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

摘要

Crayfish utilize chemosensory cues, in addition to other sensory inputs, to mediate avariety of fundamental life processes. Exotic species, like the rusty crayfish (Orconectesrusticus), are known to employ a broader range of chemosensory stimuli owing to theirsuperior adaptability and behavioural plasticity relative to native crayfish species. Theability to respond rapidly to changing biotic and abiotic conditions contributes to thesuccessful establishment of many introduced species in newly adopted ecosystems. Ireport two behavioural studies designed to measure chemically mediated associativelearning, and environment-specific chemical cue utilization, in rusty crayfish. I found thatrusty crayfish could quickly and easily form a learned attraction to a walleye (Sandervitreus) egg cue when paired with a food stimulus using a single, two-hour exposure. Ialso found that rusty crayfish from two ecologically distinct habitats respondeddifferently to sympatric v. allopatric conspecifc injury cues. Specifically, bothpopulations tested were attracted to injury cues from a lake where crayfish were likely tocannibalize with higher frequency, but showed no response to the same cue from theother study lake. My results help describe how aquatic invasive species use chemicalinformation in their environment to facilitate adaptive responses and survival in new andunfamiliar ecosystems. Observations are discussed in the context of relevant literatureand theory.