Summary of Abstract Submission

Abstract Submission No. IO50-06-0008PresentationOral

ASSESSING THE SUITABILITY OF BENTHIC FORAMINIFERAL MORPHO-GROUPS TO RECONSTRUCT PAST MONSOON FROM THE BAY OF BENGAL

Manasa M*1, Rajeev Saraswat1, Rajiv Nigam1

1 National Institute of Oceanography, Goa, India

ABSTRACT :

Temporal changes in benthic foraminiferal morpho-groups were suggested as an effective proxy to reconstruct past monsoon from the Arabian Sea. Here, in order to test the applicability of temporal variation in morpho-groups to reconstruct past monsoon from the Bay of Bengal, we have documented recent benthic foraminiferal distribution from the continental shelf region of the northwestern Bay of Bengal. Based on the external morphology, benthic foraminifera were categorized into rounded symmetrical (RSBF) and angular asymmetrical forms (AABF). A few other dominant groups were also identified based on test composition (agglutinated, calcareous) and abundance (Asterorotalids and Nonions). The relative abundance of each group was compared with the ambient physico-chemical conditions, including dissolved oxygen, organic matter, salinity and temperature. We report that the RSBF are abundant in comparatively warm and well oxygenated waters of low salinity and high energy, whereas AABF dominate low energy environment. The dissolved oxygen and seawater temperature exert a dominant control on the relative abundance of AABF, as compared to the fresh water influx induced salinity. The agglutinated foraminifera, Asterorotalids and Nonions, also dominate shallow water, low salinity regions, whereas the calcareous benthic foraminiferal abundance increases away from the riverine influx regions. We conclude that the factors associated with fresh water influx affect the distribution of benthic foraminiferal morphogroups in the northwestern Bay of Bengal and thus it can be used to reconstruct paleomosoon from BoB