<b>Effectiveness of quadrat sampling on terrestrial cave fauna survey - a case study in a Neotropical cave

Abstract

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.

Terrestrial fauna of the largest granitic cave from Southern Hemisphere, southeastern Brazil: A neglected habitat

“…This affirmation is corroborated by estimators values observed at Figure 7, allied to the intermediary values of singletons and doubletons, which represent the occurrence of only one (single) or two (double) individuals in all samplings. Gallão and Bichuette (2015) and Bichuette et al (2015), studying sandstone and limestone caves, respectively, stressed this question and proposed the necessity of replicas on subterranean studies to discuss any distribution and diversity pattern, since they are related to intrinsic temporal variations (Trajano, 2013). The spatial and temporal distribution of cave fauna is influenced by several factors which presents variation in their occurrence, such as patches of vegetable organic matter, guano, concentration of prey (Trajano, 2013), allied to the desiccation of surface habitats in climatic marked regions (in this case, cave habitats operate as seasonal shelters).…”

“…Samplings were carried out by direct search qualitative method, i.e., to search for fauna in potential areas for their occurrence (Weinstein and Slaney, 1995;Bichuette et al, 2015), in the available substrates: rocky, rocky with litter, unconsolidated sediment (sand and clay), litter, unconsolidated sediment and litter. In total, we sampled 110 hours by each collector in all samplings, since three people along 3-4 days per occasion formed the team.…”

An important site for conservation of bats in Brazil: Passa Três cave, São Domingos karst area, with an updated checklist for Distrito Federal (DF) and Goiás state

“…of 17,000 recorded caves (CECAV 2018) and a potential to 100,000 according to Auler et al (2001), and most of this heritage is under threat by mining and other huge economic purposes, such as hydro electrical projects. The São Domingos karst area, Goiás state, central Brazil, is characterized by the presence of huge cave systems crossed by allochthonous streams, with large amounts of organic matter available for cave organisms, supporting rich aquatic and terrestrial communities (e.g., Bichuette and Trajano 2003, Simões et al 2013, Bichuette et al 2015. It is the second most intensively surveyed Brazilian karst area after the Alto Ribeira, but so far no comprehensive study on the bat communities from these caves has been undertaken.…”

Influence of substrate on the richness and composition of Neotropical cave fauna

“…Furthermore, different methods have different efficiency to access determined taxonomic groups and, therefore, combined methods are essential for accurately estimating species richness (Bichuette et al 2015).…”