Table of Contents
International Journal of Oceanography
Volume 2013 (2013), Article ID 350465, 8 pages
http://dx.doi.org/10.1155/2013/350465
Research Article

Occurrence of Nitrogen Fixing Cyanobacterium Trichodesmium under Elevated pCO2 Conditions in the Western Bay of Bengal

1National Centre for Antarctic & Ocean Research, Headland Sada, Goa 403 804, India
2Ministry of Earth Sciences, Prithvi Bhavan, New Delhi 110 003, India

Received 6 March 2013; Revised 9 June 2013; Accepted 15 June 2013

Academic Editor: Lakshmi Kantha

Copyright © 2013 Suhas Shetye et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Recent studies on the diazotrophic cyanobacterium Trichodesmium showed that increasing CO2 partial pressure (pCO2) enhances N2 fixation and growth. We studied the in situ and satellite-derived environmental parameters within and outside a Trichodesmium bloom in the western coastal Bay of Bengal (BoB) during the spring intermonsoon 2009. Here we show that the single most important nitrogen fixer in today’s ocean, Trichodesmium erythraeum, is strongly abundant in high (≥300 μatm) pCO2 concentrations. N : P ratios almost doubled (~10) at high pCO2 region. This could enhance the productivity of N-limited BoB and increase the biological carbon sequestration. We also report presence of an oxygen minimum zone at Thamnapatnam. Earlier studies have been carried out using lab cultures, showing the increase in growth rate of T. erythraeum under elevated pCO2 conditions, but to our knowledge, this study is the first to report that in natural environment also T. erythraeum prefers blooming in high pCO2 concentrations. The observed CO2 sensitivity of T. erythraeum could thereby provide a strong negative feedback to rising atmospheric CO2 but would also drive towards phosphorus limitation in a future high CO2 world.