No abstract

The subterranean environment harbors species that are not capable of establishing populations in the epigean environment, i.e., the obligatory subterranean species. These organisms live in a unique selective regime in permanent darkness and usually low food availability, high air humidity in terrestrial habitats, and low temperature range allied to other unique conditions related to lithologies and past climatic influences. The pressure to increase Brazil’s economic growth relies on agricultural/pastoral industries and exporting of raw materials such as iron, limestone, ethanol, soybean, cotton, and meat, as well as huge reservoir constructions to generate electricity. Mining (even on a small scale), agricultural expansion, and hydroelectric projects are extremely harmful to subterranean biodiversity, via the modification and even destruction of hypogean habitats. The Brazilian subterranean species were analyzed with respect to their distributions, presence on the IUCN Red List, and current and potential threats to hypogean habitats. A map and three lists are presented, one with the described obligatory subterranean species, one with undescribed taxa, and one with the current and potential threats to the hypogean environment. To date, 150 obligatory subterranean species have been recorded in Brazil, plus at least 156 undescribed troglomorphic taxa, totaling 306 Brazilian troglobites/obligatory cave fauna. We also analyzed the current and potential cave threats and the conservation actions that are underway to attempt to compensate for loss of these habitats. In according to the Brazilian legislation (Decree 6640) only caves of maximum relevance are fully protected. One strategy to protect the subterranean fauna of Brazil is the inclusion of these species in the IUCN Red List (one of attributes that determines maximum relevance for caves); however, one of the IUCN assumptions is that the taxa must be formally described. It is clear that the description and proposed protection of Brazilian subterranean biodiversity depends on more systematics studies.

Subterranean environments, even though they do not possess a primary production (photosynthesis), may present high biodiversity, faunistic originality, endemism, phylogenetic isolations and unique ecological and/or evolution events, in addition to rare taxa. Studies investigating the biological diversity in Neotropical caves are relatively rare and recent, and most of them have been conducted in Brazil. We sampled caves from the state of Bahia, northeastern Brazil, and through sampling sufficiency tests and richness estimators, we demonstrate that the normatization for the Brazilian cave laws is not adequate for its conservation and that only α diversity index is not enough to verify faunistic patterns. We suggest that a phylogenetic diversity index be more robust and accurate for conservation purposes, particularly the Taxonomic Distinctness index. Moreover, we propose that the sandstone complex caves from Chapada Diamantina National Park need to be classified as being of high subterranean biodiversity in a global scope.

ABSTRACT. Quadrat sampling is a method used for a long time in plant ecology studies but only recently it has been used with focus on fauna. For the cave fauna samplings, there are rare works applying this methodology. The present study compared the methods of quadrat sampling with direct search qualitative for terrestrial cave fauna. For this, we conducted five sampling collections in a limestone cave in central Brazil. Quadrat sampling contributed with 121 exclusive species and 716 specimens and direct search qualitative method contributed with 91 exclusive species and 355 specimens. Mann-Whitney test evidenced significant differences between the two methods. We demonstrated that quadrat sampling method was slightly more efficient to analyze the species richness and much more effective to assess the abundance than the use of only direct search qualitative method, mainly considering tiny and/or cryptobiotic invertebrates (e.g., earth worms, symphylans, psocopterans, trichopterans, dipterans, small spiders, and small isopods). We recommend the association of different methods to test patterns in cave fauna, since incomplete sampling may lead to erroneous estimates and equivocated decisions about management, impact studies and cave conservation. A eficácia do método de amostragem por quadrados em levantamentos da fauna terrestre cavernícola -um estudo de caso em uma caverna Neotropical RESUMO. Amostragem por quadrados é um método utilizado há muito tempo em estudos ecológicos botânicos e apenas recentemente tem sido utilizado com foco em estudos faunísticos. Para amostragens em cavernas, raros trabalhos aplicaram esta metodologia. Nosso trabalho compara o método de amostragem por quadrados com o de busca ativa qualitativa sobre a fauna cavernícola terrestre. Para tal, realizamos cinco eventos de coleta em uma caverna calcária do Brasil central. A amostragem, utilizando o método de quadrados, contribuiu com 121 espécies exclusivas e 716 espécimes. O método de busca ativa contribuiu com 91 espécies exclusivas e 355 espécimes. O teste de Mann-Whitney mostrou diferenças significativas entre os dois métodos. Demonstramos que o método de amostragem de quadrados foi sutilmente mais eficiente para acessar a riqueza de espécies e muito mais efetivo para acessar a abundância do que apenas a utilização do método qualitativo de busca ativa, principalmente para invertebrados diminutos e/ou criptobióticos (por exemplo, vermes, sínfilos, psocópteros, tricópteros, dípteros, pequenas aranhas e pequenos isópodes). Recomendamos o uso de métodos combinados para o teste de padrões da fauna cavernícola, uma vez que amostragens incompletas podem levar a estimativas erradas e decisões equivocadas acerca de manejo, estudos de impacto e conservação de cavernas.Palavras-chave: fauna cavernícola, invertebrados terrestres, Brasil central, metodologia de amostragem.