The Role of Propagule Pressure in Invasion Success

Abstract

One of the core goals of invasion biology is the identification of factors that increase the risk of establishment success of non-native species. Historically, marine invasions have been investigated through observational studies and surveys (Cohen and Carlton 1998; Ruiz et al. 2000). These have guided ecologists towards the processes most relevant to invasion, but researchers are becoming increasingly aware of the limitations of observational studies alone. It is clear that different factors may influence invasion success at different stages of the invasion process (Kolar and Lodge 2001) and a major challenge is to quantify the relative importance of these factors. Understanding the intricacies of invasion dynamics requires a rigorous approach, in which potentially important factors can be controlled, manipulated and tested (Ruiz et al. 2000). Particularly strong calls have been made for the inclusion of propagule pressure or invader supply into our models, experiments and surveys, and this chapter reviews recent progress in elucidating the role of propagule pressure on invasion success in marine ecosystems.