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.

Caves pose significant challenges for mining projects, since they harbor many endemic and threatened species, and must therefore be protected. Recent discussions between academia, environmental protection agencies, and industry partners, have highlighted problems with the current Brazilian legislation for the protection of caves. While the licensing process is long, complex and cumbersome, the criteria used to assign caves into conservation relevance categories are often subjective, with relevance being mainly determined by the presence of obligate cave dwellers (troglobites) and their presumed rarity. However, the rarity of these troglobitic species is questionable, as most remain unidentified to the species level and their habitats and distribution ranges are poorly known. Using data from 844 iron caves retrieved from different speleology reports for the Carajás region (South-Eastern Amazon, Brazil), one of the world's largest deposits of high-grade iron ore, we assess the influence of different cave characteristics on four biodiversity proxies (species richness, presence of troglobites, presence of rare troglobites, and presence of resident bat populations). We then examine how the current relevance classification scheme ranks caves with different biodiversity indicators. Large caves were found to be important reservoirs of biodiversity, so they should be prioritized in conservation programs. Our results also reveal spatial autocorrelation in all the biodiversity proxies assessed, indicating that iron caves should be treated as components of a cave network immersed in the karst landscape. Finally, we show that by prioritizing the conservation of rare troglobites, the current relevance classification scheme is undermining overall cave biodiversity and leaving ecologically important caves unprotected. We argue that conservation efforts should target subterranean habitats as a whole and propose an alternative relevance ranking scheme, which could help simplify the assessment process and channel more resources to the effective protection of overall cave biodiversity.

Abstract:Cave entrances are transition zones with intermediate characteristics between epigean environments, which bear lower environmental stability, and hypogean environments, with lower food resources. Associated to these interfaces there is a specific community, capable of exploiting its unique and intermediate characteristics. This work investigated this community in a Brazilian limestone cave, identifying its arthropod species composition and spatial distribution, and exploring its relationships with climatic and structural environment characteristics and trophic relations. An ecotone zone was identified, with 55 species found only in the ecotone, 49 species were shared with the epigean community, 37 species with the hypogean community, and 14 species were found in the three communities. Although detritus is the base of the trophic web in the entrance, light allows the establishment of some producers and even herbivores. Species diversity in the ecotone was intermediate to that of the adjacent environments. Light is the main filter that acts near the cave entrance and determines the presence and distribution of several species in the ecotone. Therefore, this region is important for the cave ecosystem as a whole, considering that a considerable amount of trophic resources is transferred from the epigean to the hypogean environment through this area. Accordingly, conservation and management strategies regarding cave communities should incorporate actions to study and protect ecotonal communities.

The Brazilian semiarid region has a clear distinction between the dry season, which can last up to nine months, and the rainy season. Caves are connected to different extents to surface ecosystems, although they are idealized as stable environments due to their isolation. Furthermore, little is known about the effects of wet and dry seasonal variations on underground biological assemblages. Invertebrate communities were analyzed during dry and rainy seasons in 24 caves in the semiarid region of northeastern Brazil. We also investigated whether the environmental stability of caves attenuates the effects of seasonality in this particular region. Morphospecies richness and abundance and the diversity indexes of caves were significantly higher during the rainy season. In addition, more stable caves showed less variation in the community composition between seasons. Our data point to a clear influence of the surface ecosystems on the caves in Caatinga. However, the intensity of this influence apparently depends on the environmental stability of the cave, and the most stable caves present smaller changes in the structure of their invertebrate communities during different seasons.

The degradation of subterranean habitats is believed to represent a serious threat for the conservation of obligate subterranean dwellers (troglobites), many of which are short-range endemics. However, while the factors influencing cave biodiversity remain largely unknown, the influence of the surrounding landscape and patterns of subterranean connectivity of terrestrial troglobitic communities have never been systematically assessed. Using spatial statistics to analyze the most comprehensive speleological database yet available for tropical caves, we first assess the influence of iron cave characteristics and the surrounding landscape on troglobitic communities from the Eastern Amazon. We then determine the spatial pattern of troglobitic community composition, species richness, phylogenetic diversity, and the occurrence of frequent troglobitic species, and finally quantify how different landscape features influence the connectivity between caves. Our results reveal the key importance of habitat amount, guano, water, lithology, geomorphology, and elevation in shaping iron cave troglobitic communities. While mining within 250 m from the caves influenced species composition, increasing agricultural land cover within 50 m from the caves reduced species richness and phylogenetic diversity. Troglobitic species composition, species richness, phylogenetic diversity, and the occurrence of frequent troglobites showed spatial autocorrelation for up to 40 km. Finally, our results suggest that the conservation of cave clusters should be prioritized, as geographic distance was the main factor determining connectivity between troglobitic communities. Overall, our work sheds important light onto one of the most overlooked terrestrial ecosystems, and highlights the need to shift conservation efforts from individual caves to subterranean habitats as a whole.

Plants living above and around caves represent an important, albeit poorly studied, resource within cave ecosystems. The presence of plant material (root-like structures or rhizothemes, saplings, seeds, and seedlings) correlates positively with the biodiversity of the cave dwelling animals as shown for iron-ore caves in Carajás, Pará, Brazil. Plant material collected in caves has proven to be difficult to identify by traditional botanical methods, thus this research aims to provide a qualitative insight into the taxonomy and morphology of rhizothemes and other plant fragments found in the caves. The identification process used a combination of different molecular markers (ITS2, rbcL, and trnH-psbA) followed by a comparison of the sequences obtained against publicly available databases. The rhizothemes were submitted to micromorphological analysis to ascertain their putative root or stem origin and to compare their anatomy with known patterns found in the plant families or genera recovered through molecular matches. All studied samples were Angiosperms, mostly belonging to subclass Rosideae, within four orders: Malpighiales (Euphorbiaceae, Hypericaceae), Sapindales (Anacardiaceae and Sapindaceae), Myrtales (Myrtaceae), Fabales (Fabaceae), and only two belonging to subclass Asteridae, order Gentianales (Apocynaceae). Some of the samples were matched to generic level, with ITS2 being the best marker to identify the fragments because it shows high degree of sequence variation even at specific level and result reliability. All rhizothemes turned out to be roots, and correspondence was found between the existing literature and the individual anatomical patterns for the families and genera retrieved. DNA barcode has proved to be a useful tool to identify plant fragments found in this challenging environment. However, the existence of well curated, authoritatively named collections with ample biological information has proven to be essential to achieve a reliable identification.

Amblypygids are among the main predators in the ferriferous caves in Carajás National Forest, state of Pará (Amazon region of Brazil). One of the most common amblypygid species in this region is Heterophrynus longicornis (Butler 1873), and its most frequent prey are crickets of the family Phalangopsidae, which are abundant in the caves of Pará. Because they are primarily predators, necrophagy by amblypygids is not frequent in nature, and there are only two literature records of necrophagy of bats by Amblypygi. On December 11 th , 2013, we observed an individual H. longicornis eating a bat carcass in a Pará ferriferous cave. The amblypygid exhibited considerable interest in the bat's carcass, and it did not interrupt its meal even when lamps or a camera's flash were pointed in its direction. The availability of nutrients in the carcass must promote this opportunistic behavior in caves, especially considering the habitual scarcity of trophic resources in underground environments when compared to epigean environments. KEYWORDS: Heterophrynus longicornis, Chiroptera, cave, feeding behavior Necrofagia de morcego por um amblipígio (Arachnida, Amblypygi, Phrynidae) em uma caverna no leste da Amazônia brasileira RESUMO Amblipígios são considerados um dos principais predadores em cavernas de litologia ferrífera localizadas na Floresta Nacional de Carajás no estado do Pará (região da Amazônia brasileira). Uma das espécies de amblipígios mais comuns nesta região é Heterophrynus longicornis (Butler 1873), e uma das presas mais frequentes são grilos da família Phalangopsidae, abundantes nas cavernas do Pará. Por serem predadores, a necrofagia em amblipígeos foi pouco observada na natureza, sendo que existem dois registros na literatura sobre necrofagia de morcegos por amblipígios. Em 11 de dezembro de 2013, observamos um H. longicornis se alimentando da carcaça de um morcego em uma caverna de litologia ferrífera da Floresta Nacional de Carajás. Aparentemente, havia um interesse considerável pela carcaça do morcego por parte do amblipígio, uma vez que o indivíduo não interrompeu sua alimentação, mesmo quando iluminado por lanternas e o flash da câmera. A abundância de nutrientes na carcaça deve favorecer este comportamento oportunístico em cavernas, especialmente quando se considera a habitual escassez de recursos tróficos destes ambientes subterrâneos, quando comparados a ambientes epígeos.

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