29-10 Microbiological diversity in areas of groundwater seepage and surface water infiltration in Southern Appalachian headwater streams.

Session: Undergraduate Research, Part II (Posters)

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Abstract:

Within the past decade, there has been a myriad of studies analyzing groundwater and surface water interactions. An area that remains understudied is the effect of these interactions on surrounding biota--particularly in headwater streams. This project explores the effects of surface water and groundwater interactions on biodiversity taking place in a Southern Appalachian headwaters region in the Western Carolina Hydrological Research Station, specifically, the Gribble Gap Catchment. The primary objective of this study was to determine whether microbial biodiversity differs between zones of groundwater seepage (gaining reaches) and zones of surface water infiltration (losing reaches) within the Gribble Gap headwaters system. Two streams within the catchment were accessed and divided into multiple reaches, which were classified as gaining or losing based on geomorphic interpretation, temperature monitoring, and infrared thermal imaging. The data collected consists of two rounds of water sampling at the same 7 sites in the Gribble Gap catchment, once during the spring and once during the fall. HOBO temperature probes were deployed during sample collection, capturing at least one week of diurnal temperature cycles at each site. Water samples were collected at bank edges to directly sample water gaining or losing to groundwater; midstream sites were also sampled to gather data on mixed water populations. After water sampling, samples were distributed into Biolog EcoPlates to collect data about the carbon sources being consumed by the microbial communities. The raw data from the EcoPlates was analyzed with principal components analysis (PCA). Using PCA, it was found that the microbial metabolism varied significantly and had consistently the same differences in zones of groundwater seepage compared to the losing stream reaches. All data showed a general grouping of sites that matched stream gaining and losing reaches. The data also showed the mid-stream site was more comparable with losing sites than the gaining sites, likely reflecting the cumulative stream balance. We conclude that the microbiology within the zones of groundwater seepage are unique, while the sites of surface water infiltration are representative of the stream’s microbiology as a whole.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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