Abstract

TORO CASTANO, Daniel Ricardo et al. LIMNOLOGIC STUDY OF THE BLACK LAGOON. BUFFER ZONE AT THE NATIONAL NATURAL SNOW-COVERED MOUNTAINS PARK. Bol. Cient. Mus. Hist. Nat. Univ. Caldas [online]. 2012, vol.16, n.2, pp.23-38. ISSN 0123-3068.

The Black Lagoon located in the buffer zone of Nevado del Ruiz at 3,853 m.a.s.l., is a glacial lake of volcanic origin located at the side of the road to the National Natural Snow-covered Mountains Park which is a touristic symbol and source of water for the region. For several years now, it has been showing a significant reduction of water in its water miror which makes its study imperative before it disappears. The purpose of this limnological research was to describe the morphology, wealth and abundance of riparian vegetation and plankton community, water quality, microorganisms and their relation with physical-chemical variables. Two sampling campaigns were carried out: the first in of October 2009 (rainy period) and the second in March 2010 (dry period). Systematic sampling was conducted for the water study by dividing the lagoon into nine quadrants, sampling both on surface and in depth (1m). Water samples were taken for observation of plankton, physical-chemical and bacteriological parameter analysis. A bathymetric study of the lagoon was carried out and it was found that the lagoon has an area of 950 m², an average depth of 1.0 m and a maximum depth of 1.8 m. It was found that specially Carex sp. progress on the lagoon reducing the water mirror area. To study their variations and numerical relationships in two hydrological cycles, the physical-chemical and biological results in each quadrant were analyzed both in surface and in depth for either, the first and the second sampling and no significant differences were found between the sampled sites (P= 0.524 and between the samples P =0.1973). The one-way ANOVA analysis between quadrants did not show significant differences. In the first sampling fecal coliforms were found exceeding permitted standards which makes water non-consumable for human consumption without previous treatment.

Keywords : Limnology; physical-chemical parameters; plankton; water quality; Black Lagoon; moor.

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