138-145The Arabian Sea is one of the most productive regions of the
world oceans. This productivity mainly results from coastal and open ocean
upwelling in summer and cooling effects during winter. Earlier and more recent
studies showed that there are considerable spatial and temporal variations in
the area in primary productivity. Nonetheless, contrary to, earlier thinking,
it would seem that the mesozooplankton abundance in the Arabian
Sea is fairly high in the mixed layer all through the year. This
paradox of the Arabian Sea could be partly
resolved by explaining the microbial loop and a fresh set of data is presented
here in support. This is because most of the herbivorous forms are either small
filter feeders like copepods or larger mucous filter feeders like tunicates
which are able to feed on very small particles. It would seem that the Arabian Sea
sustains a
large biomass of mesopelagic fishes (about 100 million tonnes), mainly
myctophids. They mostly live in the core of oxygen minimum layer and ascend to
the surface layers during night to feed on the abundant zooplankton