Summary of Abstract Submission

Abstract Submission No. IO50-09-0016PresentationOral

SURFACE PHYTOPLANKTON IN THE INDIAN OCEAN: COMPARING NORTHERN AND SOUTHERN HEMISPHERE COMMUNITIES

Ravidas K. Naik*1, Jenson George2, Melena Soares1, Anilkumar N1

1 ESSO-National Centre for Antarctic and Ocean Research, Goa, 40, India
2 ESSO- National Institute of Ocean Technology , Chennai, 600100, India, India

ABSTRACT :

Phytoplankton, play an important role in key biogeochemical processes that are linked to higher tropic levels and climate variability. Knowledge of qualitative and quantitative distribution of phytoplankton is essential in understanding the biological response to climate variability. The present study focuses on the phytoplankton biogeography with respect to environmental variables in the Indian Ocean. The surface water phytoplankton community based on microscopy coupled with diagnostic pigment indices showed marked variation in community structure from tropical to polar latitudes of the Indian Ocean. The study areas were selected along the latitudinal transect between 3oN and 53oS (northern Indian Ocean to Indian Ocean sector of Southern Ocean). The Prokaryotic diagnostic pigment (ProkDP) dominated in the Equatorial and South Equatorial regions, the Flagellate diagnostic pigment (FlagDP) in the North Equatorial region, Southern Tropical Indian Ocean and Sub-tropical Front (STF) region whereas, the Diatom diagnostic pigment (DiatDP) dominanated only at the Polar Front (PF) region. Canonical Correspondence Analysis (CCA) of the dominant phytoplankton groups revealed that the contrasting community structure observed in the STF and PF regions of the Indian Ocean sector of Southern Ocean is governed by distinct physico-chemical features of the respective region. The influence of a suite of environmental variables - temperature, nutrients, salinity and mixed layer depth (MLD), on the dominant phytoplankton groups at the STF and PF was observed. This work has important implications to understand the shifts in biological response of the communities, ultimately resulting in the community-dependent sinking potential of atmospheric CO2.