Microzooplankton community in the Chubut River Estuary, Argentina

BARRÍA DE CAO, M.S.; PERILLO, G.M.E.; PEREZ, D.E.; PICCOLO, M.C.; HEBLING, W.E.

Bahía Blanca

Congreso; ECSA 44: SCIENCE AND MANAGEMENT OF ESTUARIES AND COASTS: A TALE OF TWO HEMISPHERES; 2008

Estuarine Coastal Science Association-Instituto Argentino de Oceanografía

Species composition, abundance and seasonal variation of microzooplankton (20-200 μm) from the Chubut River Estuary werestudied from samples collected during a year (July 2006 to June 2007) in different tidal conditions. The estuary is as salt wedgesystem in high tide and well-mixed freshwater at low tide. This is the first report on the microzooplankton from the area. Enumerationof the organisms was done with an inverted microscope following the Utermhöl´s method. Surface temperature, salinity, nutrienchlorophyll “a” and phaeopigments were measured simultaneously with the sampling. The microzooplankton community wascharacterized by ciliates, thecamebians, foraminifers, rotifers and nauplii. During strong fluvial influence (salinity: 0.6 to 18), the totalmicrozooplankton abundance ranged from 60 to 600 individuals l-1. Ciliates were the most abundant group in winter, comprising59.6 % of the total microzooplankton abundance, while thecamebians dominated during summer (89 %). Under marine influence(salinity: >18 to 32), the total abundance ranged from 40 to 500 ind. l-1 and the most conspicuous group were the ciliates,comprising 82.6 % of the total abundance during winter, and 76 % during autumn. Salinity changes did not influence themicrozooplankton abundance, but species composition was highly dependent on salinity.