Preprints
https://doi.org/10.5194/egusphere-2024-49
https://doi.org/10.5194/egusphere-2024-49
27 Feb 2024
 | 27 Feb 2024

Effects of surface water interactions with karst groundwater on microbial biomass, metabolism, and production

Adrian Barry-Sosa, Madison K. Flint, Justin C. Ellena, Jonathan B. Martin, and Brent C. Christner

Abstract. Unearthing the effects of surface water and groundwater interactions on subsurface biogeochemical reactions is crucial for developing a more mechanistic understanding of carbon and energy flow in aquifer ecosystems. To examine physiological characteristics across groundwater microbial communities that experience varying degrees of interaction with surface waters, we investigated ten springs and a river sink and rise system in North Central Florida that discharge from 10 and/or mix with the karstic Upper Floridan Aquifer (UFA). Groundwater with longer residence times in the aquifer had lower concentrations of dissolved oxygen, dissolved and particulate organic carbon, and microbial biomass, as well as the lowest rates of respiration (0.102 to 0.189 mg O2 L-1 d-1) and heterotrophic production (198 to 576 μg C L-1 d-1). Despite these features, oligotrophic UFA groundwater (< 0.5 mg C L-1) contained bioavailable organic matter that supported doubling times (14 to 62 h) and cell specific production rates (0.0485 to 0.261 pmol C cell-1 h-1) comparable to those 15 observed for surface waters (17 to 20 h; 0.105 to 0.124 pmol C cell-1 h-1). The relatively high specific rates of dissimilatory and assimilatory metabolism indicate a subsurface source of labile carbon to the groundwater (e.g., secondary production and/or chemoautotrophy). Our results link variations in UFA hydrobiogeochemistry to the physiology of its groundwater communities, providing a basis to develop new hypotheses related to microbial carbon cycling, trophic hierarchy, and processes generating bioavailable organic matter in karstic aquifer ecosystems.

Adrian Barry-Sosa, Madison K. Flint, Justin C. Ellena, Jonathan B. Martin, and Brent C. Christner

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-49', Anonymous Referee #1, 12 Mar 2024
    • RC2: 'Reply on RC1', Xiaogang Chen, 09 Apr 2024
Adrian Barry-Sosa, Madison K. Flint, Justin C. Ellena, Jonathan B. Martin, and Brent C. Christner

Data sets

Water Chemistry, Nitrogen and CDOM/FDOM Data from the Santa Fe River Watershed, North-Central Florida Madison K. Flint http://www.hydroshare.org/resource/a876020b85d6413f8486c57dc0b0e3bf

Adrian Barry-Sosa, Madison K. Flint, Justin C. Ellena, Jonathan B. Martin, and Brent C. Christner

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Short summary
This study examined springs in North Central Florida focusing on how interactions between the surface and subsurface affected the properties of groundwater microbes. We found that microbes reproduced at rates that greatly exceed those documented for any other aquifer. Although the groundwater discharged to spring runs contains low concentrations of nutrients, our results indicate that microbes have access to sources of energy and produce new cells at rates similar to surface water bodies.