Cave monitoring in Hungary: An overview

In this study, already published and new monitoring data are compiled from the Baradla and Béke caves in the Aggtelek Karst, from the Vacska Cave in the Pilis Mountains as well as from the Szemlőhegy and Pálvölgy caves in the Buda Hills. Recent investigations (2019–2020) include monitoring of climatological parameters (e.g., temperature, CO2) measured inside and outside the caves, and the chemical, trace element and stable isotopic compositions of drip waters. In the Baradla Cave, the main focus of the investigation was on the stable isotope composition and the temperature measurements of drip water. In the Vacska Cave, which belongs to the Ajándék-Ariadne cave system, CO2 measurements and drip water collection were conducted in order to perform chemical and stable isotope measurements. In the Szemlőhegy and Pálvölgy caves, the chemical and stable isotope compositions of drip waters at six sites were determined. These datasets were used to characterize the studied caves and the hydrological processes taking place in the karst, and to trace anthropogenic influences. Climatological investigation revealed seasonality in CO2 concentration related to outside temperature variation, indicating a variable ventilation regime in the caves. In addition, the contributions of the winter and summer precipitation to the drip water were also estimated, in order to evaluate the main infiltration period. The knowledge of these parameters plays a crucial role in constraining the carbonate precipitation within the cave. Thus, the dataset compiled in this study can provide a basis for the interpretation of speleothem-based proxies.

StalGrowth—A Program to Estimate Speleothem Growth Rates and Seasonal Growth Variations

Speleothems are one of the few archives which allow us to reconstruct the terrestrial paleoclimate and help us to understand the important climate dynamics in inhabited regions of our planet. Their time of growth can be precisely dated by radiometric techniques, but unfortunately seasonal radiometric dating resolution is so far not feasible. Numerous cave environmental monitoring studies show evidence for significant seasonal variations in parameters influencing carbonate deposition (calcium-ion concentration, cave air pCO2, drip rate and temperature). Variations in speleothem deposition rates need to be known in order to correctly decipher the climate signal stored in the speleothem archive. StalGrowth is the first software to quantify growth rates based on cave monitoring results, detect growth seasonality and estimate the seasonal growth bias. It quickly plots the predicted speleothem growth rate together with the influencing cave environmental parameters to identify which parameter(s) cause changes in speleothem growth rate, and it can also identify periods of no growth. This new program has been applied to multiannual cave monitoring studies in Austria, Gibraltar, Puerto Rico and Texas, and it has identified two cases of seasonal varying speleothem growth.

Optimizing speleological monitoring efforts: insights from long-term data for tropical iron caves

Understanding the factors underpinning species abundance patterns in space and time is essential to implement effective cave conservation actions. Yet, the methods employed to monitor cave biodiversity still lack standardization, and no quantitative assessment has yet tried to optimize the amount and type of information required to efficiently identify disturbances in cave ecosystems. Using a comprehensive monitoring dataset for tropical iron caves, comprising abundance measurements for 33 target taxa surveyed across 95 caves along four years, here we provide the first evidence-based recommendations to optimize monitoring programs seeking to follow target species abundance through time. We found that seasonality did not influence the ability to detect temporal abundance trends. However, in most species, abundance estimates assessed during the dry season resulted in a more accurate detection of temporal abundance trends, and at least three surveys were required to identify global temporal abundance trends. Finally, we identified a subset of species that could potentially serve as short-term disturbance indicators. Results suggest that iron cave monitoring programs implemented in our study region could focus sampling efforts in the dry season, where detectability of target species is higher, while assuring data collection for at least three years. More generally, our study reveals the importance of long-term cave monitoring programs for detecting possible disturbances in subterranean ecosystems, and for using the generated information to optimize future monitoring efforts.

Cave monitoring at Drenska Peštera (N. Macedonia) – preliminary results

<p>Southeast Europe (i.e. Balkan Peninsula) is a climatologically interesting and complex area, located in a transient zone affected by both Mediterranean and continental atmospheric influences. Speleothem paleoclimate records are limited in this region, with only a few such records from the central parts. Furthermore, in the central parts, there are almost no existing data on cave monitoring, as well as on isotopic composition of precipitation.</p><p>For that purpose, a cave monitoring campaign was initiated in October 2018 at Drenska Peštera (southern parts of N. Macedonia) that followed a precipitation monitoring program initiated in the area in April 2018. The study site, located at 1150 m a.s.l., is an old fossil cave with a relatively simple morphology, and a total depth of ~40 m. The area has a mountain climate characterized as Dfb (cold with warm summer and no dry season) according to the Köppen-Geiger climate classification. Vadose speleothems are found throughout the cave, and few broken stalagmites were collected for paleoclimate study purposes. The cave monitoring initially included only monitoring of cave air temperatures, and was expanded in 2019 to include also monitoring of dripwater hydrology and geochemistry. Air temperatures were recorded at an hourly rate at three vertically distributed locations in the cave and at one location outside. Monthly collection of dripwater was initiated at two and later expanded to three dripping sites in the cave.</p><p>Preliminary results show that the local annual precipitation is generally in low amount (~400 mm), with maximum in Summer and Spring, and lowest in Winter. δ<sup>18</sup>O values of the precipitation show strong seasonality, with two distinct periods of higher (May-October) and lower (November-April) δ<sup>18</sup>O values, when average monthly temperatures are, respectively, above or below the local mean annual temperature. The local meteoric water line has slope that is close to the global meteoric water line with somewhat higher intercept indicating mixture of North Atlantic and Mediterranean atmospheric influences. Monthly variation of deuterium-excess indicates higher contribution of Mediterranean-sourced moisture in the cold period, likely related to Mediterranean cyclogenesis.</p><p>Cave air temperatures are stable (10.8±0.1 °C), reflecting the mean annual air temperature of the outside station (10.7 °C). Cave dripping is active mostly between December and July, and decreases (or completely stops) between August and November. Mean dripwater δ<sup>18</sup>O values (-11.1 ‰) are lower than the weighted-mean value of precipitation (-8.6 ‰), indicating bias towards cooler period infiltration. Dripwater δ<sup>18</sup>O values have smaller variation but still reflect the seasonal pattern of the precipitation, albeit with a seasonal shift, as the highest δ<sup>18</sup>O values are found in the winter period. The smallest variation in δ<sup>18</sup>O, dripping rate and temperature is found at the deepest station, reflecting better mixed aquifer, and most stable environment.</p><p>This research was funded by the GINOP-2.3.2-15-2016-00009 ‘ICER’ project. We would like to thank Dragan Temovski, Biljana Temovska, Stojan Mitreski, as well as Zlatko Angeleski and Darko Nedanoski from SK Zlatovrv, for their assistance with the cave and precipitation monitoring.</p>