1. Introduction
The northern sector of the GoM is the first Indian Marine Biosphere
Reserve1. The GoM, along its Indian coastline, has a
spread of ~1500 km2 that extends
typically from Tuticorin to Mandapam8 over a distance
of ~ 190 km (Figure 1). The GoM has astonishingly rich
and diverse fauna compared to the adjacent regions, and the ’Kurusadai’
Island, one of the 21 small islands situated close to the Indian
coastline in the GoM, is traditionally known as ’Marine Biologist’s
Paradise’. During 2010 - 2011, researchers from the National Institute
of Oceanography, India including us have carried out oceanographic
observations in the GoM and the adjacent Palk Bay (PB) as a feasibility
study to link these water bodies through the Sethusamudram Ship Channel
proposed by the Govt. of India. As an outcome of this, a series of
peer-reviewed publications have come out dealing with their general
environmental setting 8-12. Even though a large number
of studies are available on the faunal diversity in the GoM, convincing
explanation on its oceanographic causes is completely
absent1. Since the GoM is an extension of the
Southeastern Arabian Sea (SEAS), differentiating the features of the GoM
from the SEAS has great importance. The main objective of this paper is
to establish the oceanographic and ecological reasons that facilitate an
unusually rich and diverse fauna in the GoM. For which we examined here,
the general characteristics of the GoM8-12 besides
elaborating upon a crucial environmental signal found in our 2010-11 in-situ studies in the GoM. Also verified these results using a
recent oceanographic survey in 2018 covering the southwest coast of
India up to the western boundary of the GoM (Tuticorin) augmented with
satellite remote sensing data sets and Regional Ocean Model System
(ROMS) projections.