Summary of Abstract Submission

Abstract Submission No. IO50-09-0079PresentationPoster

SEASONALITY OF NITROGEN AND CARBON STABLE ISOTOPES IN COPEPODS ALONG THE WESTERN CONTINENTAL SHELF OF INDIA

Analiza D'Souza*1, Manguesh U Gauns1, Siby Kurian1, Chandrasekhar Rao1

1 CSIR-National Institute of Oceanography, India

ABSTRACT :

Salient biogeochemical characteristics of Eastern Arabian Sea continental shelf are known to influence plankton ecology of the region. This study addresses seasonal variation of the isotopic composition in the pivotal secondary producers (copepods) of the marine food web at EASCS. Values of stable isotopes of nitrogen (δ15N) indicate copepod trophic level and carbon (δ13C) imply carbon sources. These parameters revealed distinct seasonal variations in copepods. Copepod, Acartia erythrea, showed enrichment in isotopic composition during monsoon (δ15N= 9.70, δ13C= -18.25) compared to post-monsoon (δ15N=8.26; δ13C= -19.50) and pre-monsoon (δ15N= 6.90; δ13C= -19.67 ) seasons. This seasonal divergence in δ15N and δ13C values seemed to be influenced by the seasonal shift in isotopic characteristics of the feed mostly phytoplankton. Lack of significant correlation (r2 =0.13; n=37) between δ15N and δ13C in copepods suggests a multiple carbon sources conveying omnivorous feeding behavior.