Journal of Environmental Biology

Changes in nutrients ratio along the central Bay of Bengal coast and its influence on chlorophyll distribution

T. Thangaradjou¹*, R.K. Sarangi², R. Shanthi¹, D. Poornima¹, K. Raja¹, A. Saravanakumar¹ and S.T. Balasubramanian¹

¹Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Annamalai University, Parangipettai-608 502, India

²Marine Biology Division, Marine, Earth and Planetary Sciences Group, Space Application Centre, Ahmedabad - 380 015, India

*Corresponding Author E-mail : umaradjou@gmail.com

Publication Data

Paper received:

12 December 2012

Revised received:

16 May 2013

Re-Revised received:

15 July 2013

Accepted:

19 August 2013

Abstract

Elemental ratio of nutrients and its influence on chlorophyll a distribution was studied along the central coast of Bay of Bengal using multivariate statistical methods. High chlorophyll concentration was observed during summer (1.81 ?gl^-1) and premonsoon (1.95 ?gl^-1), however, it was high in top 20m during premonsoon season in tandem with high nitrate (N) and silicate (Si) concentration.? N:P (phosphate) ratio was less than Redfield ratio (16:1) during all seasons, indicating the Bay of Bengal as nitrate limited and confirmed the results of Principal Component Analysis (PCA) with positive loading and multiple regression analysis showing negative correlation between this ratio and chlorophyll concentration during all seasons.? Whereas, N:Si ratio was <1 and Si:P ratio >7 in top 20 m during all seasons explained the deficiency of phosphorus and enrichment of silicate in the central Bay of Bengal.? Regression analysis between Si:P and N:Si ratios with chlorophyll showed negative correlation during premonsoon and summer respectively.? Thus, the present results confirmed that nutrient molar ratios such as N:P<16; Si:P>7 and N:Si<1 was indicative of a potential N and Si limitation and are the primary limiting nutrients in the central Bay of Bengal in determining chlorophyll concentration. ?

 Key words

Chlorophyll, Multiple regression, Nutrient ratio, Principal component analysis 

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