Lagunas periurbanas de Corrientes Argentina : de la mesotrofia a la eutrofia un camino de ida y vuelta en 20 años
Fecha
2016Autor
Poi, Alicia Susana Guadalupe
Casco, Sylvina Lorena
Neiff, Juan José
Carnevali, Romina Patricia
Gallardo, Luciana Irene
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More than 50,000 sub-rounded shallow lakes fed by rain are found on sandy hills
fed by rain in Corrientes Province. We selected two lakes near Saladas city as representative of
the wetlands prevailing in the region. The aim of this study is to describe the changes in the
ecological state of Soto and Sánches lakes, from the use of the basin and recurrence of wet and
dry periods. Thirty non periodic samplings were carried out in each lake between 1992 and 2014,
during years with different rainfall regime. According to the annual precipitation we distinguish
three periods: 1992-1999 (with high rainfalls); 2000-2010 (with prolonged droughts) and 2011-2014
(with heavy rains concentrated in autumn and spring). At both lakes the aquatic plant volume
infested differed over the years. In the first period, Soto Lake became eutrophic due to illegal
sewage connections from a new neighborhood. The high ratio depth/depth of the photic zone
indicates the state of turbid water with dominance of cyanobacteria and high mean and
maximum chlorophyll a. After operation of the treatment plant sewage, Soto Lake became
characterized as mesotrophic during the dry period and subsequently oligotrophic. During the
study period, Sánches Lake had clear water with a high phosphorus concentration, but it had a
single bloom of cyanobacteria in the last period. In lakes fed by rain, long-term studies that include
dry and wet periods allow for more accurate diagnosis of the ecological state. The use of different
indicators, besides the nutrient content is recommended to determine the trophic state. En el paisaje de la Provincia de Corrientes se destacan numerosos cursos de agua orientados con rumbo NE-SO que drenan grandes regiones de esteros y son tributarios del río Paraná. Las lomadas arenosas que los confinan están cribadas por numerosas lagunas pequeñas (< 500 ha) y sub-redondeadas alimentadas por lluvias. La mayoría de ellas tienen baja salinidad, pH variable, buena disponibilidad de oxígeno disuelto en el agua, baja concentración de nitrógeno total y aguas transparentes colonizadas por vegetación sumergida y palustre (Poi y Galassi, 2013).
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