Intrusion of the Bay of Bengal water into the Arabian Sea during winter monsoon and associated chemical and biological response

Abstract

Situated in similar latitudes and subjected to similar atmospheric forcing, the tropical basins of the Arabian Sea looses fresh water due to excess evaporation over precipitation while Bay of Bengal receives freshwater via excess rain and river run off. The hydrological imbalance thus created on an annual scale will have to be balanced by the inter‐basin exchange. In winter this happens through the intrusion of Bay of Bengal waters into the Arabian Sea, when the southward flowing East India Coastal Current carrying low salinity waters from the northern Bay feeds into the West India Coastal Current flowing north along the shelf in the Arabian Sea. Advection of nutrients by this intrusion triggers enhanced levels of chlorophyll near the southern part of the western shelf of India and may play a role in altering the biogeochemistry of this intense hypoxic region.

Influence of environmental properties on macrobenthos in the northwest Indian shelf

“…Moreover, it showed a progressive increase from south to north especially in the shallow depths (30 m and 50 m). High salinity observed in the northern region in the present study might be due to the effect of Arabian Sea High Saline Water (Wyrtki, 1971) and low salinity in the southern latitudes could be due to the low saline water that enters from Bay of Bengal (BOB) through coastal waters (Darbyshire, 1967;Wyrtki, 1971;Kumar et al, 2004). Kumar and Mathew (1997) noticed that the maximum northward extension of this low saline water was up to about 12º N in January but could be traced upto 17º N in February.…”

“…Vizakat (1991) studied the ecology and community structure of soft sediment macrobenthos of Konkan, west coast of India, suggested recolonisation of benthos when salinity increased suggested that salinity influence positively in the benthic production in tropical waters. High benthic biomass in the shallow areas can also be due to high primary productivity in the northwest coast (Radhakrishna et al, 1978, Kumar et al, 2004 because the supply of food to the sub tidal benthic environment depends on the proximity to the shore and water depths (Levinton, 1982). In the shallow region, much of the primary production enters the food web as organic detritus.…”

Phytoplankton size structure in the southern Bay of Bengal modified by the Summer Monsoon Current and associated eddies: Implications on the vertical biogenic flux

“…The conventional oceanographic view suggests that river influx contains huge amount of nitrogen sources, which can fertilize the seas to a large extent (Prasannakumar et al, 2002(Prasannakumar et al, , 2004b. This view proposes the possibility of a very high phytoplankton production in the Bay of Bengal since all the major rivers of India, Bangladesh and Myanmar empty into this ocean basin.…”

Trace Metal Concentrations in Zooplankton from the Eastern Arabian Sea and Western Bay of Bengal

“…In winter, this southward-flowing East India coastal current carries warm and low-salinity waters from the northern Bay of Bengal (probably carrying riverine waters originating from Ganges-Brahmaputra, Godavari, Krishna, and Cauveri rivers) to the southern part of the peninsular India and feeds the northward-flowing West India coastal current in the Arabian Sea. The intrusion of this Bay of Bengal water into the Arabian Sea during winter monsoon and associated chemical and biological response have been reported (Prasanna Kumar et al, 2004). The state of Goa is well known for its mining activities and major contribution to the economy from the export of more than 10 million tons per year of Fe-Mn ore (Parulekar et al, 1986).…”