A 4x2 factorial design will be used, implementing diazepam concentration as a percentage of the median lethal concentration value (LC50) and crayfish opponent type as factors to investigate the impacts diazepam has on agonistic behavior. Adult, injury-free Orconectes rusticus cCrayfish will be set in plastic mesh cages and exposed to diazepam in a flow through exposure stream (0.5 m × 0.25 m × 0.3m, L:W:H) with a water depth of 20 cm for the entire exposure period. All animals will be exposed for a for a 48 hour period. In order to mimic a natural stream, there will be continuousBackground flo flow in the flume will be kept constant , at a velocity of 10 cm/s and the flume will be lined with a 5 cm deep, as well as a sand substrate along the bottom. All cCrayfish, including non-exposed animals will placed in plastic mesh cages (7.62 cm ×5.08 cm × 2.54 cm L:W:H) within the flume. Cages will be used to reduce the variability of exposure due to turbulent dispersal of the toxin toxinamong animals within each treatment. The cages will be set 25 cm downstream of the source of the toxin, equidistant from both endssides of the exposure stream. The same location will be used for all animals across all exposure treatments. Diazepam will be delivered into the exposure stream as a solution via a Mmanostat pump to ensure constant low level exposure. Diazepam at a source concentration of XX12.2 mg/L will be stored within a reservoir and delivered into the stream via xx8 number of plastic Tygon tubes (5.0 mm OD, 4.5 mm ID)xx mm diameter pe tubing. Tube ends will be buried beneath the sand and equally spaced along the width of the plume. This method of introduction will mimic a non-point source groundwater fed type of chemical spill.4 and series of tubing configured to simulate a nonpoint source form of pollution. Diazepam will be introduced at the start of and periodicallyperiodically in 8 hour intervals throughout throughout the exposure trials. Additionally, flow velocity will be held constant during all trials. Both before and after the exposure period, all crayfish will undergo a behavioral assay. The assay will consist of agonistic interactions between two male crayfish. The agonistic assay will follow establish procedures from our lab (cite).3 Basically, fighting two crayfish will be placed within in a fight arena for a 15 minute acclimation period followed by a 15 30 minute period in which they will be allowed to interact. All fights will be video recorded for subsequent blind analysis. Crayfish from each treatment will be randomly paired with either another exposed or a non-exposed opponent. Fights between two non-exposed crayfish will serve as a control for comparison. Control fights? Two non-exposed kept in cages? Contest start time, level of interaction intensity, rate of escalation and contest stop time within the 15 30 minute trials will be recorded. From these measurements, time spent in escalated vs. non-escalated behaviors, time spent at each intensity level, and total duration of interactions will be calculated. The number of tail flips and tail flip speed will also recorded, along with tail flip angle and direction. Regression analyses will be run to evaluate any significant changes in behavior due to physiological impairment. A two way ANOVA will be used for statistical analysis.