RICHNESS, ABUNDANCE AND DIVERSITY OF BENTHIC MACROINVERTEBRATES FROM WETLANDS OF THE SOUTH AREA OF LAGUNAS DE GUANACACHE SYSTEM, SAN LUIS, ARGENTINA

COLOMBETTI P.L.; ALVAREZ, A.; JOFRE M. B.

Merlo, San Luis

Jornada; XXXV Reunión científica anual de la Sociedad de Biología de Cuyo; 2017

Sociedad de Biología de Cuyo

The wetland system Guanacache-Desaguadero-Salinas del Bebedero is part of the RAMSAR site "Lagunas de Guanacache", and its southern part suffers from growing anthropogenic impacts and risk of desertification. The objective of this study was to measure richness, abundance and diversity of benthic macroinvertebrates, in sampling points located in Desaguadero River, and at the lagoon and marshlands of Bebedero, which are included in the south portion of this wetland in San Luis. Samples of macroinvertebrates were collected using a 300 μm D net, in six points, during high water (HW) and low water (LW) periods. Collected samples were fixed in 70% ethanol and analyzed until reaching the highest possible taxonomic level, using a stereoscopic magnifier. Richness, abundance and Shannon-Wielner´s (SW) diversity were calculated. A total of 199020 individuals were quantified, and richness varied between 9 and 20 taxa. Most abundant families were Hibrobiidae (62.6% both periods) and Ceratopogonidae (27.1% HW, 16% LW). Significant differences in abundance were shown between both, sites and periods: site 4 in Desaguadero showed the highest abundance (62238 organisms during LW) and the highest variation between periods, in both, abundance (80% reduction in HW compared to LW) and richness. All the sampling points showed variations in diversity between periods; sites with the highest diversity were Desaguadero during HW (SW=1.98) and Bebedero stream during LW (SW=1.64). These results contribute to the knowledge of this poorly studied ecosystem´s fauna, and will allow, along with physical-chemical variables and evaluation of riparian state, an assessment of its environmental quality.