Descripción ambiental de la Laguna de Lobos, pcia. Bs.As. Una propuesta para su monitoreo

Abstract

Periodic hydrologic and ecological alterations in the Lobos’s shallow lake in the last few years and concern and interest of intitutions and authorities, which both value the preservation of the place as a touristic, recreative and sportive resource, have motivated the implementation of the Program of permamanent surveillance of environmental quality of Lobos’s shallow lake . This programe includes low budget and of concrete implementation initiatives using local resources for evaluating the dynamic together with the shallow lake’s environmental quality and its main afluent, Las Garzas’s stream, in a continuous period of time. This study has been carreid out in a framework which has as a main objective to periodically analyze this shallow lake and its afluent’s most significant limnologic variables and to detect any system’s alteration caused by the conjuction of environmental and/or climatic unfavorable conditions or local or regional environmental impacts of diverse origins (industrial, from sewers, or from farming activity). Seventeen samplings have been developed from January of 2000 until September of 2008 in two different areas of study: First Area: Las Garzas Stream and drainage channels, with 4 stations of sampling next to industrial and cattle areas; Second Area: Lobos’s shallow lake, with 4 stations of sampling of hydrologic interest. In each stage of the sampling, the deep, turbidity, pH, temperature and dissolved oxygen was registered and samples of fytoplankton for its cualitative and quantitative analysis were taken. In the First Area, in March of 2001, February of 2004 and Spetember of 2008 samplings show that the unload of efluents have afected the quality of the water of Las Garzas’s stream. Limonologic characteristics of the Second Area show a close relation whit season variables and, in general, the water presented conditions that can be adapted to recreative use. The death of fishes occurred in March of 2000, January of 2001 and July of 2006 coincide with the low levels of oxygen dissolved in the water, high temperatures in relation with the avareage and the amount of algaes (more than 50000 cells/ml) dominated by cyanophytes. The analysis of hydrologic and biologic variables of this shallow lake and its afluent have allowed to achieve periodic observations of this hydric environment, know its dynamic and detect the causes of ecological alterations in the environment. Besides, it has provided with new tools to fund new decisions taken regarding to the managing of the shallow lake.