Express yourself: Individuals with bold personalities exhibit increased behavioral sensitivity to dynamic herbicide...

The majority of ecotoxicological studies performed measure average responses from individuals which do not account for the inter-individual variation in the responses of animals to environmental stimuli (i.e. the personality of individuals). Thus, these designs assume that all individuals will respond to contaminant exposure in a similar manner. Additionally, commonly used constant, static exposure regime designs neglect to recognize the spatial and temporal variation in contaminant plume structures as they move throughout fluid environments. The purpose of this study was to understand the effects of the structural characteristics (concentration, duration, and frequency) of temporally and spatially variant contaminant plumes on the personality of individuals. This experimental design aimed to construct a sensitive definition of exposure by connecting sublethal effects of toxicants and realistic exposure regimes. This study used escape response of Faxonius virilis crayfish from the predatory odor of Micropterus salmoides prior to and following exposure to the herbicide, atrazine. Atrazine was delivered in pulses to flow through exposure arenas for a total of 47 h while manipulating the concentration, frequency, and duration of the herbicide pulses. Escape response of crayfish prior to exposure was used to categorize animals into bold and shy personalities. The change in escape response was analyzed and resulted in a personality-dependent behavioral sensitivity to the polluted environment. Individuals classified as bold showed increased change in response to predatory odor relative to shy animals. Bold animals exhibited decreased activity after exposure where no change was presented in shy individuals. Shifts in individual behavior have impacts on the population level (e.g. resource acquisition/value; interspecies competition) and the ecosystem level (e.g. food web dynamics; trophic cascades). This study demonstrates the importance of sensitive measures in ecological risk assessment methods.