LAGUNAS PERIURBANAS DE CORRIENTES (ARGENTINA): DE LA MESOTROFIA A LA EUTROFIA UN CAMINO DE IDA Y VUELTA EN 20 AÑOS

POI DE NEIFF, A. S.G.; CASCO, S. L.; NEIFF, J. J.; CARNEVALI, R.P.; GALLARDO, L. I.

Biología Acuática

Cristina Claps

Año: 2016 vol. 31 p. 1 - 9

1668-4869

More than 50,000 sub-rounded shallow lakes are found on sandy hills fed by rain inCorrientes Province. We selected two lakes near Saladas city as representative of the wetlandsprevailing in the region. The aim of this study is to describe the changes in the ecological state ofSoto and Sánches lakes, from the use of the basin and recurrence of wet and dry periods. Thirty nonperiodic samplings were carried out in each lake between 1992 and 2014, during years with differentrainfall regime. According to the annual precipitation we distinguish three periods: 1992-1999 (withhigh rainfalls); 2000-2010 (with prolonged droughts) and 2011-2014 (with heavy rains concentratedin 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 newneighborhood. The high ratio depth/depth of the photic zone indicates the state of turbid waterwith dominance of cyanobacteria and high mean and maximum chlorophyll a. After operation ofthe treatment plant sewage, Soto Lake became characterized as mesotrophic during the dry periodand subsequently oligotrophic. During the study period, Sánches Lake had clear water with a highphosphorus concentration, but it had a single bloom of cyanobacteria in the last period. In lakes fedby rain, long-term studies that include dry and wet periods allow for more accurate diagnosis of theecological state. The use of different indicators, besides the nutrient content is recommended todetermine the trophic state.