Bottom-Up Control of the Groundwater Microbial Food-Web in an Alpine Aquifer

• DOI: 10.3389/fevo.2022.854228
• Publication Date: 2022-05-27T07:18:01Z
• Authors: Clemens Karwautz; Yuxiang Zhou; Marie-Emanuelle K...; Markus G. Weinbauer; Christian Griebler
• Keywords: Microbial food web; Biogeochemical Cycle; Microbial loop; Carbon fibers

Groundwater ecosystems are typically poor in organic carbon and productivity sustaining a low standing stock of microbial biomass. In consequence, food webs oligotrophic groundwater hypothesized to be bottom-up controlled. To date, quantitative information on communities, web interactions, flow is relatively lacking comparison that surface waters. Studying shallow, porous alpine aquifer we collected data the numbers prokaryotes, virus-like particles heterotrophic nanoflagellates (HNFs), concentration dissolved (DOC) assimilable (AOC), bacterial production (BCP), physical-chemical conditions for 1 year hydrological cycle. The potential effects protozoan grazing viral lysis onto prokaryotic biomass was tested. Flow through estimated based from literature. abundance prokaryotes with 6.1 ± 6.9 × 10 4 cells mL –1 , seasonally influenced by dynamics, higher densities coinciding lower table. Overall, variability cell moderate, so it HNFs (179 103 ) (9.6 5.7 5 VLPs ). virus prokaryote HNF ratios ranged between 2–230 33–2,084, respectively. We found no evidence control biomass, being First estimations point at use efficiencies 0.2–4.2% production, consumed recycled phages minor importance. This first analysis strongly hints ecosystems. However, direct measurement phage mediated rates urgently needed deepen our mechanistic understanding. effect diversity population dynamics still needs addressed.