Colored microbial coatings in show caves from the galapagos islands (Ecuador): first microbiological approach

The Galapagos Islands (Ecuador) have a unique ecosystem on Earth due to their outstanding biodiversity and geological features. This also extends to their subterranean heritage, such as volcanic caves, with plenty of secondary mineral deposits, including coralloid-type speleothems and moonmilk deposits. In this study, the bacterial communities associated with speleothems from two lava tubes of Santa Cruz Island were investigated. Field emission scanning electron microscopy (FESEM) was carried out for the morphological characterization and detection of microbial features associated with moonmilk and coralloid speleothems from Bellavista and Royal Palm Caves. Microbial cells, especially filamentous bacteria in close association with extracellular polymeric substances (EPS), were abundant in both types of speleothems. Furthermore, reticulated filaments and Actinobacteria-like cells were observed by FESEM. The analysis of 16S rDNA revealed the presence of different bacterial phylotypes, many of them associated with the carbon, nitrogen, iron and sulfur cycles, and some others with pollutants. This study gives insights into subsurface microbial diversity of the Galapagos Islands and further shows the interest of the conservation of these subterranean geoheritage sites used as show caves.Ministerio del Ambiente de Ecuador (Parque Nacional Galápagos)-PC-65-14Ministerio de Economía y Competitividad de España (MINECO) y el Fondo Europeo de Desarrollo Regional de la Unión Europea (FEDER)-CGL2016-75590-PPortuguese Foundation for Science and Technology. Fundação para a Ciência e a Tecnologia (FCT)-UID/Multi/04449/2019 HERCULES/U

Karst: un concepto muy diverso

La gran diversidad intrínseca del karst y la variedad de campos científicos desde los que ha sido estudiado este medio ha generado un espectacular aumento de su conocimiento. Ese avance ha venido acompañado también de nuevas incógnitas y nuevos planteamientos. El presente trabajo trata de recoger una pequeña muestra de esa amplia diversidad, asociada a un elevado grado de especialización, que de forma integrada permite completar el puzzle del karst. Inicialmente, se presenta una revisión sintética del concepto de karst, del proceso de karstificación y de las morfologías asociadas al mismo. Seguidamente, y planteado a partir de una serie de interrogantes, se muestran algunos aspectos y curiosidades relacionadas con el karst. Las características microclimáticas subterráneas, el karst no tradicional o los depósitos y mineralizaciones asociados al karst, son algunos de los temas que se incluyen en este trabajo y que puede interesar a los docentes que imparten docencia sobre el karst

Colored Microbial Coatings in Show Caves from the Galapagos Islands (Ecuador): First Microbiological Approach

The Galapagos Islands (Ecuador) have a unique ecosystem on Earth due to their outstanding biodiversity and geological features. This also extends to their subterranean heritage, such as volcanic caves, with plenty of secondary mineral deposits, including coralloid-type speleothems and moonmilk deposits. In this study, the bacterial communities associated with speleothems from two lava tubes of Santa Cruz Island were investigated. Field emission scanning electron microscopy (FESEM) was carried out for the morphological characterization and detection of microbial features associated with moonmilk and coralloid speleothems from Bellavista and Royal Palm Caves. Microbial cells, especially filamentous bacteria in close association with extracellular polymeric substances (EPS), were abundant in both types of speleothems. Furthermore, reticulated filaments and Actinobacteria-like cells were observed by FESEM. The analysis of 16S rDNA revealed the presence of different bacterial phylotypes, many of them associated with the carbon, nitrogen, iron and sulfur cycles, and some others with pollutants. This study gives insights into subsurface microbial diversity of the Galapagos Islands and further shows the interest of the conservation of these subterranean geoheritage sites used as show caves

Organic geochemistry and mineralogy suggest anthropogenic impact in speleothem chemistry from volcanic show caves of the Galapagos

20 páginas.- 8 figuras.- 1 tabla.- 94 referencias.- Supplemental information can be found online at https://doi.org/10.1016/j.isci.2022.104556The network of lava tubes is one of the most unexploited natural wonders of the Galapagos Islands. Here, we provide the first morphological, mineralogical, and biogeochemical assessment of speleothems from volcanic caves of the Galapagos to understand their structure, composition, and origin, as well as to identify organic molecules preserved in speleothems. Mineralogical analyses revealed that moonmilk and coralloid speleothems from Bellavista and Royal Palm Caves were composed of calcite, opal-A, and minor amounts of clay minerals. Extracellular polymeric substances, fossilized bacteria, silica microspheres, and cell imprints on siliceous minerals evidenced microbe-mineral interactions and biologically-mediated silica precipitation. Alternating depositional layers between siliceous and carbonate minerals and the detection of biomarkers of surface vegetation and anthropogenic stressors indicated environmental and anthropogenic changes (agriculture, human waste, and cave visits) on these unique underground resources. Stable isotope analysis and Py-GC/MS were key to robustly identify biomarkers, allowing for implementation of future protection policies.This research work received funding from the European Commission’s 7th Framework Programme under the Marie Curie Intra-European Fellowship PIEF-GA-2012-328689-DECAVE. The financial support from the Spanish Ministry of Science and Innovation (MCIN) under the research project TUBOLAN PID2019- 108672RJ-I00 funded by MCIN/AEI/10.13039/501100011033 is also acknowledged. In addition, this work received support from: i) the Portuguese Foundation for Science and Technology (FCT) under the MICROCENO project (PTDC/CTA-AMB/0608/2020), the EROFIRE project (PCIF-RPG-0079-2018) and the project UID/Multi/04449/2019 for HERCULES/UE. A.Z.M. was supported by the CEECIND/01147/2017 contract from FCT, and the Ramón y Cajal contract (RYC2019-026885-I) from the MCIN. M.L.C. and N.T.J.M. were supported by CEECIND/00349/2017 and 2021/00711/CEECIND contracts, respectively, funded by FCT. F.G. was financially supported by the ‘‘HIPATIA’’ research program of the University of Almería and a Ramón y Cajal Fellowship (RYC2020-029811-I) of MCIN.Peer reviewe

Colored Microbial Coatings in Show Caves from the Galapagos Islands (Ecuador): First Microbiological Approach

The Galapagos Islands (Ecuador) have a unique ecosystem on Earth due to their outstanding biodiversity and geological features. This also extends to their subterranean heritage, such as volcanic caves, with plenty of secondary mineral deposits, including coralloid-type speleothems and moonmilk deposits. In this study, the bacterial communities associated with speleothems from two lava tubes of Santa Cruz Island were investigated. Field emission scanning electron microscopy (FESEM) was carried out for the morphological characterization and detection of microbial features associated with moonmilk and coralloid speleothems from Bellavista and Royal Palm Caves. Microbial cells, especially filamentous bacteria in close association with extracellular polymeric substances (EPS), were abundant in both types of speleothems. Furthermore, reticulated filaments and Actinobacteria-like cells were observed by FESEM. The analysis of 16S rDNA revealed the presence of different bacterial phylotypes, many of them associated with the carbon, nitrogen, iron and sulfur cycles, and some others with pollutants. This study gives insights into subsurface microbial diversity of the Galapagos Islands and further shows the interest of the conservation of these subterranean geoheritage sites used as show caves

Innocampus Explora: Nuevas formas de comunicar ciencia

[EN] Innocampus Explora aims to show the students of the Burjassot-Paterna campus of the Universitat de València how the different scientific degrees are interrelated. To do this we propose activities in which students and teachers work together to cover the interdisciplinary nature of science, both in everyday and professional issues. Throughout this course the activities developed relate to new ways to communicate science. With the development of this project we contribute to a transversal quality education for all the participating students.[ES] Innocampus Explora tiene por objetivo mostrar a los estudiantes del campus de Burjassot-Paterna de la Universitat de València cómo los diferentes grados científicos están interrelacionados. Para ello proponemos actividades en las que estudiantes y profesores trabajen conjuntamente para abarcar la interdisciplinariedad de la ciencia, tanto en temas cotidianos como profesionales. A lo largo de este curso las actividades desarrolladas se relacionan con las nuevas formas de comunicar ciencia. Con el desarrollo de este proyecto contribuimos a una formación transversal de calidad para todos los estudiantes participantes.Moros Gregorio, J.; Rodrigo Martínez, P.; Torres Piedras, C.; Montoya Martínez, L.; Peña Peña, J.; Pla Díaz, M.; Galarza Jiménez, P.... (2019). Innocampus Explora: Nuevas formas de comunicar ciencia. En IN-RED 2019. V Congreso de Innovación Educativa y Docencia en Red. Editorial Universitat Politècnica de València. 814-823. https://doi.org/10.4995/INRED2019.2019.10449OCS81482

Brazilian cave heritage under siege

info:eu-repo/semantics/publishe

Analytical pyrolysis and stable isotope analyses reveal past environmental changes in coralloid speleothems from Easter Island (Chile)

9 páginas.-- 3 figuras.-- 2 tablas.-- 83 referencias.-- Selected paper from the XVI Latin-American Congress on Chromatography (XVICOLACRO) and the 9th National Meeting on Chromatography (9ENC), 5–9 January 2016, Lisbon, Portugal.This study comprises an innovative approach based on the combination of chromatography (analytical pyrolysis and pyrolysis compound-specific isotope analysis (Py-CSIA)), light stable isotopes, microscopy and mineralogy analyses to characterize the internal layering of coralloid speleothems from the Ana Heva lava tube in Easter Island (Chile). This multidisciplinary proxy showed that the speleothems consist of banded siliceous materials of low crystallinity with different mineralogical compositions and a significant contribution of organic carbon. Opal-A constitutes the outermost grey layer of the coralloids, whereas calcite and amorphous Mg hydrate silicate are the major components of the inner whitish and honey-brown layers, respectively. The differences found in the mineralogical, elemental, molecular and isotopic composition of these distinct coloured layers are related to environmental changes during speleothem development. Stable isotopes and analytical pyrolysis suggested alterations in the water regime, pointing to wetter conditions during the formation of the Ca-rich layer and a possible increase in the amount of water dripping into the cave. The trend observed for δN values suggested an increase in the average temperature over time, which is consistent with the so-called climate warming during the Holocene. The pyrolysis compound-specific isotope analysis of each speleothem layer showed a similar trend with the bulk δC values pointing to the appropriateness of direct Py-CSIA in paleoenvironmental studies. The δC values for n-alkanes reinforced the occurrence of a drastic environmental change, indicating that the outermost Opal layer was developed under drier and more arid environmental conditions.A.Z. Miller acknowledges the support from the Marie Curie Intra-European Fellowship of the European Commission’s 7th Framework Programme (PIEF-GA-2012-328689). The Spanish Ministry of Economy and Competitiveness (MINECO, project CGL2013-41674-P) and the FEDER Funds are acknowledged for the financial support. N.T. Jiménez-Morillo thanks the MINECO for funding his pre-doctoral FPI fellowship (BES-2013-062573).Peer Reviewe

Analytical pyrolysis (Py-GC/MS) and Py compounds specific isotopic analysis (Py-CSIA) as proxy for the characterization of coralloid speleothems from lava tubes

Galardonado por el comité científico de dicho congreso con el premio a la mejor contribución científica.Lava tubes are a type of volcanic caves formed when lava flows down along the slopes after the eruption of the magma. They develop as a hard crust on the surface of the basaltic lava flow due to rapid cooling, while inside the lava remains liquid. Secondary mineral deposits, or speleothems, mainly of siliceous composition have been reported on the walls and ceiling of many lava tubes [1, 2]. However, lava tubes have traditionally been considered of little interest from a mineralogical point of view and the studies devoted to those secondary mineral deposits are scarce. Cave corals or coralloid-like speleothems are found either on the basalt surface or on the surface of other speleothems. Hill and Forti [3] suggested that subaerial cave corals are generated by capillary-film water, whereas other authors attribute a microbially mediated origin to their formation [2]. Siliceous minerals are sometimes intercalated with carbonate minerals [4] due to the change in the chemical composition of supplying water, environmental changes of the surface area overlying caves and probable diagenesis. However, most of the literature devoted to cave corals merely describes its geology, morphology and mineralogy. The application of chromatographic techniques to the study of speleothems is scarce due to their low content of organic compounds and low volatility. This study comprises an innovative approach based in the combination of chromatographic and isotopic analyses, which were applied to characterize coralloid speleothems from the Ana Heva lava tube in Easter Island (Chile). Analytical pyrolysis combines GC/MS with pyrolysis and has become an important tool for the characterization of sediments [5]. In addition, this study takes advantage of Py-CSIA, a relatively novel technique in which the pyrolysate is directed through a combustion into an isotope ratio mass spectrometer (Py-GC-C/TC-IRMS) to measure stable isotope proportions i.e., ¿13C, ¿15N respectively of specific pyrolysis compounds. Figure 1. A) Coralloids, B) corresponding cross-section and C) Py-GC/MS at 500ºC of the three coralloid layers from Ana Heva lava tube. Pyrochromatograms of the three different layers of this coralloid speleothem were composed by alkyl benzenes, naphthalenes, n-alkanes and a few N-containing compounds, which are typical compounds from plant remains and microorganisms. Variations in ¿13C values suggested changes in water surplus. They suggest wetter conditions during the formation of the Ca-layer and a possible increase in the amount of incoming fluids from the covering andosol. The trend observed for ¿ 15N values could indicate an increase on the average temperature along the time, which is consistent with the so-called climate warming during the Holocene.Dr. J.M. de la Rosa and A.Z. Miller thank the ¿Biocharisma¿ (PCIG12-GA-2012-333784) and ¿DECAVE¿ (PIEF-GA-2012-328689) projects, respectively, funded by the Marie Curie Actions of the EC 7th Framework Programme. The Spanish Ministry of Economy and Competitiveness (project CGL2013-41674-P) and the European Social Funds are acknowledged for the financial support.Peer reviewe

Biomineralization and biosignatures of coralloid-type speleothems from lava tubes of Galapagos Islands: evidences on the fossil record of prokaryotes

Comunicación oral presentada en la European Geosciences Union General Assembly 2016 Vienna | Austria | 17–22 April 2016Lava tubes have traditionally been considered of little interest from a mineralogical point of view. Recently, this type of volcanic caves has received particular attention because lava tubes have been described on Mars. Speleothems, or secondary mineral deposits in lava tubes are mainly composed of siliceous minerals. Coralloidtype speleothems are found either on basaltic cave walls or on the surface of other speleothems. Several authors attribute a microbially mediated origin to their formation. This type of speleothems was recorded within Royal Palm Cave of Santa Cruz Island in Galapagos Archipelago (Ecuador), a lava tube 600 m long, 5 to 15 m height and 2 to 10 m width. The Galapagos Islands are an archipelago of 19 volcanic islands located some 1500 km west of Ecuador, in the Pacific Ocean. These islands host one of the most biodiverse settings on Earth, studied by Charles Darwin. Beige and greyish small coralloids were collected in Royal Palm Cave and analysed by field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDS), X-ray micro-computed tomography (micro-CT) and mineralogical analyses for morphological, 3D microstructural and compositional characterization, as well as for assessing microbe-mineral interactions and biogenicity. In addition, 16S rRNA gene analyses were performed to identify microbial communities associated with the coralloid-type speleothems. The coralloids showed internal compositional zonation along the growth direction of the speleothems, according to micro-CT data. Internal layering was clearly discernable by the differences in opacity of the distinct mineralogical phases to X-rays, being dominated by alteration products of siliceous composition, whereas more opaque phases, usually Ca-rich minerals, were dominant in the outermost part of the speleothems. X-ray diffraction and infrared spectroscopy reinforced that the first stage of deposition is mainly composed of opal A and clay minerals, whereas the final stage mainly consists of low crystalline calcite. FESEM-EDS analysis revealed mineralized bacterial filaments rich in Si on the coralloid samples, as well as minerals precipitation associated with extracellular polymeric substances (EPS), which serve as nuclei for preferential precipitation on the extracellular sheaths. This suggests that biological activity played a major role in the development of these speleothems. In addition, imprints of filamentous cells and microboring readily preserved on siliceous minerals were observed on the coralloid speleothems. These features are recognized as biosignatures valuable for astrobiology and may represent modern analogs of the fossil record of prokaryotes. DNA-based analyses showed that bacteria belonging to Actinobacteria (31%) Gemmatimonadetes (25%) and Proteobacteria (24%) phyla dominated in this cave ecosystem, followed by Acidobacteria, Firmicutes and Nitrospirae. Most of the identified phylotypes were affiliated to chemoautotrophs, including thermophilic bacteria such as Ferrithrix thermotolerans, and other mineral utilizing microorganisms like Aciditerrimonas ferrireducens, Desulfuromonas sp. and Desulfovibrio sp., indicating that Galapagos lava tubes host highly specialized subsurface biosphere dominated by microorganisms able to interact with minerals and promote biomineralization.This work has been supported by the project PC-65-14 from the Ministry of Environment of Ecuador. AZM acknowledges the support from the Marie Curie Fellowship of the 7th EC Framework Programme (PIEF-GA-2012-328689-DECAVE). The authors acknowledge the Spanish Ministry of Economy and Competitiveness (project CGL2013-41674-P) and FEDER funds for financial supportPeer reviewe