Movement dynamics and resource selection in a lake crayfish population

Background/Question/Methods

One of the fundamental questions in population ecology postulates: how does the movement of individuals within a population relate to resource selection. Individuals can undergo resource selection to occupy different subniches within an ecosystem through the underlying process of dispersal or movement. However, there is still much to be gleaned about how the movement of organisms ties into resource selection processes, and about the variation in this resource selection among individuals. Lake crayfish represent a good system to study this question because of substantial demonstrated movement across habitats and distinct variation in life-history traits among individuals. We investigated how sex, reproductive forms, and size, relate to movement and resource selection variation within a native crayfish Cambarus bartonii population in Ontario. We also analyzed habitat selection. During two successive sampling periods spread over multiple days in a 10 ha lake in Ontario, Canada, we used mark-recapture methodology to investigate the movement of over 5,000 crayfish individuals across 600 traps.

Results/Conclusions

Our results suggest that crayfish movement is related to the variation in life-history traits. There was a positive correlation between individual size and net movement over time. Females of the population showed the greatest movement, followed by reproductively inactive males, with reproductively active males showing the smallest movements among groups. Crayfish sampling frequency showed marked variation among different habitat types. These results provide evidence of habitat selection and suggest distinct correlations between movement and life history. This has important implications for understanding population dynamics and resource selection for populations spanning species and ecosystems.