Prevailing assemblages
and depth-driven distribution patterns of pteropods in the Andaman Islands
Shah Kiran, Mohan P.M. and Vinod Swathi
Disaster Advances; Vol. 18(11); 47-56;
doi: https://doi.org/10.25303/1811da047056; (2025)
Abstract
The present study investigates the pteropod assemblages and their distribution pattern
across different depths offshore in the Andaman Islands using the samples collected
by FORV Sagar Sampada (Cruise No. 355). 22 pteropod species from 6 families were
identified from depths of 50 m, 100 m and 200 m during the study period. Heliconoides
inflatus from the family Heliconoididae displayed the highest abundance compared
to other species. The family Creseidae was more prevalent at 50 m, whereas Heliconoididae
dominated at 100 m and 200 m. Little Andaman station (200 m) had the highest species
diversity, while the lowest was at Rangat's west coast (50 m). Multivariate analyses
revealed depth-dependent occurrence trends, with PERMANOVA confirming depth (Pseudo-F=
4.79, p= 0.001) as a significant factor in structuring distinct pteropod assemblages.
The Canonical analysis of Principal Coordinates showed strong discrimination for
assemblages at 50 m and 200 m (85.71% correct for each) with 81.82% accuracy and
a minimal misclassification error rate of 18.18%. The Principal Component Analysis
indicated temperature and salinity as the key environmental factors influencing
depth-driven distribution patterns. This study provides new insights into the pteropod's
vertical zonation and showcases the unique regional distribution patterns observed
in the Andaman waters.
