Spatiotemporal dynamics of invasive crayfish ecology

In order to build a new understanding of the spatial temporal invasion and impact dynamics of a
data-deficient invasive crayfish Pontastacus leptodactylus, this thesis combines systematic
review techniques, fieldwork, and experimental methods. Throughout the thesis, the role of
individual behavioural and morphological variation is integrated into the approaches, to allow
new insights into how these factors shape establishment, range expansion, and ecological
impact. In Chapter 2, literature was reviewed and synthesised which revealed a consistent
directional trend in morphological traits with behaviour being more variable along the invasion
gradient. Chapter 3 demonstrates, through the use of biomonitoring, that early-stage invasions
have little effect on macroinvertebrate community suggesting little impact at low crayfish
densities. Chapter 4 shows morphological traits do vary along the invasion gradient, and whilst
this couldn’t be linked to behavioural traits, behavioural variation between individuals did exist.
Together, these approaches showed that invasion dispersal and establishment can be determined
by morphology and behaviour which can be used for targeted management as invasive species
begin to spread.