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Consequences of tetracycline exposure to stream periphyton in an experimental mesocosm study
Citation:
QUINLAN, E. L., C. T. NIETCH, J. M. LAZORCHAK, AND R. A. GRIFFITHS. Consequences of tetracycline exposure to stream periphyton in an experimental mesocosm study. Presented at SETAC, Tampa, FL, November 16 - 20, 2008.
Impact/Purpose:
Molecular biological approaches allow for the development of the first diagnostic indicators which (1) can be measured immediately (within hours) after exposure, (2) can diagnose exposure to stressors such as estrogen mimics in an integrated fashion even within mixtures and (3) can measure bioavailability to extremely low levels of stressors. The technology being developed has the potential to be noninvasive to the sample organism and field methods have been piloted which will allow for regional characterization of stressors never before measured in the field. The technology used in these molecular analyses is readily transferable to other Regions, Federal and state agencies, and grass roots (regional/neighborhood) environmental groups.
Description:
A significant amount of ingested, injected, and applied antibiotics are not metabolized but are excreted; entering the environment via point and non-point sources. Tetracycline and its derivatives are among the most extensively used human and animal antibiotics. We examined the consequences of tetracycline exposure within a stream periphyton community across a logarithmically dosed-series of experimental mesocosms receiving water from the East Fork of the Little Miami River in Milford, OH. Target in-stream tetracycline exposures were based upon previously reported concentrations in streams and rivers throughout the United States (<1 – 100 µg L-1), and included a control. Our results indicated significant changes in the periphyton community with in-stream tetracycline concentration as low as 0.5 µg L-1, and effects magnified in proportion with increased dosing rate, including decreases in abundance of bacteria and algae, decreased bacteria productivity, and compositional shifts in the algal community. An increase in bacteria resistance to tetracycline was also observed at all doses. Recovery of the periphyton community ranged from days to several weeks depending on the organism and dosing concentration.