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Article
Vertical Structure of the Phytoplankton Community Associated with a Coastal Plume in the Gulf of Mexico
Marine Ecology - Progress Series
  • B. Wawrik, University of South Florida St. Petersburg
  • John H. Paul, University of South Florida St. Petersburg
  • D. Griffin, United States Geological Survey
  • L. Houchin, University of South Florida St. Petersburg
  • A. Fuentes-Ortega, University of South Florida St. Petersburg
  • Frank E. Muller-Karger, University of South Florida St. Petersburg
  • L. Campbell, Texas A & M University - College Station
Document Type
Article
Publication Date
1-1-2003
Keywords
  • RubisCO,
  • gene expression,
  • Gulf of Mexico,
  • Prochlorococcus,
  • Synechococcus,
  • coastal plume,
  • recycled production,
  • microdiversity
Digital Object Identifier (DOI)
dx.doi.org/10.3354/meps251087
Disciplines
Abstract
Low salinity plumes of coastal origin are occasionally found far offshore, where they display a distinct color signature detectable by satellites. The impact of such plumes on carbon fixation and phytoplankton community structure in vertical profiles and on basin wide scales is poorly understood. On a research cruise in June 1999, ocean-color satellite-images (Sea-viewing Wide Field-of-view Sensor, SeaWiFS) were used in locating a Mississippi River plume in the eastern Gulf of Mexico. Profiles sampled within and outside of the plume were analyzed using flow cytometry, HPLC pigment analysis and primary production using C-14 incorporation. Additionally, RubisCO large subunit (rbcL) gene expression was measured by hybridization of extracted RNA using 3 full-length RNA gene probes specific for individual phytoplankton clades. We also used a combination of RT-PCR/PCR and TA cloning in order to generate cDNA and DNA rbcL clone libraries from samples taken in the plume. Primary productivity was greatest in the low salinity surface layer of the plume. The plume was also associated with high Synechococcus counts and a strong peak in Form IA rbcL expression. Form IB rbcL (green algal) mRNA was abundant at the subsurface chlorophyll maximum (SCM), whereas Form ID rbcL (chromophytic) expression showed little vertical structure. Phylogenetic analysis of cDNA libraries demonstrated the presence of Form IA rbcL Synechococcus phylotypes in the plume. Below the plume, 2 spatially separated and genetically distinct rbcL clades of Prochlorococcus were observed. This indicated the presence of the high- and low-light adapted clades of Prochlorococcus. A large and very diverse clade of Prymnesiophytes was distributed throughout the water column, whereas a clade of closely related prasinophytes may have dominated at the SCM. These data indicate that the Mississippi river plume may dramatically alter the surface picoplankton composition of the Gulf of Mexico, with Synechococcus displacing Prochlorococcus in the surface waters.
Citation / Publisher Attribution

Marine Ecology - Progress Series, v. 251, p. 87-101.

Citation Information
B. Wawrik, John H. Paul, D. Griffin, L. Houchin, et al.. "Vertical Structure of the Phytoplankton Community Associated with a Coastal Plume in the Gulf of Mexico" Marine Ecology - Progress Series Vol. 251 (2003) p. 87 - 101
Available at: http://works.bepress.com/john_paul/4/