Sulfate reducing bacteria in microbial mats: Changing paradigms, new discoveries, 0000, Baumgartner Lk, Reid Rp, Dupraz C, Decho Aw, Buckley Dh, Spear Jr, Przekop Km, Visscher Pt,

Sulfate reducing bacteria (SRB) have existed throughout much of Earth's history and remain major contributors to carbon cycling in modern systems. Despite their importance, misconceptions about SRB are prevalent. In particular, SRB are commonly thought to lack oxygen tolerance and to exist only in anoxic environments. Through the last two decades, researchers have discovered that SRB can, in fact, tolerate and even respire oxygen. Investigations of microbial mat systems have demonstrated that SRB are both abundant and active in the oxic zones of mats. Additionally, SRB have been found to be highly active in the lithified zones of microbial mats, suggesting a connection between sulfate reduction and mat lithification. In the present paper, we review recent research on SRB distribution and present new preliminary findings on both the diversity and distribution of [delta]-proteobacterial SRB in lithifying and non-lithifying microbial mat systems. These preliminary findings indicate the unexplored diversity of SRB in a microbial mat system and demonstrate the close microspatial association of SRB and cyanobacteria in the oxic zone of the mat. Possible mechanisms and further studies to elucidate mechanisms for carbonate precipitation via sulfate reduction are also discussed

Preference responses and tolerances of the troglobitic Carabid Beetle, Rhadine subterranea., 1971, Mitchell Robert W.

Studies were made on the preference responses and tolerances of the troglobitic carabid beetle Rhadine subterranea to light, temperature, and relative humidity. The beetles are weakly photonegative and appear to have a strong preference far atmospheres of low saturation deficit. Both these responses seem to be orthokineses. They have a strongly developed temperature sense, and their temperature preferendum shifts seasonally. This response seems to be a klinotaxis. They are neither strongly stenothermal nor stenohygrobic. The preference responses, especially that of temperature, are probably mechanisms tending to restrict the beetles to their habitat. The tolerance data suggest that the epigeum could, at times, be used as a dispersal route.

Preference responses and tolerances of the troglobitic Carabid Beetle, Rhadine subterranea., 1971, Mitchell Robert W.

Studies were made on the preference responses and tolerances of the troglobitic carabid beetle Rhadine subterranea to light, temperature, and relative humidity. The beetles are weakly photonegative and appear to have a strong preference far atmospheres of low saturation deficit. Both these responses seem to be orthokineses. They have a strongly developed temperature sense, and their temperature preferendum shifts seasonally. This response seems to be a klinotaxis. They are neither strongly stenothermal nor stenohygrobic. The preference responses, especially that of temperature, are probably mechanisms tending to restrict the beetles to their habitat. The tolerance data suggest that the epigeum could, at times, be used as a dispersal route.

Temperature and relative humidity responses of two Texas cave-adapted Millipedes, Cambala speobia (Cambalida: Cambalidae) and Speodesmus bicornourus (Polydesmida: Vanhoeffeniidae)., 1972, Bull Eddie, Mitchell Robert W.

The temperature and relative humidity preferences and tolerances of two Texas species of cave-adapted millipedes, Cambala speobia (Chamberlin) and Speodesmus bicornourus Causey, were studied. Both species showed gross preferences when tested in gradient chambers for temperatures and relative humidities approximating those of their cave environments. But C. speobia, the less adapted species morphologically, was the more selective of the two species for such conditions. S. bicornourus was far less tolerant of elevated temperatures and reduced relative humidities than was C. speobia. Discussed is a possible reason why a terrestrial troglobite like S. bicornourus would combine intolerance with a lessened ability to perceive those factors to which it is intolerant. Discussed also are the possible causes of the present distribution of Cambala and Speodesmus in the caves of central Texas.

Temperature and relative humidity responses of two Texas cave-adapted Millipedes, Cambala speobia (Cambalida: Cambalidae) and Speodesmus bicornourus (Polydesmida: Vanhoeffeniidae)., 1972, Bull Eddie, Mitchell Robert W.

The temperature and relative humidity preferences and tolerances of two Texas species of cave-adapted millipedes, Cambala speobia (Chamberlin) and Speodesmus bicornourus Causey, were studied. Both species showed gross preferences when tested in gradient chambers for temperatures and relative humidities approximating those of their cave environments. But C. speobia, the less adapted species morphologically, was the more selective of the two species for such conditions. S. bicornourus was far less tolerant of elevated temperatures and reduced relative humidities than was C. speobia. Discussed is a possible reason why a terrestrial troglobite like S. bicornourus would combine intolerance with a lessened ability to perceive those factors to which it is intolerant. Discussed also are the possible causes of the present distribution of Cambala and Speodesmus in the caves of central Texas.

Cueva de Villa Luz, Tabasco, Mexico: Reconnaissance Study of an Active Sulfur Spring Cave and Ecosystem, 1999, Hose, L. D. , Pisarowicz, J. A.

Cueva de Villa Luz (a.k.a. Cueva de las Sardinas) in Tabasco, Mexico, is a stream cave with over a dozen H2S-rich springs rising from the floor. Oxidation of the H2S in the stream results in abundant, suspended elemental sulfur in the stream, which is white and nearly opaque. Hydrogen sulfide concentrations in the cave atmosphere fluctuate rapidly and often exceed U.S. government tolerance levels. Pulses of elevated carbon monoxide and depleted oxygen levels also occasionally enter the cave. Active speleogenesis occurs in this cave, which is forming in a small block of Lower Cretaceous limestone adjacent to a fault. Atmospheric hydrogen sulfide combines with oxygen and water to form sulfuric acid, probably through both biotic and abiotic reactions. The sulfuric acid dissolves the limestone bedrock and forms gypsum, which is readily removed by active stream flow. In addition, carbon dioxide from the reaction as well as the spring water and cave atmosphere combines with water. The resultant carbonic acid also dissolves the limestone bedrock. A robust and diverse ecosystem thrives within the cave. Abundant, chemoautotrophic microbial colonies are ubiquitous and apparently act as the primary producers to the cave’s ecosystem. Microbial veils resembling soda straw stalactites, draperies, and “u-loops” suspended from the ceiling and walls of the cave produce drops of sulfuric acid with pH values of <0.5-3.0 ±0.1. Copious macroscopic invertebrates, particularly midges and spiders, eat the microbes or the organisms that graze on the microbes. A remarkably dense population of fish, Poecilia mexicana, fill most of the stream. The fish mostly eat bacteria and midges. Participants in an ancient, indigenous Zoque ceremony annually harvest the fish in the spring to provide food during the dry season.

Lithuanian karst region rivers' water ecology: hydrochemical and hydrobiological evaluation, 2004, Tumas R. ,

The Lithuanian karst region covers about 1000 km(3) in the northern part of the country. This is the most vulnerable area from a pollution point of view. The structure of the total dissolved solids (TDS) shows that the flow of rivers in the karst region is from hydraulically interconnected aquifers. For the last decade (1991-2000) TDS has varied considerably, from 529 to 732 mg/l. The predominant sources of nitrogen and phosphorus within the headwaters of the monitored rivers were diffuse and agricultural in nature. Downstream from the towns nitrogen and especially phosphorus showed both diffuse and point source signals. Contributions of point sources to the stream pollution by nutrients prevail. The time series of monthly dissolved oxygen (O-2) in the main karst region river - the Musa - shows the existence of multiplicative seasonality. The trend cycle (1991-1999) shows low levels of dissolved oxygen in 1991-1993, with a similar fluctuation in 1994, 1995 and 1996 (due to point pollution from the town of Siauliai) and a gradually improving situation since 1997. The general multiplicative trend of dissolved oxygen in the lower reaches of the Musa river (near the border with Latvia) is decreasing (within the accuracy limits). The abundance and species of zoo benthos are suitable criteria (biotic index - 131) for evaluation of a river's biological water quality. Zoo benthos demonstrates tolerances that vary among species, the oxygen regime and the pollution with nitrogen. The best living conditions for invertebrates are in the riverhead of the karst region rivers - 131 = 5.62-6.74 (1991-1999), where pollution with nutrients is caused mostly by agricultural activity. Rare and asynchronous data of biological water quality shows up tendencies that invertebrates prefer less contaminated reaches of rivers

Lampenflora algae and methods of growth control, 2009, Mulec J. And Kosi G.

Karst caves are unique natural features and habitats where specialized organisms live. Some caves are also important as cultural heritage sites. In recent decades, many caves have experienced intensified tourist visits. To attract visitors, artificial illumination was installed that changed conditions in the caves. As a result, communities of organisms called lampenflora develop in close and remote proximity to lights. These phototrophic organisms are inappropriate from an aesthetic point of view and cause the degradation of colonized substrata, which is a particular problem in caves with prehistoric art. Key factors that allow lampenflora to grow are light and moisture. Illuminated spots in caves can be quickly colonized by algae, some of which have broad tolerances for different substrata. Several phototrophs can survive in caves even at photon flux densities lower than the photosynthetic compensation point. In this paper, the pros and cons of physical, chemical, and biological methods to control phototrophic growth are reviewed and discussed. Experiences in show caves can be helpfulin controlling undesirable algal growth in other environments.

Biodiversity and conservation of subterranean fauna fromPortuguese karst. Ph.D. Thesis, 2012, Ana Sofia Reboleira

This research is a contribution to the study of subterranean biodiversity in karst areas of Portugal, towards its conservation.

The relative inaccessibility of the subterranean environment is a challenge for the study of its fauna, often accessible only in caves but more widely distributed. The subterranean animals are among the most rare, threatened and worldwide underprotected, often by the simple fact of being unknown.

Karst areas of Portugal occupy a considerable part of the territory and harbor more than 2000 caves. The complex biogeographical history of the Iberian Peninsula allowed the survival of several relict arthropod refugees in the subterranean environment.

Subterranean invertebrates have been ignored, as for as the protection of karst systems are concerned in Portugal, largely because knowledge was scarce and disorganized. Reviewing all the bibliographic sources about subterranean fauna from Portugal and listing troglobiont and stygobiont species and locations, was essential to understand the state of knowledge of species richness and the biogeography and conservation status for the studied areas.

In order to understand subterranean biodiversity patterns in karst areas from Portugal, one year of intense fieldwork was performed in more than 40 caves from 14 karst units. Several new species for science were discovered and 7 taxa comprising 2 new genera and 5 new species were described.

Bearing in mind that spatial distribution of subterranean species is crucial to ecological research and conservation, the distribution of hypogean species, from Portuguese karst areas, was mapped using geographic information systems. Also, its subterranean richness was compared with other areas of the world and missing species were estimated on a regional scale. The subterranean biodiversity patterns were analyzed, and several factors were tested to explain richness patterns. Evapotranspiration and the consequent high productivity on the surface may be determinant in the species richness in the different karst units of Portugal, but the depth of the caves and the unique geological features of every massif seemed to play a more important role.

In order to evaluate the tolerance of organisms to groundwater contamination, the acute toxicity of two substances were tested on stygobiont crustaceans with different degrees of troglomorphism. Our study showed that the high levels of endemism contribute to remarkably different toxicological responses within the same genus.

The major problems related to conservation of subterranean habitats were associated to direct destruction and their contamination. These ecosystems lack of specific protection, implying an adequate management of surface habitats and the establishment of priority areas. Integrating all the previous information, this study establishes a ranking of sites for conservation of subterranean fauna in karst areas of Portugal.This research is a contribution to the study of subterranean biodiversity in karst areas of Portugal, towards its conservation.

The relative inaccessibility of the subterranean environment is a challenge for the study of its fauna, often accessible only in caves but more widely distributed. The subterranean animals are among the most rare, threatened and worldwide underprotected, often by the simple fact of being unknown.

Karst areas of Portugal occupy a considerable part of the territory and harbor more than 2000 caves. The complex biogeographical history of the Iberian Peninsula allowed the survival of several relict arthropod refugees in the subterranean environment.

Subterranean invertebrates have been ignored, as for as the protection of karst systems are concerned in Portugal, largely because knowledge was scarce and disorganized. Reviewing all the bibliographic sources about subterranean fauna from Portugal and listing troglobiont and stygobiont species and locations, was essential to understand the state of knowledge of species richness and the biogeography and conservation status for the studied areas.

In order to understand subterranean biodiversity patterns in karst areas from Portugal, one year of intense fieldwork was performed in more than 40 caves from 14 karst units. Several new species for science were discovered and 7 taxa comprising 2 new genera and 5 new species were described.

Bearing in mind that spatial distribution of subterranean species is crucial to ecological research and conservation, the distribution of hypogean species, from Portuguese karst areas, was mapped using geographic information systems. Also, its subterranean richness was compared with other areas of the world and missing species were estimated on a regional scale. The subterranean biodiversity patterns were analyzed, and several factors were tested to explain richness patterns. Evapotranspiration and the consequent high productivity on the surface may be determinant in the species richness in the different karst units of Portugal, but the depth of the caves and the unique geological features of every massif seemed to play a more important role.

In order to evaluate the tolerance of organisms to groundwater contamination, the acute toxicity of two substances were tested on stygobiont crustaceans with different degrees of troglomorphism. Our study showed that the high levels of endemism contribute to remarkably different toxicological responses within the same genus.

The major problems related to conservation of subterranean habitats were associated to direct destruction and their contamination. These ecosystems lack of specific protection, implying an adequate management of surface habitats and the establishment of priority areas. Integrating all the previous information, this study establishes a ranking of sites for conservation of subterranean fauna in karst areas of Portugal.

Biodiversity and conservation of subterranean fauna of Portuguese karst. Ph.D. thesis, 2012, Ana Sofia P. S. Reboleira

This research is a contribution to the study of subterranean biodiversity in karst areas of Portugal, towards its conservation.

The relative inaccessibility of the subterranean environment is a challenge for the study of its fauna, often accessible only in caves but more widely distributed. The subterranean animals are among the most rare, threatened and worldwide underprotected, often by the simple fact of being unknown.

Karst areas of Portugal occupy a considerable part of the territory and harbor more than 2000 caves. The complex biogeographical history of the Iberian Peninsula allowed the survival of several relict arthropod refugees in the subterranean environment.

Subterranean invertebrates have been ignored, as for as the protection of karst systems are concerned in Portugal, largely because knowledge was scarce and disorganized. Reviewing all the bibliographic sources about subterranean fauna from Portugal and listing troglobiont and stygobiont species and locations, was essential to understand the state of knowledge of species richness and the biogeography and conservation status for the studied areas.

In order to understand subterranean biodiversity patterns in karst areas from Portugal, one year of intense fieldwork was performed in more than 40 caves from 14 karst units. Several new species for science were discovered and 7 taxa comprising 2 new genera and 5 new species were described.

Bearing in mind that spatial distribution of subterranean species is crucial to ecological research and conservation, the distribution of hypogean species, from Portuguese karst areas, was mapped using geographic information systems. Also, its subterranean richness was compared with other areas of the world and missing species were estimated on a regional scale. The subterranean biodiversity patterns were analyzed, and several factors were tested to explain richness patterns. Evapotranspiration and the consequent high productivity on the surface may be determinant in the species richness in the different karst units of Portugal, but the depth of the caves and the unique geological features of every massif seemed to play a more important role.

In order to evaluate the tolerance of organisms to groundwater contamination, the acute toxicity of two substances were tested on stygobiont crustaceans with different degrees of troglomorphism. Our study showed that the high levels of endemism contribute to remarkably different toxicological responses within the same genus.

The major problems related to conservation of subterranean habitats were associated to direct destruction and their contamination. These ecosystems lack of specific protection, implying an adequate management of surface habitats and the establishment of priority areas. Integrating all the previous information, this study establishes a ranking of sites for conservation of subterranean fauna in karst areas of Portugal.This research is a contribution to the study of subterranean biodiversity in karst areas of Portugal, towards its conservation.

The relative inaccessibility of the subterranean environment is a challenge for the study of its fauna, often accessible only in caves but more widely distributed. The subterranean animals are among the most rare, threatened and worldwide underprotected, often by the simple fact of being unknown.

Karst areas of Portugal occupy a considerable part of the territory and harbor more than 2000 caves. The complex biogeographical history of the Iberian Peninsula allowed the survival of several relict arthropod refugees in the subterranean environment.

Subterranean invertebrates have been ignored, as for as the protection of karst systems are concerned in Portugal, largely because knowledge was scarce and disorganized. Reviewing all the bibliographic sources about subterranean fauna from Portugal and listing troglobiont and stygobiont species and locations, was essential to understand the state of knowledge of species richness and the biogeography and conservation status for the studied areas.

In order to understand subterranean biodiversity patterns in karst areas from Portugal, one year of intense fieldwork was performed in more than 40 caves from 14 karst units. Several new species for science were discovered and 7 taxa comprising 2 new genera and 5 new species were described.

Bearing in mind that spatial distribution of subterranean species is crucial to ecological research and conservation, the distribution of hypogean species, from Portuguese karst areas, was mapped using geographic information systems. Also, its subterranean richness was compared with other areas of the world and missing species were estimated on a regional scale. The subterranean biodiversity patterns were analyzed, and several factors were tested to explain richness patterns. Evapotranspiration and the consequent high productivity on the surface may be determinant in the species richness in the different karst units of Portugal, but the depth of the caves and the unique geological features of every massif seemed to play a more important role.

In order to evaluate the tolerance of organisms to groundwater contamination, the acute toxicity of two substances were tested on stygobiont crustaceans with different degrees of troglomorphism. Our study showed that the high levels of endemism contribute to remarkably different toxicological responses within the same genus.

The major problems related to conservation of subterranean habitats were associated to direct destruction and their contamination. These ecosystems lack of specific protection, implying an adequate management of surface habitats and the establishment of priority areas. Integrating all the previous information, this study establishes a ranking of sites for conservation of subterranean fauna in karst areas of Portugal.

Exploring the sulfide tolerance of ectosymbiotic Niphargus amphipods from the Frasassi caves, central Italy, 2013, Bauermeister J. , Assig K. , Dattagupta S.

Two species of the crustacean amphipod genus Niphargus inhabit the sulfidic groundwaters of the Frasassi caves in central Italy, and both harbor filamentous, sulfide-oxidizing Thiothrix ectosymbionts. As sulfide is toxic to most aerobic organisms, it appeared possible that the ectosymbionts could help their Niphargus hosts with detoxification processes. In this study, mortality due to sulfide was compared between Niphargus individuals with ectosymbionts and individuals whose ectosymbionts had been killed by antibiotic treatment. Both Frasassi- dwelling Niphargus species revealed exceptionally high tolerances to sulfide compared to other amphipod species studied so far. Niphargus individuals without viable ectosymbionts tolerated sulfide levels exceeding those occurring in Frasassi cave waters. Thus, the amphipods may employ Thiothrix-independent mechanisms for sulfide resistance.

Cold tolerance in terrestrial invertebrates inhabiting subterranean habitats., 2014,

Most organisms are able to survive shorter or longer exposure to sub-zero temperatures. Hypothetically, trogloxenes characterized as not adapted, and troglophiles as not completely adapted to thermally stable subterranean environment, have retained or partially retained their ability to withstand freezing, while most troglobionts have not. We tested this hypothesis experimentally on 37 species inhabiting caves in Slovenia, analyzing their lower lethal temperatures in summer and winter, or for one season, if the species was not present in caves during both seasons. Specimens were exposed for 12 hrs to 1°C-stepwise descending temperatures with 48 hr breaks. In general, the resistance to freezing was in agreement with the hypothesis, decreasing from trogloxenes over troglophiles to troglobionts. However, weak resistance was preserved in nearly all troglobionts, which responded in two ways. One group, withstanding freezing to a limited degree, and increasing freezing tolerance in winter, belong to the troglobionts inhabiting the superficial subterranean habitats. The other group, which equally withstand freezing in summer and winter, inhabit deep subterranean or other thermally buffered subterranean habitats. Data on cold resistance can thus serve as an efficient additional measure of adaptation to particular hypogean environments.

Niche differentiation in Meta bourneti and M. menardi (Araneae, Tetragnathidae) with notes on the life history, 2014,

Meta menardi and M. bourneti are two species of spiders inhabiting caves and other subterranean habitats. The occurrence of both species within the same cave has never been proved convincingly and several authors hypothesized a complete niche differentiation mainly based on microclimatic conditions.In order to study the apparent niche differentiation of the two species, we studied several populations of M. menardi and M. bourneti occurring in six caves in the Western Italian Alps (NW Italy). A series of squared plots were monitored monthly from March 2012 to February 2013. At each survey, we counted individuals and we collected the main environmental variables at each plot, namely distance from cave entrance, structural typology (wall, floor or ceiling), light intensity, wind speed and counts of potential prey. Moreover, temperature and relative humidity were continuously logged in each cave. We run several statistical models (GLMMs) in order to relate the counts of individuals to the environmental parameters. The distance from the cave entrance, structural typology and prey availability resulted most important factors driving the abundance of both species within the cave. On the other hand, despite life cycles appeared very similar, the two species seems to exhibit different tolerance to the microclimatic variations within the cave, which emerged as the main factors determining the differentiation of their niche. At least in our study area, M. bourneti tolerates broad microclimatic fluctuations and is potentially able to colonize a wide variety of caves. On the other hand, when the climatic conditions in a cave are suitable for M. menardi (narrow ranges of relatively low temperature and high humidity), M. bourneti is excluded.

Earliest evidence of pollution by heavy metals in archaeological sites, 2015, Guadalupe Monge, Francisco J. Jimenezespejo, Antonio Garcíaalix, Francisca Martínezruiz, Nadine Mattielli, Clive Finlayson, Naohiko Ohkouchi, Miguel Cortés Sánchez, Jose María Bermúdez De Castro, Ruth Blasco, Jordi Rosell, José Carrión, Joaquí

Homo species were exposed to a new biogeochemical environment when they began to occupy caves. Here we report the first evidence of palaeopollution through geochemical analyses of heavy metals in four renowned archaeological caves of the Iberian Peninsula spanning the last million years of human evolution. Heavy metal contents reached high values due to natural (guano deposition) and anthropogenic factors (e.g. combustion) in restricted cave environments. The earliest anthropogenic pollution evidence is related to Neanderthal hearths from Gorham's Cave (Gibraltar), being one of the first milestones in the so-called “Anthropocene”. According to its heavy metal concentration, these sediments meet the present-day standards of “contaminated soil”. Together with the former, the Gibraltar Vanguard Cave, shows Zn and Cu pollution ubiquitous across highly anthropic levels pointing to these elements as potential proxies for human activities. Pb concentrations in Magdalenian and Bronze age levels at El Pirulejo site can be similarly interpreted. Despite these high pollution levels, the contaminated soils might not have posed a major threat to Homo populations. Altogether, the data presented here indicate a long-term exposure of Homo to these elements, via fires, fumes and their ashes, which could have played certain role in environmental-pollution tolerance, a hitherto neglected influence.