THE
DISTRIBUTION OF SOME MINOR AND MAJOR ELEMENTS IN THE SEPIA OFFICINALIS SHELLS AS INDICATORS FOR MONITORING HEAVY METAL
WATER POLLUTION
Geasa, N. M. Sh. and Sharshar, Kh. M.
Department of zoology,
Faculty of Science,
Tanta University, Tanta,
Egypt.
email:
nmohamed@future. Com. e.g.
The chemical composition, minor and major elements
concentration and microstructure of juvenile and adult shells of Sepia officinalis were investigated by
using electron X-rays and scanning electron microscope. The results generally showed significantly
higher metal concentration in the juvenile shell than in the adult shell,
except calcium and aluminum. However
the highest accumulation was in copper, lead, and cadmium .The relationships
between metal concentration and shell length, shell weight, and shell position
were determined.
However, no relationships between heavy metals pollution
and microstructure of the shells of the investigated cephalopod were observed.
It is a known fact that the marine invertebrates
accumulate metals in their tissues and due to this ability; they are currently
used as indicators of metal pollution (Rainbow, 1993). Mollusks also contains relatively high
concentration of certain trace elements, focusing mainly transition metals in
their soft tissues (Vinogradov, 1953; Bowen, 1966; Pentreath, 1973; Salanki et al; 1982; Abdel Moati and Farag
(1991); El Fayomy (1994) and Ibrahim et
al., (1997)
However, the molluscan shell has been the subject of
intensive research in ecology and paleoecology for many years. This research has centered on the examination of macroscopic growth
features on the surface of the shells and utilization of these growth bands in
the investigation of environmental and paleoenvironmental conditions in marine
ecosystems. Most of this research was
carried out on analysis of bivalves shells, but very little is known about
cephalopod shells.
In the present study an explanation of
the effect of environmental pollutants on the shell microstructure and chemical
composition of Sepia officinalis has
been attempted. In addition, special concern has been paid to declare the
correlation between shell age and percentage of accumulating metals in an
attempt to use shell as an indicator for metal pollution.
Adult and
juvenile specimens of Sepia officinalis were
caught from the same localities in Abo-Qir, Alexandria waters. They were
immediately dissected and their shells were removed for further investigation.
Scanning electron microscopy (SEM):
The shells were washed and immersed in sodium hypochlorite for one
hour to remove adhering organic matter.
Then, they were washed with distilled water, dehydrated in ethanol, and
they were dried in air. Small pieces of
shells from three different regions were cut and attached to aluminum stubs
with duco-cement and sputter coating with gold-palladium then they were
examined by J.S.M5300 Jeol SEM.
Instrumentation:
X-ray electron
analysis was used for determination of the concentration of major and minor
elements.
Shell microstructure:
The juvenile and
adult specimens shells share many similarities in their microstructure. The
shells have calcified phragmocone which extend forward to form a preostracum
spine like figure and guard which are surrounded by two wings which consist of
non calcified fibrous like (Figs.1, 2 and 4). The phragmocone consists of many
chambers separated from each other by calcified septa (Fig. 5). Each one has
central pore surrounded by septa necks and form siphuncle (cord) in the frontal
region (Figs. 2, 3). The Shells consist
of three layers: outer calcified periostracum (Figs. 6,7and 8), middle
prismatic (Figs. 6, 9, 10 and 11), and the last Lamellar (Figs. 6 and 12).
Analyses of the shells:
The analysis was carried out on the outer and inner parts of both types of shells. Considerable variations in their composition were observed. The total concentration of the major elements indicated a high concentration of sodium, potassium and chlorine, and there is a less calcium content in the juvenile shell (Table 1) and (Figs.13, 14, 15 and 16), these results agree with Vinogradov, (1953) and Rosenberg (1972, 1973). Although the great concentration of aluminum was found in the external parts of the adult shell, calcium concentration continues to increase with age.
The concentration of trace elements also showed considerable variation from the juvenile and adult, also from one surface to another (Table, 1 and Figs. 13,14,15 and 16) .The comparatively large variations in concentration of heavy metals were observed. The juvenile shell contains unusually high concentration of copper, lead and cadmium (Table, 1 and Figs, 13 and 14). This result agrees with Pip, (1990) who reported that copper and lead concentrations per unit body weight of A. grandis mussels decreased as size of the individual increased. Similarly, Foster and Bater (1978) found that copper concentration in Quadrula quadrula were inversely related to body weight. Hinch and Stephenson (1987) showed that smaller individuals of Elliptio complanate contamined higher levels of copper in the gills than did larger one.
The present
study found that the same result but in the Sepia
officinalis shells. However, metal concentrations tended to decrease with
increased size and body weight. So, younger animals may accumulate metal to
higher concentrations in many organs than do older individuals, and there fore
may be at greater risk in polluted environments .It should be noted that size
and weight were only broad indicator a of relative age. In the present study,
copper and lead were correlated with each other in the greatest number of
shells. However the greatest
concentration of copper and lead were found in the inner parts of juvenile
shell (Fig. 14). This fact show that the
effect of copper is dependent not only upon concentration and duration of
exposure but also on the age or size of the animals .In addition copper
interferes with growth and development.
However, the
higher concentration of the cadmium was found in the external parts of juvenile
shells. It is interesting to note that this result may be due to adherence of
extraneous material. The amounts of cobalt and nickel are similar in external
and internal parts of both shells. (Table 1)
In general, the
results of this study supported the finding of Hich and Stephenson (1987) and
Green et al (1989) that concentration
in mollusks depend on the metal, tissue type, size and age. Many other
variables may also potentially influence metal accumulation, for example growth
rate, reproductive activity and presence of other metals and pollutants.
We wish to thank Prof. Dr.
M.H. Mona for constructive criticism during reading manuscript and for his
valuable help . And also thanks to Mr. I.H.El-Shamy and Dr. R.A.El-Erian .
REFERENCES
Abdel-Moati, A.R. and
Farag, E.A, (1991): Toxicological and
bioaccumulation studies of Cu, Zn andPb on the freshwater gastropod Lanistes bolteni Chemnitz. J. Egypt.
Ger. Soc. Zool., 4: 289-299.
Bowen, H.H.,
(1966): Trace Elements in Biochemistry. London: Academic Press
El-Fayomy, R.
(1994): Ecological studies of certain aquatic habitats in Domietta region
and their pollution impacts on some limnic and marine organisms. M. Sc. Theis,
Domietta faculty of Science, Mansoura University.
Foster, R.B.
& Bater; J.M. (1978): Use of freshwater mussels to monitor
point source industrial discharges. Environmental science and Technology 12:
958-962
Green, R.H.,
Bailey, R.C., Hinch, S.G., Metcalfe, J.L. & Young, V.H. (1989): Use of
fresh-water mussels (Bivalvia: Unionidae) to monitor the nearshore environment
of Iakcs. Journal of Great lakes Research, 15: 635-644.
HINCH, S.G &
Stephenson, l.A. (1987): Size-and age-specific patterns of trace
metal concentration in fresh water clams from an acid-sensitive and
circumneutral lake. Canadian journal of Zoology 65:2436-2442.
Ibrahim, A.,
Sleem, S., Bahgat, F. and Ali, A.
(1997): Effect of certain water pollutants on the biology of the
fresh water clam Caelatura (unio)
Aegyptica (bivalvia). Egypt. J. Aquat. Biol. & Fish., vol1, no. 1; 47-65.
Pantereath, R.T.
(1973): The accumulation from sea water of Zn, Mn, Cu, and Fe by the
thorn back ray, Raja Clavata. J. of
Exp. Mar. Biol. & Ecology, 12: 327.
Pip, E. (1990): Copper, lead
and cadmium concentration in a sample of lake Winnipeg Anodonta grandis.Nautulus.103: 140-142
Rainbow, P.S.
(1993): Thesignificance of trace metal concentration in marine
invertebrates. In: (R. Dallinger and P.S. Rainbow eds.) Ecotoxicology of metals
in invertebrates. Lewis Pub l, Boca Raton, Forida,3-23.
Rosenberg, G.D.
(1973): Calcium concentration in the bivalve Chione undatella Sowerby, Nature (London) 244: 155-156.
Rosenberg, G.D.,
(1972): Patterned growth of the bivalve Chione undatella Sowerby relative to the environment, Ph.D. dissertation,
university of California, Los Angeles, 220 pp.
Salanki, J.V.,
Balogh, K. and Betra, E. (1982): Heavy metals in animals of lake
Balaton. Water RS., 16: 1147-1152.
Vinogradoy, A.P.
(1953): The elementary chemical composition of marine organisms. (Trans1.
from the Russian). Sears Found Mar. Res., Mem. 11, 647pp.Yale university.
Table (1):
Elemental composition of the shells of the juvenile and adult of Sepia officinalis
|
Elemental composition |
Juvenile |
Adult |
||
|
Ex 2 |
In 2
|
Ex 1
|
In 1 |
|
|
Sodium |
16.84 |
0.45 |
6.62 |
4.07 |
Aluminum
|
7.34 |
3.86 |
11.28 |
0.28 |
|
Chlorine |
19.84 |
1.37 |
6.49 |
1.59 |
|
Potassium |
0.85 |
0.74 |
- 0.17 |
0.92 |
|
Calcium |
48.56 |
85.52 |
73.87 |
96.84 |
|
Nickel |
0.63 |
- 0.52 |
0.99 |
- 2.23 |
|
Cobalt |
0.73 |
- 0.60 |
1.04 |
- 2.40 |
|
Copper |
4.19 |
8.35 |
2.32 |
0.52 |
|
Cadmium |
1.75 |
0.23 |
- 1.40 |
- 1.99 |
|
Lead |
0.318 |
0.730 |
0.140 |
0.099 |
|
Iron |
|
0.33 |
|
0.98 |
|
Mn |
|
- 0.01 |
- |
0.47 |
CO = Cord
CS = Calcified septa
F = Fibrous
PR = Prismatic
LA = Lamellar
Figs. (1,2,3 and
4): Scanning electron photographs of prostracum wings and the
spihuncle in adult Sepia officinalis.
X 15, x 200 and x 75.
Figs. (3): Scanning
electron photographs of phragmocone septa in phragmonone chambers. X 75.
Figs. (6,7 and
8): Scanning electron photographs of the outer layer periostracum. X
150,x2000 and x 2000
Figs. (9 and
10): Scanning electron photographs of the middle layer prismatic .X100
and x1000.
Fig. (11): Scanning
electron photographs of the shape of calcium crestal in the prismatic layer. X
500.
Fig. (12): Scanning electron
photographs of the last Lamellar layer. X35.
Fig. (13): Distribution of
juvenile shell elements in the outer layer of
Sepia officinalis .
Fig. (14): Distribution of
the juvenile shell elements in the inner layer of Sepia officinalis.
Fig. (15): Distribution of
the adult shell element in the outer layer Sepia
officinalis
Fig. (16): Distribution of the adult
shell elements in inner layer. of Sepia
officinalis