Spatiotemporal distribution of invertebrate fauna in a mesovoid shallow substratum in iron formations

Iron Formations (IF) are among the most threatened environments due to the extensive mining activities. Mesovoid Shallow Substratum (MSS) in IF represents a poorly known subterranean environment and evaluating its fauna has the potential for expanding knowledge about the distribution of troglobiotic populations. We evaluated the spatiotemporal distribution of the subterranean fauna in the MSS of IF in Brazil. We sampled the MSS invertebrate fauna and described the community patterns of troglobiotic and non-troglobiotic species. A total of 22,821 individuals and 276 morphospecies belonging to two phyla were found: Annelida and Arthropoda. Acariformes, Diptera, Hymenoptera, Blattodea, and Collembola represented 92.2% of the individuals sampled. Nine troglobiotic morphospecies belonging to four groups were sampled: Araneae (1), Entomobryomorpha (6), Poduromorpha (1), and Pseudoscorpiones (1). We found a high compositional dissimilarity of troglobiotic and non-troglobiotic species in terms of spatial β-diversity (among MSS sites) and temporal β-diversity (among months). The observed spatial β-diversity of troglobiotic species sampled in the MSS is greater than that of non-troglobiotic species. The temporal variation is similar for both groups. The richness difference component contributed more to spatial and temporal β-diversity for troglobiotic species, while higher replacement values for non-troglobiotic species were observed. Average values of temporal β-diversity and the replacement component were greater for non-troglobiotic than for troglobiotic species, while the richness difference component had an opposite pattern. The spatiotemporal β-diversity patterns suggest a medium-to-low connectivity of invertebrate populations that colonize the MSS, favoring the adoption of strategies for conserving broader areas in the context of IF.