Towards an integrated understanding of how micro scale processes shape groundwater ecosystem functions

Non‐random processes determine the colonization of groundwater sediments by microbial communities in a pristine porous aquifer

“…However, this framework was conceptualized for biofilms in resourcerich, high-productivity environments like activated sludge, wetlands and lakes (Jackson, 2003). Although we cannot exclude that alpha diversity may have increased again with a prolonged incubation time, we may argue that diverse, specialized niches that develop in mature, spatially heterogeneous biofilms might not form to such an extent in the small, patchily distributed microcolonies that typically colonize groundwater sediments (Schmidt et al, 2017). Hence, the total niche space in such microcolonies may be smaller compared with mature biofilms in other environments, similar to what Graham and colleagues (2016b) have proposed for sediments in the hyporheic zone.…”

“…Compared with the hyporheic zone, pristine groundwater environments (in the absence of surface water impacts) are more stable and only experience little environmental changes (Griebler and Lueders, ), which may promote the effect of stochastic processes on community assembly compared with more dynamic environments (Ofiţeru et al ., ; Stegen et al ., ; Wang et al ., ; Zhou et al ., ). Moreover, in contrast to the typically studied biofilms in other environments like surface waters, which form dense, spatially coherent, heterogeneous structures that can reach a thickness in the range of several 100 micrometres (Battin et al ., ), sediment‐attached microbial communities in groundwater aquifers occur as small, patchily distributed microcolonies that consist of only a few cells (Schmidt et al ., ), which may be hypothesized to be more prone to stochastic effects than their biofilm counterparts in other environments.…”

Elucidating the impact of micro-scale heterogeneous bacterial distribution on biodegradation

“…Microbial degradation of organic compounds in groundwater is one of the most important processes controlling the fate of chemicals in the subsurface. In particular, natural attenuation and contaminant remediation commonly rely on this microbial ecosystem service, which emphasizes its relevance for environmental quality and water resources management [1], [2]. It is thus important to know where exactly, and under which circumstances, microbial degradation occurs, and how it can be promoted most effectively.…”

Stygofaunal community trends along varied rainfall conditions: Deciphering ecological niche dynamics of a shallow calcrete in Western Australia

“…Stygofaunal activities such as grazing, burrowing or bioturbating help maintain the hydraulic connectivity between aquifers and surface environments (Murray, Zeppel, Hose, & Eamus, 2008). Stygobionts also interact with microbes, vital actors in shaping groundwater biogeochemical cycling of nutrients , and their consumption and excretion of organic matter regulates the proliferation of microbial biofilms (Mermillod-Blondin & Rosenberg 2006;Schmidt, Cuthbert, & Schwientek, 2017). As a result, groundwater functional integrity is dependent on the health of its stygofaunal community assemblages (Boulton, Fenwick, Hancock, & Harvey, 2008).…”

“…On the other, the understanding of the role of biotic interactions still remains poor in many ecosystems (Soberón & Nakamura, 2009). These obstacles grow exponentially when groundwater environments are considered, due to the poor accessibility of these systems (Halse et al, 2014), and the sparse knowledge of stygofaunal population dynamics (Guzik et al, 2011) and biotic interactions between stygofauna and microbial communities (Schmidt et a., 2017). As a result, studies of ecological niches in groundwater environments are scant, with the majority being surveys at a regional scale carried out in Europe (Dole-Olivier et al, 2009;Galassi, Stoch, Fiasca, Di Lorenzo, & Gattone, 2009;Martin et al, 2009).…”