International Journal of Marine Science 2015, Vol.5, No.51: 1-11
6
Figure 3 Monthly mean variation in oligochaete abundance in
paddy fields and channels in Maranchery Kole wetlands
Figure 4 Monthly variation in oligochaete diversity paddy fields
and channels in Maranchery Kole wetlands
Figure 5 Monthly variation in oligochaete richness in paddy
fields and channels in Maranchery Kole wetlands
and minimum values in January (1.14) and April (0.32)
respectively. In channels the maximum and minimum
values were in April (1.23) and May (0.60) respectively.
The distance between data points on nMDS plot
showed no clear delineation of data points between
paddy fields and channels (i.e., data points were more
Figure 6 Monthly variation in oligochaete evenness in paddy
fields and channels in Maranchery Kole wetlands
close) however a clear separation in some months
especially in May and February 2011 (i.e., data points
were more dispersed) was apparent (Figure 7). The
appearance of the species,
Allonais gwaliorensis,
Allonais paraguensis
and
Dero zeylanica
exclusively
in the channels due to the increased abundance in May
2011
caused the separation of the channel from the
rest of the group in May 2011 in the nMDS ordination
plot. The low abundance and the absence of
Aulodrilus
pluriseta
in the sample caused the delineation of the
paddy fields in May 2011 whereas in February 2011,
the absence of
Aulodrilus pluriseta
and
Aulodrilus
sp.
lead to the separation in the nMDS ordination plot.
Relationship between biotic and environmental
patterns
BIOENV results for the paddy fields and channels are
given in (Table 3). The results revealed a moderate
correlation with the combination of a few environmental
parameters. Dissolved oxygen and the percentage of
clay were the BEST environmental variables explaining
the variability of oligochaetes in paddy fields (r=0.29)
whereas dissolved oxygen, the percentage of clay and
the percentage of silt were the important variable in
channels. (r=0.28).
Discussion
Faunal Composition
Though paddy fields and channels differed in the
physical structure, there was no significant difference
in environmental parameters between them. A lower
water and sediment temperature in the paddy fields
could be due to the shading by paddy plants. Higher
organic matter in paddy fields could be due to the
accumulation of paddy leaves also a higher water
