Complexidade e heterogeneidade de hábitats em diferentes escalas : efeitos e influências sobre a comunidade de Chironomidae da planície de inundação do alto rio Paraná.

Abstract

Habitat structure plays a decisive role on aquatic communities. The habitat heterogeneity, provided by aquatic macrophytes, is considered an important factor influencing the invertebrate community. Macrophytes create several patches in diffrent sizes and scales, with wide range diversity of micro-habitats and micro-environmental conditions that influence the interactions and community structure. This can be especially important for organisms such as Chironomidae larvae. These insects have ample food and environmental plasticity and contain species adapted to colonize large variety of habitats. This study aimed at exploring the Chironomidae community associated to habitats with different architectures, complexity and heterogeneity and investigate variations in its community structure (composition, distribution and diversity) in different scales and dimensions. Monthly samplings of Chironomidae larvae associated to macrophytes and submerged branches were performed from August 2007 to July 2008, in different environments of the upper Paraná River floodplain. Chironomidae larvae were identified to the lowest possible level. Predominant taxa were Ablabesmyia (Karelia), Polypedilum spp. and Tanytarsus spp. All the attributes of the Chironomidae community were different according to the different habitats complexities. Structure of macrophytes stands also influenced the density, richness and community composition. The differences in density, diversity and composition were greater at microscale than in meso- and macro-scales. Nevertheless, temporal differences were most affected by environmental characteristics than by the structure and complexity of the habitats.