Ecologic Role and Distribution Patterns of Heterotrophic Planktonic Community

Project Description
Ecologic Role and Distribution Patterns of the Heterotrophic
Planktonic Community from the Rio de la Plata Estuary, Southwestern
Atlantic and Antarctic

During the years 2002 to 2004,we plan to study the ecological role of
nano- and microplanktonic heterotrophic protists (flagellates,
ciliates, dinoflagellates, radiolarians and foraminifers) in
association with picoplanktonic components in the Southwestern
Atlantic (including the Atlantic Sector of the Antarctic Ocean, the
Argentine Sea, and the Rio de la Plata estuary), analyzing the main
specific associations, their distribution patterns and their
relationships with biotic and abiotic environmental
parameters. Materials for this survey, largely available already, are
collected from the icebreaker "Almirante Irizar" (Direccion Nacional
del Antartico; Argentine Sea and Antarctic Ocean), and the BIP
"Capitan Canepa" (Instituto Nacional de Investigacion y Desarrollo
Pesquero; Rio de la Plata estuary) by means of continuous pump and
discrete bottle samplings during the summers of 1999 through 2003. At
oceanographic stations, located at 30ft. intervals, but with a lower
spacing in areas of steep environmental gradients (as indicated by
variables measured continuously or semi-continuously, mainly
temperature and fluorometry), two series of samples will be collected:
one aimed at measurementes of temperature, salinity, nutrients, pico-
and nanoplankton, and the second for studies of the
microzooplankton. Preservation of these materials will follow
different protocols, according to the purpose of the sample (taxonomic
identifications, cell counts, etc.). Through epifluorescence
techniques we will emphasize the analysis of the specific composition
and the numerical abundance of one of the least known size fractions
in this area: the nanozooplankton, including its trophic affinities
and factors that favor mixotrophy.

Microzooplankton will be examined and counted under the inverted
microscope using the Utherm?l method. Situ-derived information,
complemented with laboratory grazing experments, will furnish an
integrated picture of the structure and dynamics of the
microheterotrophic plankton that contributes to the "biological pump"
in the area.

Espanol:
Nombre del Proyecto: Rol ecologico y patrones distributivos de la
comunidad heterotrofica microbiana planctonica del estuario del Rio de
la Plata, Atlantico Sudoccidental y Antartico. (Proyecto en
colaboracion con Universidad de Buenos Aires)

Director: Dra. Viviana Andrea Alder
Co-Director: Dr. Demetrio Boltovskoy
E-mails: viviana@bg.fcen.uba.ar / demetrio@bg.fcen.uba.ar

Resumen del Proyecto: Se estudiara el rol ecologico de los protozoos
heterotroficos nano y microplanctonicos en relacion con los
componentes picoplanctonicos del Atlantico Sudoccidental y Antartico,
analizando sus asociaciones especificas, sus patrones distributivos y
sus dependencias de los parametros bioticos y abioticos. El material,
en gran parte ya disponible, es colectado por los buques "Almirante
Irizar" (DNA; Mar Argentino y Oceano Antartico) y BIP "Capitan Canepa"
(INIDEP; estuario del Rio de la Plata) mediante muestreos continuos
con bomba de succion y con botellas oceanograficas, durante los
veranos 1999 a 2003. En cada estacion oceanografica se colectaran dos
series de muestras, que seran preservadas segun diferentes protocolos:
la primera destinada para las determinaciones de salinidad,
nutrientes, pico y nanoplancton, y la segunda para el estudio de la
fraccion microzooplanctonica. Mediante la aplicacion de t?cnicas de
epifluorescencia se realizara la evaluacion numerica del
nanozooplancton, incluyendo el estudio de sus afinidades troficas y de
los factores que favorecen la mixotrofia. El microzooplancton sera
cuantificado bajo microscopio invertido (tecnica de Uthermol).

La informacion obtenida in situ, sera complementada con experimentos
de pastoreo en laboratorio, aportando una vision integral de la
estructura y dinamica de los componentes microheterotroficos
planctonicos que contribuyen a la "bomba biologica" en el area.

Duracion: 2002 - 2004