Biological invasions in aquatic systems: The economic problem

Biological invasions are recognised to be a problem of growing severity. Encompassing new human pathogens, weeds or pests in terrestrial systems, and dominant alien species in freshwater or marine aquatic systems, they are the second most important proximate cause of biodiversity loss worldwide. They also impose significant costs in terms of forgone output or costs of control in every major system except for pelagic marine systems. Coastal, coral reef, and estuarine systems are among the most vulnerable. This paper considers the economics of the problem in the context of a simple generic model of invasions and invasion control. It shows that the dynamical characteristics of the problem are driven not only by population dynamics but by the costs and benefits of 'native' and alien 'invasive' species.