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Marine Ecology Progress Series

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MEPS 461:31-46 (2012)  -  DOI:

Temporal dynamics of carbon flow through the microbial plankton community in a coastal upwelling system off northern Baja California, Mexico

Lorena Linacre1, 2,*, Michael R. Landry3, Ramón Cajal-Medrano4, J. Rubén Lara-Lara5, J. Martín Hernández-Ayón6, Rosa R. Mouriño-Pérez2, Ernesto García-Mendoza5, Carmen Bazán-Guzmán5

1Programa de Doctorado en Oceanografía Costera, Facultad de Ciencias Marinas/Instituto de Investigaciones Oceanológicas,
4Facultad de Ciencias Marinas, and 6Instituto de Investigaciones Oceanológicas; Universidad Autónoma de Baja California (UABC), Ensenada, Baja California 22860, Mexico
2Departamento de Microbiología, División de Biología Experimental y Aplicada, and
5Departamento de Oceanografía Biológica, División de Oceanología; Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Baja California 22860, Mexico
3Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093-0227, USA

ABSTRACT: We investigated the temporal dynamics of carbon flow through the microbial food web of a coastal upwelling system (ENSENADA station) off northern Baja California during 6 cruises (September 2007 to November 2008). Carbon biomass assessments for major autotrophic size groups (pico- to micro-sized cells) and their microzooplankton grazers were based on analyses using flow cytometry, HPLC pigments and epifluorescence microscopy. Taxon-specific phytoplankton growth and microzooplankton grazing rates were determined from 24 h in situ incubations in the euphotic zone using an abbreviated 3-treatment dilution technique. Carbon biomass and instantaneous growth and grazing rate determinations were used to estimate daily rates of taxon-specific production and losses due to microzooplankton grazing. Overall, microbial biomass showed a close balance between autotrophic and heterotrophic components, except during a period of very strong upwelling (April 2008), which favored large phytoplankters and high primary production. Throughout a wide range of environmental conditions, the community primary production (PP) attributed both to small (mostly picophytoplankton and prasinophytes) and large (mostly diatoms and autotrophic dinoflagellates) autotrophs was significantly grazed (78 ± 9% of PP) by small (<20 µm) and large (>20 µm) ciliates and flagellates (including mixotrophic dinoflagellates), respectively, showing complementary temporal shifts in protistan grazer types that matched the dominant phytoplankton. While large diatoms were strongly consumed by large ciliates during the 2 most productive periods (September 2007 and April 2008), pico- and nano-sized phytoplankton were grazed most by nanoflagellates and small ciliates from November 2007 to January 2008. Consequently, biogenic carbon production in this ecosystem is transferred through a multivorous food web.

KEY WORDS: Biogenic carbon flow · Multivorous food web · Phytoplankton growth rate · Phytoplankton grazing rate · Primary production

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Cite this article as: Linacre L, Landry MR, Cajal-Medrano R, Lara-Lara JR and others (2012) Temporal dynamics of carbon flow through the microbial plankton community in a coastal upwelling system off northern Baja California, Mexico. Mar Ecol Prog Ser 461:31-46.

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