Chemoreception in invasive rusty crayfish (Orconectes rusticus): Learning and adaptation in aquatic ecosystems of Northwestern Ontario

Crayfish utilize chemosensory cues, in addition to other sensory inputs, to mediate a variety of fundamental life processes. Exotic species, like the rusty crayfish (Orconectes rusticus), are known to employ a broader range of chemosensory stimuli owing to their superior adaptability and behavioural plasticity relative to native crayfish species. The ability to respond rapidly to changing biotic and abiotic conditions contributes to the successful establishment of many introduced species in newly adopted ecosystems. I report two behavioural studies designed to measure chemically mediated associative learning, and environment-specific chemical cue utilization, in rusty crayfish. I found that rusty crayfish could quickly and easily form a learned attraction to a walleye (Sander vitreus) egg cue when paired with a food stimulus using a single, two-hour exposure. I also found that rusty crayfish from two ecologically distinct habitats responded differently to sympatric v. allopatric conspecific injury cues. Specifically, both populations tested were attracted to injury cues from a lake where crayfish were likely to cannibalize with higher frequency, but showed no response to the same cue from the other study lake. My results help describe how aquatic invasive species use chemical information in their environment to facilitate adaptive responses and survival in new and unfamiliar ecosystems. Observations are discussed in the context of relevant literature and theory.