Zooplancton de una laguna pampásica (Monte) y su afluente (El Totoral): caracterización estructural en un ciclo anual

Abstract

This investigation represents the first approach to the knowledge of the zooplankton communities present in San Miguel del Monte pond and its affluent (El Totoral stream). Monthly samples were carried out from 9/97 to 8/98, obtaining duplicated samples of zooplankton in the deepest sector of the pond, in the region of its connection with other pond (Las Perdices) and in the tributary (El Totoral stream) at approximately 300 m of its outlet in San Miguel deI Monte pond. The zooplankton community of the pond, typical of an eutrophic environment, was dominated by rotifers over ciliates and crustaceans. The specific diversity ( Shannon & Weaver index), for both sectors of the pond, was similar with a maximum in late summer - autumn (2,s) coincident with a decrease of satinity. This ciliates prevailed in the stream, where important amounts of aIIocthonous organic matter and Iow dissolved oxygen concentrations area present. In spite of these stress conditions, the specific diversity was higher than those recorded in the pond with maximum values in summer-autumn (2,9). In this period, the ciliates, predominantly bacteriophagous, found optimal conditions for their development.