Structure and Diversity of stream insect assemblages applied to assessment: the Lules river (Tucumán, Argentina).

FERNÁNDEZ, H. F. ROMERO, S. COHEN AND V. MANZO

Brasil

Congreso; XXI International Congress of Entomology; 2000

Sociedad Entomológica de Brasil - EMBRAPA

The use of stream Insect Assemblages for water quality and anthropogenic impact assessment is becoming more and more important. Based on the previus knowledge of insect assessment as bionindicators stablished for the rivers of Tucumán province, we started a study on a mountain river that is going to be dammed. These data obtained befote the dam construction Hill be very valuable for the evaluation of the dam impact. Lules river ans its affluents dain approxinalety 4,200km2, with an annual flor of 6,07 m3/s. The studied segmento f the river runs through rain mountain forest (Yungas province). The sampling was carried out in 4 stations, located from 490 to 880 m, using Surber sampler with 3 replications in each station. The results of this study, obtained in the Lules drainage, showed tht the water quality using as biotic index a store – system and confirmed by physic – chemical análisis was good in all stations and seasons. Forty-five insect taxa were collected, but for the multivariate analices only 27 were used (scare and infrecuent taxa were not included). Using the Canonical Correspondense Analysis (l1 = 0,52; l2 = 0,35), all the stations grouped together except the summer and fall simples of the first stations (880m). The taxa responsable for the separation of this satation were Paragyractis sp. (Pyralidae) in summer and Thinobius sp. (Staphilinidae) in fall. The results of this study show that the summer spates have a stronger impacto in station1, wich persit through most of the fall season. For the damage on the river side, the relation spate / normal flow is also bigger in station 1. These results are also important at the moment of water quality assessment through iotic index.