Ten specimens of African cuttlefish, Sepia bertheloti, from the coastal waters off Qua Iboe River, Southeast Nigeria, were analyzed for the relationship between the concentration of the elements and the size of the species. Energy Dispersive X-ray fluorescence technique was employed to determine the elemental composition of the species. Eleven elements were identified in the body of cuttlefish. These were Chlorine, Strontium, Potassium, Calcium, Bromine, Iron, Copper, Zinc, Manganese, Nickel and Selenium of these elements, the concentration of calcium, potassium. Copper and strontium had a positive correlation with the weight, while the concentrations of manganese, nickel, chlorine, iron were negatively correlated with their weights. However, only manganese had a significantly negative correlation (p<0. 05). Bromine and zinc had no correlation with the weights of the species. There also existed a significant positive correlation between Ca and K, Se and Ni, Cu, Br and Zn and St and K. We conclude that African cuttlefish, irrespective of size is a rich source of nutritional elements and is especially recommended for pregnant women and for all age groups

Akpan, I.

Ama-Abasi, D.

Aquatic Commons

Cephalopods including cuttlefish and squids support the largest catches ot"all molluscan fisheries with an
annual world landing approaching 2 million tons (King 1995). Akpan et ul (2007) identified eleven
nutritional elements in the species to include, Calcium, Potassium, Chlorine, Strontium, Bromine,
Manganese, Nickel, Copper, Iron, Zinc and Selenium. Apart from this. there is no other documented
245
African cuttlefish occurs along the continental waters of West Afiica to the southern-most point of Africa
(Boletzky, 1983). lt is a valued food species among the coastal communities of Nigeria particularly off the
Cross River and Qua Iboe River estuaries. Most people prefer it as a delicacy. It is caught by bottom trawls
and also occurs as by-catch in bottom trawls together w ith other cuttlefish tSchneider 1990'1.The species is
benthic and can be captured inthe sub-littoral depth of abolit20-140m.
The order Sepiidae possesses an internal shell called cuttlebone made up of calcium carbonate just Iike the
shell of'pcriwinkle and snails. The basic colouring in cuttlefish varies although it typically displays a mottled
black or brown colour. African cuttlefish, Sepia bertheloti ismottled dark and white. Like chameleon, colour
changes are possible in cuttlefish. This is due to three types of structures contained within its skin called
chrornatophores, leucophores and iridophorcs. These structures are filled with coloured ink, which can be
expanded and contracted to comrnun icatc to others or as camouflage against the background. These
structures allow the cuttlefish to reflect a myriad of colours and change the texture of their skin (Rorer et al
19)34).
INTRODUCTION.
African cuttlefish, Sepia bertheloti is a member of the class Cephalopoda. a group of marine animals, which
include octopus, squid. cuttlefish and chambered nautilus. Cuttlefish, just like squid, possesses eight arms
and two tentacles. Adult cuttlefish measures up to 13cl11mantic length as females while the males may
measure up to 17.5 em mantle length. Mantle length refers to the length of the main body area above the eyes,
excluding the arms and the tentacles (King 1995).
Keywords: cuttlefish, size, elemental concentration, nutrition, t\ igerian coastal \\ aters
*Author to whom all correspondence must be addressed.
ABSTRACT
Ten specimens of African cuttlefish, Sepia bertheloti, from the coastal waters o.(r Qlla lboe River.
Southeast Nigeria, were analyzed for the relationship between the concentration of the elements and the size
of the species. EnerJ.._rvDispersive Xsrayfluorescence technique was employed to determine the elemental
composition of the species. Eleven elements were identified in the body of cuttlefish. These were Chlorine,
Strontium. Potassium. Calcium, Bromine. Iron, Copper; Zinc. Manganese, Nickel and Selenium. Of these
elements. {he concentration of calcium, potassium. Copper and strontium had apositive correlation with the
weight, while the concentrations of manganese, nickel, chlorine, iron were negatively correlated with their
weights. However only manganese had a significantly negative correlation (p<O.05).Bromine and zinc had
110 correlation with the weights of/he species. There also existed a significant positive correlation between
Co and K, Se andNi,Cu. Br and Zn andSt-and K Weconclude that African cuttlefish irrespective of size isa
rich source of nutritional elements and is especially recommended for pregnant women and jor all age
groups.
I"'D.Ama-Abasi, zI. Akpan,
'Institute of Oceanography, University of Calabar,
2Department of Physics, University ofCalabar.
ELEMENTAL CONCENTRATION AND SIZE RELATIONSHIP IN AFRICAN
CUTTLEFISH Sepia berthelot', FROM THE COASTAL WATERS OFF QUA 180E
RIVER, NIGERIA
_ ----_ _--_-- _- _---
246
Fog I: Mc.n concentration cf elernents ttl euulefish
2000
o ,_._,£1,
('I K O. Mn Fe Ni rll 7n Br S~ .~r
Element
I~\)(J(J
IGOOO
~ 14000
~ 12000'
~ 1(000)
c< 8000g
8 """
There were positive correlations between the concentration of the following elements and the weights of the
cuttlefish: Potassium (P= 0.05, r~= 0.326, 11=]0), calcium (p= 0.05, r~ - 0.408, n-l 0), Copper (P> n.os, r1 =
0.373,n--l 0), Strontium (p= 0.05, r~ = 0.304, n= I0), Selenium (P- (l.OS, r1 = 0.231. n=1 0). Fig lire 2b shows
the correlation between weight of cuttlefish and copper concentration. Again as shown, these positive
correlations were not significant. There appear to be no correlation between the concentrations of zinc and
bromine and the weight of the cuttlefish
WeighteJementconcentration relationship
Acorrclation analysis using spearman correlation reveals that there is some level of correlation between the
elements and weight of the-species. A correlation was established between the various elements and the
weight of the cuttlefish. As shown ib Fig. 2a, there was a significant negative correlation between the
concentration ofmanganese and the weight of the cuttlefish (P=0.05, r2- -0.662, n= 10). The concentration of
the following elements also showed a negative correlation with the weight of the specimens: chlorine (P=-
0.05,r!- -0.272, n=10), iron (P=- 0.05, r2=-0.366, n=IO), nickel (P- 0.05, r2 - -0.270, n-l 0). As shown by
tileresu Its, the correlation WH:)however not significant at 0.05 level of significance.
)1ATERIALS ANDMETHODS.
The cuttlefish samples were collected from the trawl fisheries in the Gu If of Guinea coastal waters off Qua
lboc River Southeast ofN igcria. The samples were weighed with electronic balance to the nearest 0.1 g. They
were then thoroughly washed with double distilled water and sun-dried to a constant weight. The dried
samples were homogenized by grinding in an agar mortar. Three sub-samples (0.3 g) of each cuttlefish
sample were pressed into thick pellets of 13mrn diameter in Spee-r 'aps without binders.
The elemental analysis of the samples was performed using the Energy Dispersive X-ray
Fluorescence (EXDRF) spectrometer after the method of AkpHI1, et 01 (2007). Each sample pellet was
irradiated for 1000 seconds at fixed condition of 25 kV and 50flA. the spectral data analysis was done with
the AXIL filling programme contained in the QXAS software package supplied by the International Atomic
Energy Agency, Vienna (JAEA 1996).
RESULTS
Elemental composition of cuttlefish:
The following elements were identified in African cuttlefish, Sepia bertheloti: chlorine, potassium. calcium,
manganese, iron. nickel, copper, zinc, selenium, bromine and strontium. Of theses elements. the following
occur in very high proportion in that order: Chlorine, strontium. potassium, calcium, and bromine. Iron,
copper, zinc and manganese occurred as medium elements while nickel and selenium occurred as trace
elements. rig 1 shows the relative composition of the elements in the body of cuttlefish in ppm body weight,
evidence of this species in Nigerian coastal waters even though it is unique in the diet of the coastal dwellers.
Asa follow lip to Akpan, et al (2007). we report on the relationship between the weight of the species and the
concentration of the elements idcnt ificd.
247
Fig 2b: Positive correlation between weight of cuttlefish and concentration of copper (p'> 0.05 ... 2=- 0.37,
11"""10)
Weight (g)
302010
40~ ~~ __
o
o
o o
o---»-«:" c---------
/c
o
90
c.g 70
nJ-=C
OJ
(Ja 60
(J...
OJ
0..
0..o
o 50
C> 80~--01
E-
Fig 2 a: Negative correlation between weight of cuttlefish and manganese concentration (p<O.05, r2=
0.66, n=I O)
Weight (g)
302010o
o._ ~~------------~--------------~n
2
12
o
14
---------
C> 10
~
C)
E
~ 8
g
~C 6
8co(.)4
24R
"
J.j\lulrilion.Levander, O.A. (1997). Nutrition and newly emerging viral diseases. An overview.
27:9485-505. ~"
RKFERENCES
Akpan. I., O. Ama-Abasi, F.1. Obiajunwa and F'vI.Adebiyi (2007)· Analysis of elemental
composition of African cuttlefish. Sepia berthe loti , from the Gulf of Gumea using Energy
dispersive X-ray Fluorescence (EDXR.F) technique. Journal oj Food Analysis (in press)
Boletzky. S.V (I ')X3): Sepia officinalis In : Cephalopoda Life Cycles. Vol.l , In: P.R.Boyle (ed). Academic.
Toronto. Pp. 31-52.
Higdon, .I. 2004. Linus Pauling Institute. Oregon Stale University. Ilttp:llw\,,\..lpc.orcUnn state.
edu.linforcenter/minerais/potassiun1
International atomic energy Agency (IAEA) (1996): Quantitative X-ray Analysis System
(QXAS) Users manual.
King, M. (1995): Fisheries Biology, Assessment and Management. Fishing News Books, Oxford, 441 pp.
ACKNOWLEDGE)ffiNT:
This work was supported by the University ofCalabar through Senate Research Grant provided to Dr
DanielAma-Abasi and Dr lta Akpan. Grant No.: LJCIDD/23.
Generally, all the elements identified in African cuttlefish are of very significant importance in the diet of
man. We strongly recommend cuttlefish meals for all age groups but more especially for pregnant women,
nursing mothers and growing children.
The higher concentration of calcium, potassium, strontium. and selenium in bigger species means that
patients who are deficient in these elements should eat more of the bigger cuttlefish in their diet than the
younger ones.
Conversely. the negatively correlation between the concentration of manganese and the weight of the species
shows that as the animal grows bigger the concentration or (he spices becomes lower. In this case, young
cuttle fish are richer in manganese than older ones. Patients who are deficient in manganese should eat more
of the younger cuttlefish than the older ones. This is applicable to patients who are deficient in iron, nickel
and chlorine The lack of correlation betw CCIl the concentrations of bromine and zinc shows that cuttlefish
whether older ones or younger ones can be eaten without any fear of deficiency of the two clements.
The presence of selenium, nickel. zinc and copper and their subsequent correlation in cuttlefish is of very
significant interest. A combination of these four dement" In their varying degrees and shades may be
responsible for dark metallic appearance of the fresh specimen ofthe species. One of the allotropic forms of
Selenium is a dark grey or black solid with metallic luster. Selenium when distilled is of a reddish- brown
colour. when reduced to powder is red, when fused in a mass it is of a lead grey colour and metallic luster.
These properties of selenium are probably responsible for the mottled dark or grey appearance of the
cuttlefish. Jt is this property that conveys the camouflaging capability of the species in different
backgrounds, which of course is a strong adaptation for protection.
DISCUSSION
According to Akpan et al (2007), the presence of the four major clements shown above, chlorine, strontium,
potassium and calcium, are of nutritional significance. These clements play major roles ill the structural and
functional composition of humans. Nelson (1987) Tolonen( I990),Higdon (2004) and the curing of certain
ailments (Levander 1997).
The positive correlations between the weight of cuttlefish and the concentration of calcium means that as the
animal grows bigger the calcium deposit is also higher. This is because the major component of the
cuttlebone is calcium carbonate. The cuttlebone becomes larger as the animal grows bigger. The high
presence of calcium is characteristic of the mollusk since calcium is a major component of their shells. The
cuttlebone, which is the internal shell of cuttlefish. is purely of calcium carbonate in composition (King
1995).
249
Tolonen, M. (1990): Vitamins and minerals inHealth and Nutrition. Ellie;Horwood Land.
Schneider, W. (1990): Field guide to the commercial marine resources of the Gulf of Guinea. FAO series
RAFR/l-1I90/2
Roper, C.F.E. M.J. Sweeney and c.r.Nauen (1984). FAO species catalogue. Vo!.3cephalopods of the world
.An annotated and illustrated cata loguc of species of interest FAO fish synop. ~
Nelson. C.E. (1987). Chemical anc.lBiochemical Constitution innatural egg yolk pigmentation. Proceedings
of the seventh Australian Poultry and feed Convention, Sydney.Australia.
t • e-


Elemental concentration and size relationship in African cuttlefish Sepia bertheloti, from the coastal waters of Qua Iboe River, Nigeria

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Elemental concentration and size relationship in African cuttlefish Sepia bertheloti, from the coastal waters of Qua Iboe River, Nigeria

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