Assessment of water quality in a pampean wetland by using epipelic diatoms

FABIANI, A. C.; ESQUIUS, K. S.; ESCALANTE, A. H.

La Plata

Congreso; VI Congreso Argentino de Limnología; 2014

Instituto de Limnología Dr. A. Ringuelet y la Facultad de Ciencias Naturales y Museo (UNLP)

The Pampa plain waterbodies undergo the impact of different human activities (agriculture, livestock, industries) that deteriorate their water quality. Diatoms constitute the most used group for the evaluation of these ecosystem environmental conditions, as they noticeably respond to physical, chemical and biological changes that take place therein. The aim of the present study was to evaluate Los Padres Lake water quality by means of epipelic diatoms. This wetland is located in one of the most important zone of fruit-horticultural production in Buenos AiresProvince, and is a Mar del Plata city key natural area, from touristic and recreational points of view. Two sites from Los Padres Lake were chosen for seasonal samplings: La Isla Club and La Tapera stream, where nautical, commercial, and camping activities are developed. In each sampling occasion the main physical and chemical parameters were in situ estimated, and sediment and water samples were collected for epipelic community analysis, and for phytoplankton chlorophyll a, and biological oxygen demand, dissolved oxygen, main ions, and nutrients determinations, respectively. Epipelon community analysis was focused on diatom qualitative and quantitative study, to be used subsequently for the Pampean Diatom Index (IDP) calculation. Diatoms constituted the most diverse and abundant group at both sites, representing more than 70% of the community composition. As IDP concerns, significant seasonal differences between sampling sites, except in spring, were registered. Values of this index in La Isla Club ranged from 1.41 to 1.67, while in La Tapera stream ranged from 1.71 to 2.11. According to this biotic characterization, La Isla Club showed good water quality, except in spring. La Tapera stream waters were acceptable (except in summer), and with a moderate organic pollution and eutrophication level. This agrees with a previous study carried out at the same stream, but applying the IDP to periphyton diatoms. Contrarily, La Isla Club, that undergoes a greater human impact, showed a better water quality during the whole annual cycle.