L - Cochin University of Science and Technology

transect stations. At 75 m zone also evenness was fluctuating with comparatively
high evenness observed in the northern transect stations than southern transect
stations. Maximum evenness was observed otT Veraval and minimum otT Mumbai.
At 100 m zone, northern latitude stations observed comparatively high evenness and
southern transect stations otT Monnugao and Ratnagiri had low evenness. At 150 m
zones, high evenness was observed off Mumbai and Porbandar but low off Veraval.
Beyond 150 m depth, only 2 observations made, and no comparison was possible. In
general, at most of the depth zones comparatively high evenness was observed in the
northern transect stations.
6.1.2.2.1.3. Species diversity (Shannon index, H')
Depth wise average diversity for polychaete species (Fig. 37c) showed that it
was generally high from 30 m to 100 m depth zones and beyond 100 m zone
diversity reduced sharply with maximum diversity at 75 m. Species diversity showed
a more consistent pattern of distribution in southern transects than northern transects
(Table 24). In the southern transects it ranged between 1.84 and 4.35. In the northern
transects relatively high diversity was observed in most of the stations than southern
transects and it varied from 0.28 to 4.38 and showed a more patchy distribution
(Table 24). Average diversity for the study area was 3.14 with high spatial variation
(C. V. % =463.43%). Transect wise diversity distribution in each depth zones is
given in Fig. 40. At 30 m zone a gradual increase towards north was observed with
minimum diversity otT Monnugao and maximum otT Dwaraka. At 50 m depth zone,
more or less similar diversity was observed in most transects with high value off
Mumbai and exceptionally low value off Ratnagiri. At 75 m depth zone, diversity
was fluctuating along transects and maximum diversity was observed off Ratnagiri
and minimum otT Mumbai. At 100 m zone, a general increasing trend was noticed
towards north with lowest value otT Monnugao and highest otT Veraval. At 150 m
zone also northern latitude station (off Dwaraka) recorded maximum diversity.
Exceptionally low diversity met with otT Veraval as an exception from the previous
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