Characterizing Vectors of Marine Invasion

The arrival of an invasive species in a new region is the culmination of a set of relatively discrete steps, including the invader ' s initial association with a transport vector, its tolerance of environmental conditions encountered during transit, and its survival upon entering its new ecosystem (Ruiz and Carlton 2003). In the chapters that follow, a number of issues related to this process are presented. Chapter 6, Hewitt et al., discusses shipping, the most important of the marine invasion pathways. Chapter 7, Johnston et al., discusses the role of propagule pressure, how the quantity and quality of invader propagules determine invasion success. Chapter 8, Miller and Ruiz, follows with a framework for considering the distinct roles of source region, vector, and recipient region in assessing invasion success or failure within species pools. In addition, several vectors are discussed in relation to specific species and locales in the Geographic Perspectives section, which includes some assessments of temporal shifts in trading patterns (e.g. Chap. 24, Hayden et al.; Chap. 28, Fofonoff et al.). The importance of pathways, vectors, and modelling human activities is discussed in previous sections (Chap. 2, Carlton; Chap. 4, Wonham and Lewis)