International Journal of Marine Science 2016, Vol.6, No.22, 1-14
12
The present study showed the population of
D. blanfordi
was present the whole year at Clifton and Korangi Creek.
The males were found more abundant as compared to females (Hartnoll, 1973). Small changes in body size can lead
to disproportionate increase in the coefficient correlation showing the relationship between carapace length, width
and abdominal width is proportional with each other Lavajoo et al., 2012).
In whole study male individuals showed high density as compared to female individuals. High density of male
individuals is due to some females dying after breeding. The male individuals were also larger in size as compared to
female individuals, which was convenient in reproductive activity (Pravinkumar, 2013; Litulo, 2004; Mouton and
Felder 1995). It was noted that the ovigerous females did not occur throughout the year. In present study mostly
breeding period occurred from March to July 2007 and February 2008. One previous study described the breeding
period from September to March (Prasad and Tampi, 1953). Whereas Rehman (1966) described that the breeding
was not limited for few months, and the whole year breeding continued. The presence of ovigerous females in the
sample provided an indication of reproductive activity. There were many variations found in numbers, size and
colour of egg mass that was due to capturing of ovigerous females at different stages of eggs maturation (Litulo,
2004). The colour of eggs was the sign of maturation. In present study the mature egg mass colour was dark yellow
with large numbers of egg in abdominal flip whereas when numbers of egg were small in abdominal flip the colour
of egg mass was light yellow.
The results of allometric growth relationship between C.W of ovigerous females and number of eggs were
positive in present study are comparable with other studies (Litulo, 2004; Mouton and Felder, 1995). The
fecundity of in
D. blanfordi
crabs found in present study was similar to that studied previously in different areas of
the world in their local species (Litulo, 2004; Costa and Soares-Gomes
，
2009).
It was observed that wet substrate was more favorable for both reproduction and population as compared to dry
substrate. Previous studies mention that the environmental factors (temperature, salinity, food availability etc.)
might also affect on distribution, density, reproduction and fecundity of macro fauna like fiddler crab Uca
annulipes (Pravinkumar et al., 2013; Litulo, 2004) It was tested in the present study at the time of sampling that
presence of more sunlight and temperature feeding activity increased with numbers of burrow of crabs, it mean
there was positive correlation found in between physical parameters and density and reproduction of crab. It is
fact Ocypodid crabs mating in burrow (Henmi et al., 1993).
The present study showed spatial and temporal variation in the occurrence and quantity of crab species. The
results showed that both sites Clifton and Korangi Creek were more productive site for the reproduction of
D.
blanfordi
. From the present study it was also concluded that the population of
D. blanfordi
crabs was affected by
both exogenous (temperature, light, food availability) and endogenous (gonad development period, eggs
incubation time releasing of larvae and age of attaining sexual maturity). Costa and Soares-Gomes (2009)
described in a tropical coastal lagoon, southeast Brazil in their study that the temperature at lagoon seems to
favour adequate conditions over all year long to social behavior, feeding, gonadal maturation and egg incubation.
The observations in whole study showed that male individuals showed high density as compared to female
individuals. High density of male individuals is due to some females dying after breeding. The male individuals
were also larger in size as compared to female individuals, which was convenient in reproductive activity
represents the sexual dimorphism. Difference in morphological sexual maturity was observed within sexes also.
From the present study it is suggested that Ocypodid crabs can be used as pollution indicators for assessment of
environmental health of our coastal areas.
