A study on the length-weight relationship of common intertidal molluscs from Mumbai showed a high degree of correlation between their length and weight. Most of the molluscs exhibited isometric growth pattern but in some species, allometric growth was found, which is attributed to maturity, nonlinear growth of shell and the ecological conditions. The variations in the growth rate of Gafriarium divaricatum sampled from two geographically separate sites, Bandstand and NCPA, is a result of variation in ecological conditions

Jaiswar, A.K.

Kulkarni, B.G.

Aquatic Commons

Journal of the Indian Fisheries Association 
29, 2002, 55-63 
55 
LENGTH-WEIGHT RELATIONSHIP OF INTERTIDAL MOLLUSCS FROM 
MUMBAI, INDIA 
A. K. Jaiswar and B. G. Kulkarni* 
Central Institute of Fisheries Education, Versova, Mumbai - 400 061 
'
1
'The Institute of Srience, 15, Madam Cama Road, Nfumbai - 400 032 
ABS'rRACT 
A study on the length-weight relationship of common intertidal molluscs 
from Mumbai showed a high degree of correlation between their length and 
weight. Most of the molluscs exhibited isometric growth pattern but in some 
species, allometric growth was found, which is attributed to maturity, non-
linear growth of shell and the ecological conditions. The variations in the 
growth rate of Gafrarium divaricatum sampled from two geographically 
separate sites, Bandstand and NCP A, is a result of variation in eco~ogical 
conditions. 
Key words: Length-weight, intertidal 1nolluscs 
JNTRODUCTION 
A mathematical representation of 
the len1,.,:rth-weight relations::hip derived from 
the analysis of a number of specimens of 
different sizes from a particular area is a 
useful tool for study of population dynamics. 
According toLe Cren (1951), "Length of an 
animal is often more rapidly and accurately 
measured than weight. It is convenient to 
determine weight, where only length is 
la.iown and vice versa". Besides providing 
a means for calculating weight from length, 
it may also give taxonomic difference and 
events in the life history ofthe fish/mollusc. 
Any deviation from the relationship thus 
derived indicates variation in the ecology of 
the habitat or physiology of the animal or 
both. Considerable data are generated on 
the length-weight relationship of fishes, 
which are useful in the management of 
their fisheries. However, except for few 
reports (Mohan, 1980; Shanmugam, 1997), 
the work on the length-we:ight relationship 
of molluscs is scanty. Therefore, the present 
work on the length-weight relationship of 
selected gastropods and bivalves ofMumbai 
coast was undertaken in an attempt to fill 
the lacuna. 
MATERIAL ANDMETHODS 
For- the present investigation, the 
molluscan specimens were collected from 
Bhores a~jacent to TaUt Institute of 
Fundamental Research (TIFR), National 
Centre for performing Arts (NCPA), 
Girgaon Chowpatty, Bandstand and Gorai 
creek of lVIumbai during' spring-low tid£~ 
from September 1997 to August 1998 (Fig. 
1). Total length of shell in bivalves and 
56 A. K. JAISWAR AND B. G. KULKARNI 
7t30' 
BASSEIN ---4 
A CREEl< 
R 
19. A 8 15' I v 
A 
N 
s 
E 
A iv 
• 19 
N 
ii 
• 95 
Fig. 1. Sampling spots inMumbai (i) TIFR (iiNCPA (iii) Girgaon Chowpatty 
(iv) Bandstand (v) Gorai Creek 
LENGTH-WEIGHT RELATIONSHIP OF INTERTIDAL 
MOLLUSCS FROM MUMBAI, INDIA 
57 
height of shell in gastropods were measured 
in millimetres and wet weight in grammes 
using digital balance after drying on a 
blotting paper. The data on length and 
weight were put in its logarithmic form 
log W = log a+ b log L (Le Cren, 1951). 
Significance of regression coefficient 'b' was 
tested to verify whether it was deviating 
from 3, using 't' test as follows: 
b-3 
t=----Where,b = coefficient of regression 
sb 
sb =standard deviation calculated as' 
Sb = b~X2 - (LX)2/n 
N n-1 
The co-efficients of regression 'b' for 
Gafrariurn divaricaturn collected from 
NCPA and Bandstand were compared to 
know the significant difference in growth 
using 't' test: 
szp ( 1.. + 1.. ) 
I.xz I.xz 2 
where, b 1 
coefficients, 
and b2 = two regress10n 
S2p =variance, calculated as 
Where, n1 =number of observations for b1 
n 2 = number of observations for b2; 8
2
1 
and 82 2 = variances to b1 and b2, 
respectively. 
Coefficient of correlation 'r' was estimated 
to measure the degree of interdependence 
of two observations (total length and animal 
weight) calculated as : 
r = 
n 
where, x =total length (shell) 
y = animal weight 
n 
n = number of observations 
A significance test was applied to 
coefficient of determination 'r2' to predict 
the chances of error in drawing conclusions 
by the test 
N n- 2 
r·--;:::=======--N 1- r2 
Where, r = coefficient of correlation 
n = number of observations 
RESULTS AND DISCUSSION 
A curvilinear relationship was obtained 
for gastropods,Hernifusus pugilinus,Bursa 
tuberculata, Euchelus indicus, Nassarius 
ornatus, Nerita oryzarurn, N. polita, N. 
albicilla, Neritina crepidularia, and bivalves 
G. divaricaturn, Perna viridis and Cardita 
antiquata, when weights ofthe specimens 
were plotted against the total length of 
shell (Fig. 2-4). This indicates that like in 
other animals, in these molluscs too, the 
rate of growth by weight is faster than 
their length (Le Cren, 1951). Furthermore, 
when log of animal weight and total length 
observed were treated with formula W = a 
L h, the logarithmic form oflength-weight 
relationship was obtained as: 
log W = -log 0.4906 + 2.5957 log L for C. 
antiquata, 
log W =-log 0.5573 + 2.3683log L for P. 
viridis, 
58 
260 
2l.O 
220 
200 
180 
160 
{,~.o 
Ol 
E120 
0 
0 
~100 
80 
60 
40 
20 
150 
5·5 
5· 
t.,s 
!.,· 
3: 3·5 
<t 
~:n3· 
E 
g 2·5 
0 
>< 2· 
1·5 
l· 
·5 
0 
A. K. JAISWAR AND B. G. KULKARNI 
P2rnq Viridis 
20 30 1.0 
... ·. 
·'· .,_ 
50 60 
TL(m) 
Gafrarium dfvoricatum 
NCPA· 
10 20 
TL (mm l 
. '·~. 
70 
30 
.. : 
BO 90 100 
S·O 
5·5 
:, 
l.-5 
4 
3·5 
3 
~ 
2·5 
tn 2 
E 
g,.s 
0 
~ 
)( 
·5 
1.0 45 
120 
110 Cordi Ia on tiqua Ia 
100 
90 
80 
70 
!: ~ 60 
30 
20 
10 
110 20 30 1.0 
TL(mm) 
Gal rarium divaricatum 
Bund stand 
10 20 30 
Tl (mm) 
50 55 
1.0 t.S 
Fig. 2. Length-weight relationship of P. viridis, C. antiquata, G. divaricatum (NCPA 
and Bandstand) 
LENGTH-WEIGHT RELATIONSHIP OF INTERTIDAL 59 
MOLLUSCS FROM MUMBAI, INDIA 
ll. 
Euchttlus indicus Hamifusus pu9ilinus 
13 55 
,~ 50 
11 45 
~ 
~ 10 40 
0 ~35 E 9 
0 
~~ Q'l 
>< 8 EJO 
0 
0 
~ 
7 ).( 25 
G 20 
5 15 
4 10 
3 5 
..... 
-,-
12 14 16 18 20 22 24 26 28 20 L.O 60 80 100 120 11.0 1SO 
TL ( mm) TL (mm) 
14 
13 Borsa tuberculata 5 Nassar ius or notus 
12 
~11 4 
~ 
01 10 
E 3: 
:::> 9 <t 3 :::> 
01 
)( E 8 0 
0 
~ 
7 ).( 2 
6 
s 
4 
r T" 
5 10 15 20 15 30 35 l.O 45 12 13 14 15 16 17 18 19 20 
TL ( mm) H(mm) 
Fig. 3. Length-weight relationship of E. indicus, H. pugilinus, B. tuberculata, 
N. ornatus 
60 A. K. JAISW AR AND B. G. KULKARNI 
Neritino cNpidularia N~rilo nlbicilla 
·6 H) 
E E 
Ol ·5 011-5 
c c 
~ ·4 :Cl-4 
Ol C) 
'. 'iii 
'iii 
-3 ~ 1·3 ~ 
" 
0 
E ·2 ,. E1·2 
·c: : . c 
<:( <:( 
·1 H 
0 l:.f 5 10 15 20 25 30 35 
H. Total l<ln g th in mm Total l~ngth in mm 
1·3 
1·2 F2 
1·1 Nerito oryzorum 1·1 N~rita poI ito 
1{) 1·0 
·9 ·9 
E 
·8 01·8 
E 
c 01 
c ·7 
..... 
·7 
.c. 
Ol 
~·6 ·;y. 6 
OJ 3: 
~ 
·5 - ·S 0 
0 E E 
·c: ·l, 
·- ·l, c <( 
<:( 
·3 .. ·J 
:z ·2 
·1 . ~ .. ., 
-·-· ., __ ... .,. .... _ .. , 
0 s 10 15 20 25 0 5 10 15 
Tot a I len9th in mm Total length If\ mm 
Fig. 4. Length-weight relationship of N. crepidularia, N. albicilla, N. oryzarum, 
N. polita 
20 
LENGTH-WEIGHT RELATIONSHIP OF INTERTIDAL 
MOLLUSCS FROM MUMBAI, INDIA 
61 
log W =-log 0.4058 + 2.5012log L for G. 
divaricatum (Bandstand), 
log W =-log 1.3957 + 3.1087log L for G. 
divaricatum (NCPA), 
log W = -log 1.4965 + 2.8667 log L for H. 
pugilinus, 
log W = log 0.7737 + 1.4533 log L for B. 
tuberculata, 
log W =-log 0.5713 + 2.6165 log L for E. 
indicus, 
log W =-log 0.9959 + 2.8481log L for N. 
ornatus, 
log W =-log 0.4242 + 2.4528log L for N. 
oryzarum, 
log W =-log 0.3798 + 2.3241log L for N. 
pol ita, 
log W = log 0.9540 + 1.4794log L for N. 
albicilla, 
log W =-log 1.0983 + 2.9905 log L for N. 
crepidularia 
Animals with regression coefficient 'b' 
closer to 3 indicate isometric growth, 
whereas those deviating significantly from 
3 are considered to indicate allometric 
growth. It has been shown that in isometric 
growth, increase in weight of animal is 
proportionate to the cube of its length and 
they maintain specific body shape 
throughout their life, whereas in allometric 
growth, increase in weight of an animal is 
not proportionate to the cube of its length. 
However, they maintain specific body shape 
throughout their life (Le Cren, 1951; 
Acharya ,1980; Bhattacharya andAcharya, 
1982). During the present investigation, 
'b' values of three gastropods, H. pugilinus, 
N. ornatus, and N. crepidularia, and a 
bivalve G. divaricatum at NCPA did not 
show significant variation from 3 when 't' 
test was applied at 5% significance level for 
all the molluscs separately. Therefore, 
these gastropods showed isometric growth 
pattern maintaining specific body shape 
throughout their life. However, "b" value 
of gastropods, B. tuberculata, E. indicus, 
N. oryzarum, N. polita and N. albicilla, 
and bivalves C. antiquata, P. viridis and 
G. divaricatum at Bandstand showed 
significant variation from 3, indicating an 
allometric growth pattern. These results 
are in agreement with Shanmugam (1997) 
who observed allometry in gastropod, 
Cassidula nucleus at Pichavaram and 
attributed it to the sexual maturity of the 
gastropod. But, allometric growth found in 
P. viridis from the Kochi coast was related 
to the non-linear growth of shell (Mohan, 
1980). Merella et al. (1997) studied 15 
cephalopods from Balearic Island and found 
isometric growth in five species and 
allometric growth in 10 species. The 
allometric growth observed in a large 
number of fishes has been shown as the 
result of surrounding indispensable 
ecological conditions (Benedito-Cecilio et 
al., .1997). Therefore, different ecological 
conditions existing in the surrounding 
environment of the molluscs and sexual 
maturity may be responsible for different 
growth patterns observed in the present 
investigation. 
Sparre et al. (1989) have shown that 
length-weight relationships vary 
geographically, whereas, Le Cren (1951) 
and Acharya and Bhattacharya (1983) have 
established that variation in ecological 
conditions of two habitats or variation in 
. the physiology of the animals, or both are 
responsible for variation in growth rate in 
the same species from different localities. 
Krishnakumari (1990), Fernandes (1991), 
and Zingde and Govindan (1997) mentioned 
62 A. K. .JAISWAR AND B. G. KULKARNI 
that pollution of the medium leads to lower 
growth rate of molluscs. In the present 
study also, the 'b' values of G. divaricatum 
at NCPA (3.1087) and Bandstand (2.5012) 
showed significant variations when 't' test 
was applied, thereby indicating variation 
in their growth rates at the two shores. 
NCPA and Bandstand shores are 
geographically away (15 km) from each 
other having different ecological conditions. 
NCPA is a semi-open man-made shore 
subjected to less wave action, while 
Bandstand is an open and natural rocky 
shore subjected to wave action throughout 
the year. Bandstand shore being adjacent 
to Mahim creek, also receives anthropogenic 
waste and is highly polluted (Zingcle and 
Govindan 1997). In addition, unlike NCPA, 
Bandstand area also receives large quantity 
of effluents from different drainage 
channels. These factors may be responsible 
for the low value of'b' (allometric growth) 
of G. divaricatum at Bandstand and higher 
value of'b' at NCPA shore. 
Coefficient of correlation estimated for 
these molluscs showed high degree. of 
interdependence in the length-weight 
Table 1 : Coefficient of correlation 'r', coefficient of determination 'r2~ and 
't' obtained for length -weight relationship of selected molluscs 
Species N r r2 Observed Critical 't' 
't' at 5% level 
of probability 
Cardita antiquata 
( Girgaon Chowpatty) 48 0.8943 0.7997 13.5527 1.960 
Perna viridis 
CGirgaon Chowpatty) 69 0.9375 0.8789 22.0535 1.960 
GafrariUJn divaricatum 
(Bandstand) 33 0.8793 0.7731 10.2778 1.960 
Gafrarium divaricatum 
(NCPA) 46 0.6147 0.3778 5.1690 1.960 
Ht;!mifusus pugilinus 
(Girgaon Chowpatty) 26 0.9513 0.9050 15.1174 2.064 
Bursa tul;;erculata (NCPA) 33 0.8461 0.7159 8.8394 1.960 
Euchelus indicus (N CPA) 27 0.9802 0.9607 24.7230 2.060 
Nassarius ornatus 
(Girgaon Chowpatty) 30 0.9104 0.8288 11.6440 2.045 
Ne-rita oryzarum ( NCPA) 58 0.9560 0.9139 24.3804 1.960 
Nerita polita ( NCPA) 52 0.8709 0.7584 12.5281 1.960 
Nerita albicilla (TIFR) 13 0.8570 0.7345 5.5164 2.201 
Neritina crepidu.laria 
( Gorai Creek) 46 0.9618 0.9252 23.3288 1.960 
(Critical 't' at 5% level varied from 12.706 at 1° of freedom to 1.960 at infinite degrees of 
freedom, whereas in the present study, the degree of freedom varied from 12 to 68. Therefore, 
critical 't' cannot be less than L96) 
LENGTH-WEIGHT RELATIONSHIP OF INTERTIDAL 
MOLLUSCS FROM MUMBAI, INDIA 
63 
relationship except for G. divaricatum from 
NCPA (0.614 7) and significance test of 'r2' 
(Table 1) revealed no chances of error in 
drawing the conclusions. 
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Acharya, P., 1980. lvforphometry and 
Biology of N emipterus japonicus 
(Bloch) of Bornbay Coast, M. Sc. 
Thesis Univ. of Bombay, Bombay. 308 
pp. 
Acharya, P. and Bhattacharya, D., 1983. 
A note on the length weight relationship 
and ponderal index of Upenneus 
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Benedito-Cecilio, E., Agostinho, A.A. 
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Length-weight relationship of intertidal molluscs from Mumbai, India

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Length-weight relationship of intertidal molluscs from Mumbai, India

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