Fatores que governam as assembleias de macroinvertebrados bentônicos em nascentes tropicais de áreas protegidas

Abstract

Springs are known as relatively stable ecosystems characterized by specific environmental conditions that differ them from all other aquatic environments. They are constituted by three large ecotones that occur at the interface between surface water, groundwater and the terrestrial ecosystem, resulting in a series of micro-habitats that sustain a high species richness. Springs are an ideal place to examine the relationships between faunistic communities and the environmental parameters that influence their distribution, but the understanding of these relationships is still poorly known. Studies of the fauna of the springs of tropical regions are still sparse, being mostly concentrated in temperate and alpine zones. The objective of this work was to examine the influence of environmental and spatial variables on the distribution of benthic fauna, also evaluating the habitat complexity represented by the three types of springs (Helocrene, Limnocrene and Rheocrene) on the composition of macroinvertebrate assemblages. Three samples composed of substrate (stone, sand and foliage) were obtained in twenty one springs of three Conservation Units of the state of Minas Gerais, Brazil. A total of 19.373 specimens were identified and the group of insects showed more abundance in relation to non-insects. The results of the partial redundancy analysis showed that both environmental variables and spatial variables were essential for structuring the benthic fauna of the springs studied. The composition of the benthic fauna also differed between the Rheocrene, Helocrene and Limnocrene springs and between the conservation units. The heterogeneity of micro-habitats present in the different types of springs exerts a strong influence on the structure of macroinvertebrate fauna, resulting in a diverse fauna. It is concluded that the environmental and spatial variables are of great importance for the structuring of the fauna jointly with the variety of micro-habitats present in the different types of springs and their preservation becomes essential, because the loss of any of these habitats can affect regional biodiversity.