Opening the black box of spring water microbiology from alpine karst aquifers to support proactive drinking water resource management

Abstract

Over the past 15 years, pioneering interdisciplinary research has been performed on the microbiology of hydrogeologically well‐defined alpine karst springs located in the Northern Calcareous Alps (NCA) of Austria. This article gives an overview on these activities and links them to other relevant research. Results from the NCA springs and comparable sites revealed that spring water harbors abundant natural microbial communities even in aquifers with high water residence times and the absence of immediate surface influence. Apparently, hydrogeology has a strong impact on the concentration and size of the observed microbes, and total cell counts (TCC) were suggested as a useful means for spring type classification. Measurement of microbial activities at the NCA springs revealed extremely low microbial growth rates in the base flow component of the studied spring waters and indicated the importance of biofilm‐associated microbial activities in sediments and on rock surfaces. Based on genetic analysis, the autochthonous microbial endokarst community (AMEC) versus transient microbial endokarst community (TMEC) concept was proposed for the NCA springs, and further details within this overview article are given to prompt its future evaluation. In this regard, it is well known that during high‐discharge situations, surface‐associated microbes and nutrients such as from soil habitats or human settlements—potentially containing fecal‐associated pathogens as the most critical water‐quality hazard—may be rapidly flushed into vulnerable karst aquifers. In this context, a framework for the comprehensive analysis of microbial pollution has been proposed for the NCA springs to support the sustainable management of drinking water safety in accordance with recent World Health Organization guidelines. Near‐real‐time online water quality monitoring, microbial source tracking (MST) and MST‐guided quantitative microbial‐risk assessment (QMRA) are examples of the proposed analytical tools. In this context, this overview article also provides a short introduction to recently emerging methodologies in microbiological diagnostics to support reading for the practitioner. Finally, the article highlights future research and development needs.This article is categorized under: Engineering Water > Water, Health, and SanitationScience of Water > Water ExtremesWater and Life > Nature of Freshwater Ecosystems

In‐depth prospection of Avène Thermal Spring Water reveals an uncommon and stable microbial community

“…In the last decade, several studies using molecular surveys have described the microbial diversity of karst systems 14 . Surprisingly, most of the phylotypes affiliated to Nitrospirae in the core community were not closely related (identity <97%) to 16S rRNA gene sequences reported in this and other studies and likely represent previously undescribed bacterial species.…”

“…Therefore, to survive in these extreme habitats they may have developed specific functions and adopted a chemolithotrophic lifestyle using inorganic resources to provide them with the energy and nutrients necessary for survival 13 . The microbial composition of groundwaters and their stability with time are good indicators of ecosystem confinement and of the good quality of resource management 14 . Some studies have shown a direct impact on groundwater microbial communities with the modification of discharge conditions, or long‐term diversity changes after drilling 15,16 .…”

Spatial and temporal dynamics of bacterioplankton community composition in a subtropical dammed karst river of southwestern China

“…Karst rivers are commonly regulated by damming, yet the influence of these dams on changes in hydrological series of water discharge is negative or positive (Miao, Ni, Borthwick, & Yang, ). Although the diversity and dynamics of microbes in karst springs (Farnleitner et al., ; Ohad et al., ; Savio et al., ), unsaturated and saturated karst aquifers (Cooper et al., ; Gray & Engel, ; Johnson et al., ; Lin et al., ; Menning et al., ), and water pools (Shabarova et al., ) as well as in groundwater‐surface water exchange systems (Li, Song, et al., ) have been discussed in the literature, much less attention has been paid to the structure of bacterioplankton communities in dammed karst rivers. In addition, previous studies on bacterioplankton communities in the canyon‐shaped and meso‐eutrophic Rimov Reservoir (Simek et al., ), the dammed Ebro River (Ruiz‐González, Proia, Ferrera, Gasol, & Sabater, ), and the rivers controlled by the Three Gorges Dam (Huang et al., ; Li, Lu, et al., ; Yan et al., ) did not include the seasonal variation or depth dynamics in bacterioplankton.…”

Using genetic microbial source tracking (MST) markers to identify fecal pollution sources in spring water of a large alpine karst catchment

“…Identifying the sources of fecal pollution in the water resource, as originally determined by standardized SFIB assays, can be an essential part for system assessment (i.e. water safety planning, sanitation safety planning), target-oriented catchment management, and finally, can serve also as a very important starting point for hazard-and risk assessment and MST-guided QMRA (Savio et al, 2018).…”

“…Thus, water resources from (alpine) karst aquifers require sustainable protection from fecal pollution within the catchment and proper microbial quality management at and after the spring (e.g. optimized spring water abstraction, adjusted treatment and disinfection measures) if used for drinking water supply (Farnleitner et al, 2018;Savio et al, 2018).…”