Capturing arthropod diversity in complex cave systems

Abstract

Aim Identify the optimal combination of sampling techniques to maximize the detection of diversity of cave‐dwelling arthropods. Location Central‐western New Mexico; north‐western Arizona; Rapa Nui, Chile. Methods From 26 caves across three geographically distinct areas in the Western Hemisphere, arthropods were sampled using opportunistic collecting, timed searches, and baited pitfall trapping in all caves, and direct intuitive searches and bait sampling at select caves. To elucidate the techniques or combination of techniques for maximizing sampling completeness and efficiency, we examined our sampling results using nonmetric multidimensional scaling (NMDS), analysis of similarity (ANOSIM), Wilcoxon signed‐rank tests, species richness estimators and species accumulation curves. Results To maximize the detection of cave‐dwelling arthropod species, one must apply multiple sampling techniques and specifically sample unique microhabitats. For example, by sampling cave deep zones and nutrient resource sites, we identified several undescribed cave‐adapted and/or cave‐restricted taxa in the south‐western United States and eight new species of presumed cave‐restricted arthropods on Rapa Nui that would otherwise have been missed. Sampling techniques differed in their detection of both management concern species (e.g., newly discovered cave‐adapted/restricted species, range expansions of cave‐restricted species and newly confirmed alien species) and specific taxonomic groups. Spiders were detected primarily with visual search techniques (direct intuitive searches, opportunistic collecting and timed searches), while most beetles were detected using pitfall traps. Each sampling technique uniquely identified species of management concern further strengthening the importance of a multi‐technique sampling approach. Main conclusions Multiple sampling techniques were required to best characterize cave arthropod diversity. For techniques applied uniformly across all caves, each technique uniquely detected between ~40% and 67% of the total species observed. Also, sampling cave deep zones and nutrient resource sites was critical for both increasing the number of species detected and maximizing the likelihood of detecting management concern species.

Distributional dynamics of a specialized subterranean community oppose the classical understanding of the preferred subterranean habitats

“…The fauna was recorded by visual inspection and by pitfall trapping. We applied simultaneously two sampling methods, since it is documented that complementary sampling approaches maximize the detection and completeness of diversity assessments of cave‐dwelling arthropods (Kozel et al, ; Wynne et al, ; Wynne et al, ).…”

Cave millipede diversity with the description of six new species from Guangxi, China

“…Conversely, while advancing our knowledge of regional troglomorphic millipede diversity stands to contribute significantly to the conservation value of the SCK, a more comprehensive understanding (i.e., for all cave-dwelling taxa) of regional diversity, as well as advancing procedures to assessing the vulnerability of cave systems to anthropogenic impact should be considered. Wynne et al (2018Wynne et al ( , 2019 provides a systematic framework and guidance for sampling cave-dwelling arthropods using a repeatable framework, which can be modified for application in the SCK. Using such an approach, these data may be then be examined by applying principles similar to the cave vulnerability assessment developed by Tanalgo et al (2018).…”

Finding answers in the dark: caves as models in ecology fifty years after Poulson and White

“…species exploiting subterranean habitats in certain phases of their life cycle (Diesel et al 1995, Polak 1997, Culver and Sket 2002, Glover and Altringham 2008, Novak et al 2010a, Chelini et al 2011, Polseela et al 2011, Baker 2015, Lipovšek et al 2016. As a direct consequence, there can be conspicuous temporal turnovers in the species composition in a typical subterranean community (Nitzu et al 2011, Bento et al 2016, Yun et al 2016, Bichuette et al 2017, especially in the vicinity of the surface (Rendoš et al 2012) which should be taken into account when designing ecological studies and sampling protocols (Culver and Sket 2002, Meleg et al 2015, Wynne et al 2018). For instance, different arthropods may actively move from larger cave chambers to the stable network of fissures and vice versa (Chapman 1985), or rearrange their spatial distribution along the cave length in different seasons (Crouau-Roy et al 1992, Mammola et al 2015a, 2017a, Lunghi et al 2017.…”

“…For instance, different arthropods may actively move from larger cave chambers to the stable network of fissures and vice versa (Chapman 1985), or rearrange their spatial distribution along the cave length in different seasons (Crouau-Roy et al 1992, Mammola et al 2015a, 2017a, Lunghi et al 2017. As a direct consequence, there can be conspicuous temporal turnovers in the species composition in a typical subterranean community (Nitzu et al 2011, Bento et al 2016, Yun et al 2016, Bichuette et al 2017, especially in the vicinity of the surface (Rendoš et al 2012) which should be taken into account when designing ecological studies and sampling protocols (Culver and Sket 2002, Meleg et al 2015, Wynne et al 2018).…”