Scenarios for the Altamira cave CO2 concentration from 1950 to 2100.

A data-driven approach insensitive to the initial conditions was developed to extract governing equations for the concentration of CO2 in the Altamira cave (Spain) and its two main drivers: the outside temperature and the soil moisture. This model was then reformulated in order to use satellite observations and meteorological predictions, as a forcing. The concentration of CO2 inside the cave was then investigated from 1950 to 2100 under various scenarios. It is found that extreme levels of CO2 were reached during the period 1950-1972 due to the massive affluence of visitors. It is demonstrated that it is possible to monitor the CO2 in the cave in real time using satellite information as an external forcing. For the future, it is shown that the maximum values of CO2 will exceed the levels reached during the 1980s and the 1990s when the CO2 introduced by the touristic visits, although intentionally reduced, still enhanced considerably the micro corrosion of walls and pigments.

A Second Fungal Outbreak in Castañar Cave, Spain, Discloses the Fragility of Subsurface Ecosystems.

Castañar is a cave with strict visitor control measures since it was open to public visits in 2003. However, in recent years, the cave suffered two fungal outbreaks, the first in 2008 and controlled by cleaning the contaminated sediments and subsequent closure of the cave until 2014. The cave was reopened but limited to a maximum of 450 visitors/year. Despite these restrictions on visit, the cave experienced a second outbreak in 2021, originating from the installation of a steel grating walkway, aiming at protecting the ground sediments from the visitors' footsteps. Here, we conducted an analysis using Next-Generation Sequencing and culture-dependent techniques to investigate the fungal communities related to the second outbreak and compare with those present before the cave suffered the outbreak. The results show that the most abundant fungi involved in the 2021 outbreak were already detected in 2020, and even in 2008 and 2009, although the main species that originating both outbreaks were different, likely due to the different carbon sources introduced into the cave.

Adaptive response of prokaryotic communities to extreme pollution flooding in a Paleolithic rock art cave (Pindal Cave, northern Spain).

A flood event affecting Pindal Cave, a UNESCO World Heritage site, introduced a substantial amount of external sediments and waste into the cave. This event led to the burial of preexisting sediments, altering the biogeochemical characteristics of the cave ecosystem by introducing heightened levels of organic matter, nitrogen compounds, phosphorus, and heavy metals. The sediments included particulate matter and waste from a cattle farm located within the water catchment area of the cavity, along with diverse microorganisms, reshaping the cave microbial community. This study addresses the ongoing influence of a cattle farm on the cave ecosystem and aims to understand the adaptive responses of the underground microbial community to the sudden influx of waste allochthonous material. Here, we show that the flood event had an immediate and profound effect on the cave microbial community, marked by a significant increase in methanogenic archaea, denitrifying bacteria, and other microorganisms commonly associated with mammalian intestinal tracts. Furthermore, our findings reveal that one year after the flood, microorganisms related to the flood decreased, while the increase in inorganic forms of ammonium and nitrate suggests potential nitrification, aligning with increased abundances of corresponding functional genes involved in nitrogen cycling. The results reveal that the impact of pollution was neither recent nor isolated, and it was decisive in stopping livestock activity near the cave. The influence of the cattle farm has persisted since its establishment over the impluvium area, and this influence endures even a year after the flood. Our study emphasizes the dynamic interplay between natural events, anthropogenic activities, and microbial communities, offering insights into the resilience of cave ecosystems. Understanding microbial adaptation in response to environmental disturbances, as demonstrated in this cave ecosystem, has implications for broader ecological studies and underscores the importance of considering temporal dynamics in conservation efforts.

Microclimate, airborne particles, and microbiological monitoring protocol for conservation of rock-art caves: The case of the world-heritage site La Garma cave (Spain).

Cave heritage is often threatened by tourism or even scientific activities, which can lead to irreversible deterioration. We present a preventive conservation monitoring protocol to protect caves with rock art, focusing on La Garma Cave (Spain), a World Heritage Site with valuable archaeological materials and Palaeolithic paintings. This study assessed the suitability of the cave for tourist use through continuous microclimate and airborne particles monitoring, biofilm analysis, aerobiological monitoring and experimental visits. Our findings indicate several factors that make it inadvisable to adapt the cave for tourist use. Human presence and transit within the cave cause cumulative effects on the temperature of environmentally very stable and fragile sectors and significant resuspension of particles from the cave sediments. These environmental perturbations represent severe impacts as they affect the natural aerodynamic control of airborne particles and determine bacterial dispersal throughout the cave. This monitoring protocol provides part of the evidence to design strategies for sustainable cave management.

Impact of a Cardiogenic Shock Program on Mortality in a Non-Transplant Hospital.

INTRODUCTION: Cardiogenic shock is associated with high in-hospital morbidity and mortality. Improvements in this care process could lead to better outcomes. METHODS: This retrospective study of patients with cardiogenic shock compared two periods: no specific program to address cardiogenic shock and implementation of a cardiogenic shock program. This program included the establishment of a multidisciplinary team (shock team), early alert to the transplant hospital, initiation of a ventricular assist extracorporeal membrane oxygenation (ECMO) program, and extension of continuous care by acute cardiovascular care specialists. The primary objective was to analyse whether there were differences between in-hospital mortality and mortality during follow-up. Predictors of in-hospital mortality were examined as a secondary objective. RESULTS: A total of 139 patients were enrolled: 69 of them in the previous period and 70 in the cardiogenic shock program period. There was a significant reduction in in-hospital mortality (55.1% vs 37.1%; p=0.03) and mortality during follow-up (62.7% vs 44.6%; p=0.03) in the second period. Diabetes mellitus, ejection fraction, out-of-hospital cardiac arrest, and implementation of the cardiogenic shock program were independent predictors of in-hospital mortality. CONCLUSIONS: The implementation of a comprehensive cardiogenic shock program in a non-transplanting hospital improved in-hospital and follow-up mortality of patients in cardiogenic shock.

Prokaryotic communities inhabiting a high-radon subterranean ecosystem (Castañar Cave, Spain): Environmental and substrate-driven controls.

Castañar Cave (Caceres, Spain) is a unique show cave known for its high natural radiation levels. This study presents a comprehensive analysis of its prokaryotic diversity, specifically focusing on investigating the influence of environmental conditions and substrate characteristics on the prokaryotic community structure in the cave sediments. Additionally, the research aims to evaluate the potential impact of human activities on the cave ecosystem. The identification of distinct bioclimatic zones within the cave was made possible through a combination of environmental and microbial monitoring (ATP assays). The results reveal sediment texture as a significant factor, notably affecting the structure, diversity, and phylogenetic variability of the microbial community, including both Bacteria and Archaea. The proportion of clay minerals in sediments plays a crucial role in regulating moisture levels and nutrient availability. These substrate properties collectively exert a significant selective pressure on the structure of prokaryotic communities within cave sediments. The molecular approach shows that heterotrophic bacteria, including those with chitinolytic enzymes, primarily inhabit the cave. Furthermore, chemoautotrophic nitrifiers such as the archaea Nitrososphaeria and the genus Nitrospira, as well as methanotrophic bacteria from the phyla Methylomirabilota, Pseudomonadota, and Verrucomicrobiota, are also present. Remarkably, despite being a show cave, the cave microbiota displays minimal impacts from human activities and the surface ecosystem. Prokaryotic populations exhibit stability in the innermost areas, while the tourist trail area experiences slightly higher biomass increases due to visitor traffic. This suggests that conservation efforts have successfully limited the entry of external nutrients into the innermost cave areas. Additionally, the results suggest that integrating biomarkers like ATP into environmental monitoring can significantly enhance the methods used to study the negative impacts of tourism on cave ecosystems.

Uncommon short- and long-term cardiological side effects of thoracic radiation: a report of two cases.

Radiotherapy is an essential treatment of more than 50% of oncohematological patients. Pericardial disorders and valvular heart disease are two common radiotherapy complications. Acute pericarditis is infrequent and usually underdiagnosed. Therefore, diagnostic suspicion and early treatment are mandatory to avoid the evolution to constrictive pericarditis. The prevalence of radiation-induced valvular heart disease is common in patients with a history of Hodgkin's lymphoma and breast cancer. It has distinctive characteristics from other etiologies and, thus, different therapeutic approaches. We present two cases of unusual complications of radiotherapy; the first one in the acute setting and the second one during the follow-up in the chronic phase. A multidisciplinary and individualized approach with specific considerations is decisive in the management of these patients.

New insights into the structure, microbial diversity and ecology of yellow biofilms in a Paleolithic rock art cave (Pindal Cave, Asturias, Spain).

In the absence of sunlight, caves harbor a great diversity of microbial colonies to extensive biofilms with different sizes and colors visible to the naked eye. One of the most widespread and visible types of biofilm are those with yellow hues that can constitute a serious problem for the conservation of cultural heritage in many caves, such as Pindal Cave (Asturias, Spain). This cave, declared a World Heritage Site by UNESCO for its Paleolithic parietal art, shows a high degree of development of yellow biofilms that represents a real threat to the conservation of painted and engraved figures. This study aims to: 1) identify the microbial structures and the most characteristic taxa composing the yellow biofilms, 2) seek the linked microbiome reservoir primarily contributing to their growth; 3) seed light on the driving vectors that contribute to their formation and determine the subsequent proliferation and spatial distribution. To achieve this goal, we used amplicon-based massive sequencing, in combination with other techniques such as microscopy, in situ hybridization and environmental monitoring, to compare the microbial communities of yellow biofilms with those of drip waters, cave sediments and exterior soil. The results revealed microbial structures related to the phylum Actinomycetota and the most characteristic bacteria in yellow biofilms, represented by the genera wb1-P19, Crossiella, Nitrospira, and Arenimonas. Our findings suggest that sediments serve as potential reservoirs and colonization sites for these bacteria that can develop into biofilms under favorable environmental and substrate conditions, with a particular affinity for speleothems and rugged-surfaced rocks found in condensation-prone areas. This study presents an exhaustive study of microbial communities of yellow biofilms in a cave, which could be used as a procedure for the identification of similar biofilms in other caves and to design effective conservation strategies in caves with valuable cultural heritage.

Changes in echocardiographic parameters over time in paradoxical low-flow low-gradient aortic stenosis.

AIMS: To assess the progression of the disease and evolution of the main echocardiographic variables for quantifying AS in patients with severe low-flow low-gradient (LFLG) AS compared to other severe AS subtypes. METHODS AND RESULTS: Longitudinal, observational, multicenter study including consecutive asymptomatic patients with severe AS (aortic valve area, AVA < 1.0 cm²) and normal left ventricle ejection fraction (LVEF ≥ 50%). Patients were classified according to baseline echocardiography into: HG (high gradient; mean gradient ≥ 40 mmHg), NFLG (normal-flow low-gradient; mean gradient < 40 mmHg, indexed systolic volume (SVi) > 35mL/m2), or LFLG (mean gradient < 40 mmHg, SVi ≤ 35 mL/m²). AS progression was analyzed by comparing patients' baseline measurements and their last follow-up measurements or those taken prior to aortic valve replacement (AVR). Of the 903 included patients, 401 (44.4%) were HG, 405 (44.9%) NFLG, and 97 (10.7%) LFLG. Progression of the mean gradient in a linear mixed regression model was greater in low-gradient groups: LFLG vs. HG (regression coefficient 0.124, P = 0.005) and NFLG vs. HG (regression coefficient 0.068, P = 0.018). No differences were observed between the LFLG and NFLG groups (regression coefficient 0.056, P = 0.195). However, AVA reduction was slower in the LFLG group compared to the NFLG (P < 0.001). During follow-up, in conservatively-managed patients, 19.1% (n = 9) of LFLG patients evolved to having NFLG AS and 44.7% (n = 21) to having HG AS. In patients undergoing AVR, 58.0% (n = 29) of LFLG baseline patients received AVR with a HG AS. CONCLUSION: LFLG AS shows an intermediate AVA and gradient progression compared to NFLG and HG AS. The majority of patients initially classified as having LFLG AS changed over time to having other severe forms of AS, and most of them received AVR with a HG AS.

Invasive management of significant tricuspid regurgitation in clinical practice.

BACKGROUND: Tricuspid regurgitation (TR) is a prevalent condition inside valvular heart disease (VHD) with relevant prognosis implications. However, concordance between real management in clinical practice and invasive treatment recommendations of European Society of Cardiology (ESC) guidelines is unknown. METHODS: A substudy of ESC VHD II survey was performed to evaluate the real treatment of TR compared to the clinical ESC guidelines recommendations published in 2012, 2017 and 2021 was performed. TR cases with surgical indication were divided in 3 groups: 1: severe isolated TR without previous left VHD; 2: moderate/severe TR and concomitant severe left VHD; 3: severe TR plus previous left VHD surgery. RESULTS: Of 902 patients assessed, 123 had significant TR. Fifty (41%) cases demonstrated ESC guidelines 2012-2017 Class I or IIa recommendations for invasive treatment: 9(18%) of group 1, 37(74%) of group 2 and 4(8%) of group 3. Surgery was performed in 24 patients (48%); 1 in group 1(4%), 22 in group 2(92%) and 1 in group 3(4%). Overall concordance was 48% (group 1: 11%; group 2: 59%; group 3: 25%). Regarding the 2021 ESC guidelines only one patient changed groups with an overall concordance of 47% (group 1: 10%; group 2: 59%; group 3: 25%). CONCLUSION: Concordance between 2012, 2017 and 2021 ESC guidelines recommendations and clinical practice for TR surgical intervention is low, especially in those without concomitant severe left VHD. These results suggest the need to improve further guideline implementation and alternative treatments, such as percutaneous, which could resolve potential discrepancies in those clinical scenarios.

Ventricular Intramyocardial Dissecting Hematoma: What Is its True Clinical Evolution and the Best Treatment?

Intramyocardial dissecting hematoma (IDH), in the setting of an acute coronary syndrome, is a rare type of cardiac rupture. However, the best treatment for IDH in each clinical scenario is not clearly defined. We present a case in which the best approach for IDH and its final outcome are discussed.

Diversity of Microfungi in a High Radon Cave Ecosystem.

Castañar Cave is a clear example of an oligotrophic ecosystem with high hygrothermal stability both seasonal and interannual and the particularity of registering extraordinary levels of environmental radiation. These environmental conditions make the cave an ideal laboratory to evaluate both the responses of the subterranean environment to sudden changes in the matter and energy fluxes with the exterior and also any impact derived from its use as a tourist resource under a very restrictive access regime. In 2008, a fungal outbreak provoked by a vomit contaminated the sediments which were removed and subsequently treated with hydrogen peroxide. Fungal surveys were carried out in 2008 and 2009. The visits were resumed in 2014. Here, 12 years after the outbreak, we present an exhaustive study on the cave sediments in order to know the distribution of the different fungal taxa, as well as the prevalence and spatio-temporal evolution of the fungi caused by the vomit over the years under the conditions of relative isolation and high radiation that characterize this cave.

Multimodality Imaging in the Study of the Left Atrium.

The left atrium (LA) plays a vital role in maintaining normal cardiac function. Many cardiac diseases involve the functioning of the LA directly or indirectly. For this reason, the study of the LA has become a priority for today's imaging techniques. Assessment of LA size, function and wall characteristics is routinely performed in cardiac imaging laboratories when a patient undergoes transthoracic echocardiography. However, in cases when the LA is the focus of disease management, such as in atrial fibrillation or left atrial appendage closure, the use of multimodality is critical. Knowledge of the usefulness of each cardiac imaging technique for the study of LA in these patients is crucial in order to choose the most appropriate treatment. While echocardiography is the most widely performed technique for its evaluation and the study of wall deformation analysis is increasingly becoming more reliable, multidetector computed tomography allows a detailed analysis of its anatomy to be carried out in 3D reconstructions that help in the approach to interventional treatments. In addition, the evaluation of the wall by cardiac magnetic resonance imaging or the generation of electroanatomical maps in the electrophysiology room have become essential tools in the treatment of multiple atrial pathologies. For this reason, the goal of this review article is to describe the basic anatomical and functional information of the LA as well as their study employing the main imaging techniques currently available, so that practitioners specializing in cardiac imaging techniques can use these tools in an accurate and clinically useful manner.

Post-mortem toxicology analysis in a young sudden cardiac death cohort.

Risk of sudden cardiac death (SCD) increases with age, and several studies have examined the impact of different drugs on cardiovascular function. However, few studies have integrated epidemiological drug consumption data and genetic background in the context of cardiac death. We performed a retrospective population-based study in forensic sudden death cases from a 9-year period in Catalonia. The young cohort included 924 cases 18-50 years old, 566 of which had a cardiac cause of death. Complete autopsy, toxicological, and histopathological studies were performed. Molecular autopsy using next-generation sequencing was performed in nearly 400 cardiac cases. Cases related with fatal acute intoxication were excluded. Drug consumption prevalence was similar between forensic cases of cardiac and non-cardiac origin (62.5% versus 69.5%), with the exception of alcohol, which was more prevalent in the cardiac group than in the non-cardiac group (23.3% versus 17.1%). Individuals in the toxicology-positive group were carriers of more rare genetic variants and were significantly younger than the toxicology-negative group. Psychopharmacological drugs were identified in 22.3% of cardiac cases, and molecular autopsy identified an association between antiepileptic drugs or caffeine and pathogenic or likely pathogenic variants in arrhythmogenic genes. Specific substances could therefore play an essential role as triggers of SCD in genetically predisposed young people.

Prognosis of Paradoxical Low-Flow Low-Gradient Aortic Stenosis: A Severe, Non-critical Form, With Surgical Treatment Benefits.

Objectives: To determine the risk of mortality and need for aortic valve replacement (AVR) in patients with low-flow low-gradient (LFLG) aortic stenosis (AS). Methods: A longitudinal multicentre study including consecutive patients with severe AS (aortic valve area [AVA] < 1.0 cm2) and normal left ventricular ejection fraction (LVEF). Patients were classified as: high-gradient (HG, mean gradient ≥ 40 mmHg), normal-flow low-gradient (NFLG, mean gradient < 40 mmHg, indexed systolic volume (SVi) > 35 ml/m2) and LFLG (mean gradient < 40 mmHg, SVi ≤ 35 ml/m2). Results: Of 1,391 patients, 147 (10.5%) had LFLG, 752 (54.1%) HG, and 492 (35.4%) NFLG. Echocardiographic parameters of the LFLG group showed similar AVA to the HG group but with less severity in the dimensionless index, calcification, and hypertrophy. The HG group required AVR earlier than NFLG (p < 0.001) and LFLG (p < 0.001), with no differences between LFLG and NFLG groups (p = 0.358). Overall mortality was 27.7% (CI 95% 25.3-30.1) with no differences among groups (p = 0.319). The impact of AVR in terms of overall mortality reduction was observed the most in patients with HG (hazard ratio [HR]: 0.17; 95% CI: 0.12-0.23; p < 0.001), followed by patients with LFLG (HR: 0.25; 95% CI: 0.13-0.49; p < 0.001), and finally patients with NFLG (HR: 0.29; 95% CI: 0.20-0.44; p < 0.001), with a risk reduction of 84, 75, and 71%, respectively. Conclusions: Paradoxical LFLG AS affects 10.5% of severe AS, and has a lower need for AVR than the HG group and similar to the NFLG group, with no differences in mortality. AVR had a lower impact on LFLG AS compared with HG AS. Therefore, the findings of the present study showed LFLG AS to have an intermediate clinical risk profile between the HG and NFHG groups.

Role of subterranean microbiota in the carbon cycle and greenhouse gas dynamics.

Subterranean ecosystems play an active role in the global carbon cycle, yet only a few studies using indirect methods have focused on the role of the cave microbiota in this critical cycle. Here we present pioneering research based on in situ real-time monitoring of CO2 and CH4 diffusive fluxes and concurrent δ13C geochemical tracing in caves, combined with 16S microbiome analysis. Our findings show that cave sediments are promoting continuous CH4 consumption from cave atmosphere, resulting in a significant removal of 65% to 90%. This research reveals the most effective taxa and metabolic pathways in consumption and uptake of greenhouse gases. Methanotrophic bacteria were the most effective group involved in CH4 consumption, namely within the families Methylomonaceae, Methylomirabilaceae and Methylacidiphilaceae. In addition, Crossiella and Nitrosococcaceae wb1-P19 could be one of the main responsible of CO2 uptake, which occurs via the Calvin-Benson-Bassham cycle and reversible hydration of CO2. Thus, syntrophic relationships exist between Crossiella and nitrifying bacteria that capture CO2, consume inorganic N produced by heterotrophic ammonification in the surface of sediments, and induce moonmilk formation. Moonmilk is found as the most evolved phase of the microbial processes in cave sediments that fixes CO2 as calcite and intensifies CH4 oxidation. From an ecological perspective, cave sediments act qualitatively as soils, providing fundamental ecosystem services (e.g. nutrient cycling and carbon sequestration) with direct influence on greenhouse gas emissions.

Rare variants in genes encoding structural myocyte contribute to a thickened ventricular septum in sudden death population without ventricular alterations.

Unexpected cardiac deaths are a current challenge to healthcare systems. In adults, coronary artery disease and acquired cardiomyopathies are the most frequent causes of sudden cardiac death while in younger than 35 years old, the main cause is represented by non-ischemic diseases, usually inherited. Nowadays, around 10%-15% of unexpected deaths remain without a definite cause of decease after a complete autopsy, then classified as deaths potentially due to an inherited arrhythmia. Discrete abnormalities in some of the heart measures have been considered as potential predictors or risk factors for sudden cardiac death. However, role of non-benign genetic variants in these scattered heart alterations remains to be clarified, especially if variants are classified of ambiguous role. Clinicians usually only take into consideration pathogenic variants for decision-making. It is yet unclear what the role of VUS genetic variants in modifying the anatomical parameters of the heart. We hypothesize that some heart measures might be influenced by polygenic components as some variants may individually confer minor risk but may actually produce additive effects when combined with others. Our aim was to investigate whether carrying non-benign rare variants in genes related to inherited arrhythmias may contribute to scattered cardiac alterations in anatomical normal hearts. The study is composed by 761 samples collected from autopsies of SD suffered by adults from 18 to 50 years of age who occurred in Catalonia (Spain) in a 9-year period. Complete medico-legal autopsy was performed to determine the cause of death. Molecular autopsy was performed as part of our forensic protocol, including genes associated with inherited diseases.To evaluate the effect of genetic rare variants into hearts measures we performed a linear regression model and data were presented as regression. This study showed, for the first time, that rare variants, regardless of significance (pathogenic, probably pathogenic or uncertain significance), may contribute to interventricular septum width in the structurally normal heart. While the cohort is based on sudden death cases, further studies and case-control studies will be necessary to conclude that the genetic determinants of septal thickness contributes to sudden cardiac death. We conclude that non-benign rare variants contribute to modify scattered septum width in structural normal hearts, being a potential risk factor of arrhythmia in genetic harbors. These evidence support the current recommendation in forensic protocols of including histologic analysis of septum when inherited arrhythmogenic disease is suspicious cause of decease.

Predictors of Ascending Aorta Enlargement and Valvular Dysfunction Progression in Patients with Bicuspid Aortic Valve.

Bicuspid aortic valve (BAV) patients are at high risk of developing progressive aortic valve dysfunction and ascending aorta dilation. However, the progression of the disease is not well defined. We aimed to assess mid-long-term aorta dilation and valve dysfunction progression and their predictors. Patients were referred from cardiac outpatient clinics to the echocardiographic laboratories of 10 tertiary hospitals and followed clinically and by echocardiography for >5 years. Seven hundred and eighteen patients with BAV (median age 47.8 years [IQR 33-62], 69.2% male) were recruited. BAV without raphe was observed in 11.3%. After a median follow-up of 7.2 years [IQR5-8], mean aortic root growth rate was 0.23 ± 0.15 mm/year. On multivariate analysis, rapid aortic root dilation (>0.35 mm/year) was associated with male sex, hypertension, presence of raphe and aortic regurgitation. Annual ascending aorta growth rate was 0.43 ± 0.32 mm/year. Rapid ascending aorta dilation was related only to hypertension. Variables associated with aortic stenosis and regurgitation progression, adjusted by follow-up time, were presence of raphe, hypertension and dyslipidemia and basal valvular dysfunction, respectively. Intrinsic BAV characteristics and cardiovascular risk factors were associated with aorta dilation and valvular dysfunction progression, taking into account the inherent limitations of our study-design. Strict and early control of cardiovascular risk factors is mandatory in BAV patients.

Dominance of Arcobacter in the white filaments from the thermal sulfidic spring of Fetida Cave (Apulia, southern Italy).

The thermal spring of Fetida Cave, a still active sulfuric acid cave opening at sea level and located in Santa Cesarea Terme, southeastern Salento (Apulia region, Southern Italy) hosts abundant floating white filaments. The white filaments were mainly composed of sulfur crystals surrounded by microbial mass of the phyla Epsilonbacteraeota, Proteobacteria, Bacteroidetes, and Patescibacteria. The most abundant genus in the white filaments collected from the waters in the innermost part of the cave dominated by sulfidic exhalations was Arcobacter. This abundance can be related to the higher concentration of sulfide dissolved in water, and low oxygen and pH values. Conversely, lower Arcobacter abundances were obtained in the filaments collected in the entrance and middle part of the cave, where sulfidic water mixes with seawater, as the cave is subjected to tides and the mixing of fresh (continental) with marine water. The geochemical analysis of water and atmospheric gases confirmed these environmental constraints. In fact, the highest concentrations of H2S in the air and water were recorded closest to the spring upwelling in the innermost part of the cave, and the lowest ones near the cave entrance. The metabolic versatility of Arcobacter might provide a competitive advantage in the colonization of water bodies characterized by high sulfide, low oxygen, and dynamic fluid movement.