Microbial Community Response To Contaminants Of Emerging Concern In The Kāne‘ohe Watershed

Abstract

Coastal pollution is an important concern as it affects local ecosystems, public health, and aquifer reserves. Anthropogenic contaminants travel through both surface runoff and groundwater movement in streams and can have a continuous presence through consistent use. A survey on groundwater discharge flux within the Kāne‘ohe Watershed (O‘ahu, Hawaiʻi) found that groundwater volumetric contributions equaled surface runoff, supporting the hypothesis that groundwater discharge contributes significantly to water quality in streams and the coastal ocean. This influence includes submarine groundwater discharge (SGD), which has been recently demonstrated to be a major source of Contaminants of Emerging Concern (CEC) to nearshore environments on O‘ahu. This project aims to observe distributions of CECs found in the Northern Kāne‘ohe watershed - glyphosate, caffeine, and sulfamethoxazole - and how they may interact with microbial community metabolism. I hypothesized that CEC concentration will differ between streams according to onsite sewage disposal system (OSDS) density, CECs will be differentially attenuated along stream reaches in different areas of the watershed, and that water column microbial degradation would differ among upstream, downstream, and estuarine habitats. Specifically, I examined which areas in the stream system may contain naturally occurring microbial taxa able to attenuate the studied CECs and asked what this would mean for microbial processes in the Kahaluʻu and ʻĀhuimanu streams. To test whether the contaminants of interest could be attenuated by natural aquatic microbial communities I added CECs to water samples and measured changes in contaminant concentrations and associated growth responses by the microbe community. These observations will help us understand the prevalence of CECs in this region and whether their concentrations can be attenuated through microbial interactions affecting their residence time.