Geological and ecological assessment of the exposure degree of the Zăton-Bulba karst system (Mehedinţi Plateau) to anthropogenic hazards: intrinsic vulnerability and biodiversity study

The Mehedinţi Plateau represents an area highly marked by the intensity of the karst processes and by the diversity of the exokarst and endokarst features. The analyzed area includes two parallel limestone bars, developed on the Carpathian structures direction (NNE-SSW). The geological and geomorphological research, guided by a working protocol similar to that of the EPIK method, highlighted the role played by the lithology, structure, tectonics, epikarst and protective cover, related to the infiltration conditions, flow parameters and impact area of a potential contamination event; also, we carried on microtectonic studies on the Bulba Valley, Peşterii Hill, Podul Natural Cave and Bulba Cave. In addition to the results obtained following the EPIK method protocol, we bring forward data concerning the water quality, performing hydrogeochemical analyses on water samples collected from the main sources in the region. Our research has been focused on TDS, on cations (Ca2+, Mg2+, Na+, K+, NH4+) and on anions (HCO3-, Cl-). We conclude by modelling the cumulative abundance and the species richness of the harvestmen (Opiliones) in the studied area, under different degrees of human impact on habitat

Soil mite (Acari: Mesostigmata) communities and their relationships with some environmental variables in experimental grasslands from Bucegi Mountains in Romania

The main objective of the study was to analyse, for the first time in Romania, the relationships between five experimental grasslands and Mesostigmata fauna, considering: (1) the structural differences between mite communities; (2) the variations in some important abiotic factors (vegetation cover, soil temperature, soil moisture content, pH, soil resistance at penetration); and (3) the influence of these abiotic factors on the structures of Mesostigmata mite communities and the dispersal rates of these communities between the investigated plots. In total, 250 soil samples were analysed in July 2017, revealing the presence of 30 species, with 1163 individuals. Using the multivariate analysis, we observed that each experimental plot was defined by characteristic environmental conditions, i.e., vegetation cover, soil moisture content, and soil temperature differed significantly between the experimental grasslands. Each experimental plot was characterised by a specific indicator species and population parameters (numerical abundance and species richness). The effects of these soil variables were even demonstrated at species level: Veigaia planicola, Geolaelaps nolli, and Gamasellodes insignis were influenced by vegetation cover, Lysigamasus conus and Dendrolaelapsfoveolatus by soil temperature. The dispersal rates of mite communities from one plot to another were higher in the grasslands, where there were euconstant–constant species

Mesovoid shallow substratum as a biodiversity hotspot for conservation priorities: analysis of oribatid mite (Acari: Oribatida) fauna

International audienceThe mesovoid shallow substratum (MSS) is a unique habitat that shelters and serves as a microrefuge for epigean, endogean and hypogean invertebrate species. Understanding the MSS community′s spatio-temporal structure and species diversity patterns in relation to the environmental parameters plays a crucial role in conservation. In this study we investigated: i) the diversity and community structure of oribatid mites from edaphic habitat, superficial MSS (i.e., the upper layer of MSS) and deep MSS (i.e., lower layer of MSS) in an alpine region of Southern Carpathians, Romania, and ii) the relationships between the oribatid mite communities and the environmental variables, such as temperature and humidity. The composition and the structure of oribatid communities differed along the three habitats indicating possible habitat specialization. The structure of the oribatid community was influenced by temperature and humidity. The rich and mixed oribatid communities in the MSS and the oribatid communities\' response to surface and subsurface environmental variables suggest that the MSS may offer a micro-refuge for edaphic species when the conditions in the surface habitats become too harsh. Thus, we suggest that MSS should be prioritized for conservation because it may be the key component in maintaining biodiversity

Shifts in amphibian population dynamics in response to a change in the predator community

Predation can affect prey behavior, demography, abundance, and distribution, particularly in lentic freshwater ecosystems. Fish are predators known to reduce the abundance of their prey and to restrict the distribution of species. Using time series which spanned 43 and 22 yr, respectively, we analyzed the effect of a change in the fish predator community on the dynamics of two pond‐breeding amphibian populations (Rana temporaria and Rana dalmatina). Specifically, we used a state‐space time series model which allows for density dependence and observation error, to ask whether the change in predation risk affects population growth rate and the return point around which the populations fluctuate. The results showed that the type of observation error assumed did not affect the biological parameters. We found evidence for density dependence in both populations. The effect of the change in fish predation on population growth rate and the return point was strong in the population where fish invaded a previously fish‐free pond. The effect was weaker in the population where the change was from cyprinid fish to pike. The results showed that fish predation can have strong effects on amphibian population dynamics. The observed population dynamical pattern is phenomenologically similar to alternative stable states

A case of color aberration in a fire salamander (Salamandra salamandra) larva

Color aberrations in salamanders are caused by defective chromatophores or by disrupted synthesis of the pigments, and have been previously reported in Europe. In this paper we report the first case of leucism in a fire salamander larva from a cave-dwelling population in Romania. The leucistic larva was larger and heavier compared to the other larvae from the same breeding habitat

Food level and light conditions affect the antipredator behavior in larvae of a stream-breeding amphibian

Understanding how long-term changes in environmental conditions influence the way that individuals cope with threats is essential in the context of behavioral adaptation to a rapidly changing world. However, little is known about the behavioral responses to predation risk for individuals that experienced different environmental conditions for extended periods of time, such as food levels and light conditions. In this experimental study, we tested whether previous long-term exposure to different food levels (low versus high) and light conditions (0-hour light versus 8-hour light) play a significant role in shaping the antipredator response (i.e., the probability of emerging from the refuge and the distance moved) to stimuli from caged larval dragonflies, in larvae of the fire salamander (Salamandra salamandra). Specifically, we quantified behavioral differences in the response to predation risk in larval salamanders that were reared in the laboratory for two months under controlled food and light conditions. The results of this study showed that the interaction between food level and light conditions affected the antipredator behavior of the larvae. Fire salamander larvae maintained at low food levels and in 8-hour light conditions emerged from the refuge with a higher probability (i.e., took more risk) than larvae maintained at high food levels and all other combinations of light conditions. Thus, our results highlight the complexity of antipredator responses, pointing attention to the fact that interactions among environmental factors are likely to determine the magnitude of antipredator response

Food level and light conditions affect the antipredator behavior in larvae of a stream-breeding amphibian

Understanding how long-term changes in environmental conditions influence the way that individuals cope with threats is essential in the context of behavioral adaptation to a rapidly changing world. However, little is known about the behavioral responses to predation risk for individuals that experienced different environmental conditions for extended periods of time, such as food levels and light conditions. In this experimental study, we tested whether previous long-term exposure to different food levels (low versus high) and light conditions (0-h light versus 8-h light) plays a significant role in shaping the antipredator response (i.e., the probability of emerging from the refuge and the distance moved) to stimuli from caged larval dragonflies, in larvae of the fire salamander (Salamandra salamandra). Specifically, we quantified behavioral differences in the response to predation risk in larval salamanders that were reared in the laboratory for 2 months under controlled food and light conditions. The results of this study showed that the interaction between food level and light conditions affected the antipredator behavior of the larvae. Fire salamander larvae maintained at low food levels and in 8-h light conditions emerged from the refuge with a higher probability (i.e., took more risk) than larvae maintained at high food levels and all other combinations of light conditions. Thus, our results highlight the complexity of antipredator responses, pointing attention to the fact that interactions among environmental factors are likely to determine the magnitude of antipredator response

Comparing three body condition indices in amphibians: a case study of yellow-bellied toad Bombina variegata

Body condition is important because it is correlated with population and habitat quality parameters. Since the direct measurements are either lethal or unreliable, a wide range of non-lethal body condition indices has been proposed. The aim of our study was to apply and compare three body condition indices (Fulton's index, relative body condition mass index and residual index) using body size indicator - body mass data for 24 populations of the yellow bellied toad (Bombina variegata). The condition index should be independent of body size indicator, in this case snout vent length (SVL). Therefore we tested all three indices for the statistical independence of SVL and for the normality of distribution. Fulton's index violated the independence assumption, whereas the relative body condition mass index did not have a normal distribution. Residual index was found both independent of SVL and normally distributed. Moreover, the residual index highlighted biological significant differences on the basis of altitude and season. Our results recommend the residual index as a useful tool in amphibian monitoring and conservation

Factors affecting butterfly and plant diversity in basiphilous dry grasslands of Transylvania, Romania

Cultural landscapes, shaped by centuries of traditional low-intensity agricultural practices, have been declining all over the world. In Transylvania (Romania), traditionally mown and extensively grazed grasslands have been part of a diverse landscape mosaic for centuries. In contrast to Western European countries, these species-rich grasslands are still present in Transylvania, but have declined in recent years, due to the pressure of intensification or abandonment, and inconsistent land use policies. The quality of these grasslands could easily be assessed using plants and butterflies, which are considered among the best indicators for habitat quality because of their characteristic response to land use change. Our study aimed to assess butterfly and plant community assemblages, richness and diversity in Transylvania’s most typical grassland type, by using transect and relevé methods. We investigated the drivers of change in butterfly and plant community assemblages, and decline in biodiversity of basiphilous dry grasslands. We found that present and past land use practices, geographic distance between sites and soil physical–chemical characteristics have major impacts on different aspects of plant and butterfly diversity (like species composition and richness). Grasslands that were converted to croplands in the past have lost their typical species assemblages and have not completely recovered in the last 30 years. Mown grasslands supported the most diverse communi- ties of butterflies and plants, and diversity declined with land use change to extensive and then intensively grazed pastures. For the conservation of basiphilous dry grasslands in Transylvania, we recommend a case-by-case analysis of grasslands, with emphasis on prioritizing long-term traditional mowing when applying agro-environmental schemes

Arthropod communities and drivers of their species diversity and composition in caves

Understanding the drivers of diversity patterns in ecological communities remains a major challenge in ecology. Moreover, few studies have considered invertebrate or subterranean communities and little is known about which factors are responsible for structuring arthropod communities in caves. In this study we:assessed the abundance, richness, and composition of arthropod communities from eight caves located in Banat and Mehedinti region, Romania; anddetermined whether altitude, cave physical characteristics (temperature, relative humidity, light intensity) and features (cave extension, hight, width, heterogeneity, substrate (wall versus floor)) influence cave arthropod communities along the horizontal development of the cave (i.e. from the cave entrance, through the intermediate zone, to the aphotic zone).Overall, 89 species were found, of which three were obligate subterranean dwellers and 17 were endemic species. Species abundance distributions showed evident variation in species numbers among cave zones and between the wall and floor substrate. Species abundance was influenced by cave extension, relative humidity and light intensity. Species richness was related to cave extension while relative humidity and cave heterogeneity affected the species diversity. The results also indicated differences in species abundance, richness and diversity among cave zones and between substrate types. The arthropod community structure and composition was determined by altitude, relative humidity, temperature and substrate. The floor and wall substrate had different species composition while the species composition of the three cave zones largely overlapped. We conclude that several biotic and abiotic factors explain the diversity and composition of cave arthropods communities and that our results may be relevant to other types of island-like habitats