Caracterização limnológica e análise de comunidades bentônicas sujeitas à invasão por espécies exóticas, em lagos do Vale do Rio Doce, MG, Brasil / Limnological characterization and analysis of benthic communities subject to the invasion by exotic species in Rio Doce Valley lakes, MG, Brazil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Benthic macroinvertebrates are important components of aquatic ecosystems due to their role in the energy flow and material cycling. They have gradually received more attention in ecological studies in the last decades. The present study aimed a comparative limnological characterization of four lakes belonging to the middle Rio Doce Valley lacustrine system, MG (Águas Claras, Almécega, Verde and Carioca lakes), and the study of its benthic macroinvertebrate communities with emphasis on the taxonomical composition, spatial and temporal distribution and diversity, besides an evaluation of possible relationships with the occurrence of exotic species in the system. The lakes are located in the interplanaltic depression of Rio Doce Valley, an extense drainage web surrounded by Atlantic Forest remnants (19 DEGREES 45’ 25,7” and 19 DEGREES 53’ 11,6” South; 42 DEGREES 37’ 35,6” and 42 DEGREES 35’ 11,3” West). Samplings for physical, chemical and biological analyses were carried out in September and December 2002 and in March and June 2003. Sediment sampling for granulometric determinations and for benthic community analyses were performed with a Van Veen (337 CM POT.2 ) dredge. Considering the four lakes and the sampling seasons, 77 stations were sampled. A total of 56 taxa were identified, 2 belonging to the Mollusca, Gastropoda; 13 to Oligochaeta and 1 to the Hirudinae, Annelida; 1 to Nematoda and 41 Insecta, Arthropoda. Among the Insecta 27 taxa belonged to the family Chironomidae. The highest richness of taxa was recorded in lake Carioca (43 taxa) and the lowest in lake Águas Claras (27 taxa). Melanoides tuberculata, an invader molusc was the numerically dominant taxon in Águas Claras and Almécega lakes. In lake Verde this species ocurred in densities 5 times lower than in those lakes where its populations are already well established. This mollusc does not occur in lake Carioca. This was among the lakes studied, the one where the highjest richness of taxa was recorded and Chironomidae were the most representative benthic macroinvertebrates. There were seasonal changes in the population densities. There are also diferences regarding the taxonomic composition of the benthic community among the littoral and the limnetic regions evidencing the system compartimentalization. The sediments of lake Águas Claras, Almécega and Verde have low organic matter content in the littoral region, being classified as mineral and sandy, whereas the sediment of lake Carioca is loamy and organic. Regarding the general limnological conditions the results indicate that lake waters are slightly acidic and well oxygenated. Nutrient concentrations in the water column are relatively low. The lakes Águas Claras, Almécega and Verde can be classified as oligotrophic and lake Carioca as meso-oligotrophic.

ASSUNTO(S)

benthic community rio doce valley lakes lagos vale do rio doce comunidade bentônica chironomidae melanoides tuberculata macroinvertebrados macroinvertebrates invader species biodiversidade melanoides tuberculata biodiversity espécie invasora chironomidae

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