High resolution food web viewed via 15N/14N of amino acids�
Yoshito Chikaraishi
Acknowledgements: Y. Takizawa1, N. Ohkouchi2, Y. Takano2, M. Tsuchiya2, S. A. Steffan3, P. S. Dharampal3��(1. Hokkaido University, 2. JAMSTEC, 3. Wisconsin University, USA)�

Grazing food web�

Illustration of trophic hierarchy

We often arrange organisms in food-chains according to trophic position (TP), whichforms a “food web pyramid” from a broad base of primary producers (TP=1) to a relatively
less of herbivores (TP=2) and more-less of carnivores (TP=3), and finally to a few of top
predators (TP=4-5). This arrangement is particularly useful， if you want to see the trophic
hierarchy and associated energy flow (or energy transfer) in the ecosystem.
SIA of bulk tissues	

Food web pyramid	Top predators(large fish)

4.0

TP = 4

TP = 3

Carnivores(small fish)

TP = 2.x

3.4 ± 1.1‰

TP = 2

Herbivores(zooplankton)

TP = 1Primary Producers(phytoplankton)

δ13C

Trophic position (TP)0.8 ± 1.1‰

Omnivores(crab)【Orange & vegetable farm】

Yugawara

JR Yugawara st.

0.8 ± 1.1‰

Multiple carnivores(lobster)δ15N

3.4 ± 1.1‰

【Stony shore】【Sandy beach】

DeNiro & Epstein (1978, 1981), Minagawa & Wada (1984)

V. mandarinia
3.5 ± 0.2	

3.0
P. jokahamae(3.1 ± 0.1	P. japonicus
3.0 ± 0.1	

2.0
P. rapae(2.1 ± 0.2)

Aphidoidea sp.
(2.0)

A. mellifera(2.1 ± 0.1)

【Sandy beach】

TP =δ15NGlu − δ15NPhe + β
7.6+13β : −3.4‰ for aquatic (algae, and cyanobacteria
+8.4‰ for terrestrial (vascular plants)

Trophic level (or Trophic position)

Possible mechanism

Trophic position (TPGlu/Phe)

0.4‰

Paralichthys sp.
3.8	

S. Japonica
3.8	

S. dumerili 3.3	

T. niphobles
3.3	

S. lucens
2.9	

2.0

C. semigranosa(1.8)

S. eneionema 3.4	

S. meerdervoortii 3.4	

H. truncatifrons
3.4	
T. japonicus
3.1	

M. chinensis(2.3)

S. esculenta(3.5)

Pleuronectes sp.
2.9	
S. australasicus 3.1	

T. jarbua 3.2	
P. trituberculatus(3.0)

E. japonicus(2.8)

P. jedoensis
2.3	

P. aponicus 3.9 ± 0.1	S. niphonius 4.0	

C. farreri
2.4	

C. leana(2.5)

G. imperialis
2.5	

M. victor(2.5)

L. exaratus(2.6)

C. japonica(2.6)

S. globosa
2.1	

Deamination

Deamination

A. schlegeli 3.3	

T. Niphobles
3.3	

P. siebold
3.3 ± 0.1	O. asciatus
3.4 ± 0.0	

3.0

C. rivulata 3.1	
G. punctata
2.9 ± 0.1	M. strigatus
2.9 ± 0.1	

P. Trilineatum(2.9 ± 0.1	

D. temmincki
3.0	

L. stellatus
3.1	

Pagurus sp.
2.3	

H. discus
1.7 ± 0.0	

B. cornutus
2.0 ± 0.0	

P. flagellifer
3.2	

P. dentipes 2.6	

P. lanissimum
2.3	

O. pfeifferi
2.0 ± 0.1	G. zonatus
3.2	

Crassostrea sp.
2.4	

A. crassispina
H. pulcherrimus
2.0	
1.8	

S. filicinum
0.9 ± 0.1	

E. cava
1.1	

E. bicyclis
0.9	

G. japonicum
1.0 ± 0.1	

B. californica
1.2	

Chikaraishi(et(al.,(2004,(Ecol.&Evol.&4,(242322449

Advantages of this method
Tyrosine

Little change
in 15N/14N

1. TP estimates can be achieved based on δ15N offset in a pair of amino acids (e.g., Glu & Phe) from a single organism of interest. Unlike thetraditional bulk method, this method does not require the characterization of δ15N of primary producers as the basal resource of food webs.
2. δ15N of phenylalanine reflects an integrated value for δ15N of primary producers that are actually eaten by consumers in the studied food web.

Accumulationin 14N

3. Very small sample size (0.5-1.0 nmol/amino acid) is required for the δ15N analysis of amino acids by GC/IRMS.
a-Ketoglutamic acid

O. Vulgaris 3.8	

P. percoides 3.6	

O. punctatus
3.2	P. crassipes
2.5 ± 0.1	

2.0

U. pinnatifida
1.0 ± 0.2	Unpublished data (very sorry)

Hydroxylation
Phenylalanine

G. kidako
4.6 ± 0.1	A. Semilineatus
3.5 ± 0.1	
H. Poecilopterus
3.4 ± 0.1	

1.0

1.0

Different metabolic reactions in consumers cause large Δδ15N for Glu but little for Phe.
Source AAs (e.g., Phe)	

S. inermis 3.9 ± 0.1	

4.0

S. japonica 3.4	

T. baillonii 2.8	

3.0

T. lepturus 3.9	

S. anastomella 3.9	Trophic position (TPGlu/Phe)δ15N (‰)

S. marmoratus 4.1 ± 0.1	T. scyllium 4.1	Glutamic acidH. japonica (2.1)
P. protenor (2.0)

P. machaon (1.9)

Phenylalanine

Glutamic acid

4.0

Trophic AAs (e.g., Glu) 	

P. rapae(2.1 ± 0.1)

【Stony shore】

8.0‰

NH4+

X. appendiculata(2.1 ± 0.1)

Chikaraishi(et(al.,(2014,(Ecol.&Evol.&4,(242332449

8.0‰

Accumulationin 15NB. diversus(2.2 ± 0.1)

Higher'Plants 1.0'±'0.2	

A unique offset in 15N/14N (δ15N, ‰ vs. Ari) between glutamic acid (Glu) and phenylalanine(Phe) in a single organism enables TP estimates of organisms in food webs. We proposed
the following equation to calculate TP of organism (Chikaraishi et al. 2009).

2T. aridifolia (3.2)

G. Mikado (2.6)

δ15N of amino acids vs. TPβ

V. analis 3.6 ± 0.1	M. sexmaculatus
H. axyridis(3.1 ± 0.1)
3.1 ± 0.1	P. indica
I. koebelei
3.0 ± 0.1	 C. septempunctata(3.1 ± 0.1)
3.0 ± 0.1	P. rothneyi
3.0 ± 0.1	

P. Mandarinus
2.9	

V. flaviceps 3.5	1.0or Trophic level (TL)

1V. simillima 3.5	

V. ducalis 4.0±0.1	

Trophic position (TPGlu/Phe)

TP = 3.x【Orange & vegetable farm】

We employed this method to see the trophic structure with high-resolution
among approximately >300 free-roaming organisms in coastal and sandy
ocean and in terrestrial ecosystems.

4. The error in TP estimates is substantially small (1σ=0.12 and 0.17 for for aquatic and terrestrial food webs, respectively).

Phenylpyruvic acid
Chikaraishi et al., 2009, 2010