Sophie Hammond

Title: Effects of the tire chemical derivative, 6PPDQ, on olfactory-mediated behaviors in coho salmon

Abstract:

6PPD (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) is a chemical widely used as anantidegradant in vehicle tires. 6PPD reacts with ozone in the air and produces 6PPD-Quinone(6PPDQ), a chemical that has been classified by the U.S. Environmental Protection Agency asvery highly toxic to aquatic organisms along with adverse implications to terrestrial ecosystemsand human health. However, the potential sub-lethal, toxicological effects of 6PPDQ onolfactory-mediated behaviors in fish have yet to be explored. This study examined how 6PPDQexposure affects the olfactory system of coho salmon (Oncorhynchus kisutch) through analysisof avoidance behavior to L-serine or a conspecific alarm substance. Juvenile coho salmon wereexposed to 50 ng/L of 6PPDQ for 18 hours or 200 ng/L of 6PPDQ for 3 hours proceedingY-maze testing, and behaviors were recorded and analyzed for 10 minutes in which fish couldswim in the arm delivering the alarm substance (“scented arm”) or DI water (“unscented arm”).Control fish were found to avoid the scented arm to a statistically significant degree. Statisticalanalyses indicated that although control salmon showed avoidance of the scented arm, avoidancein 6PPDQ-exposed coho salmon did not differ significantly from the controls (p>0.5). We notedthat exposed salmon did trend towards less avoidance compared to controls in several of thetrials, but further testing is needed to confirm observed trends. Our results provide someevidence of potential inhibitory effects of 6PPDQ on olfactory systems, which could haveimplications on foraging, migration, and predator-avoidance of coho salmon exposed toenvironmentally-relevant 6PPDQ concentrations.