Cave lithology determining the structure of the invertebrate communities in the Brazilian Atlantic Rain Forest

In Brazil, only limestone caves and a few caves in sandstone, iron ore and granite rocks had their invertebrate communities evaluated. Being such, the present study aimed to promote a comparative analysis of the structure of the invertebrate communities in caves associated to carbonatic, magmatic, siliciclastic and ferruginous rocks of the Brazilian Atlantic forest. Significant differences in the relative richness, abundance and diversity were observed between lithologies. The average relative richness was higher in the ferruginous caves (0.53 spp). The total number of troglomorphic species was significantly different among caves and the highest average richness occurred at ferruginous caves (5.79 spp/cave). Siliciclastic, carbonatic and magmatic caves presented a higher quantitative similarity of the fauna. Ferruginous caves revealed communities with a fauna composition different from the other lithologies. The total richness of invertebrates correlated significantly and positively with the linear development in the siliciclastic caves (R_s = 0.67, P < 0.05), carbonatic (R_s = 0.71, P < 0.05) and ferruginous (R_s = 0.74, P < 0.05). The rock type in which the cave is inserted can determine differences in the richness of invertebrate troglophyles and troglobites. Therefore, on creating value attributes, the size of the caves should always come related to their lithology by the fact that same sized caves associated to different lithologies, possess communities with quite diverse structures.     

Cave invertebrate assemblages differ between native and exotic leaf litter

Abstract Allochtonous leaf litter is an important source of energy and nutrients for invertebrates in cave ecosystems. A change to the quality or quantity of litter entering caves has the potential to disrupt the structure and function of cave communities. In this study, we adopted an experimental approach to examine rates of leaf litter decomposition and the invertebrate assemblages colonizing native and exotic leaf litter in limestone caves in the Jenolan Caves Karst Conservation Reserve, New South Wales, Australia. We deployed traps containing leaf litter from exotic sycamore (Acer pseudoplatanus) and radiata pine (Pinus radiata) trees and native eucalypts (Eucalyptus spp.) in twilight zones (near the cave entrance) and areas deep within the caves for 3 months. Thirty‐two invertebrate morphospecies were recorded from the litter traps, with greater richness and abundance evident in the samples from the twilight zone compared with areas deep within the cave. Sycamore litter had significantly greater richness and abundance of invertebrates compared with eucalypt and pine litter in samples from the twilight zone, but there was no difference in richness or abundance among litter samples placed deep within the cave. Relative rates of decay of the three litters were sycamore > eucalypt > pine. We discuss the potential for the higher decomposition rates and specific leaf area in sycamores to explain their higher invertebrate diversity and abundance. Our findings have important implications for the management of exotic plants and the contribution of their leaf litter to subterranean ecosystems.     

Capturing arthropod diversity in complex cave systems

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.

     

Ecological preferences of neotropical cave bats in roost site selection and their implications for conservation

Bats frequently use caves as roosts due to higher environmental stability and protection. However, species-specific ecological and physiological requirements and conditions of roosts and their surroundings can influence species presence. Little is known on cave choice by bats in the Neotropics, a species- and cave-rich region. Understanding how bats, cave characteristics and the surrounding landscape are related with each other helps the management and conservation of bats and caves. Based on sampling 19 caves using both diurnal observations and captures, we tested (1) whether bat richness was positively related to cave temperature, humidity, size, stability, and heterogeneity of microhabitats, and the preservation and heterogeneity of the surrounding landscape in central Brazil; (2) whether cave and landscape characteristics influenced on species composition; (3) how species responded to cave and landscape variables; and (4) whether these relationships changed between seasons. Temperature was a limiting factor, whereas environmental stability, humidity, and structural attributes of caves favored the occurrence of more species. Larger caves, rich in microhabitats – but more stable than the external environment – supported more species, especially in the dry season. Landscape context did not influence species richness and composition in the caves, but the percentage of vegetation around caves was important for certain species. Our results highlight the influence of environmental variables in the process of cave selection by Neotropical bat species. Moreover, we emphasize the importance of cave protection for bats and provide useful information for decision-making in processes of environmental licensing.     

Exploring the homogeneity of terrestrial subterranean communities at a local spatial scale

1. Although caves are generally perceived as isolated habitats, at the local scale, they are often interconnected via a network of fissures in the bedrock. Accordingly, caves in close proximity are expected to host the same, or very similar, animal communities. 2. We explored the extent to which subterranean arthropod communities are homogenous at a local spatial scale of less than 1 km², along with which cave-specific environmental features result in a departure from the expected homogeneous pattern. We approached this question by studying richness and turnover in terrestrial invertebrate communities of 27 caves in a small karst massif in the Western Italian Alps. 3. Specialised subterranean species were homogeneously distributed among caves and were not influenced by seasonality. The only factor driving their distribution was the distance from the cave entrance, with deeper caves yielding a greater diversity of species. 4. Significant spatio-temporal turnover in species not specialised to subterranean life was observed. In summer, there was a significant homogenisation of the community and a more even distribution of species among sites; in winter, these species were missing or found exclusively at greater depths, where environmental conditions were more stable. Furthermore, caves at lower elevations yielded, on average, a greater diversity and abundance of these species. 5. This study demonstrated that the theoretical expectation of no turnover in community composition in caves in close proximity is not always met. Turnover can be mostly attributed to seasonal patterns and sampling depth; thus, our findings have implications for planning sampling and monitoring activities in caves.     

Energy and speleogenesis: Key determinants of terrestrial species richness in caves

The aim of this study was to unravel the relative role played by speleogenesis (i.e., the process in which a cave is formed), landscape‐scale variables, and geophysical factors in the determination of species richness in caves. Biological inventories from 21 caves located in the southeastern Iberian Peninsula along with partial least square (PLS) regression analysis were used to assess the relative importance of the different explanatory variables. The caves were grouped according to the similarity in their species composition; the effect that spatial distance could have on similarity was also studied using correlation between matrices. The energy and speleogenesis of caves accounted for 44.3% of the variation in species richness. The trophic level of each cave was the most significant factor in PLS regression analysis, and epigenic caves (i.e., those formed by the action of percolating water) had significantly more species than hypogenic ones (i.e., those formed by the action of upward flows in confined aquifers). Dissimilarity among the caves was very high (multiple‐site β_sim = 0.92). Two main groups of caves were revealed through the cluster analysis, one formed by the western caves and the other by the eastern ones. The significant—but low—correlation found between faunistic dissimilarity and geographical distance (r = .16) disappeared once the caves were split into the two groups. The extreme beta‐diversity suggests a very low connection among the caves and/or a very low dispersal capacity of the species. In the region under study, two main factors are intimately related to the richness of terrestrial subterranean species in caves: the amount of organic material (trophic level) and the formation process (genesis). This is the first time that the history of a cave genesis has been quantitatively considered to assess its importance in explaining richness patterns in comparison with other factors more widely recognized.     

Ecotone delimitation: Epigean–hypogean transition in cave ecosystems

Abstract The ecotone zone between epigean and hypogean environments has been delimited for two limestone caves using a new method proposed herein. The richness and the diversity of the ecotone, epigean and hypogean environments and their similarities have also been determined. The ecotones were delimited using a similarity matrix between the inner and outer sectors of each cave. The ecotone of Dona Rita's cave was estimated to be 12 m long and the ecotone of Retiro's cave 16 m. The richness (S) of arthropods in Dona Rita's cave was higher in the ecotone (S = 131), intermediate in the epigean environment (S = 75) and lower in the hypogean system (S = 45). The invertebrate diversity (H′) was lower in the hypogean environment (H′ = 2.89) and not statistically different between the epigean environment and the ecotone (H′ = 3.56 and H′ = 3.76, respectively). The richness in Retiro's cave was higher in the ecotone (S = 86), intermediate in the epigean environment (S = 39) and lower in the hypogean system (S = 12). The invertebrate diversity was lower in the hypogean environment (H′ = 0.48), intermediate in the ecotone (H′ = 3.02) and higher in the epigean region (H′ = 3.29). Species migration patterns, differential environmental barriers and determination of accidental versus trogloxenes/troglophylous species are topics that are primarily approached by establishing ecotone zones in caves. The aim of the present paper is to establish the delimitation of theses zones.     

Multi-spatial analysis on cave ecosystems to predict the diversity of subterranean invertebrates

Subterranean habitats around the world can shelter diversified and threatened faunal communities. However, issues related to alterations in the landscape and structure of subterranean habitats still need to be better understood. Therefore, we used a multi-spatial scale analysis of land cover, land use, and cave habitats to predict the diversity of communities of subterranean invertebrates. We hypothesized that changes in land cover promote alterations in both faunal richness and composition and microhabitat diversity and that microhabitat features determined subterranean biodiversity. Sixteen limestone caves were sampled in Brazil at micro, meso, and macro scales using quadrats (1m²), transects (100 meters) as sample units inside caves and buffers with the radius of 100 and 250 meters in the surroundings of the cave entrances. Models performed showed that land cover and land use influenced cave environments, regarding both microhabitats traits and terrestrial invertebrate richness and composition. We also observed a relationship between microhabitat structure and terrestrial invertebrate richness and composition. Our results showed that deforested areas had negative effects on species richness and changed their composition, while natural areas had positive effects on microhabitat diversity. The same effects were observed for both 100 and 250 meters buffers. Invertebrate richness was negatively predicted by deforested areas while positively predicted by natural areas. Richness was also positively predicted by the combination of all microhabitat traits, and dissimilarity of fauna was influenced by microhabitat diversity in mesoscale and microscale by all microhabitat elements. The results highlight the importance of the landscape surrounding the caves to conserve the subterranean habitats and their fauna. Due to the spatial and temporal changes in the global environmental scenario, we argue the urgency of further detailed studies in fragmented landscapes to define minimum areas of protection for cave environments.     

中国喀斯特洞穴维管植物多样性

洞穴是喀斯特景观中普遍存在的地质地貌结构, 拥有丰富的植物资源。仅2001-2020年间, 就发表了中国喀斯特洞穴维管植物新属1个; 新种(含种下等级) 170个, 隶属于16科31属, 占近20年发表的中国维管植物新种的3.9%, 说明洞穴植物具有较高的物种多样性潜力。据统计, 中国喀斯特洞穴维管植物有110科339属871种, 主要分布于广西、广东、贵州、云南、重庆等地。物种数排名前5的科包括苦苣苔科、荨麻科、鳞毛蕨科、秋海棠科和茜草科, 其所含物种数共占整个洞穴植物种类的39.4%; 排名前5的属包括报春苣苔属(Primulina)、楼梯草属(Elatostema)、耳蕨属(Polystichum)、秋海棠属(Begonia)和凤尾蕨属(Pteris), 其所含物种数共占整个洞穴植物种类的25.1%。本名录的所有洞穴植物中, 草本习性的种类占一半以上。从洞内分布来看, 仅有10.7%的种类分布于弱光带, 其中石松类和蕨类植物占比远高于被子植物, 说明前者更能适应弱光带的极端环境。不仅如此, 洞穴维管植物也具有较高的特有性成分, 其中省级特有种占比25.8%, 分别包括非洞穴特有种(11.0%)、多洞穴特有种(3.3%)和单洞穴特有种(11.5%)。依据文献显示受威胁种类有115种(占13.0%)。受威胁种类占比较高的类群均是近年来发表新种较多的科, 包括鳞毛蕨科、苦苣苔科、荨麻科、秋海棠科、茜草科等。针对这些类群, 有待更详细地调查来完善对它们的评估。此外, 本名录中至少有36%的种类没有任何分子数据, 亟待补充。     

Sampling adequacy in an extreme environment: species richness patterns in Slovenian caves

Caves harbor a rich fauna unique to subterranean environments. Although extensive records of cave animals are available, only a small fraction of known caves in any region have been biologically assessed. We investigated the impact of incomplete sampling using one of the richest, best documented cave faunas in the world – that of the Dinaric karst of Slovenia. We utilized time snapshots (1940, 1970, and 2000) of the caves and cave fauna to analyze stability of hotspots, spatial pattern, and relationship between number of species and number of caves. Using data aggregated into 100km² hexagons, the location of hotspots, black–white joins, Moran's I, and spatial autocorrelation all remained constant, at least from 1970 on. The linear regression coefficient of the relationship between number of caves and number of species declined with time. Most hexagons had been sampled, but there was no indication that any hexagon had been sampled intensively enough for the accumulation curve of number of caves versus number of species within a hexagon to reach an asymptote. This appeared to be the result of a highly skewed distribution of species richness among caves. Number and position of hotspots can be predicted from information on these few high diversity caves.     

Big family,warm home,and lots of friends: Pteronotus large colonies affect species richness and occupation inside caves

Roosts are essential for the survival of most animals. Due to homothermic requirements, mammals are particularly dependent on roost quality and availability. Bats select their roosts in a species-specific way, likely related to species´ different physiological and adaptive needs. Unlike species whose individuals roost solitarily, roost selection is critical for bats forming large colonies due to the requirements for maintaining thousands of individuals in a single shelter. This is the case of Pteronotus (Mormoopidae), whose colonies reach hundreds of thousands of bats. Using captures, bioacoustics, and automated censuses, we evaluated how cave size, ceiling characteristics, environmental stability, temperature, and humidity influence the formation of exceptionally large colonies, species richness and composition in caves in north-eastern Brazil. We expected that colonies would be positively related to cave size and stability, internal cave selection would be species-specific, but larger and more environmentally stable caves would have higher richness. Pteronotus colonies were positively related to cave size, stability, and ceiling characteristics, and their presence strongly influenced cave temperature variation. Species richness was positively correlated to a cave stability index. Species other than Pteronotus preferred different climatic and ceiling characteristics. We detected an indirect influence of the large colonies of Pteronotus on the species richness and occupation inside caves. On the other hand, such caves favor species coexistence, as they offer a range of microenvironments, reducing niche overlap in their interior. Pteronotus gymnonotus and Pteronotus personatus are both key- and umbrella-species for cave ecosystems, stressing the need for specific conservation strategies in Brazil. Abstract in Portuguese is available with online material.     

Regional species richness in an obligate subterranean dwelling fauna – epikarst copepods

Aim  The diversity of the obligate cave-dwelling fauna has proved difficult to measure because of the highly localized distributions of most species. We investigated: (1) the local and regional diversity patterns of a major component of the obligate cave-dwelling fauna living in the epikarst zone, the karst layer closest to the surface; (2) variations in local and regional patterns of species richness; and (3) sampling sufficiency at multiple scales.
Location  Caves in the Dinaric Mountains of Slovenia.
Methods  We sampled continuously the abundance of 37 species of copepods dislodged from the epikarst from 35 ceiling drips in six caves for a period of one year. Copepods were collected in a specially designed net that allowed continuous collection.
Results  Based on species accumulation curves and Chao estimates of total diversity, we determined that 3–4 months of continuous sampling were sufficient to find 90% of the species in a drip, that five drips were sufficient to find 90% of the species in a cave, and that five caves were sufficient to find 90% of the species in a region.
Main conclusions  The epikarst copepod fauna is a significant part of the aquatic cave fauna, contributing about 20% at the regional level. Because of the scale of variation, much of which occurs within a cave, and because of the availability of continuous sampling devices, the epikarst component of subterranean diversity seems to be more thoroughly and accurately measured than do other components.     

Habitat Use,Roost Selection and Conservation of Bats in Tsingy De Bemaraha National Park,Madagascar

Although the land mammals of Madagascar have been the subject of many studies, the island’s bats have yet to feature prominently on the research or conservation agenda. In this study we used mist nets, acoustic sampling and cave surveys to assess habitat use, seasonality and roost selection. Four microchiropteran species (Triaenops rufus, T. furculus, Miniopterus manavi and Myotis goudoti) appeared to be strongly associated with the forest interior based on trapping, but analysis of time-expanded echolocation recordings revealed that T. rufus and M.␣manavi were frequently recorded in forest edges and clearings. Bat activity was significantly lower inside the forest than at the interface between agricultural land and forest. The caves visited most often by tourists were low in bat abundance and species richness. Anjohikinakina Cave, which was visited infrequently by people, was used by five species and contained between 54% (winter) and 99% (summer) of bats counted in 16 caves and is a site of national importance for bat conservation. Hipposideros commersoni was only netted in our study area during October and may be a migrant to the site or present but inactive during the austral winter. The forest surrounding the caves is therefore important because it provides cover for emerging bats and a potential source of invertebrate prey whilst the forest edge is important to foraging bats.     

Evaluating the sampling bias in pattern of subterranean species richness: combining approaches

We investigated the pattern of species richness of obligate subterranean (troglobiotic) beetles in caves in the northwestern Balkans, given unequal and biased sampling. On the regional scale, we modeled the relationship between species numbers and sampling intensity using an asymptotic Clench (Michaelis–Menten) function. On the local scale, we calculated Chao 2 species richness estimates for 20 × 20 km grid cells, and investigated the distribution of uniques, species found in only one cave within the grid cell. Cells having high positive residuals, those with above average species richness than expected according to the Clench function, can be considered true hotspots. They were nearly identical to the observed areas of highest species richness. As sampling intensity in a grid cell increases the expected number of uniques decreases for any fixed number of species in the grid cell. High positive residuals show above average species richness for a certain level of sampling intensity within a cell, so further sampling has the most potential for additional species. In some cells this was supported by high numbers of uniques, also indicating insufficient sampling. Cells with low negative residuals have fewer species than would be expected, and some of them also had a low number of uniques, both indicating sufficient sampling. By combining different analyses in a novel way we were able to evaluate observed species richness pattern as well as identify, where further sampling would be most beneficial. Approach we demonstrate is of broad interest to study of biota with high levels of endemism, small distribution ranges and low catchability.     

A spider diversity model for the Caucasus Ecoregion

Precise information on spatial patterns of species richness and endemic species distribution is important for effective species conservation. In the Caucasus Ecoregion such information is virtually non-existent for invertebrate taxa. Using occurrence data from a large database we calculated species distribution models with the GARP algorithm for 471 spider species to visualize the diversity distribution of spider species in this region. Overall species diversity was highest in mountain forests of the North Caucasus, east-central Georgia, the southern slopes of the eastern Great Caucasus and south-east Azerbaijan. A regression tree analysis Chi squared automatic interaction detector method revealed the mean temperature of the driest quarter and precipitation parameters to be the main environmental factors shaping these patterns. Diversity of endemic species was correlated with overall species diversity but hotspots of endemic species (10+ percent of all species) exists in high-mountain areas, suggesting post-glacial speciation events in the high mountains as the main sources of high endemism in Caucasus. Further information on the spatial distribution of species diversity of invertebrate taxa in the Caucasus Ecoregion is needed to improve conservation efforts in this biodiversity hotspot.     

Invertebrate fauna of ephemeral streams on Hauturu-o-Toi/Little Barrier Island in northern New Zealand

ABSTRACT

The invertebrate fauna of five ephemeral forest streams on Hauturu-o-Toi/Little Barrier Island in northern New Zealand was assessed in January 2014. Low summer flows restricted benthic sampling largely to pools that would, during periods of ‘normal’ flow, be main-channel riffle/run habitat. Additionally, adult stages of aquatic insects were sampled by light trapping. Fifty-three aquatic species/morphospecies were recorded during the study, including 25 new records, bringing total island species richness to 65. The fauna was dominated by Ephemeroptera and Trichoptera; species richness of Plecoptera and Diptera was low, and only single species of Mollusca and Crustacea were recorded. Species found were either common with broad New Zealand distributions, or species restricted to the North Island. No species was endemic to the island. Faunal comparisons with adjacent mainland streams indicated the island had similar assemblages of core taxa, but generally lower species richness, likely resulting from physiographic differences found there.     

Environmental correlates of plant and invertebrate species richness in ponds

Ponds (lentic water bodies <2 ha) constitute a considerable biodiversity resource. Understanding the environmental factors that underlie this diversity is important in protecting and managing the habitat. We surveyed 425 ponds for biological and physical characteristics with 78 of those also surveyed for chemical characteristics. A total of 277 invertebrate species and 265 plant species were found. Species richness varied between 2 and 99 (mean 27.2 ± 0.6 SE) for invertebrates and 1 and 58 (mean 20.8 ± 0.4 SE) for plants. Generalised additive models were used to investigate variables that correlate with the species richness of plants and invertebrates, with additional models to investigate insect, Coleoptera, Odonata, Hemiptera, Trichoptera and Mollusca species richness. Models performed reasonably well for invertebrates in general (R ² = 30.3%) but varied between lower-order invertebrate taxa (12.7–34.7%). Ponds with lower levels of shading and no history of drying contained higher numbers of species of plants and all invertebrate groups. Aquatic plant coverage positively correlated with species richness in all invertebrate groups apart from Trichoptera and the presence of fish was associated with high invertebrate species richness in all groups apart from Coleoptera. The addition of chemistry variables suggested non-linear relationships between oxygen demand and phosphate concentration and higher-order richness. We demonstrate that the composition of biological communities varies along with their species richness and that less diverse ponds are more variable compared to more diverse ponds. Variables positively correlated with richness of one taxon may be negatively correlated with that of another, making comprehensive management recommendations difficult. Promoting a high landscape-level pond biodiversity will involve the management of a high diversity of pond types within that landscape.     

贵州省松桃县锰矿区洞穴动物群落结构与环境因子的关系

主要选取松桃锰矿区周边大洞、下洞为对象,研究洞穴环境因子与洞穴动物群落的关系,探索两洞穴环境中是否存在重金属Mn污染,对比分析两洞穴动物群落结构,探讨不同重金属、环境因子与两洞穴动物群落之间的相关性是否一致。通过采集,共获标本1274号,其中大洞660号,隶属于5门10纲21目24科26种,下洞614号,隶属于4门7纲15目21科26种。群落多样性分析结果显示,多样性指数由高到底的顺序为群落D(2.4745)C(1.4036)A(1.3549)B(1.1935)E(1.1384)F(0.7265)。分析大洞、下洞洞穴群落多样性与环境因子Pearson相关系数矩阵得出,大洞土壤中As、Mn与物种数均呈显著正相关,P值分别为0.039、0.029,下洞水体中重金属As与物种优势度呈显著正相关(0.021),重金属Mn与多样性指数呈显著负相关(0.044),温度是影响下洞洞穴群落数量、分布的主要原因。重金属污染评价显示,两洞穴水质污染小,土壤中的重金属除Hg达到极严重污染外,其余重金属均未超过中度污染等级。     

贵州仙家洞和忆苦洞洞穴动物群落多样性及其环境因子的影响

为了解矿区洞穴动物群落多样性特征及其影响因素,于2019年3月对贵州松桃锰矿区仙家洞和忆苦洞的动物进行了调查,运用主成分(PCA)综合分析了环境因子对洞穴动物群落多样性的影响,并利用潜在生态危害指数对洞穴内土壤重金属的生态风险水平进行了评价.结果 表明:共获动物标本445号,隶属4门8纲18目32科,其中仙家洞178号...