Biodiversidade enterrada: nicho ambiental, funcional e ameaças a isópodes troglóbios

Abstract

Recently, there has been an increase in the number of troglobitic isopod (Oniscidea) new species. However, the knowledge about the ecology and threats to these organisms is incipient. Therefore, it is difficult to outline adequate measures for the conservation of this rare and sensitive fauna, since information is limited to caves of known occurrence and to the taxonomic characteristics. Accordingly, we evaluated the landscape change through satellite images from the years 1984 and 2009 at 14 ottobasins, in order to identify the threats to which Spelunconiscus troglobitic species are subject in the region of Arcos-Pains-Doresópolis. We also evaluated the mining processes registered with the National Department of Mineral Production to identify the possible impacts that the ottobasins will be subject to in medium and long term. In addition, we categorized the ottobasins in terms of impacts, in order to identify the areas that demand the most conservation efforts. Although vegetation cover has increased in 11 ottobasins, anthropic activities also increased. These, however, were more prominent upstream, posing a greater negative potential for troglobitic species. The mining processes registered show that the region is under strong mining pressure, given the application processes and mining concessions in the studied areas. Moreover, we performed a functional niche analysis of 12 Styloniscidae species to verify whether the environmental filter and phylogeny determine the functional attributes, as well as whether these are related to the microhabitats of species occurrence. Although the results have not shown a relationship from the environmental filter and phylogeny in determining the type of microhabitat and the attribute expressed by the species, it was possible to observe that those that occur in more environmentally variable microhabitats had greater functional volume. Finally, we sought to identify which environmental variables influence the genus Spelunconiscus (Oniscidea) species abundance, in addition to verifying whether they demonstrate environmental niche overlap. Among the variables analyzed, only dissolved oxygen and the distance from the travertine dams’ recharge area had an influence on species abundance. Furthermore, niche overlap between species was not observed. The generated data, although incipient, shed light on processes that structure the troglobitic isopod communities, as well as highlight the need for investments to conserve the species’ occurrence areas, as they are under strong anthropogenic pressure.