DISTRIBUTION AND OCCURRENCE OF BENTHIC MACROINVERTEBRATES IN RIVERS WITH RICE CULTURE AREA IN ITAJAÍ VALLEY - SC

Abstract

Rice is one of the main cereals grown in Brazil. The discharge of the rice culture may impact the river. The main goal of this research was to evaluate the distribution and occurrence of benthic macroinvertebrates in rivers with rice plantations. This research was developed in Gaspar and Agrolândia, in Itajaí River Basin, Santa Catarina. In Gaspar, macroinvertebrate data and environmental information were collected quarterly, in August/04, November/04 and Febrary/05. In Agrolândia, they were also collected quarterly in October/04, January/05 and April/05. Benthic macroinvertebrates samples were collected using Surber. The macroinvertebrates were identified at family level. Diversity was estimated using Shannon Index, Margalef and Evenness. To compare the diversity among these sites, T Student Test was used. Richness and Dominance were also determinated. 21.831 organisms were collected at the six sites. 73% were Diptera with predominance of Chironomidae family with 14.956 individuals. Site 4 had the lowest diversity and the highest dominance. Rivers under influence of the rice culture it is observed predominance of taxons resistant to pollution. Taxons more sensitive to pollution were hardly found at the six sites, demonstrating the inappropriate conditions for their development.