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Locating Noctiluca miliaris in the Arabian Sea: An optical proxy approach

DRS at CSIR-National Institute of Oceanography

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Title Locating Noctiluca miliaris in the Arabian Sea: An optical proxy approach
 
Creator Thibodeau, P.S.
Roesler, C.S.
Drapeau, S.L.
Matondkar, S.G.P.
Goes, J.I.
Werdell, P.J.
 
Subject optical proxy
phytoplankton
bloom
upwelling
 
Description Coincident with shifting monsoon weather patterns over India, the phytoplankter Noctiluca miliaris has recently been observed to be dominating phytoplankton blooms in the northeastern Arabian Sea during the winter monsoons. Identifying the exact environmental and/or ecological conditions that favor this species has been hampered by the lack of concurrent environmental and biological observations on time and space scales relevant to ecologic and physiologic processes. We present a bio-optical proxy for N. miliaris measured on highly resolved depth scales coincident with hydrographic observations with the goal to identify conducive hydrographic conditions for the bloom. The proxy is derived from multichannel excitation chlorophyll a fluorescence and is validated with microscopy, pigment composition, and spectral absorption. Phytoplankton populations dominated by either diatoms or other dinoflagellates were additionally discerned. N. miliaris populations in full bloom were identified offshore in low-nutrient and low?N : P ratio surface waters within a narrow temperature and salinity range. These populations transitioned to high-biomass diatom-dominated coastal upwelling populations. A week later, the N. miliaris blooms were observed in declining phase, transitioning to very-low-biomass populations of non?N. miliaris dinoflagellates. There were no clear hydrographic conditions uniquely associated with the N. miliaris populations, although N. miliaris was not found in the upwelling or extremely oligotrophic waters. Taxonomic transitions were not discernible in the spatial structure of the bloom as identified by the ocean color Chl imagery, indicating that in situ observations may be necessary to resolve community structure, particularly for populations below the surface.
 
Date 2014-12-04T11:57:05Z
2014-12-04T11:57:05Z
2014
 
Type Journal Article
 
Identifier Limnology and Oceanography, vol.59(6); 2014; 2042-2056
http://drs.nio.org/drs/handle/2264/4651
 
Language en
 
Rights An edited version of this paper was published by American Society of Limnology and Oceanography. Copyright [2014] American Society of Limnology and Oceanography
 
Publisher Association for the Sciences of Limnology and Oceanography