A 3 x 2 factorial design will be used, implementing length of exposure period and aspirin concentration as factors. Adult, injury-free Orconectes virilis crayfish will be exposed to aspirin in a flow through exposure stream (1.0 m × 0.5 m × 0.3m, L: W: H) with a water depth of 15 cm for the entire exposure period. Animals will be exposed for a 7 day period to one of two environmentally relevant concentrations (0.5 µg/L, 1.5 µg/L) of aspirin.8, 11 Background flow in the flume will be kept constant at a velocity of 2.5 cm/s and the flume will be lined with a 3 cm deep gravel substrate. All crayfish will be tethered within the flume to reduce variability of exposure due to turbulent dispersal of the toxin. The crayfish will be set 50 cm downstream of the source of the toxin, equidistant from both sides of the exposure stream. The same location will be used for all animals across all exposure treatments. Acetylsalicylic acid (ASA) will be delivered into the exposure stream as a solution via a gravity feed to ensure constant low level exposure. ASA at a source concentration of 0.0045 g/L will be stored within a reservoir and delivered into the stream via a plastic Tygon tube (5.0 mm OD, 4.5 mm ID). Tube ends will be buried beneath the gravel at the most upstream end of the plume. This method of introduction will mimic a non-point source groundwater fed type of chemical spill.4 ASA will be introduced at the start of the trial and run continuously until the end. Additionally, flow velocity will be held constant during all trials. All crayfish will undergo a behavioral assay daily. The assay will consist of placing a single crayfish into a Y-maze for 15 minute acclimation period. Afterward, a food source will be located in the end of one arm. The crayfish will then be allowed to explore the Y-maze for 15 minutes. All Y-maze trials will be video recorded for subsequent blind analysis. The amount of time spent in each arm of the Y-maze and amount of time spent eating will be recorded. The mass of food eaten will also be recorded. From these measurements, percentage of time spent foraging versus exploring will be calculated. A MANOVA will be run for statistical analysis. Additionally, all crayfish will be sacrificed by freezing in order to assess if aspirin accumulates in their tissue. Samples of the gill tissue, abdominal muscle, and hepatopancreas will be taken from each crayfish and analyzed for the amount of aspirin present compared to unexposed crayfish. Analysis will be performed via mass spectrometry of tissues samples.