s i n g f l ux e s o f b i o g e n i c s u b s t a n c e s .

R e c e n t p r o g r e s s i n i s o t o p e b i o g e o c h e m i s t r y m a y h e l p t o m e e t t h is r e q u i r e m e n t , A ne n r i c h m e n t o f t SN a l o n g t h e f o o d c h a i n w a s f i r st f o u n d b y M 1Y AK E a n d W A D A ( 19 6 7 ) a n dl a t e r c o n f i r m e d i n c u l t u r e e x p e r i m e n t s (D E NIR O a n d E P S T E I N , 1 9 81 ) a n d i n m a r i n e a n dt e r r e s t r i a l e c o s y s t e m s (ScHCIENINGER t a l . , 1 9 8 3 ; S CH O EN IN G ER a n d D E N I R o , 1 9 8 4 ) . T h ee n r i c h m e n t o f ~5N is w i d e s p r e a d a m o n g m o s t a n i m a l s , i n v o lv i n g i n v e r t e b r a t e s a n dv e r t e b r a t e s i r r e sp e c t i v e o f t r o p h i c l e v el s , h a b i t a t , f o r m o f n i t r o g e n e x c r e t e d a n d g r o w t h

* Mitsubishi -Kasei Inst i tute of Life Sciences, 11 M inamiooy a, Machida , Toky o 194, Japan.t Ocean Resea rch Ins t i t u t e , Unive rs i ty o f Toky o , 1 -15-1 Minamida i . Nakano . T okyo 164 , Japan .829


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830 E. WAUAel aLrate. ~SN enrichment averages +3.4 + 1.1%o for a single feeding process (MINAO,\WA alldWADA, 1984). On the othe r hand, 8~5N of phytoplankton is variable, depending upon thenitrogen source used for growth and on physiological conditions (WA~)A, 19801. Thelatter factors also affect the 8~3(-" values of phytoplankton.

Indeed, a close relationship between i5~3C values of phytoplankton and ambientseawater temperature (SAcKE'Vre t a l . , 1973), strongly suggests the significance of growthrates on the var iation of 8~3C. Rau e t a l . (1982) proposed that the latitudinal discrepan-cies in the ~'~C conten t of plankton depend upon geographic dif ferences in the kineticisotope effect associated with plankton biosynthesis. The 813C values of animal tissue arcvery close to those in their diet, and a small increase in ~-~C content sometimes occur,,with increasing t rophic level (DEN~RO and Et'S~HN, 1978, FRy e t a l . , 1978: R,\tJ c~1a/1983; FRY and SHIRR, 1984). The lines of evidence described above suggest that ti~cisotopic composition of nitrogen and carbon in marine biota can provide basic infoi-mation on their growth condition, food source, and trophic level.

The Antarctic Ocean provides a particularly good environment for examining ti~cphysiochemical and biological structures of an ecosystem. The cold climate lowers watcitemperatures in the euphotic zone and promotes vertical mixing which supplies nutrientsalts and high Pco, to the euphotic zone. Primary production is moderate (ttOLM-tt-xNSte t a l . , 1977) under low tempera ture and low light intensity. Furthermore , nitrateconcentration in the euphotic zone exceeds 2(1 ~M throughout the year, and the fractionof primary production that can be regarded as new production that can be transfered to :~higher trophic level should be high (Du(;DALE and GOERING, 1967; OLSON, 1981).

Seasonal variation of chlorophyll a in the euphotic zone as well as under fast ic~generally exhibits a single maximum during the austral summer season (HART, 1942:FUKUCm e t a l . , 1984). According to HASl.E (1969), diatoms are the most dominant groupamong phytoplankton. Krill, a herbivore, act as a central dietary source h)r carnivorou~zooplankton, seals and whales (MACKINTOStt, 1960). In light of these facts, the stableisotope ratios of nitrogen and carbon for biogenic substances were investigated t~describe the isotopic structure of the Antarctic ecosystem and to examine the applicabi.lity of isotopic methods for food web analysis.

MA' t t . 'R IA LS AND Mf ; I ' II ( )I_ )S

Samples were collected in the southern Ocean Australian Sector during the KH-83-4cruise of the R.V. H a k u h o - M a r u as a part of the BIOMASS SIBEX-I project (22November, 1983-24 February, 19841. The hydrographic data have been presented byNEMOTO and TERAZAKI (19851. Additional sampling of macrofauna was carried out by theJapanese pilot fishery for Antarctic krill and whale in the areas between 43W and44.5W during 1982-1983.Water samples from a depth of 5 m (100 1) were collected with a water pump, andparticulate organic matter (POM) was collected on Whatman type F glass-fiber filterspretreated at 400C for several hours. Plankton samples were collected by horizontaltows of MTD nets, 56 cm in diameter and with meshes of 0.10 mm (XX13) and 0.33 mm(GG54), and by vertical tows (0-200 m) with NORPAC nets (XX13). Other macrofaunasuch as Euphausiacea, Copepoda, Amphipoda and pisces, were collected from theindicated depth by ORI-69 nets or by IKMT nets with a diameter of 10 feet. Surfacesediments were obtained by using a box core. Settling particles collected in sediment


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15N and E~C abund ances in the An tarc t ic Ocean 831

t r a p s w e r e s u p p l i e d b y D r s S . T s u n o g a i a n d K . H a r a d a o f H o k k a i d o U n i v e r s i ty . D e t a il so f th e t r a p s y s t e m a n d m o o r i n g a r r a y a r e r e p o r t e d e l s e w h e r e ( T su N oG A I et al., 1982).

S a m pl e m a t e r i a l s w e r e f r oz e n ( - 80 C ) a nd l a t e r va c uum - d r i e d i n t he l a bo r a t o r y .M a c r o f a u na w e r e c r u s he d , a n d pa s s e d t h r ough a 1 m m ope n i ng s t a in l e s s - st e e l s i e ve . A llb i o lo g i c al s am p l e s ( 2 - 5 m g N ) w e r e c o n v e r t e d t o a m m o n i u m b y K j e l d a h l d i g es t io n . T h ea m m o n i um p r o du c e d w a s s t e a m - d i s t i ll e d , c o l l e c t e d i n a 0 . 25 N H 2S O 4 t r a p a nd t he nc o n v e r t e d in vacuo t o n i t r oge n ga s w i t h a l ka li ne hy pob r om i t e . A l i qu o t s o f the d i s t il l at ew e r e t a ke n f o r n i t r oge n de t e r m i na t i on by c a l o r i m e t r y . T he n i t r oge n ga s w a s pu r i f ie dbe f o r e m a s s s pe c t r o m e t r i c a na l y s is . D e t a i l s o f t he m e t h od a r e r e p o r t e d e l s e w h e r e ( W A DAa nd H A q 'z O RI, 1976 ). B e f o r e 613C m e a s u r e m e n t , a ll s a m p l e s w e r e t r e a t e d w i t h 1 N H C I ,f r e e z e - d r i e d , a n d t h e n c o n v e r t e d t o C O 2 i n a n I R G o l d I m a g e F u r n a c e c o m b u s t i o ns ys t e m (M L ZU TA ~I a nd W A D A , 1985 ). T he C O 2 e vo l v e d w a s m e a s u r e d by vo l um e t r y u s i nga m e r c u r y m a nom e t e r a nd t he n u s e d f o r c a r bon i s o t op i c m e a s u r e m e n t s ( N A K A M t ~ R . , \ etal., 1984),

I s o t o p e r a t i o s w e r e m e a s u r e d b y a H i t a c h i R M U - 6 R m a s s s p e c t r o m e t e r f i t t e d w i t h adoub l e c o l l e c t o r f o r r a t i om e t r y a nd e xp r e s s e d i n pe r r a i l de v i a t i ons f r om a s t a nda r d a sde f i ne d by t he f o l l ow i ng e qua t i on :

o r 6 ' 3 C ( % o ) = ( R ..... pl~ 13 x 1 000 ,515N\ R s l a n d a r d /

w h e r e R = 15N: 14N o r 13C:12C. A t m os p he r i c n i t r oge n ( f o r ~ 15N ) a nd P e e de e be l e m n i t e( P D B ) ( f o r 6 1 3 C ) w e r e u s e d a s th e s t a n d a r d s. A m m o n i u m s u l fa t e s o l u t io n s ( - 3 . 4 a n d1 . 3 % ) a n d s o d i u m c a r b o n a t e s o l u t io n s ( - 1 9 . 4 a n d - 1 1 . 0 % ) w e r e u s e d as r u n n i n gs t a nda r ds f o r 8L ~ N a nd 613C m e a s u r e m e n t s , r e s pe c t i ve ly . A l l da t a f o r 61 :~ C w e r ec o r r e c t e d f o r oxy ge n e r r o r s a c c o r d i ng t o t he m e t ho d o f CR A IG ( 1957 ). T he a na l y ti c a lp r e c i s i ons f o r i s o t op i c a na l y s i s a r e w i t h in 0 .2%0 f o r bo t h i s o t ope s ,

R E S U L T S

M i c r os c op i c s t ud i e s r e ve a l e d t ha t a l m o s t a ll pa r ti c u l a t e o r ga n i c m a t t e r ( P O M onW h a t m a n G F / F ) c o n s i s te d o f d i a to m s . T h e 8 15 N ( 0 .4 - 0. 5 % o ) a n d ~ 1 3C ( - 2 7 , 4 t o - 2 6 . 4 % )f o r th e P O M w e r e p a r t ic u l a rl y l o w i n m a r i n e p e l ag i c p h y t o p l a n k t o n . I n d e e d t h e 8 15 N v a l u eo f 0.4%o w a s t he l ow e s t a m ong t he p r e s e n t s a m p l e s ( T a b l e s 1 a nd 2 ) a nd a s l ow a s t hos efor N 2 f ix ing b lu e -gr een a lgae , Trichodesmium. N e t t e d p l a n k t o n m o s t l y c o n s i s t e d o fp h y t o p l a n k t o n ( X X 1 3 ) a n d z o o p l a n k t o n ( G G 5 4 ) w i t h a n e g l i g i b l e d e t r i t a l c o m p o n e n t .T h e s e m i x e d s a m p l e s to g e t h e r w i th E u p h a u s i a , a n d C o p e p o d a g a v e v a r i ab l e 6 15 N ( 0 . 6 -9 .8%0) a nd 61 3C ( - 32 . 3 t o -26 .6%0) va l ue s . A m on g t he z oo p l a n k t on , t h e c a r n i vo r ousC o p e p o d a s h o w e d h ig h 5 1 5 N v a l u e s , w h e r e a s t h e 8 1 3 C v a l u e s ( a v e r a g e - 2 9. 1% o ) w e r es ig n i fi ca n tl y lo w e r t h a n a v e r a g e P O M , T h e h e r b i v o r o u s a n i m a ls (Euphausiacea a n dSalpa) e x h i b i t e d ~ 1 5 N v a l u e s ( 1. 8- 3 ,1 % o ) i n t e r m e d i a t e b e t w e e n P O M a n d p o l y c h a e t a .M a c r o f a u na , s uc h a s p i s c e s a nd s qu i d , c om m o n l y s ho w e d r a t h e r h i gh ~ SN a nd 13Cc on t e n t s . T he h i ghe s t va l ue s ~15N (10.4%o) an d ~13C( -23 .4%0) in th i s s tud y were fo un d inTrematomus bernacchir ( T a b l e 2 ) . 615N va l ue s o f t he m a r i ne b i o t a c o l l e c t e d on 13J a nu a r y 1984 at S ta . 3 ' ( 61 32 'S , 150 26 'E ) i nc r e a s e d i n t he f o ll ow i ng o r de r : P O M(0.5%0) < Euphausia superba, young (1 .0%o) < Salpa thomp soni (1.8%o) < E. superba,a du l t ( 3 . 1%o) < po l y c ha e t a s p . ( 4 . 8%0) < Sagi t ta maxima (5 .6%0) < Notolepis coasti


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834 E. WADAet al.

7"able 2. 8~3Cand 615N o f m arine a nimals co l lected f rorn the Antarct ic Ocean during the Japanese p i lo t f i shervSampling N (' 615N e;~( 'Samples date Location (%) (%) (%,0 (%,,1

Euphausiid 15 Jan., 1 9 8 3 5925'S,4309'W 6.75 45.3 . . . . . 29315 Jan ., 1 9 8 3 5925'S,4309'W 10.9 30.6 4.2 25.712 Jan. , 1 9 8 3 5940'S,4313'W 13.7 22,9 6.0 2~ !)quidKo n d a ko r iaIongirnama

PiscesTrema to m u sbernacchir

,4..'~ 7.0 -2(~. 14Jan ., 1 9 8 3 5934'S,4316'\V 14.2 ' -16 Jan , 1 9 8 3 5949'8,4347'W 15.1 21.6 7.2 --2-1.526 Jan ., 1 9 8 3 5'457'S,4430'W 15.4 21.0 6.5 2"~ 525 Jan ., 1982 South of Elepha nt 13.2 33.2 10.4 2~,4Island, west coast ofAntarctic Peninsula

(7.1%o) < Electrona antarctica ( 7 . 5%o) . T he s e s a m p l e s , e xc e p t f o r P O M , w e r e c o l l e c t e ds i m u l t a ne ous l y by a n ob l i que t ow ( 0 - - 535 m ) o f a n I K M T n e t . O n t h e o t h e r h a n d , t h e8t3C va lues o f these mater ia l s d id not increase in the same manner and the lowest va luew a s f o u n d f o r Euphausia superba (-29.1%o), whi le the h ighest value was for Notoch,psiscoasti (-25.8%0).Sed ime ntary organ ic m atter co l l ec ted a t the three s ta t ions d i f fered in LSN and ~ (abundance from surface PO M (Tab le 11. Th e 6~5N va lues ranged from 4 .9 to 5 .5%o ( theaverage was 5 .2%0) . Furthermore , a very h igh t3C va lue o f -20 .5%0 was found for thesed im ent sam ple from Sta . 3B, wh i l e -25 .4%o was ob ta ined for o ther sed iments .

, = 23

" 2 ' 8 - ~ ; 7 - : ; e -:is - ~ / 4 6 ~ 3 c ~ * / * *- 3 - 2 -I 0 l 615NaW/oo

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Fig. 1. Verti cal profi les of 6~5N and /SL~C values for settl ing particles ~,t Sta. 3(6033.0'S,15027.0'E) of the KH-83-4 cruise of the H o k u h o - M a r u . Collections were performedat dep ths of 0.69, 0.93, 1.33, 2.33, and 3.13 km to t 24 days from 10 Decemb er, 1983 to 13January, 1984. The depth of this station is 3580 m. Open circles and triangles denote the 6~N andthe ~3C values, respectively.


7/13

tSN and ~3C abun danc es in the A ntarctic O cean 835

T h e m a t e r i a l c o l l e c te d b y s e d i m e n t t r a p s c o n s i s t e d m a i n l y o f d i a t o m f r u s t u l e s a n d f e c a lpe l l e t s pa c ke d w i t h f r u s tu l e s . T he ~ I S N a nd 6 t 3C va l ue s o f the t r a p s a m p l e s ga ve s i m i la rve r t ic a l p r o f il e s w i t h de p t h ( F ig . 1 ). T he ~ S N o f t he 690 m s a m p l e w a s - 0.5%0 a n di nc r e a s e d t o 0 . 86%o a t 1330 m ( a m a x i m um va l ue ) a nd t h e n de c r e a s e d t o -3 .0%0 a t3130 m . T he l ow e s t 8~3C va l ue w a s ob t a i ne d f o r t he 690 m s a m p l e ( - 27 .9%0) , f o l l ow e d bya m a x i m um ( -25 .6%o) a t 1330 m , a nd t he n a de c r e a s e t o -26 .7%0 b e l ow 2330 m .

D I S C U S S I O NS a m p l e s f o r t hi s s tu d y w e r e c o l l e ct e d s o u t h o f th e P o l a r F r o n t w h e r e n e a r - u n i fo r m

n u t r i en t , t e m p e r a t u r e a n d s a l in i ty d i s t ri b u t io n s w e r e o b s e r v e d i n t h e e u p h o t i c z o n e . T h es u r f ac e t e m p e r a t u r e r a n g e d f r o m - 0 . 5 t o 2 C a n d t h e P c o , o f th e s u r f a c e w a t e r s w a ss i gn i f i c a n t l y h i ghe r t ha n t he a t m os phe r i c P c o : (INouEand SUGIMURA, 1985) . T he ra te ofp r i m a r y p r o d u c t i o n w a s l im i t e d b y w a t e r t e m p e r a t u r e (YAM AGUC HI et a l , , 1985) . Then i t ra t e c o n c e n t r a t i o n w a s u b i q u i t o u s l y h ig h e r t h a n 2 0 g M a n d t h e a m m o n i u m c o n c e n -t r a t i on w a s < 0 . 5 gM . A c c o r d i ng t o O L SO N ( 1981 ) , pe r c e n t n i t r a t e up t a ke [ n i tr a t e up t a k er a t e / ( a m m o n i u m + n i t r at e u p t a k e r a t es ) 1 00 ] r a n g e s f r o m 8 . 1 t o 7 0 . 3 % ( a v e r a g e4 3 . 1 % ) i n t h e n i t ra t e- ri c h w a t e r s o f t h e S c o t i a S e a . T u r n o v e r t i m e f o r a m m o n i u m u p t a k em a y be l e s s t ha n 2 w e e ks . P hy t op l a nk t on i n t he s e c ond i t i ons , t hus , u s e n i t r a t e a nda m m on i um , t ha t i s u l t i m a t e l y de r i ve d f r om a m bi e n t n i t r a t e f o r t he i r g r ow t h .

T he 15N a nd ~3C c on t e n t s in P O M a nd ne t p l a nk t on ( X X 1 3) w e r e qu i t e l ow (615N ca .1%o; ~ I 3c - 28%0) i n c om p a r i s on t o t hos e o f t e m pe r a t e r e g i ons ( S A C K E ~ e t a l . , 1973;SWEENEY e t a l . , 1978; WADA e t a l . , 1984). T h e n i t r oge n i s o t op i c f r a c t i ona t i on b e c o m e sl a r ge r i n c a s e s w h e r e a m b i e n t n i t r a t e p l u s a m m o n i um c onc e n t r a t i on doe s no t l im i t t heass imi la t ion ra te s , and a h igh va lue of 1 .005 was repor ted for n i t r a te a s s imi la t ion in thebo r e a l a r e a s o f t he N or t h P a c if ic O c e a n w h e r e n i t r a te i s no t l im i t ing ( W A D A , 1980 ). I nt he s t udy a r e a , t he phys i c o - c he m i c a l c ond i t i ons o f t he e uph o t i c z one w e r e q u i t e s im i l a rt o t hos e i n t he bo r e a l N or t h P a c i f i c a s t he phy t op l a nk t on g r ow t h w a s l i m i t e d by l owt e m pe r a t u r e s a nd pos s i b l y by l ow l igh t in t e ns i ty . T h i s c ond i t i on e nha nc e d t he k i ne t ici s o t ope e f f e c t a nd p r o du c e d a de p l e t i on o f ~ SN i n t he a l gal bod y . T he ~ 15N va l ue s o fn i t r a te i n t h is r e g i on m a y be 7%0 , a s h igh a s t hos e i n t he N o r t h P a c if ic O c e a n (WADA,1980) ; a f r ac t iona t ion fac tor of ca . 1 . 006 i s ob t a i ne d f o r t he a s s i m i l a t i on o f i no r ga n i cn i t r o g e n o u s c o m p o u n d d u r i n g a l g a l g r o w t h .

O 'L E A R Y ( 1981 ) de m on s t r a t e d t ha t t he c a r bo n i s o t ope e f f e c t i n t he C 3 pa t hw a y i spa r t i al l y r a t e - l im i t e d by d i f f u s ion o f C O 2 , a nd t h is s e r ve s to m a ke t he i n v i vo f r a c t i ona -t i on s m a l le r . T he f r a c t i ona t i on w a s f ound t o be i nve r s e l y c o r r e l a t e d w i t h P c o ; a nd g r ow t hr a t e ( C A L D E R a n d P A R K E R , 1973; MIZUTANI an d WADA,1982 ; W A D A a nd P AR KER ,u n p u b l i s h e d d a t a ) . I t w a s th u s c o n c l u d e d t h a t H C O ~ - C O 2 i s o t o p e e x c h a n g e e q u i l ib r i u ma t t e m p e r a t u r e s b e l o w 2 C , lo w l ig h t i n te n s i ty , h ig h P c o , , a n d l o w t e m p e r a t u r e c a u s e dve r y low 13C c on t e n t i n t he phy t o p l a n k t on . A m e a n f r a c t i ona t i on f a c t o r o f 1 .029 w a so b t a i n e d f o r t h e p h o t o s y n t h e t i c c a r b o n f i x a t i o n b e t w e e n H C O q a n d t h e a l g a l b o d y .T h e r e a r e m a ny r e p o r t s o f t he f e e d i ng h a b i t s o f a n i m a l s l iv i ng i n t he A n t a r c t i c O c e a n .P a r a t h e m i s t o g a u d i c h a u d i i ( A m p h i p o d a ) is a t y p ic a l v o r ac i o u s c a rn i v o r o u s z o o p l a n k t e rb u t i t s y o u n g i s o m n i v o r o u s . P . g a u d i c h a u d i i i s ve r y i m p or t a n t a s t he f oo d o f s e i w ha l e s(NEMOTO and Y oo , 1970) a nd i s a l so co m su m ed by m any f i shes (HURLEY, 1959) .P o l y c h a e t a , S a g i t t a m a x i m a ( C h a e t o g n a t h a ) a n d C o e l e n t e r a t a a r e a l so ca r n i v o r es , a n dco pe po ds a re the i r ma in fo od o rgan isms (ALVARINO, 1965; FAUCHALDa n d JUMARS, 1979).


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836 E . W A D A et al.O n t h e o t h e r h a n d , Euphausia triacamha, E. superba ( E u p h a u s i a c e a ) a n d Salpathompsoni ( T h a l i a c e a ) a r e h e r b i v o r e s ( M A t t C tt I. IN E an d F I S H E R , 1969; AI.IA)REI)(;E an dMARDIN, 1982). P i sces living in the An ta rc t ic Oc ean ma in ly c onsu m e Euphausia superha( PE R M m N , 1 97 0) . E u p h a u s i a c e a a n d C o p e p o d a a r e t h e m a i n f o o d o r g a n i s m s o f M i n k eW h a l e , Balaenoptera acutorostrata (NEMOTO . 1970). A dd itio na lly , ANDRIAS~I~V (1968 )d e f i n e d t r o p h i c l e v e l s ( T L ) f o r A n t a r c t i c o r g a n i s m s . B a s e d o n t h e a b o v e s t u d i e s , t h ep o s s i b l e T L o f o r g a n i s m s i n th e A n t a r c t i c e c o s y s t e m w a s d e t e r m i n e d ( T a b l e 3 ). O n t h eb a s is o f t h is c l as s if i ca t io n , T L o f re p r e s e n t a t i v e s a m p l e s w e r e d e t e r m i n e d a n d c o m p a r e dw i t h e a c h c o r r e s p o n d i n g 6 ~SN v a l u e . C l e a r i n c r e a s e s i n 6 1 5 N a r e s u g g e s t e d f r o m t h e f o o dbase o f a com m uni ty to the h igh e r TL (Fig . 2 ) . A l inea r r eg ress ion an a lys i s gave 6~SN(an ima l ) %0 = 3 .3 (TL-1 ) -0 .2 wi th a co r re la t io n coe f f ic ien t o f 0 .997 (Fig . 2 ) . The ave rageinc rease o f 8 tSN pe r TL was 3 .3%, , f rom the s lope o f the bes t - f i t l ine . T h is va lue i s c lo se tothe 3 .4 _+ 1 .3%o va lue fo r the m ean en r ich m en t va lue fo r m ar ine and land an ima lsrep o r te d by MINAGAWA and WADA (1984) . The 613C va lues , on the o th e r hand , show edno s ign i fican t t r ends . As wi l l be d i scussed la te r , the 6~SN va lue o f phy top la nk to n(4 ) .2%0 in the equa t ion ) seems to be va r iab le du r ing the aus t ra l summer season . A~

Table 3. The t rophic level of the representat ive organisms in the foo d web of the Antarct icecosys temT r o p h i c l e v e l O r g a n i s m s

(I. Nu trien t sal ts ( N O ~ , H C O i )1 . Phy t op l ank t on2 . H c r b i w ) r e s . zoop l ank t on

3 . C a r n i v o r e s , z o o p h m k t o n4 . C ar n i vor e s , nek t on

D i a t oms : PO M ( 1 .2 )E u p h a u s i a c e a : E. triacantha ( . 9--2.3).E . superba (1 .9) ; Sa l pa t hom pson i( l.~)Pol ychac t a ( 2 .6 ) , C hae t ogna t hu ( 2 .8LC oe l en t e r a t e ( 3 .1 )Pisces: Trem at om us bernac ( h t r (4.2)N umer i ca l va l ues i n pa r en t heses s t and f o r t he ca l cu l a t ed va l ues o f t r oph i c l eve l s o fo r gan i sms us i ng t he equa t i on 8 tSN %0 = 3 .3 ( T L - 1) - 0 .2 .

* / . / . , ,- 2 5 1 5

- 3 0 1 0

- 3 5 5

- 4 0 0

. 0

6 ' ~ c , 4 50 /

, , ~ . /

T r o p h i c l e v e l ( T L . )Fi g . 2 . A n i ma l 615N ve r sus tr oph i c l eve l f o r the b i o t a f r om t hc A n t a r c t i c O cean . T h e I r oph i cl eve l s w e r e e s t i m a t ed f r om t he p r ev i ous know l edge o f each an i ma l ' s f eed i ng bab i ts . A so l i d l inefor 8~SN i s der iv ed f ro m l ine ar regre ss ion o f the m ean 8~SN and t i l e trophic level (TL) . ~ ,]c PO M :0 , E u p h a u s i a spp . ; A , Salf m tho mp son i: U], Sagit ta ma xim a; II , ( 'oelenterata; , Tremutomu,shernacchir,


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~SN a n d ~3C a b u n d a n c e s in th e An ta r c t i c Oc e a n 8 3 7

p r e s e n t , h o w e v e r , w e d o n o t h a v e e n o u g h d a t a t o e v a l u a t e t h e m e a n ~ I S N v a l u e o fp h y t o p l a n k t o n i n t h e A n t a r c t i c O c e a n .

T he l i ne a r r e la t i on b e t w e e n t he ~ l S N va l ue o f a n i m a l s a nd t he i r T L s e e m s to bea pp l i c a b l e t o o r ga n i s m s no t i nc l ude d i n t he r e g r e s s i on . F o r i n s t a nc e , a m e a n T L o f3 . 1 _ 0 . 1 ( n - - 4 ) w a s c a lc u l a t e d f o r s qu i d t ha t m a i n l y c on s um e E up ha u s i a c e a ( N EM oT oet a l . , 1985) . Young E u p h a u s i a s u p e r b a a n d y o u n g E u t h e m i s t o g a u d i c h a u d ii e x h i b i t e d T Lva l ue s o f 1 .4 a nd 1 .6 , r e s pe c t i ve l y , a nd t he l a t t e r i s om n i vo r ous . T he T L va l ue f o rm i c r o n e k t o n w a s 3 .3 w h i c h c o u l d b e e x p e c t e d f r o m d i f f e re n c e s in t h e i r f e e d in g h a b i t sr e l a t ive t o t he l ar ge p i sc e s ( T L = 4 ) . T he X X 13 s a m p l e s c o l l e c t e d f r om t he s u r f a c e l a ye rse x h i b i t e d s m a l le r T L v a l u e s ( 1 . 2 - 1 .7 ) t h a n t h o s e ( 1 . 7 - 2 .7 ) o f t h e G G 5 4 s a m p l e s .H e r b i v o r o u s z o o p l a n k t o n s u ch a s C a l a n o id e s a c u t u s, C a l a n u s p r o p i n q u u s , R h i n c a l a n u sg ig a s ( c o p e p o d a ) a n d S a l p s s p p , w e r e a b u n d a n t i n t h e G G 5 4 s a m p l e , w h i l e t h e f o r m e rs a m pl e s m a i n l y c ons i s t e d o f d i a t om s . E u a u g a p t i l u s , E u c h a e t a a n d P s e u d o c h i r e l l a ( m e s o -p e l ag i c c o p e p o d s ) f e e d o n h e r b i v o r o u s a n d c a r n i v o r o u s z o o p l a n k t o n (H A R DIN G , 1 94 7).T h e h ig h T L v a l u e s o f ca. 4 . 0 f o r t he s e c ope pods m a y r e f l e c t t he i r f e e d i ng i n t he de e pe rl a ye r s. F u r t h e r m o r e , o u r r e c e n t s t u d y f o u n d t h a t B a l a e n o p t e r a a c u t o r o s t r a t a ( M i n k eW ha l e ) f r o m A n t a r c t i c a e x h i b i t e d a n a ve r a ge 815N va l ue o f 6 .1 + 0 . 6 ( 1 S . D . ) %0( u n p u b l i s h e d d a t a ) w h i c h c o r r e s p o n d e d t o a T L v a l u e o f 2 .9 . M i n k e W h a l e i s a w el lk n o w n a n i m a l t h a t fe e d s o n E . s u p e r b a . C o p e p o d s f r o m th e S o u t h e r n C a l if o r n ia B i g h tw e r e f ou nd t o ha v e h i ghe r 6~ 5N va l ue s t ha n t h os e f r om t he N or t h P a c if ic C e n t r a l G y r e ,r e f le c t ing d i f f e r e nc e s in the s ou r c e o f i no r ga n i c n i t r oge n ous c om po un ds f o r t he g r ow t h o fa s s oc i a t e d phy t op l a nk t on ( M V L L l Y et a l . , 1984) . C ons e que n t l y , t he e qua t i on f o r t her e l a ti on be t w e e n 8~ 5N va l ue s o f a n i m a l s a n d t he i r t r oph i c l e ve l i s r e s t r i ct e d t o ou r s t udyr e g i on .

N o c o r r e l a t i on w a s obs e r ve d b e t w e e n t he ~ f SN a nd 6~ 3C va l ue s in t h i s s t udy ( F i g . 3 ) .M or e t ha n ha l f o f t he a n i m a l s ha d l ow e r ~ 3 C v a l ue s t ha n t he pa r t i c u l a t e o r ga n i c m a t t e r

10

~shalopoda

Polychaeta

. ~ Zooplankton GG54)EuphausiaceaX X 1 3 ]0 , ' ' I i i

- 30 .0 -27 .5 -25 .0613CPDB (o1~ )

i- 22 .5

F ig . 3 . Re la t io n s h ip b e tw e e n ~1 5N a n d 8 1 3C v a lu e s o f An ta r c t i c b io g e n ic n i t r o g e n . Ve r t i c a l a n dh o r iz o n ta l b a r s in d ic a te 1 S . D . Or g a n i s m s we r e d iv id e d in to s e v e r a l g r o u p s b a s e d o n th e i r f e e d in gh a b i t a n d s p e c ie s .


10/13

83 8 E. WADA t al.a t 5 m de p t h : T h i s f a c t c on t r a s t s w i t h p r e v i ous r e po r t s o f an e n r i c hm e n t o f a bou t 1%o o !613C val ue for a s ingle fee din g s te p (DENtRO and EPSTEIN, 1978: HAJNS and MONTA(;t I ,1979; RAU and ANDERSON, 1981) . T he l ip id f r ac t ion s of organ isms ub iqui to us ly sh owl ow e r 6~ 3C va l ue s r e l a ti ve t o w ho l e o r ga n i s m s a nd o t he r p r o t e i n - r i c h f r a c t i ons ( P a RK J m1964; DEGENS e t a l . , 1968; GOR ML an d SACKETT, 1977; FRY e t a l . , 1978) . F o r c xa m pi c ,m e s o pe l a g i c c op e po ds w i t h l ow 613C va l ue s (F i g . 3 ) a r e kno w n t o c on t a i n a h igh a m oun to f l ip i d i n t he i r bod y ( L E E a nd H m O T A , 1973 ). D i f f e r e n c e s i n li p id c on t e n t a m o ng t he s ea n i m a l s a r e s t r ong l y s ugge s t e d , t he r e f o r e , a s a m a i n c a us e o f t he 613C a nom a l y . T he 6~ ( 'v a l u e s o f z o o p l a n k t o n w e r e m o r e v a r i a b l e t h an t h o s e o f m a c r o f a u n a s u c h a s s q u id a n dp i s c e s, w h i c h s ugge s t s t he va r i a t i on o f ~ 3C c on t e n t in phy t op l a n k t on .

T he h i gh 6Z3C va l ue o f - 20 . 5% o f o r t he s e d i m e n t a r y o r ga n i c m a t t e r a t S ta . 3B ha s ne ve rb e f o r e b e e n f o u n d i n t h e A n t a r c t i c O c e a n ( S A c K E V r e t a l . , 1973) . The sediment a t th i ss t a t ion m o s t l y c ons i s t e d o f s i l ic e ous ooz e , a n a s s e m b l y o f de a d d i a t om s . A 6~-~C va l uen e a r -2 0% o c a n o n l y b e u n d e r s t o o d i f p h y t o p l a n k t o n h a d g r o w n u n d e r a l im i t ed s u p p l y o fc a r bo n d i ox i de . A h i gh pH o f 9 w a s s om e t i m e s obs e r ve d i n A n t a r c t i c f a st ic e w he n i cea l ga e w e r e b l o om i ng ( H os ft lA I , 1981 ). I c e a lga e a r e , t hus , s ug ge s t e d t o b e one o f t hep r o ba b l e c a nd i da t e s f o r t he o r ga n i c m a t t e r s o u r c e i n th i s s e d i m e n t . T he 6L~ N va l ue s ~ ls e d i m e n t a r y o r ga n i c m a t t e r ( 4 .9 - 5 .5%0) w e r e s ign i f ic a n t ly d i f f e r e n t f r om t hos e o f P O Ma nd s e t tl i ng pa r t i c le s ( - 3 . 0 t o 0 . 5%0) . T he h i gh 6L ~N i n the s e d i m e n t m a y be a r e s u l t o fn i t r oge n i s o t ope f r a c t i ona t i on t ha t t a ke s p l a c e du r i ng e p i d i a ge ne s i s o f pa r t i c u l a t e o r ga n i cm a t e r i a l s i n de e pe r l a ye r s .

T he l ow 6L SN va l ue o f t he s e t t li ng pa r t i c l e s c l e a r l y i nd i c a te s t ha t t he y o r i g i na t e t r omd i a t om s , a s no m a t e r i a l s o t he r t ha n phy t op l a nk t on a nd f e c a l pe l l e t s c a n g i ve s uc h l ow6~5N va l ue s . T h i s is a l s o s uppo r t e d by m i c r os c op i c obs e r va t i o ns . H o w e ve r , a n e xa c treaso n fo r the shape of the ve r t i ca l p rof i l e s of 615N and 6J3C in these pa r t i c le s (F ig . 1 i~no t kno w n . P e r h a ps t he va r i a t i ons r e f le c t a n a l gal b l oom i ng c yc l e t ha t oc c u r s in t heA n t a r c t i c O c e a n d u r i ng a us t r a l s um m e r ( H A R T , 1942 ; HA S I E, 1969; FUKt~(IU e t a l . , 1984),T he m a x i m um va l ue s obs e r ve d a t 1330 m c ou l d t he r e f o r e a r i s e f r om d i a t om s t ha t g r c ~ ,r a p i d l y du r i ng t he a l ga l b l oom , s i nc e h i gh va l ue s unde r t he s e c o r ] d i t i ons a r e e xpe c t e df r o m c u l t u r e e x p e r i m e n t s (WAI) , . , , and HATTORI , t978: WADA and PARKrR, in p r e p -a r a t i on ) .

T he i s o t op i c - b i og e oc he m i c a l s tr uc t u r e o f t he A n t a r c t i c e c os y s t e m is s c he m a t i c a l l yi l lu s t r a te d i n F ig . 4. T he f l uc t ua t ion o f the i s o t op i c a bund a nc e s in t he f oo d w e b m a i n l y

r -~ I I "''''-~ ........ I I ' ' 'Ij 16'~=3~TL-3.S,~p - c

ml ~ 5 - v v~ J Z N H z . 0 . 5 - 2 u g o t . N / [ ) ~J - 7 . 5 * / ,J 3 3 o - 4 oL p p m c a~ l ( S e t t l in g P Q r tic le s ~ ( S e d i m e n t ]I PN:-~.O;tSz. / / 6"N: s.2:o.3v-/V e r t i M i x i n g L 6 '~ E : '2 6 ; 1 - + 0 ' 8 % 'J L 6 ~ C : -2 5 ~ -2 5 "4 1 ~

F i g . 4 , S c h e m a t i c p r e s e n t a t i o n o f t h e i s o t o p ic s t r u c t u r e o f t h e A n t a r c t i c e c o s y s t e m ,


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~SN a n d t3C a b u n d a n c e s in th e An ta r c t i c O c e a n 839

r e s u l t s f r o m t h e v a r i a t i o n o f ~ 5 N a n d 13C c o n t e n t s i n p h y t o p l a n k t o n g r o w n u n d e rd i f f e r e n t c o n d i t i o n s d u r i n g a u s tr a l s u m m e r . I n f a c t , t h e s t a n d a r d v a r i a t i o n s o f 8 1 S N a n d8 ~3 C o f p h y t o p l a n k t o n a p p e a r t o b e u p t o 2 % 0, j u d g i n g f r o m t h e v a r i a t io n s f o r n e t t e dp l a n k t o n a n d s e t t l in g p a r t i c le s . O n t h e o t h e r h a n d , t h e c o e f f i c i e n t o f v a r i a t i o n o fm a c r o f a u n a is e x p e c t e d t o b e s m a l l , s i n c e t h e t im e d e p e n d e n c y o f p h y t o p l a n k t o n m a y b es m o o t h e d o u t b y a n a v e r a g i n g e f f e c t o v e r s e v e r a l s e a s o n s . S i g n i f i c a n t c o r r e l a t i o n sb e t w e e n 8 1 5 N v a l u e s o f t h e m a c r o f a u n a a n d t h e i r T L a r e s t i l l t o b e e x p e c t e d i n t h eA n t a r c t ic O c e a n . W i t h r e s p ec t t o c a r b o n is o t o p e s , t h e m e a s u r e m e n t o f th e l ip i d -f r e ef r a c t i o n is r e q u i r e d f o r f u r t h e r d i s c u s s i o n . I n c o n c l u s i o n , t h e A n t a r c t i c e c o s y s t e m s e e m st o b e a n i s o t o p i c a l l y o r d e r e d c h e m i c a l s y s t e m i n a f i r s t a p p r o x i m a t i o n , a n d t h e ~ S Na b u n d a n c e s i n t h e e c o s y s t e m m a y b e u s e f u l f o r c l a s s i f y i n g i t s c o m p o n e n t s .

A c k n o w l e d g e m e n t s - - T h e a u t h o r s a p p r e c i a t e t h e c o o p e r a t i o n o f a l l t h e c r e w m e m b e r s o f t h e H a k u h o M a r u .T h e y a l so e x t e n d t h e i r g r a t i tu d e t o D r s S . T s u n o g a i a n d K . H a r a d a , H o k k a i d o U n i v e r s i t y fo r k in d l y s up p l y i n gt h e t r a p s a m p l e s. T h e a u t h o r s a r e i n d e b t e d t o D r L . A . C o d i s p o t i f o r r e v i ew i n g t h e m a n u s c r i p t .

R E F E R E N C E SAI,L DREDGE A. L . a n d C . P . MARDI N ( 1 9 8 2 ) P e lag ic tu n ic a tc s : U n iq u e h e r b iv o r e s in th e m a r in e p h m k to n .Bio S c ie n c e , 3 2 , 6 5 5 - 6 6 3 .AEVAR1NO A. ( 1 9 6 5 ) Ch a e to g n a th a . O c e a n o g r a p h y a n d M a r i n e B i o l o g y , A n n u a l R e v i e w , 3, 115-194 .ANDRIASHE V A. P . ( 1 9 6 8 ) T h e p r o b le m o f th e l i f e c o m mu n i ty a s s o c ia t e d w i th th e A n ta r c t i c f a s t i c e .S y m p o s iu m o n An ta r c t i c o c e a n o g r a p h y , S a n t i a g o , Ch i l e , 1 9 6 6 , R . I . CURRI F , c d i to r , S c o t t P o la rR e s e a r c h I n s t i t u t e , C a m b r i d g e , p p . 1 4 7- 1 55 .CAL DE R J . A . a n d P . L . P ARKE R ( 1 ~7 3 ) Ge o c h e mic a l im p l i c a t io n s o f in d u c e d c h a n g e s in C ~3 f r a c t io n a t io n b yb lu e - g r e e n a lg a e . Ge o c h imic a e t Co s ' mo c h imic a Ac ta , 37, 133-140.CRAIO H. ( 1 9 5 7 ) I s o to p ic s t a n d a r d s f o r c a r b o n a n d o x y g e n a n d c o r r e c t io n f a c to r s f o r ma s s - s p e c t r o m e t r i ca n a ly s i s o f c a r b o n d io x id e . G e o c h i m i c a e t ( 'o s m o c h i m i c a A e t a , 12, 133-149.DEGENS E. T . , M. BEHRENDT, B. GOTr lIARDT and E. REPPMANN (1968) M etab ol ic f r a c t io na t i on of ca rb oni s o t o p e s i n m a r i n e p l a n k t o n - - I I . D a t a o n s a m p l e s c o l l ec t e d o ff t h e c oa s t o f P e r u a n d E c u a d o r . De e p - S e aRe s e a r c h , 15, 11-20.DE NIRO M. J . a n d S . E P S TE IN ( 1 9 7 8 ) I n f lu e n c e o f d ie t o n th e d i s t r ib u t io n o f c a r b o n i s o to p e s in a n ima l s .G e o c h i m i c a e t C o s m o c h i m i c a A c t a , 4 2 , 4 9 5 - 5 0 6 .DE NmO M . J . a n d S . E P ST HN ( 1 9 8 1 ) I n f lu e n c e o f d ie t o n th e d i s t r ib u t io n o f n i t r o g e n in a n ima l s . Ge o c h imic a e tC o s m o c h i m i c a A c ta , 4 5 , 3 4 1 - 3 5 1 .DUGDALE R , C . a n d J . J . GOE mNG ( 1 9 6 7 ) Up ta k e o f n e w a n d r e g e n e r a te d l \ ) r ms o f n i t r o g c n i s p r im a r yp r o d u c t iv i ty . L i m n o l o g y a n d O c e a n o g r a p h y , 12, 196-206.FAU( 't tAI .D K. an d P . A. JUMARS (1979) The d ie t o f worm s: a s tudy o f po lych ae te f eed in g gu i lds . O c e a n o g r a p h ya n d M a r i n e B i o l o g y , A n n u a l R e v i e w , 17, 193-284.F RY B . a n d E . B . S HE RR ( 1 9 8 4 ) ~SC m e a s u r e m e n t s a s in d ic a to r s o f c a r b o n f lo w in ma r in e a n d f r c s h wa te re c o s y s te ms . ( 2 mtr ib u t io n s in Ma r in e S c ie n c e , 27, 13-47 .FRY B. , W. L. JEN G, R. S . SCALAN and P , L . PARKER (1978) 13C food w eb an a lys is o f a Fex as sa nd d unec o m m u n i t y . G e o c h i m i c a e t C o s m o c h i m i c a A c t a , 42, 1299-131)2.FUKUCHI M . , A . TANIMURA and H. OHTSUKA (1984) Seas ona l c han ge of ch lo roph yl l a un der f as t ice in Li i tzow-H o l m B a y , A n t a r c t i c a . Me mo ir s o f th e Na t io n a l I n s t i tu te fo r Po la r Re s e a r c h , Spec ia l I s sue , 32 , 51-59 .GORME Y J . R . a n d W . M. S ACKHq " ( 1 9 7 7 ) Ca r b o n i s o to p e e v id e n c e f o r th e m a tu r a t io n o f m a r in e l ip id s .A d v a n c e s i n O r g a n i c G e o c h e m i s o y , 1975, 321-341).HAINE S E . B . a n d C . L . MONT AGUE ( 1 9 7 9 ) F o o d s o u r c e s o f e s tu a r in e in v e r t e b r a te s a n a ly s e d u s in g ~C/~eCra t ios . E c o l o g y , 6 0 , 4 8 - 5 6 .HARDING G. C . H . ( 1 9 7 4 ) T h e f o o d o f d e e p - s e a c o p e p o d s . J o u r n a l o f th e Ma r in e B io lo g ic a l As s o c ia t io n o ] ' th eU n i t e d K i n g d o m , 5 4 , 141-155 .HART T . J . ( 1 9 4 2 ) P h y to p la n k to n p e r io d ic i ty in An ta r c t i c s u r f a c e wa te r . Dis c o v e r y Re p o r t , 2 1 , 2 6 1 - 3 5 6 .HAS I_E G . R , ( 1 9 6 9 ) An a n a ly s i s o f th e p h y to p la n k to n o f th e P a ci f ic S o u th e r n O c e a n : Ab u n d a n c e , c o mp o s i t io na n d d i s t r ib u t i o n d u r in g th e Br a te g g y E x p e d i t io n , 1 9 47 -1 9 48 . Hv a lr a d e t s S k r i f t e r , 5 2 , 1-168 .HOLM-HANSEN O. , S . D. EL-SAYED, G. A. FRANCES('I I1NI and R. L . CUtlEL (1977) P r im ary p rod uc t ion and t hef a c to r s c o n t r o l l i n g p h y t o p l a n k t o n g r o w t h i n t h e S o u t h e r n O c e a n . I n : Ad a p ta t io n s w i th An ta r c t i c e c o s y s -t e ms , G . A . L E AN O , e d i t o r , G u l f P u b l i s h i n g C o . , H o u s t o n , T X , p p . 1 1 -5 0 .


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HOSI]IAI T. (1981) Prol iferation of ice algae in the Syowa Station are a, Antarc tica. Memoir .s o[ t ll e Nam ma /Institute for Pola r Research, Series E, 34, 1-12.HURLEY D. E. (1959) Amp hipoda Hyper iidea . B .A .N .Z . Antarct ic Research Krpedi t ion R~TJort. ?,eric~ t~'. 8.107-114.INOUE H. and Y. SUGIMURA (1985) PCO, and its tS~C values in surface seawaters and atmosph ere in southernOceans. Abstract in the Seventh ~vmposium on Polar Biology. National Institute of Polar ResearchJapan, p. 2.Lt- t : R. F. and J. HIROTA (19731 Wax estcrs in tropical zoo plank ton and nek ton and the geographicaldistribution of wax esters in marine copepods. L i m n o l o g y a n d O c e a n o g r a p h y , 18, 227--239.MACKINTOSH N. A. (1960) The pat tern of distribut ion of Antarct ic fauna. Proceedings ( the Roy al So, .' ie tv 4L o n d o n , B152, 624-631.MAUCHLINE J. and L. R. FISIIER (1969) The biology of euphausiids. A dvances i n Mar i ne B i o l ogy , 7 , 454 pp.MtNA(iAWA M. and E. WADA (1984) Stepwise enr ichment of ~SN along food chains: Furt her evidence and therelation between ~SN and animal age. G eoch#n i ca e t C osm och i m i ca A c t a , 48, t135-1140MIYAKE Y. and E. WADA (1967) The abu ndance ratio o f ";N/14N in marine cnvironment~ . Rc(ord~ ,tO ceanograph i c Works i n Japan , 9, 32-53.MIZUTANI H. and E. WADA ( 19821 Effect of high atmosph eric CO2 concen trat ion on 6~17 ot algae. A possiblecause for the average depletion of ~:~C in Precambrian reduced ca rbon. Origin of Li]e, 12,377-390MIZUTANt H. and E. WADA (1986) Combustion of organic samples by infr ared furnace for carbon isotopeanalysis. A nal y t i ca l B i ochem i s t r y , 146,911-95.MULLIN M. M., G. H. RAU and R. W. EI,PLIi~ (19841 Stable nitrogen isotopes in zooplankton: ~omcgeographic and temporal variations in the North Pacific. Li m n ol ogy and O ceanograph 3 , 29, 1267--1273NAKAMURA K., E. WADA and Y. TAKAI (1984) Mass spect rometric analysis li)r stable ca rbon isotope ratios mbiogenie substances collected from paddy fields. , lournal o f the Science ~[ Soil an d Manure, Japall 55,151-159.NE~,IOTO T. (19701 Feeding pattern of baleen whale m the ocean. In: Mar i ne f i ) od cha i n . J. tt . S II~:HA , ct|i~t*[,California Press, 552 pp.NEMOTO T. and K. I. Yoo (1970) An amphipod, f 'arathemisto gaudichaudii us a food of Ihc Antarctic SciWhale. Scientif ic Re ports ~ / the Wh ales Research Institute, 22, 153-158.NEMOTO T, and M. TERAZAKI 11985) Preliminary repor t of the H a k u h o M a r u Cruise KH-83-4.NEMOTO T., M. OKIYAMA and M. TAKAHASIII 119851 Asp ect of the roles of squid in food chain of marineAntarctic ecosystems. Proc. 4th A nt . Biol. ~S~vmp.O'LEARV M. H. 119811 Carbon isotope fractionation in plant. P hy t ochem i s t o , , 20, 553-567.OLSON R. J. (1981) JSN tracer studies of the primary nitrite maximum. Jo urn al c~[" Ma rine Researc h 39.21/_3--226.PARKER P. L. (1964) The biogeochemistry o1 the stable isotopes of carbon in a marine bay. ( ;eochinm~ , '~C o s m o c h i m i c a A c t a , 28, 1155-1164.PERMITIN Y. E. (19711) The consumpt ion of krill by Antarctic fishes. A nt arc t i c E co l ogy , I~ 177-.I,S2.RALI G. H, and N. H. ANDt-RSON (19811 Use o f 13(?:,2C to trace dissolved and particulate organic mat~clutilization by populations of an aquatic inve rtebrate, Oecologia, 48, 19-21.RAU G. H, , R. E. SWEENEY and I. R. KAPI_AN (19821) Plankton ~3C:~-~(? rat io changes with latitude: dill )icncc~between the northern and southern ocean. Deep-Sea Research, 29, 1035-1039,RAU G. H., A. J. MEARNS, D. R. YotJN;, R. J. OI,SON, H. A. SCtIAI-'FRand 1. R. KAPI,A>. ( 19831Anim~d :( ,JeC correlates with trophic level in pelagic food webs. E col ogy , 64, 1314-1318.SA,TKET-I" W. M., B. J. EADIE and M. E. EXNER 1t9731 Stable isotope compos ition of organic carbon in recentantarctic sediments. A dvances i n O rgan i c G eochem i s t r y , 661-671,SCllOENINGER M. J. and M. J. DENtRo (1984) Nitrogen and carbon isotopic composition ot bone collagen fr~mmarine and terrestrial animals. G eoch i m i ca e l C osm och i m i ca A c t a , 48, 625-639.SCHOENINGER M. J . , M. J. DENIRO and H. TAUBER (1983) tSN/'4N ratios of bone collagen reflect marine mr!

terrestrial components of prehistoric human diet. Science, 220, 1381-1383.SWEENEY R. E. , K. K. LIU and I. R. KAPI.AN11978) Oceanic nitrogen isotopes and their use m de termining thesource of sedimentary nitrogen. In: Stable isotope chemistry. Proc. Inl. Symp., New Zealand, Dept. SciInd. Res. Bull. 2211 pp. 9-26."IsLINOC, AI S. , M. UEMATSU,S. NORIK1, N. TANAKA and M. YAMADA (1982) Sediment t rap exper iment in thenort hern North Pacific: Undula tion of settling particles. G eochem i ca l Journa l, 16, 129-147.WADA E. 11980) Nitrogen isotop e fractionation and its significance in biogeoehemical processes occurring inmarine environments. In: I sotope marine chemis t ry , E. D. GOLI)BF,RG, Y. HORIBE and K. SARLqtAS}tl,editors, Uchida-Rokkakuho, Tokyo, pp. 375-398.WADA E. and A. HA1T'ORt (1976) Natural abunda nce o f t"N in particulate organic matt er m the North PaciticGeochirnica e t Cosmochimica Acta, 40, 249-251.WADA E. and A. HATFORI (1978) Ni trogen isotope effec ts in the assimilation of inorganic n itrogcnow,compounds by marine diatoms. G eom i erob i oh) gy , I, 85-101.


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WADA E . , H. MIZUTANI , K. KARASAWA, Y. KABAYA, M. MINAGAWA, S . YONEMOTO and T. TsUJI (1984)C a r b o n a n d n i t r o g e n i s o t o p i c c o m p o s i t i o n a s t r a c e r s o f t r a n s p o r t o f o r g a n i c m a t t e r a l o n g t h e O t s u c h iw a t e r s h e d . Chikyukagaku (Geochemistry), 18, 89-98 .YAMAGUCHIY., S. OSAKI and Y. ARUGA (1985) S u m m e r p r i m a r y p r o d u c t i o n i n t h e A u s t r a l a s i a n S e c t o r o f t h eA n t a r c t i c O c e a n . A b s t r a c t i n t h e S e v e n t h S y m p o s i u m o n P o l a r B i o lo g y . N a t i o n a l I n s t i t u t e o f P o l arRe s e a r c h , J a p a n , p . 1 9 .

15n and 13c abundances in the atlantic ocean

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