Oribatid mite communities in mountain scree: stable isotopes (15N, 13C) reveal three trophic levels of exclusively sexual species

Abstract

Mountain scree habitats are intermediate habitats between the base of the soil and the bedrock. They are composed of a network of small cracks and voids, and are commonly situated at the lower levels of scree slopes. Their environment is defined by empty spaces inside the scree, the absence of light and photoperiod, low temperature, and resource poor conditions. Soil arthropod communities, their trophic structure as well as their use of basal resources in mountain scree are little studied despite the fact that they are important components of these systems. Here, we investigate stable isotope ratios (15N/14N, 13C/12C) of oribatid mites (Oribatida, Acari) to understand their trophic niches and their variation with depth (50 and 75 cm) at two mountain scree sites (Cerdacul Stanciului, Marele Grohotis) in the Romanian Carpathians. Further, we used existing data to investigate the reproductive mode of the species in that habitat, as this may be related to resource availability. We hypothesized that trophic niches of oribatid mites will not differ between the two mountain scree regions but will be affected by depth. We furthermore hypothesized that due to the resource poor conditions oribatid mite species will span a narrow range of trophic levels, and that species are sexual rather than parthenogenetic. Our results showed that (1) oribatid mite trophic structure only slightly differed between the two sites indicating that the trophic ecology of oribatid mites in scree habitats is consistent and predictable, (2) oribatid mite trophic structure did not differ between the two studied soil depths indicating that the structure and availability of resources that were used by oribatid mites in deeper scree habitats varies little with depth, (3) oribatid mite species spanned only three trophic levels indicating that the habitat is rather resource poor, and (4) that all studied oribatid mite species were sexual supporting the view that resource poor conditions favour sexual reproduction.

Mite communities (Acari: Mesostigmata, Oribatida) in the red belt conk, Fomitopsis pinicola (Polyporales), in Polish forests

“…The third most numerous oribatid mite in the study -Carabodes subarcticus -was also found in such microhabitats as soil (e.g., Kagainis et al 2010Kagainis et al , 2015Hågvar et al 2014), touchwood, moss-covered branches (Żbikowska-Zdun et al 2006) and bark of deadwood (Bluhm et al 2015). The next species in terms of numbers was Oribatella calcarata which is ascribed to various trophic levels (Nae et al 2021) and is known to inhabit such habitats as soil, cave mud, dead wood, leaves, and guano in the caves (Niedbała and Rohloff 1971;Maślak and Barczyk 2011).…”

“…This mycophagous species (Schneider et al 2005) is known from sporocarps (Hågvar et al 2014) and is also found in litter, which combines patchily distributed microhabitats that are inhabited by specialised species groups (Wehner et al 2016) with soil (e.g., Błoszyk and Olszanowski 1997;Seniczak et al 2006;Manu and Honciuc 2010), nests of Formica rufa ants (Sell 1990), cave mud, deadwood, leaves and guano (Maślak and Barczyk 2011). In addition, Carabodes areolatus -a species categorised as secondary decomposer (Nae et al 2021) -was found not only in polypores (Hågvar and Steen 2013;Hågvar et al 2014;Maraun et al 2014), but also in soil (Błoszyk and Olszanowski 1997;Lebedeva and Krivolutsky 2003), feathers of hooded crow (Corvus corone cornix), magpie (Pica pica) and rook (Corvus frugilegus) (Krivolutsky and Lebedeva 2004). The third most numerous oribatid mite in the study -Carabodes subarcticus -was also found in such microhabitats as soil (e.g., Kagainis et al 2010Kagainis et al , 2015Hågvar et al 2014), touchwood, moss-covered branches (Żbikowska-Zdun et al 2006) and bark of deadwood (Bluhm et al 2015).…”

Impact of forest disturbance on microarthropod communities depends on underlying ecological gradients and species traits

“…Although most of the OTUs were not identified to species level, feeding preferences of species are mostly the same within each family ( Krantz & Walter, 2009 ; Potapov et al, 2016 ). Soil mites were divided in predators (including omnivorous) and no predators (including primary and secondary decomposers) ( Schneider et al, 2004 ; Krantz & Walter, 2009 ; Maraun et al, 2011 ; Fischer, Meyer & Maraun, 2014 ; Maaß et al, 2015 ; Schaefer & Caruso, 2019 ; Nae et al, 2021 ). We preferred using such broader categorization since the trophic guilds of many species are still unknown.…”

From a volcanic area on the Kamchatka peninsula (Northeast Asia) to a rock glacier in the Swiss Alps: a new record of Aspilota umbrosa Belokobylskij, 2007 (Hymenoptera, Braconidae)

“…MSSs are inhabited by species with different ecological requirements (epigean, edaphobionts, and troglobionts, among others) (e.g., Nitzu et al, 2014;Jiménez-Valverde et al, 2015;Mammola et al, 2016). Recently, new and rarely captured species have been frequently discovered in MSSs (e.g., Baquero et al, 2017;Gilgado et al, 2017;Ledesma et al, 2019;Jordana et al, 2020), allowing for a deeper understanding of the ecology of soil and subsoil habitats (Rendoš et al, 2012(Rendoš et al, , 2016Nitzu et al, 2014;Nae & Băncilă, 2017;Ledesma et al, 2020;Nae et al, 2021). MSS-research began in the Pyrenees (Juberthie et al, 1980(Juberthie et al, , 1981 and has been largely conducted in Europe (Mammola et al, 2016).…”