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Journal of Marine Biology
Volume 2012, Article ID 801248, 6 pages
http://dx.doi.org/10.1155/2012/801248
Research Article

Vertical Patterns of Early Summer Chlorophyll a Concentration in the Indian Ocean with Special Reference to the Variation of Deep Chlorophyll Maximum

1Key Laboratory of Marine Bio-Resources Sustainable Utilization, South China Sea Institute of Oceanology, CAS, Guangzhou 510301, China
2Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, CAS, Guangzhou 510160, China

Received 3 June 2012; Revised 2 July 2012; Accepted 11 July 2012

Academic Editor: E. A. Pakhomov

Copyright © 2012 Gang Li 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

Vertical patterns of early summer chlorophyll a (Chl a) concentration from the Indian Ocean are presented, as well as the variations of depth and size-fractioned Chl a in the deep chlorophyll maximum (DCM). A total of 38 stations were investigated from 12 April to 5 May 2011, with 8 discrete-depth samples (7 fixed and 1 variable at real DCM) measured at each station. Depth-integrated Chl a concentration (βˆ‘Chlπ‘Ž) varied from 11.5 to 26.8 mg mβˆ’2, whereas Chl a content at DCM ranged from 0.17 to 0.57 μg Lβˆ’1 with picophytoplankton (<3 μm) accounting for 82% to 93%. The DCM depth varied from 55.6 to 91 m and shoaled latitudinally to northward. Moreover, our results indicated that the βˆ‘Chlπ‘Ž could be underestimated by up to 9.3% with a routine sampling protocol of collecting samples only at 7 fixed depths as the real DCM was missed. The underestimation was negatively correlated to the DCM depth when it varied from 55.6 to 71.3 m (π‘Ÿ=βˆ’0.63, 𝑃<0.05) but positively correlated when it ranged from 75.8 to 91 m (π‘Ÿ=0.68, 𝑃<0.01). This indicates that in the Indian Ocean the greater the departure of the DCM from 75 m depth, the greater the underestimation of integrated Chl a concentration that could occur if the real DCM is missed.