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International Journal of Marine Science 2013, Vol.3, No.12, 98-104
http://ijms.sophiapublisher.com
101
1.2 Feeding intensities in relation to different seasons
The percentage of feeding intensity values for
different seasons was calculated and presented in
Table 2. Active feeding was noticed during January
post monsoon to May (summer) but it was below 50%
during June (summer) to September (premonsoon),
whereas during October and monsoon the feeding
intensities were very low. The poor feeding during
these periods may be due to monsoon season.
Table 2 Percentage of feeding intensities in relation to different
seasons in
B. boddarti
Premonsoon Monsoon
Post
monsoon
Summer
Gorged
3.92
0
16.32
4.52
Full
11.21
6.15
15.18
11.98
¾ full
30.73
7.13
43.79
48.32
Actively fed 45.86
13.28
75.29
64.82
½ full
21.02
38.27
9.02
13.13
Moderately
fed
21.02
38.27
9.02
13.13
¼ full
5.99
22.15
0
5.73
Trace
27.13
26.3
0
6.93
Poorly fed
33.12
48.45
0
12.66
Empty
0
0
15.69
9.39
Table 3 Percentage of feeding intensities in relation to juveniles,
males, and females of
B. boddarti
Feeding intensity
Juveniles Males
Females
Gorged
19.05
13.91
14.01
Full
23.12
15.73
16.88
¾ full
37.35
24.15
20.72
Actively fed
79.52
53.79
51.61
½ full
12.23
16.02
15.02
Moderately fed
0
16.02
15.02
¼ full
0
8.27
12.21
Trace
8.25
9.13
8.13
Poorly fed
8.25
17.40
20.34
Empty
0
12.79
13.03
1.3 Feeding intensities in relation to juveniles,
males, and females
The percentage of feeding intensities in juveniles,
males and females of
B. boddarti
is presented in Table 3.
It is clear that the percentage of actively fed
mudskipper was more in juveniles than males and
females. But it was also been observed that the
percentages of moderately fed mudskippers were same
among males and females but less in juveniles. While
comparing the feeding intensities between males and
females, it was observed that the percentage of
feeding intensity of actively fed and moderately fed
mudskippers was more in males than females. But in
the case of fully fed and empty stomachs, the
percentage of feeding intensities was more in females
than males. The feeding intensity of empty stomachs
in juveniles is completely absent in the present study.
2 Discussion
The mudskipper
B. boddarti
inhabits the mudflats
along the Pichavaram mangroves, southeast coast of
India. The results of the present study on the food and
feeding habits of this species clearly revealed that the
fish is a herbivore especially feeding predominantly
on diatoms. This is in concordance with the study
made by Macnae (1968) describing
B. boddarti
as a
herbivore. In general, mudskippers of the genera,
Periophthalmus
and
Periophthalmodon
are carnivores
while those of
Boleophththalmus
are herbivores and
Scartelaos
omnivores (Clayton, 1993). The extent of
exposure of the mudflats at air depends on the tides,
which occur normally twice a day. During this time,
the fish emerges from the water-filled burrow and
starts to move on the soft mudflats. While doing so, it
skims off a thin layer of mud and algae from the
surface (Macnae, 1968). The mouthful of such
materials is then placed in the mouth, as can be seen
by vibrating movements of the lips and opercular
region. The mudskipper
B. boddarti
feeds more on
diatoms than the other items. Fenchel (1969) stated
that the benthic diatoms constitute an important source
of food for benthic organisms and other meiobenthos
while Heald and Odum (1970) explained that the
diatoms play vital role in establishing the food chain
relationships between different groups of organisms in
the ecosystems.
The stomach content analysis of the present study
showed that the diatoms were reprersented by
Coscinodiscus, Gyrosigma, Navicula, Nitzschia,
Pleurosigma, Rhizosolenia
, and
Thalassionema.
Other
food items were nematodes, polychaetes, fish eggs
and algae. Nematodes such as
Desmodora,
Paralinhomoeus
and
Terschillingia
constituted the
second food items with high percentage following the
diatoms. Polychaetes (
Nereis
and
Euclymene
) formed
another food item next to nematodes. This
corroborates with the
B. dussumieri
, which was
examined by Mutsaddi and Bal (1969) from Gujarat,