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Federica Papi, 2016, doctoral dissertation

Abstract: The karst ecosystem shows heterogeneity and variability of geology, hydrology, morphology and ecology in space and time. Chemical composition of water in karst plays a crucial role not only in dissolution of karst rocks and deposition but also in ecological processes. The heterogeneous nature of karst aquifers leads to difficulties in predicting groundwater flow and contaminant transport direction and travel times. For its position at the top of karst, epikarst represents the interface between surface and underground. Epikarst ecology, biodiversity and fauna have rarely been systematically studied. The typical absence of enterable passages makes necessary an indirect approach. In this research, epikarst biodiversity in relation to environmental conditions was studied in seven Alpine and Pre-Alpine caves, located at different altitudes, in Slovenia and in Italy: Snežna jama na planini Arto (1556 m a.s.l.), Jama pod Babjim zobom (860 m a.s.l.), Zadlaška jama (300 m a.s.l.) and Pološka jama (500 m a.s.l.), in Slovenian Alps and Pre-alps, and Grotta A del Ponte di Veja (600 m a.s.l.), Covolo della Croce (875 m a.s.l.) and Grotta di Roverè Mille (1005 m a.s.l.) in Lessinian Massif. In these caves, percolating water was monthly monitored for fauna in the period of one year. Temperature, discharge, conductivity and pH were measured at the same time, and water samples for the laboratory analyses of total hardness, concentrations of various ions (calcium, chlorine, nitrate, sulphate and phosphate) and dissolved organic carbon were taken. 66 aquatic and terrestrial, mostly hypogean, species were found. Aquatic fauna was dominant in all caves, with the exception of Covolo della Croce. Caves located at higher elevations harbour less diverse communities. No animals were found when discharge was very low and in correspondence of moonmilk formations. The most abundant and diverse group was Copepoda, with thirteen different species and 776 individuals at different maturity stadia, totally representing 61% of the community (between two and three copepod species per cave in Slovenia and between one and six per cave in Italy). The 62% of copepod species were stygobionts. Some copepod species (e.g. Speocyclops infernus) have wide ecological tolerance to environmental variables, other have more restricted tolerances (e.g. Lessinocamptus insoletus). With regard of copepods, there was a good agreement between the number of observed species and the total number of predicted species, confirming that the sampling method was appropriate and sampling complete. Correlations between the copepod community structure and measured parameters, obtained with Pearson correlation coefficient and principal component analysis (PCA) show different patterns. Presence of copepods was positively correlated with conductivity and dissolved organic carbon in Grotta di Roverè Mille, and with carbonate and nitrate in Pološka jama. In other caves not so high correlations were found between copepod species and measured parameters and between pairs of species. Investigations of the Alpine and Pre-alpine epikarst fauna can help to understand better the ecology of the epikarst fauna and its roles within the large range of different shallow subterranean habitats.
Found in: ključnih besedah
Keywords: Epikarst, Alpine and Pre-Alpine caves, percolating water, speleobiology, fauna.
Published: 31.08.2016; Views: 2798; Downloads: 203
.pdf Fulltext (2,00 MB)

Ecological evaluation of aquatic and terrestrial subterranean fauna in a karst cave
Peter Kozel, 2018, doctoral dissertation

Abstract: Studies on environmental parameters−subterranean fauna relationship and spatial and temporal patterns of subterranean fauna have dealt with either aquatic or terrestrial faunas. So far, no simultaneous ecological evaluation of aquatic and terrestrial faunas has been performed. To address this issue, we conducted a pilot study dealing in parallel with these two faunas in the cave Zguba jama near Postojna, Slovenia, applying monthly sampling over one year. Aquatic fauna was sampled from permanent water drips, and terrestrial fauna by visual inspection and advanced baited pitfall trapping, along with recording the main abiotic parameters. In percolating water, we recorded aquatic fauna, Copepoda being the dominant taxon, and species-rich troglobiotic fauna, which most probably coexist with aquatic species in a semi-aquatic epikarst environment. Analyses revealed that temperature, distance from the entrance and ceiling thickness are the most important parameters that influence the presence of stygobionts; higher values of these parameters result in a higher probability of the presence of stygobionts in percolation water. The recorded spatial distribution of stygobionts varied distinctly among the sampling sites. This indicates that fauna in sampled drips originated from aquatic or semiaquatic epikarst microhabitats, being completely or nearly completely separated from each other, and probably varied according to environmental characteristics. The temporal pattern of the stygobiotic fauna dynamics presumably occurred because of variable water flow rates and the specific physical and chemical characteristics of the water. The abundance of troglobionts showed distinctive spatial distribution pattern over the seasons. In spring and summer, the highest abundances and the highest probability of presence were found near the entrance. In autumn and winter, unfavorable conditions in the entrance zone most likely triggered the migration of troglobionts towards the climatically more stable deep cave zone, and from the cave into the adjacent fissure network. The highest abundance of troglobionts was found at 7–9°C and relatively high ground substrate moisture. Additionally, we found a higher probability of the presence of troglobionts in cave sections with a larger passage cross-section size, which is probably due to the greater variability of microhabitat types in spacious cave sections. In addition, the higher probability of presence relates to higher substrate pH. One potential explanation for this could be that the specific microorganism communities present in such conditions support the nutritional needs of troglobionts. Most troglobiotic species preferred the deep cave zone where the highest species richness and diversity were also observed. Species richness, abundance and diversity of troglophiles and trogloxenes were highest in the entrance zone and showed relatively similar patterns within the cave. However, troglophiles were more abundant in the transition zone and the initial part of the inner zone. The temporal pattern of trogloxenes and presumably of most troglophiles occurred because of migration between the surface and the cave. The probability of the presence of trogloxenes was highest in the entrance zone and in winter, owing to massive overwintering in the cave. A modified technique of pitfall trapping by placing traps in two parallel sets, a ground and an upper one along the cave, resulted in recording greater species diversity in comparison with the traditional method, i.e., ground pitfall trapping alone. It turned out that such sampling contributes at the same time to both more effective and less invasive inventory of subterranean fauna. The dynamics of relative abundance and species richness of stygobionts and troglobionts within the cave showed partly comparable annual patterns. Nevertheless, our findings point toward the need for a long-term and more detailed study in future to address this question properly.
Found in: ključnih besedah
Summary of found: ...coexist with aquatic species in a semi-aquatic epikarst environment. Analyses revealed that temperature, distance from...
Keywords: biological inventories, epikarst fauna, faunal dynamics, microhabitats, stygobionts, troglobionts, troglophiles, trogloxenes, Zguba jama
Published: 16.02.2018; Views: 1645; Downloads: 202
.pdf Fulltext (5,25 MB)

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