Multitrophic Effects of Invasions in Marine and Estuarine Systems

Abstract

Invasions in marine and estuarine systems are no longer news to the coastal ecolo-gists who have been documenting the numerous introduced species appearing in coastal systems over the last several decades. We are now faced with a dramatically altered benthic landscape that includes a diversity of both native and non-native species. As ecologists, we seek to understand not only how these altered systems function, but predict future changes despite the fact that the species assemblage is continually shifting. In a background of seemingly constant change, one of the top priorities for ecologists is to understand why some introductions result in large changes to native communities, changes that alter ecosystem function or services and that have large impacts on the natural and/or human sphere (Parker et al. 1999; Ruiz et al. 1999; Grosholz et al. 2000). We wish to understand what the consequences of invasions are and how we can learn from these to predict future impacts. Why is it that some invasions, perhaps not many, cause dramatic changes, whereas others appear to result in comparatively little change?