Baltimore Ecosystem Study Institute of Ecosystem Studies

2014 BES Annual Meeting Presentation and Poster Abstracts


Kelly, John
Co-Authors: Emma Rosi-Marshall and Lee Blaney

Abstract: Benthic microbial communities are essential components of stream ecosystems due to their contributions to nutrient cycling and primary production. Pharmaceuticals, including antibiotics, are increasingly detected in surface waters throughout the world as a result of human activities, and these contaminants have the potential to impact microbial communities within these habitats. We have explored the relationship between pharmaceutical exposure and activity and composition of benthic bacterial communities at multiple sites within the Baltimore Ecosystem Study (BES) using several approaches. A field survey demonstrated that streams within BES receiving varied levels of anthropogenic inputs had significant differences in concentrations of a range of pharmaceuticals within the water column. These sites also had significant differences in the diversity and composition of benthic bacterial communities as revealed by next-generation sequencing analysis, with the most heavily impacted site showing significantly higher relative abundance of bacteria capable of metabolizing aromatic compounds. We also used in-situ contaminant exposure substrates to examine the influence of the antibiotic ciprofloxacin on the development of stream biofilms along a range of sites within BES. In the most urban stream cipro-exposure substrates supported bacterial biofilms with dramatically different taxonomic composition but equivalent function (respiration) as compared to control substrates. In contrast, at the least urban site cipro-exposure substrates supported communities with less-altered taxonomic composition but significantly decreased function as compared to control substrates. These data suggest that the occurrence of pharmaceuticals within BES streams may significantly alter the composition and activity of benthic bacterial communities as well as their sensitivity to pollution.