Baltimore Ecosystem Study Institute of Ecosystem Studies

2015 BES Annual Meeting Presentation and Poster Abstracts

Effects of urban chemical stressors on stream biofilms
Lee, Sylvia
Co-Authors: Emma Rosi-Marshall, Alexander J. Reisinger, John Kelly, Miguel Rojas, Sujay Kaushal

Abstract: Urban streams receiving wastewater contain contaminants including nutrients, road salt, and pharmaceuticals. Contaminants may have complex, sublethal consequences on ecosystem structure and function. Using an artificial stream experiment, we tested the effects of nutrients, road salt, and a cocktail of 8 pharmaceuticals on stream biofilm communities. We used environmentally relevant concentrations of contaminants detected at Gwynns Run, one of the most urban stream sites of the long- term monitoring study area of the BES LTER. Nutrients enhanced gross primary production (GPP) and community respiration (CR), while salt suppressed GPP and CR. However, the High treatment streams, which received a combination of high nutrient and salt concentrations, selected for a highly productive (and presumably, salt tolerant) community. Adding the drug cocktails to the streams resulted in functional suppression of the water column microbial community, except in the High streams. This result may be in part because of more tolerant algae and antibiotic resistant bacteria in the water column of the High streams. Our study shows that even urban streams can have high function, especially because of high microbial activity. We plan to continue research on whether tolerant communities can maintain function in urban stream ecosystems, which challenges the current paradigms regarding diversity and ecosystem function.