L - Cochin University of Science and Technology

H2./.l.4. Dominance (Pie/ou's index)
Average values showed that dominance was decreased from 30 m to 75 m
depth then it increased to deep with highest value at 150 m depth (Fig. 37 d). Very
low species dominance was observed in the southern transects (ranged from 0.04 to
0.82) in most of the stations whereas in the northern transects, most of the stations
comparatively higher values were noticed (ranged from 0.1 to 1.0) thus showing an
inverse relationship with species richness and diversity in general. Species
dominance was very low (X = 0.31) with high spatial variation (C.V. %= 82.43%).
Dominance at different depth zones showed that (Fig. 41) at 30 m zone, eventhough
dominance was fluctuating with transect, relatively high dominance was observed in
south and decreasing to north with ofT Mormugao having highest value followed by
off Mumbai and lowest ofT Veraval. At 50 m zone, it was fluctuating with
comparatively high dominance off Veraval and low off Mumbai. At 75 m depth, a
slight increase in dominance was observed towards north with minimum value found
offRatnagiri and maximum value off Porbandar. At 100 m zone, a similar trend was
observed with an increasing dominance towards north except ofT Dwaraka. Lowest
dominance was observed off Mormugao and highest ofT Veraval. At 150 m depth
lone, an increasing trend was noticed towards north as that of 75 m and 100 m zone
with lowest dominance observed off Ratnagiri and highest ofT Dwaraka. The
dominance observed ofT Dwaraka was due to the presence of a single species. In
general increased dominance was observed in the northern transect.
6.2.2.1.2. Community structure of groups
Community structure of groups showed that number of groups varied from
to 10 with benthic abundance of 40 to 4820. In the southern transects number of
species varied from 1 to 10 and density varied from 90 to 4820/m 2 and in the
northern transects number of species varied from 2 to 7 and density varied from 40 to
4100/m2.
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