Environmental Engineering Reference
In-Depth Information
Fig. 2.35
Mangrove mudflats and vegetation are the survival ground for wide spectrum of microbial strains
and sulphur dynamics and contribute to soil veg-
etation patterns (Sherman et al.
1998
). Methano-
genic bacteria
Zobell
s marine agar was recorded almost three
times greater in pre-monsoon at mangrove-
dominated area in comparison to non-mangrove
zone (Tables
2.20
and
2.21
). The bacterial den-
sity in the other media (nutrient agar) also
exhibited the same trend.
The high microbial density in the monsoon
season in both the mangrove and non-mangrove
zones as revealed in Tables
2.20
and
2.21
may be
attributed to the presence of excessive nutrient
concentrations in the ambient aquatic phase due to
run-off from the adjacent landmasses and the sup-
porting vegetation matter (Banerjee et al.
2001
).
The marine and estuarine environments, the
mangrove ecosystem and the brackish water
aquacultural farms have also become the dwell-
ing spots of variety of pathogenic organisms.
These organisms known as coliform bacteria are
discharged from the human intestine and their
'
are
seasonally abundant
in
sediments where
species dominate
(Ramamurthy et al.
1990
; Mohanraju and Natra-
jan
1992
). Subsurface bacterial communities
(along with epibenthic microalgae) may sequester
nutrients and hold them within nutrient-limited
mangrove mud (Alongi et al.
1993
; Rivera-Mon-
roy and Twilley
1996
).
A comparative study done in two selected
stations of Indian Sundarbans showed unique
variation of microbial population, which may be
attributed to the presence of mangrove
Avicennia
ora. It
was found that the total bacterial density was
high in the soil collected from mangrove belt
rather than the non-mangrove habitat. Seasonal
variation of microbial load was also recorded in
both the stations. Abundance of microbes in
fl
Table 2.20
Seasonal distribution of different types of microbes at mangrove-dominated zone during March 1998 to
February 1999
Medium
Nutrient agar
Zobell
'
s marine agar
Proteolytic medium
Season
Pre-monsoon (March
June)
13
20
08
-
Monsoon (July
October)
19
45
10
-
Post-monsoon (November
February)
08
13
05
-
Dilution factor 10
3
/l ml
