Distribution and Diversity of Soil Microfauna from East Antarctica: Assessing the Link between Biotic and Abiotic Factors

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From: PLoS ONE(Vol. 9, Issue 1)
Publisher: Public Library of Science
Document Type: Article
Length: 12,020 words
Lexile Measure: 1420L

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Author(s): Alejandro Velasco-Castrillón 1,*, Mark B. Schultz 2, Federica Colombo 3, John A. E. Gibson 4, Kerrie A. Davies 5, Andrew D. Austin 1, Mark I. Stevens 6,7

Introduction

Desert ecosystems are often regarded as some of the simplest on Earth, in terms of trophic levels and biodiversity, which is contrasted to temperate and tropical ecosystems [1]. In hot desert environments, soil microfaunal composition and diversity are linked to plant distribution and organic matter accumulation [2]. Water has also been shown to be a potential determinant for species diversity in these kinds of environments [3], [4]. Examination of hot and cold deserts, often lacking vascular plants and where water is a limiting factor, offers the opportunity to understand biotic interactions at multiple spatial scales. Such interactions are difficult to elucidate in less extreme environments that tend to have more intricate soil structures [2], [5]. Organisms that survive in Antarctic (cold desert) refuges are constantly subjected to extreme abiotic stresses such as low temperatures, freeze-thaw cycles, available liquid water, high salt content, months of darkness, excessive solar radiation and nutrient and carbon restrictions [6], [7], [8], [9]. Only those species with specific physiological adaptations have been able to survive under such extreme conditions, and this has been hypothesised as one of the main reasons for a depauperate soil microfaunal community [9], [10], [11]. Soil microfauna play an essential role in recycling nutrients and aiding decomposition, forming a vital component in Antarctic food webs [1], [12]. Low diversity food webs found in these soils ensure that nutrient recycling and trophic level interactions are restricted to microbial and metazoan invertebrate communities [13], [14]. It has been increasingly recognised that biotic soil communities are influenced by soil geochemical and physical properties [15], [16], [17], in particular organic carbon [1], [7], [18], conductivity [7], [9], and availability of liquid water [17], [19] as the main suggested drivers.

Even within ice-free areas, the distribution of microfaunal populations remains irregular and taxonomically limited [20], [21]. It remains unclear if these populations are limited by edaphic factors, microclimatic conditions, vegetation, or topography (e.g. [22]), with more abundant and diverse communities usually occurring in connection with patches of moss, lichens, algae [9], [11] and bird colonies [23], [24]. Rotifers, nematodes, tardigrades, protozoans [25], [26], [27] and, to a lesser extent, mites and springtails [28] make up the invertebrate communities of soil microfauna in East Antarctica (EA). Invertebrates are patchily distributed in soil and vegetation from ice-free areas in coastal and continental Antarctica and inland nunataks (exposed ridges or mountain peaks) [24], [29], [30], [31], [32]. Recent studies revealed that several Antarctic localities remained ice-free throughout the Last Glacial Maximum [9], [33] and that many terrestrial habitats are likely to have only become available for colonisation from refuges within the current inter-glacial period (<17,000 years) [9], [34]. However, there is compelling evidence that some regions are likely to have been ice-free for much longer and so it is likely that there exists an Antarctic terrestrial invertebrate fauna that consists of...

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Gale Document Number: GALE|A478832218