Abstract

MEICHTRY DE ZABURLIN, Norma; VOGLER, Roberto Eugenio; LLANO, Victor Martín  and  MABEL MARTENS, Irmgard Sandra. Phytoplankton of the Yacyretá Reservoir (Argentina-Paraguay) after a decade from its filling. Rev. Mex. Biodiv. [online]. 2013, vol.84, n.1, pp.225-239. ISSN 2007-8706.  https://doi.org/10.7550/rmb.26831.

In this study, we analyzed the structure and dynamics of the phytoplankton of the Yacyretá Reservoir and its relationship with the main limnological variables between December 2004 and November 2005, 10 years after the filling of the reservoir. Qualitative and quantitative samples were collected at 6 sampling stations, following a longitudinal zonation criterion. Density, composition, specific richness, diversity, equitability and dominance were analyzed. During the studied period, the Yacyretá Reservoir did not present thermal stratification, and the dissolved oxygen concentration in the water column was high. Two hundred species in 9 algae classes were recorded. The number of species per sample varied between 14 and 45 taxa and the specific diversity between 1.55 y 4.61 bits. Density ranged among 66 and 10 060 ind/ml, with dominance of Cryptophyceae and Bacillariophyceae in different regions of the reservoir. An increase in the Cyanobacteria density at the begining of Autumn and at the end of Spring, mainly in the stations with longer time of permanence of water, was recorded. During the analysis period the composition and density of the phytoplankton presented a noticeable spatial and temporal variation, determined mainly by the hydrosedimentologic cycle variations.

Keywords : Paraná River; environmental variables; blooms; spatial-temporal variation.

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